[FFmpeg-devel] [PATCH v1 0/4] webp: add support for animated WebP decoding

[FFmpeg-devel] [PATCH v1 0/4] webp: add support for animated WebP decoding

[Thilo Borgmann]

Follow-up to [1], the decoder only.

In [1] we found a hanging sample. In frame-threading, this led to an
infinite wait, damaged frames otherwise. So warn acordingly and do
best-effort in single-thread mode.

Also split into more patches to make reviewing easier.

[1] http://ffmpeg.org/pipermail/ffmpeg-devel/2023-April/308965.html

Josef Zlomek (1):
  libavcodec/webp: add support for animated WebP decoding

Thilo Borgmann (3):
  avcodec/webp: move definitions into header
  avcodec/webp_parser: parse each frame into one packet
  avcodec/webp: make init_canvas_frame static

 Changelog                |   1 +
 libavcodec/codec_desc.c  |   3 +-
 libavcodec/version.h     |   2 +-
 libavcodec/webp.c        | 724 +++++++++++++++++++++++++++++++++++----
 libavcodec/webp.h        |  55 +++
 libavcodec/webp_parser.c | 132 ++++---
 6 files changed, 800 insertions(+), 117 deletions(-)
 create mode 100644 libavcodec/webp.h

-- 
2.37.1 (Apple Git-137.1)

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[FFmpeg-devel] [PATCH v1 1/4] avcodec/webp: move definitions into header

[Thilo Borgmann]

---
 libavcodec/webp.c | 17 +--------------
 libavcodec/webp.h | 55 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 56 insertions(+), 16 deletions(-)
 create mode 100644 libavcodec/webp.h

diff --git a/libavcodec/webp.c b/libavcodec/webp.c
index d35cb66f8d..15152ec8fb 100644
--- a/libavcodec/webp.c
+++ b/libavcodec/webp.c
@@ -52,22 +52,7 @@
 #include "thread.h"
 #include "tiff_common.h"
 #include "vp8.h"
-
-#define VP8X_FLAG_ANIMATION             0x02
-#define VP8X_FLAG_XMP_METADATA          0x04
-#define VP8X_FLAG_EXIF_METADATA         0x08
-#define VP8X_FLAG_ALPHA                 0x10
-#define VP8X_FLAG_ICC                   0x20
-
-#define MAX_PALETTE_SIZE                256
-#define MAX_CACHE_BITS                  11
-#define NUM_CODE_LENGTH_CODES           19
-#define HUFFMAN_CODES_PER_META_CODE     5
-#define NUM_LITERAL_CODES               256
-#define NUM_LENGTH_CODES                24
-#define NUM_DISTANCE_CODES              40
-#define NUM_SHORT_DISTANCES             120
-#define MAX_HUFFMAN_CODE_LENGTH         15
+#include "webp.h"
 
 static const uint16_t alphabet_sizes[HUFFMAN_CODES_PER_META_CODE] = {
     NUM_LITERAL_CODES + NUM_LENGTH_CODES,
diff --git a/libavcodec/webp.h b/libavcodec/webp.h
new file mode 100644
index 0000000000..90baa71182
--- /dev/null
+++ b/libavcodec/webp.h
@@ -0,0 +1,55 @@
+/*
+ * WebP image format definitions
+ * Copyright (c) 2020 Pexeso Inc.
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * WebP image format definitions.
+ */
+
+#ifndef AVCODEC_WEBP_H
+#define AVCODEC_WEBP_H
+
+#define VP8X_FLAG_ANIMATION             0x02
+#define VP8X_FLAG_XMP_METADATA          0x04
+#define VP8X_FLAG_EXIF_METADATA         0x08
+#define VP8X_FLAG_ALPHA                 0x10
+#define VP8X_FLAG_ICC                   0x20
+
+#define ANMF_DISPOSAL_METHOD            0x01
+#define ANMF_DISPOSAL_METHOD_UNCHANGED  0x00
+#define ANMF_DISPOSAL_METHOD_BACKGROUND 0x01
+
+#define ANMF_BLENDING_METHOD            0x02
+#define ANMF_BLENDING_METHOD_ALPHA      0x00
+#define ANMF_BLENDING_METHOD_OVERWRITE  0x02
+
+#define MAX_PALETTE_SIZE                256
+#define MAX_CACHE_BITS                  11
+#define NUM_CODE_LENGTH_CODES           19
+#define HUFFMAN_CODES_PER_META_CODE     5
+#define NUM_LITERAL_CODES               256
+#define NUM_LENGTH_CODES                24
+#define NUM_DISTANCE_CODES              40
+#define NUM_SHORT_DISTANCES             120
+#define MAX_HUFFMAN_CODE_LENGTH         15
+
+
+#endif /* AVCODEC_WEBP_H */
-- 
2.37.1 (Apple Git-137.1)

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Re: [FFmpeg-devel] [PATCH v1 1/4] avcodec/webp: move definitions into header

[James Zern]

On Thu, Jun 8, 2023 at 7:20 AM Thilo Borgmann <thilo.borgmann@mail.de> wrote:
>
> ---
>  libavcodec/webp.c | 17 +--------------
>  libavcodec/webp.h | 55 +++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 56 insertions(+), 16 deletions(-)
>  create mode 100644 libavcodec/webp.h
>

lgtm.
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Re: [FFmpeg-devel] [PATCH v1 1/4] avcodec/webp: move definitions into header

[Andreas Rheinhardt]

Thilo Borgmann:
> ---
>  libavcodec/webp.c | 17 +--------------
>  libavcodec/webp.h | 55 +++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 56 insertions(+), 16 deletions(-)
>  create mode 100644 libavcodec/webp.h
> 
> diff --git a/libavcodec/webp.c b/libavcodec/webp.c
> index d35cb66f8d..15152ec8fb 100644
> --- a/libavcodec/webp.c
> +++ b/libavcodec/webp.c
> @@ -52,22 +52,7 @@
>  #include "thread.h"
>  #include "tiff_common.h"
>  #include "vp8.h"
> -
> -#define VP8X_FLAG_ANIMATION             0x02
> -#define VP8X_FLAG_XMP_METADATA          0x04
> -#define VP8X_FLAG_EXIF_METADATA         0x08
> -#define VP8X_FLAG_ALPHA                 0x10
> -#define VP8X_FLAG_ICC                   0x20
> -
> -#define MAX_PALETTE_SIZE                256
> -#define MAX_CACHE_BITS                  11
> -#define NUM_CODE_LENGTH_CODES           19
> -#define HUFFMAN_CODES_PER_META_CODE     5
> -#define NUM_LITERAL_CODES               256
> -#define NUM_LENGTH_CODES                24
> -#define NUM_DISTANCE_CODES              40
> -#define NUM_SHORT_DISTANCES             120
> -#define MAX_HUFFMAN_CODE_LENGTH         15
> +#include "webp.h"
>  
>  static const uint16_t alphabet_sizes[HUFFMAN_CODES_PER_META_CODE] = {
>      NUM_LITERAL_CODES + NUM_LENGTH_CODES,
> diff --git a/libavcodec/webp.h b/libavcodec/webp.h
> new file mode 100644
> index 0000000000..90baa71182
> --- /dev/null
> +++ b/libavcodec/webp.h
> @@ -0,0 +1,55 @@
> +/*
> + * WebP image format definitions
> + * Copyright (c) 2020 Pexeso Inc.
> + *
> + * This file is part of FFmpeg.
> + *
> + * FFmpeg is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * FFmpeg is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with FFmpeg; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
> + */
> +
> +/**
> + * @file
> + * WebP image format definitions.
> + */
> +
> +#ifndef AVCODEC_WEBP_H
> +#define AVCODEC_WEBP_H
> +
> +#define VP8X_FLAG_ANIMATION             0x02
> +#define VP8X_FLAG_XMP_METADATA          0x04
> +#define VP8X_FLAG_EXIF_METADATA         0x08
> +#define VP8X_FLAG_ALPHA                 0x10
> +#define VP8X_FLAG_ICC                   0x20
> +
> +#define ANMF_DISPOSAL_METHOD            0x01
> +#define ANMF_DISPOSAL_METHOD_UNCHANGED  0x00
> +#define ANMF_DISPOSAL_METHOD_BACKGROUND 0x01
> +
> +#define ANMF_BLENDING_METHOD            0x02
> +#define ANMF_BLENDING_METHOD_ALPHA      0x00
> +#define ANMF_BLENDING_METHOD_OVERWRITE  0x02
> +
> +#define MAX_PALETTE_SIZE                256
> +#define MAX_CACHE_BITS                  11
> +#define NUM_CODE_LENGTH_CODES           19
> +#define HUFFMAN_CODES_PER_META_CODE     5
> +#define NUM_LITERAL_CODES               256
> +#define NUM_LENGTH_CODES                24
> +#define NUM_DISTANCE_CODES              40
> +#define NUM_SHORT_DISTANCES             120
> +#define MAX_HUFFMAN_CODE_LENGTH         15
> +
> +
> +#endif /* AVCODEC_WEBP_H */

1. Some of these defines (like MAX_CACHE_BITS) are unused now and seem
to stay that way in your patchset.
2. If you move defines in a header, you need to ensure that they are
properly prefixed so that no conflicts can arise. This is particularly
true of defines like VP8X_FLAG_* whose name actually indicates that they
belong into a vp8.h.
3. It seems that your patchset only includes this header in webp.c; they
are not used outside of it. So there is no need for a header.

- Andreas

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Re: [FFmpeg-devel] [PATCH v1 1/4] avcodec/webp: move definitions into header

[Thilo Borgmann]

Am 14.06.23 um 12:08 schrieb Andreas Rheinhardt:
> Thilo Borgmann:
>> ---
>>   libavcodec/webp.c | 17 +--------------
>>   libavcodec/webp.h | 55 +++++++++++++++++++++++++++++++++++++++++++++++
>>   2 files changed, 56 insertions(+), 16 deletions(-)
>>   create mode 100644 libavcodec/webp.h
>>
>> diff --git a/libavcodec/webp.c b/libavcodec/webp.c
>> index d35cb66f8d..15152ec8fb 100644
>> --- a/libavcodec/webp.c
>> +++ b/libavcodec/webp.c
>> @@ -52,22 +52,7 @@
>>   #include "thread.h"
>>   #include "tiff_common.h"
>>   #include "vp8.h"
>> -
>> -#define VP8X_FLAG_ANIMATION             0x02
>> -#define VP8X_FLAG_XMP_METADATA          0x04
>> -#define VP8X_FLAG_EXIF_METADATA         0x08
>> -#define VP8X_FLAG_ALPHA                 0x10
>> -#define VP8X_FLAG_ICC                   0x20
>> -
>> -#define MAX_PALETTE_SIZE                256
>> -#define MAX_CACHE_BITS                  11
>> -#define NUM_CODE_LENGTH_CODES           19
>> -#define HUFFMAN_CODES_PER_META_CODE     5
>> -#define NUM_LITERAL_CODES               256
>> -#define NUM_LENGTH_CODES                24
>> -#define NUM_DISTANCE_CODES              40
>> -#define NUM_SHORT_DISTANCES             120
>> -#define MAX_HUFFMAN_CODE_LENGTH         15
>> +#include "webp.h"
>>   
>>   static const uint16_t alphabet_sizes[HUFFMAN_CODES_PER_META_CODE] = {
>>       NUM_LITERAL_CODES + NUM_LENGTH_CODES,
>> diff --git a/libavcodec/webp.h b/libavcodec/webp.h
>> new file mode 100644
>> index 0000000000..90baa71182
>> --- /dev/null
>> +++ b/libavcodec/webp.h
>> @@ -0,0 +1,55 @@
>> +/*
>> + * WebP image format definitions
>> + * Copyright (c) 2020 Pexeso Inc.
>> + *
>> + * This file is part of FFmpeg.
>> + *
>> + * FFmpeg is free software; you can redistribute it and/or
>> + * modify it under the terms of the GNU Lesser General Public
>> + * License as published by the Free Software Foundation; either
>> + * version 2.1 of the License, or (at your option) any later version.
>> + *
>> + * FFmpeg is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>> + * Lesser General Public License for more details.
>> + *
>> + * You should have received a copy of the GNU Lesser General Public
>> + * License along with FFmpeg; if not, write to the Free Software
>> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
>> + */
>> +
>> +/**
>> + * @file
>> + * WebP image format definitions.
>> + */
>> +
>> +#ifndef AVCODEC_WEBP_H
>> +#define AVCODEC_WEBP_H
>> +
>> +#define VP8X_FLAG_ANIMATION             0x02
>> +#define VP8X_FLAG_XMP_METADATA          0x04
>> +#define VP8X_FLAG_EXIF_METADATA         0x08
>> +#define VP8X_FLAG_ALPHA                 0x10
>> +#define VP8X_FLAG_ICC                   0x20
>> +
>> +#define ANMF_DISPOSAL_METHOD            0x01
>> +#define ANMF_DISPOSAL_METHOD_UNCHANGED  0x00
>> +#define ANMF_DISPOSAL_METHOD_BACKGROUND 0x01
>> +
>> +#define ANMF_BLENDING_METHOD            0x02
>> +#define ANMF_BLENDING_METHOD_ALPHA      0x00
>> +#define ANMF_BLENDING_METHOD_OVERWRITE  0x02
>> +
>> +#define MAX_PALETTE_SIZE                256
>> +#define MAX_CACHE_BITS                  11
>> +#define NUM_CODE_LENGTH_CODES           19
>> +#define HUFFMAN_CODES_PER_META_CODE     5
>> +#define NUM_LITERAL_CODES               256
>> +#define NUM_LENGTH_CODES                24
>> +#define NUM_DISTANCE_CODES              40
>> +#define NUM_SHORT_DISTANCES             120
>> +#define MAX_HUFFMAN_CODE_LENGTH         15
>> +
>> +
>> +#endif /* AVCODEC_WEBP_H */
> 
> 1. Some of these defines (like MAX_CACHE_BITS) are unused now and seem
> to stay that way in your patchset.
> 2. If you move defines in a header, you need to ensure that they are
> properly prefixed so that no conflicts can arise. This is particularly
> true of defines like VP8X_FLAG_* whose name actually indicates that they
> belong into a vp8.h.
> 3. It seems that your patchset only includes this header in webp.c; they
> are not used outside of it. So there is no need for a header.

All true, I believe. Having it in a header originates from the original patchset 
including a parser where the header is then used as well. Because the parser did 
not get any feedback I posted only the decoder here and kept the header file 
anyway to keep the decoder patch smaller. I can keep it in there if you wish, 
though - then the need for prefixing becomes void, IIUC.

I think it makes no sense to drap these defines into vp8.h as I believe they 
make sense only in the VP8-in-WebP case.

v2 will include it in the decoder then, thx!

-Thilo

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[FFmpeg-devel] [PATCH v1 2/4] avcodec/webp_parser: parse each frame into one packet

[Thilo Borgmann]

---
 libavcodec/webp_parser.c | 132 ++++++++++++++++++++++++++-------------
 1 file changed, 90 insertions(+), 42 deletions(-)

diff --git a/libavcodec/webp_parser.c b/libavcodec/webp_parser.c
index bd5f94dac5..d10d06bd0e 100644
--- a/libavcodec/webp_parser.c
+++ b/libavcodec/webp_parser.c
@@ -25,13 +25,17 @@
 
 #include "libavutil/bswap.h"
 #include "libavutil/common.h"
+#include "libavutil/intreadwrite.h"
 
 #include "parser.h"
 
 typedef struct WebPParseContext {
     ParseContext pc;
+    int frame;
+    int first_frame;
     uint32_t fsize;
-    uint32_t remaining_size;
+    uint32_t remaining_file_size;
+    uint32_t remaining_tag_size;
 } WebPParseContext;
 
 static int webp_parse(AVCodecParserContext *s, AVCodecContext *avctx,
@@ -41,62 +45,106 @@ static int webp_parse(AVCodecParserContext *s, AVCodecContext *avctx,
     WebPParseContext *ctx = s->priv_data;
     uint64_t state = ctx->pc.state64;
     int next = END_NOT_FOUND;
-    int i = 0;
+    int i, len;
 
-    *poutbuf      = NULL;
-    *poutbuf_size = 0;
-
-restart:
-    if (ctx->pc.frame_start_found <= 8) {
-        for (; i < buf_size; i++) {
+    for (i = 0; i < buf_size;) {
+        if (ctx->remaining_tag_size) {
+            /* consuming tag */
+            len = FFMIN(ctx->remaining_tag_size, buf_size - i);
+            i += len;
+            ctx->remaining_tag_size -= len;
+            ctx->remaining_file_size -= len;
+        } else {
+            /* scan for the next tag or file */
             state = (state << 8) | buf[i];
-            if (ctx->pc.frame_start_found == 0) {
-                if ((state >> 32) == MKBETAG('R', 'I', 'F', 'F')) {
-                    ctx->fsize = av_bswap32(state);
-                    if (ctx->fsize > 15 && ctx->fsize <= UINT32_MAX - 10) {
-                        ctx->pc.frame_start_found = 1;
-                        ctx->fsize += 8;
+            i++;
+
+            if (!ctx->remaining_file_size) {
+                /* scan for the next file */
+                if (ctx->pc.frame_start_found == 4) {
+                    ctx->pc.frame_start_found = 0;
+                    if ((uint32_t) state == MKBETAG('W', 'E', 'B', 'P')) {
+                        if (ctx->frame || i != 12) {
+                            ctx->frame = 0;
+                            next = i - 12;
+                            state = 0;
+                            ctx->pc.frame_start_found = 0;
+                            break;
+                        }
+                        ctx->remaining_file_size = ctx->fsize - 4;
+                        ctx->first_frame = 1;
+                        continue;
                     }
                 }
-            } else if (ctx->pc.frame_start_found == 8) {
-                if ((state >> 32) != MKBETAG('W', 'E', 'B', 'P')) {
+                if (ctx->pc.frame_start_found == 0) {
+                    if ((state >> 32) == MKBETAG('R', 'I', 'F', 'F')) {
+                        ctx->fsize = av_bswap32(state);
+                        if (ctx->fsize > 15 && ctx->fsize <= UINT32_MAX - 10) {
+                            ctx->fsize += (ctx->fsize & 1);
+                            ctx->pc.frame_start_found = 1;
+                        }
+                    }
+                } else
+                    ctx->pc.frame_start_found++;
+            } else {
+                /* read the next tag */
+                ctx->remaining_file_size--;
+                if (ctx->remaining_file_size == 0) {
                     ctx->pc.frame_start_found = 0;
                     continue;
                 }
                 ctx->pc.frame_start_found++;
-                ctx->remaining_size = ctx->fsize + i - 15;
-                if (ctx->pc.index + i > 15) {
-                    next = i - 15;
-                    state = 0;
-                    break;
-                } else {
-                    ctx->pc.state64 = 0;
-                    goto restart;
+                if (ctx->pc.frame_start_found < 8)
+                    continue;
+
+                switch (state >> 32) {
+                    case MKBETAG('A', 'N', 'M', 'F'):
+                    case MKBETAG('V', 'P', '8', ' '):
+                    case MKBETAG('V', 'P', '8', 'L'):
+                        if (ctx->frame) {
+                            ctx->frame = 0;
+                            next = i - 8;
+                            state = 0;
+                            ctx->pc.frame_start_found = 0;
+                            goto flush;
+                        }
+                        ctx->frame = 1;
+                        break;
+                    default:
+                        break;
                 }
-            } else if (ctx->pc.frame_start_found)
-                ctx->pc.frame_start_found++;
-        }
-        ctx->pc.state64 = state;
-    } else {
-        if (ctx->remaining_size) {
-            i = FFMIN(ctx->remaining_size, buf_size);
-            ctx->remaining_size -= i;
-            if (ctx->remaining_size)
-                goto flush;
 
-            ctx->pc.frame_start_found = 0;
-            goto restart;
+                ctx->remaining_tag_size = av_bswap32(state);
+                ctx->remaining_tag_size += ctx->remaining_tag_size & 1;
+                if (ctx->remaining_tag_size > ctx->remaining_file_size) {
+                    /* this is probably trash at the end of file */
+                    ctx->remaining_tag_size = ctx->remaining_file_size;
+                }
+                ctx->pc.frame_start_found = 0;
+                state = 0;
+            }
         }
     }
-
 flush:
-    if (ff_combine_frame(&ctx->pc, next, &buf, &buf_size) < 0)
+    ctx->pc.state64 = state;
+
+    if (ff_combine_frame(&ctx->pc, next, &buf, &buf_size) < 0) {
+        *poutbuf      = NULL;
+        *poutbuf_size = 0;
         return buf_size;
+    }
 
-    if (next != END_NOT_FOUND && next < 0)
-        ctx->pc.frame_start_found = FFMAX(ctx->pc.frame_start_found - i - 1, 0);
-    else
-        ctx->pc.frame_start_found = 0;
+    // Extremely simplified key frame detection:
+    // - the first frame (containing headers) is marked as a key frame
+    // - other frames are marked as non-key frames
+    if (ctx->first_frame) {
+        ctx->first_frame = 0;
+        s->pict_type = AV_PICTURE_TYPE_I;
+        s->key_frame = 1;
+    } else {
+        s->pict_type = AV_PICTURE_TYPE_P;
+        s->key_frame = 0;
+    }
 
     *poutbuf      = buf;
     *poutbuf_size = buf_size;
-- 
2.37.1 (Apple Git-137.1)

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[FFmpeg-devel] [PATCH v1 3/4] libavcodec/webp: add support for animated WebP decoding

[Thilo Borgmann]

From: Josef Zlomek <josef@pex.com>

Fixes: 4907

Adds support for decoding of animated WebP.

The WebP decoder adds the animation related features according to the specs:
https://developers.google.com/speed/webp/docs/riff_container#animation
The frames of the animation may be smaller than the image canvas.
Therefore, the frame is decoded to a temporary frame,
then it is blended into the canvas, the canvas is copied to the output frame,
and finally the frame is disposed from the canvas.

The output to AV_PIX_FMT_YUVA420P/AV_PIX_FMT_YUV420P is still supported.
The background color is specified only as BGRA in the WebP file
so it is converted to YUVA if YUV formats are output.

Signed-off-by: Josef Zlomek <josef@pex.com>
---
 Changelog               |   1 +
 libavcodec/codec_desc.c |   3 +-
 libavcodec/version.h    |   2 +-
 libavcodec/webp.c       | 714 ++++++++++++++++++++++++++++++++++++----
 4 files changed, 658 insertions(+), 62 deletions(-)

diff --git a/Changelog b/Changelog
index d51e03b8eb..31651b8c29 100644
--- a/Changelog
+++ b/Changelog
@@ -16,6 +16,7 @@ version <next>:
 - nlmeans_vulkan filter
 - RivaTuner video decoder
 - xfade_vulkan filter
+- animated WebP parser/decoder
 
 version 6.0:
 - Radiance HDR image support
diff --git a/libavcodec/codec_desc.c b/libavcodec/codec_desc.c
index 41293a78dc..383d7c2394 100644
--- a/libavcodec/codec_desc.c
+++ b/libavcodec/codec_desc.c
@@ -1259,8 +1259,7 @@ static const AVCodecDescriptor codec_descriptors[] = {
         .type      = AVMEDIA_TYPE_VIDEO,
         .name      = "webp",
         .long_name = NULL_IF_CONFIG_SMALL("WebP"),
-        .props     = AV_CODEC_PROP_INTRA_ONLY | AV_CODEC_PROP_LOSSY |
-                     AV_CODEC_PROP_LOSSLESS,
+        .props     = AV_CODEC_PROP_LOSSY | AV_CODEC_PROP_LOSSLESS,
         .mime_types= MT("image/webp"),
     },
     {
diff --git a/libavcodec/version.h b/libavcodec/version.h
index 2618016a83..d6e0724326 100644
--- a/libavcodec/version.h
+++ b/libavcodec/version.h
@@ -30,7 +30,7 @@
 #include "version_major.h"
 
 #define LIBAVCODEC_VERSION_MINOR  17
-#define LIBAVCODEC_VERSION_MICRO 100
+#define LIBAVCODEC_VERSION_MICRO 101
 
 #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \
                                                LIBAVCODEC_VERSION_MINOR, \
diff --git a/libavcodec/webp.c b/libavcodec/webp.c
index 15152ec8fb..bee43fcf19 100644
--- a/libavcodec/webp.c
+++ b/libavcodec/webp.c
@@ -35,12 +35,16 @@
  * Exif metadata
  * ICC profile
  *
+ * @author Josef Zlomek, Pexeso Inc. <josef@pex.com>
+ * Animation
+ *
  * Unimplemented:
- *   - Animation
  *   - XMP metadata
  */
 
+#include "libavcodec/packet.h"
 #include "libavutil/imgutils.h"
+#include "libavutil/colorspace.h"
 
 #define BITSTREAM_READER_LE
 #include "avcodec.h"
@@ -178,6 +182,8 @@ typedef struct ImageContext {
 typedef struct WebPContext {
     VP8Context v;                       /* VP8 Context used for lossy decoding */
     GetBitContext gb;                   /* bitstream reader for main image chunk */
+    ThreadFrame canvas_frame;           /* ThreadFrame for canvas */
+    AVFrame *frame;                     /* AVFrame for decoded frame */
     AVFrame *alpha_frame;               /* AVFrame for alpha data decompressed from VP8L */
     AVPacket *pkt;                      /* AVPacket to be passed to the underlying VP8 decoder */
     AVCodecContext *avctx;              /* parent AVCodecContext */
@@ -189,9 +195,24 @@ typedef struct WebPContext {
     int alpha_data_size;                /* alpha chunk data size */
     int has_exif;                       /* set after an EXIF chunk has been processed */
     int has_iccp;                       /* set after an ICCP chunk has been processed */
-    int width;                          /* image width */
-    int height;                         /* image height */
-    int lossless;                       /* indicates lossless or lossy */
+    int vp8x_flags;                     /* global flags from VP8X chunk */
+    int canvas_width;                   /* canvas width */
+    int canvas_height;                  /* canvas height */
+    int anmf_flags;                     /* frame flags from ANMF chunk */
+    int width;                          /* frame width */
+    int height;                         /* frame height */
+    int pos_x;                          /* frame position X */
+    int pos_y;                          /* frame position Y */
+    int prev_anmf_flags;                /* previous frame flags from ANMF chunk */
+    int prev_width;                     /* previous frame width */
+    int prev_height;                    /* previous frame height */
+    int prev_pos_x;                     /* previous frame position X */
+    int prev_pos_y;                     /* previous frame position Y */
+    int await_progress;                 /* value of progress to wait for */
+    uint8_t background_argb[4];         /* background color in ARGB format */
+    uint8_t background_yuva[4];         /* background color in YUVA format */
+    const uint8_t *background_data[4];  /* "planes" for background color in YUVA format */
+    uint8_t transparent_yuva[4];        /* transparent black in YUVA format */
 
     int nb_transforms;                  /* number of transforms */
     enum TransformType transforms[4];   /* transformations used in the image, in order */
@@ -555,7 +576,7 @@ static int decode_entropy_coded_image(WebPContext *s, enum ImageRole role,
     img->frame->height = h;
 
     if (role == IMAGE_ROLE_ARGB && !img->is_alpha_primary) {
-        ret = ff_thread_get_buffer(s->avctx, img->frame, 0);
+        ret = ff_get_buffer(s->avctx, img->frame, 0);
     } else
         ret = av_frame_get_buffer(img->frame, 1);
     if (ret < 0)
@@ -1053,7 +1074,7 @@ static int apply_color_indexing_transform(WebPContext *s)
     return 0;
 }
 
-static void update_canvas_size(AVCodecContext *avctx, int w, int h)
+static void update_frame_size(AVCodecContext *avctx, int w, int h)
 {
     WebPContext *s = avctx->priv_data;
     if (s->width && s->width != w) {
@@ -1076,7 +1097,6 @@ static int vp8_lossless_decode_frame(AVCodecContext *avctx, AVFrame *p,
     int w, h, ret, i, used;
 
     if (!is_alpha_chunk) {
-        s->lossless = 1;
         avctx->pix_fmt = AV_PIX_FMT_ARGB;
     }
 
@@ -1093,7 +1113,7 @@ static int vp8_lossless_decode_frame(AVCodecContext *avctx, AVFrame *p,
         w = get_bits(&s->gb, 14) + 1;
         h = get_bits(&s->gb, 14) + 1;
 
-        update_canvas_size(avctx, w, h);
+        update_frame_size(avctx, w, h);
 
         ret = ff_set_dimensions(avctx, s->width, s->height);
         if (ret < 0)
@@ -1290,7 +1310,6 @@ static int vp8_lossy_decode_frame(AVCodecContext *avctx, AVFrame *p,
         s->v.actually_webp = 1;
     }
     avctx->pix_fmt = s->has_alpha ? AV_PIX_FMT_YUVA420P : AV_PIX_FMT_YUV420P;
-    s->lossless = 0;
 
     if (data_size > INT_MAX) {
         av_log(avctx, AV_LOG_ERROR, "unsupported chunk size\n");
@@ -1308,7 +1327,7 @@ static int vp8_lossy_decode_frame(AVCodecContext *avctx, AVFrame *p,
     if (!*got_frame)
         return AVERROR_INVALIDDATA;
 
-    update_canvas_size(avctx, avctx->width, avctx->height);
+    update_frame_size(avctx, avctx->width, avctx->height);
 
     if (s->has_alpha) {
         ret = vp8_lossy_decode_alpha(avctx, p, s->alpha_data,
@@ -1318,41 +1337,17 @@ static int vp8_lossy_decode_frame(AVCodecContext *avctx, AVFrame *p,
     }
     return ret;
 }
+int init_canvas_frame(WebPContext *s, int format, int key_frame);
 
-static int webp_decode_frame(AVCodecContext *avctx, AVFrame *p,
-                             int *got_frame, AVPacket *avpkt)
+static int webp_decode_frame_common(AVCodecContext *avctx, uint8_t *data, int size,
+                               int *got_frame, int key_frame)
 {
     WebPContext *s = avctx->priv_data;
     GetByteContext gb;
     int ret;
     uint32_t chunk_type, chunk_size;
-    int vp8x_flags = 0;
 
-    s->avctx     = avctx;
-    s->width     = 0;
-    s->height    = 0;
-    *got_frame   = 0;
-    s->has_alpha = 0;
-    s->has_exif  = 0;
-    s->has_iccp  = 0;
-    bytestream2_init(&gb, avpkt->data, avpkt->size);
-
-    if (bytestream2_get_bytes_left(&gb) < 12)
-        return AVERROR_INVALIDDATA;
-
-    if (bytestream2_get_le32(&gb) != MKTAG('R', 'I', 'F', 'F')) {
-        av_log(avctx, AV_LOG_ERROR, "missing RIFF tag\n");
-        return AVERROR_INVALIDDATA;
-    }
-
-    chunk_size = bytestream2_get_le32(&gb);
-    if (bytestream2_get_bytes_left(&gb) < chunk_size)
-        return AVERROR_INVALIDDATA;
-
-    if (bytestream2_get_le32(&gb) != MKTAG('W', 'E', 'B', 'P')) {
-        av_log(avctx, AV_LOG_ERROR, "missing WEBP tag\n");
-        return AVERROR_INVALIDDATA;
-    }
+    bytestream2_init(&gb, data, size);
 
     while (bytestream2_get_bytes_left(&gb) > 8) {
         char chunk_str[5] = { 0 };
@@ -1363,6 +1358,10 @@ static int webp_decode_frame(AVCodecContext *avctx, AVFrame *p,
             return AVERROR_INVALIDDATA;
         chunk_size += chunk_size & 1;
 
+        // we need to dive into RIFF chunk
+        if (chunk_type == MKTAG('R', 'I', 'F', 'F'))
+            chunk_size = 4;
+
         if (bytestream2_get_bytes_left(&gb) < chunk_size) {
            /* we seem to be running out of data, but it could also be that the
               bitstream has trailing junk leading to bogus chunk_size. */
@@ -1370,10 +1369,26 @@ static int webp_decode_frame(AVCodecContext *avctx, AVFrame *p,
         }
 
         switch (chunk_type) {
+        case MKTAG('R', 'I', 'F', 'F'):
+            if (bytestream2_get_le32(&gb) != MKTAG('W', 'E', 'B', 'P')) {
+                av_log(avctx, AV_LOG_ERROR, "missing WEBP tag\n");
+                return AVERROR_INVALIDDATA;
+            }
+            s->vp8x_flags    = 0;
+            s->canvas_width  = 0;
+            s->canvas_height = 0;
+            s->has_exif      = 0;
+            s->has_iccp      = 0;
+            ff_thread_release_ext_buffer(avctx, &s->canvas_frame);
+            break;
         case MKTAG('V', 'P', '8', ' '):
             if (!*got_frame) {
-                ret = vp8_lossy_decode_frame(avctx, p, got_frame,
-                                             avpkt->data + bytestream2_tell(&gb),
+                ret = init_canvas_frame(s, AV_PIX_FMT_YUVA420P, key_frame);
+                if (ret < 0)
+                    return ret;
+
+                ret = vp8_lossy_decode_frame(avctx, s->frame, got_frame,
+                                             data + bytestream2_tell(&gb),
                                              chunk_size);
                 if (ret < 0)
                     return ret;
@@ -1382,8 +1397,13 @@ static int webp_decode_frame(AVCodecContext *avctx, AVFrame *p,
             break;
         case MKTAG('V', 'P', '8', 'L'):
             if (!*got_frame) {
-                ret = vp8_lossless_decode_frame(avctx, p, got_frame,
-                                                avpkt->data + bytestream2_tell(&gb),
+                ret = init_canvas_frame(s, AV_PIX_FMT_ARGB, key_frame);
+                if (ret < 0)
+                    return ret;
+                ff_thread_finish_setup(s->avctx);
+
+                ret = vp8_lossless_decode_frame(avctx, s->frame, got_frame,
+                                                data + bytestream2_tell(&gb),
                                                 chunk_size, 0);
                 if (ret < 0)
                     return ret;
@@ -1392,14 +1412,16 @@ static int webp_decode_frame(AVCodecContext *avctx, AVFrame *p,
             bytestream2_skip(&gb, chunk_size);
             break;
         case MKTAG('V', 'P', '8', 'X'):
-            if (s->width || s->height || *got_frame) {
+            if (s->canvas_width || s->canvas_height || *got_frame) {
                 av_log(avctx, AV_LOG_ERROR, "Canvas dimensions are already set\n");
                 return AVERROR_INVALIDDATA;
             }
-            vp8x_flags = bytestream2_get_byte(&gb);
+            s->vp8x_flags = bytestream2_get_byte(&gb);
             bytestream2_skip(&gb, 3);
             s->width  = bytestream2_get_le24(&gb) + 1;
             s->height = bytestream2_get_le24(&gb) + 1;
+            s->canvas_width  = s->width;
+            s->canvas_height = s->height;
             ret = av_image_check_size(s->width, s->height, 0, avctx);
             if (ret < 0)
                 return ret;
@@ -1407,7 +1429,7 @@ static int webp_decode_frame(AVCodecContext *avctx, AVFrame *p,
         case MKTAG('A', 'L', 'P', 'H'): {
             int alpha_header, filter_m, compression;
 
-            if (!(vp8x_flags & VP8X_FLAG_ALPHA)) {
+            if (!(s->vp8x_flags & VP8X_FLAG_ALPHA)) {
                 av_log(avctx, AV_LOG_WARNING,
                        "ALPHA chunk present, but alpha bit not set in the "
                        "VP8X header\n");
@@ -1416,8 +1438,9 @@ static int webp_decode_frame(AVCodecContext *avctx, AVFrame *p,
                 av_log(avctx, AV_LOG_ERROR, "invalid ALPHA chunk size\n");
                 return AVERROR_INVALIDDATA;
             }
+
             alpha_header       = bytestream2_get_byte(&gb);
-            s->alpha_data      = avpkt->data + bytestream2_tell(&gb);
+            s->alpha_data      = data + bytestream2_tell(&gb);
             s->alpha_data_size = chunk_size - 1;
             bytestream2_skip(&gb, s->alpha_data_size);
 
@@ -1444,14 +1467,13 @@ static int webp_decode_frame(AVCodecContext *avctx, AVFrame *p,
                 av_log(avctx, AV_LOG_VERBOSE, "Ignoring extra EXIF chunk\n");
                 goto exif_end;
             }
-            if (!(vp8x_flags & VP8X_FLAG_EXIF_METADATA))
+            if (!(s->vp8x_flags & VP8X_FLAG_EXIF_METADATA))
                 av_log(avctx, AV_LOG_WARNING,
                        "EXIF chunk present, but Exif bit not set in the "
                        "VP8X header\n");
 
             s->has_exif = 1;
-            bytestream2_init(&exif_gb, avpkt->data + exif_offset,
-                             avpkt->size - exif_offset);
+            bytestream2_init(&exif_gb, data + exif_offset, size - exif_offset);
             if (ff_tdecode_header(&exif_gb, &le, &ifd_offset) < 0) {
                 av_log(avctx, AV_LOG_ERROR, "invalid TIFF header "
                        "in Exif data\n");
@@ -1464,7 +1486,7 @@ static int webp_decode_frame(AVCodecContext *avctx, AVFrame *p,
                 goto exif_end;
             }
 
-            av_dict_copy(&p->metadata, exif_metadata, 0);
+            av_dict_copy(&s->frame->metadata, exif_metadata, 0);
 
 exif_end:
             av_dict_free(&exif_metadata);
@@ -1479,21 +1501,64 @@ exif_end:
                 bytestream2_skip(&gb, chunk_size);
                 break;
             }
-            if (!(vp8x_flags & VP8X_FLAG_ICC))
+            if (!(s->vp8x_flags & VP8X_FLAG_ICC))
                 av_log(avctx, AV_LOG_WARNING,
                        "ICCP chunk present, but ICC Profile bit not set in the "
                        "VP8X header\n");
 
             s->has_iccp = 1;
-            sd = av_frame_new_side_data(p, AV_FRAME_DATA_ICC_PROFILE, chunk_size);
+            sd = av_frame_new_side_data(s->frame, AV_FRAME_DATA_ICC_PROFILE, chunk_size);
             if (!sd)
                 return AVERROR(ENOMEM);
 
             bytestream2_get_buffer(&gb, sd->data, chunk_size);
             break;
         }
-        case MKTAG('A', 'N', 'I', 'M'):
+        case MKTAG('A', 'N', 'I', 'M'): {
+            const AVPixFmtDescriptor *desc;
+            int a, r, g, b;
+            if (!(s->vp8x_flags & VP8X_FLAG_ANIMATION)) {
+                av_log(avctx, AV_LOG_WARNING,
+                       "ANIM chunk present, but animation bit not set in the "
+                       "VP8X header\n");
+            }
+            // background is stored as BGRA, we need ARGB
+            s->background_argb[3] = b = bytestream2_get_byte(&gb);
+            s->background_argb[2] = g = bytestream2_get_byte(&gb);
+            s->background_argb[1] = r = bytestream2_get_byte(&gb);
+            s->background_argb[0] = a = bytestream2_get_byte(&gb);
+
+            // convert the background color to YUVA
+            desc = av_pix_fmt_desc_get(AV_PIX_FMT_YUVA420P);
+            s->background_yuva[desc->comp[0].plane] = RGB_TO_Y_CCIR(r, g, b);
+            s->background_yuva[desc->comp[1].plane] = RGB_TO_U_CCIR(r, g, b, 0);
+            s->background_yuva[desc->comp[2].plane] = RGB_TO_V_CCIR(r, g, b, 0);
+            s->background_yuva[desc->comp[3].plane] = a;
+
+            bytestream2_skip(&gb, 2); // loop count is ignored
+            break;
+        }
         case MKTAG('A', 'N', 'M', 'F'):
+            if (!(s->vp8x_flags & VP8X_FLAG_ANIMATION)) {
+                av_log(avctx, AV_LOG_WARNING,
+                       "ANMF chunk present, but animation bit not set in the "
+                       "VP8X header\n");
+            }
+            s->pos_x      = bytestream2_get_le24(&gb) * 2;
+            s->pos_y      = bytestream2_get_le24(&gb) * 2;
+            s->width      = bytestream2_get_le24(&gb) + 1;
+            s->height     = bytestream2_get_le24(&gb) + 1;
+            bytestream2_skip(&gb, 3);   // duration
+            s->anmf_flags = bytestream2_get_byte(&gb);
+
+            if (s->width  + s->pos_x > s->canvas_width ||
+                s->height + s->pos_y > s->canvas_height) {
+                av_log(avctx, AV_LOG_ERROR,
+                       "frame does not fit into canvas\n");
+                return AVERROR_INVALIDDATA;
+            }
+            s->vp8x_flags |= VP8X_FLAG_ANIMATION;
+            break;
         case MKTAG('X', 'M', 'P', ' '):
             AV_WL32(chunk_str, chunk_type);
             av_log(avctx, AV_LOG_WARNING, "skipping unsupported chunk: %s\n",
@@ -1509,21 +1574,508 @@ exif_end:
         }
     }
 
-    if (!*got_frame) {
-        av_log(avctx, AV_LOG_ERROR, "image data not found\n");
-        return AVERROR_INVALIDDATA;
+    return size;
+}
+
+int init_canvas_frame(WebPContext *s, int format, int key_frame)
+{
+    AVFrame *canvas = s->canvas_frame.f;
+    int height;
+    int ret;
+
+    // canvas is needed only for animation
+    if (!(s->vp8x_flags & VP8X_FLAG_ANIMATION))
+        return 0;
+
+    // avoid init for non-key frames whose format and size did not change
+    if (!key_frame &&
+        canvas->data[0] &&
+        canvas->format == format &&
+        canvas->width  == s->canvas_width &&
+        canvas->height == s->canvas_height)
+        return 0;
+
+    // canvas changes within IPPP sequences will loose thread sync
+    // because of the ThreadFrame reallocation and will wait forever
+    // so if frame-threading is used, forbid canvas changes and unlock
+    // previous frames
+    if (!key_frame && canvas->data[0]) {
+        if (s->avctx->thread_count > 1) {
+            av_log(s->avctx, AV_LOG_WARNING, "Canvas change detected. The output will be damaged. Use -threads 1 to try decoding with best effort.\n");
+            // unlock previous frames that have sent an _await() call
+            ff_thread_report_progress(&s->canvas_frame, INT_MAX, 0);
+            return AVERROR_PATCHWELCOME;
+        } else {
+            // warn for damaged frames
+            av_log(s->avctx, AV_LOG_WARNING, "Canvas change detected. The output will be damaged.\n");
+        }
+    }
+
+    s->avctx->pix_fmt = format;
+    canvas->format    = format;
+    canvas->width     = s->canvas_width;
+    canvas->height    = s->canvas_height;
+
+    // VP8 decoder changed the width and height in AVCodecContext.
+    // Change it back to the canvas size.
+    ret = ff_set_dimensions(s->avctx, s->canvas_width, s->canvas_height);
+    if (ret < 0)
+        return ret;
+
+    ff_thread_release_ext_buffer(s->avctx, &s->canvas_frame);
+    ret = ff_thread_get_ext_buffer(s->avctx, &s->canvas_frame, AV_GET_BUFFER_FLAG_REF);
+    if (ret < 0)
+        return ret;
+
+    if (canvas->format == AV_PIX_FMT_ARGB) {
+        height = canvas->height;
+        memset(canvas->data[0], 0, height * canvas->linesize[0]);
+    } else /* if (canvas->format == AV_PIX_FMT_YUVA420P) */ {
+        const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(canvas->format);
+        for (int comp = 0; comp < desc->nb_components; comp++) {
+            int plane = desc->comp[comp].plane;
+
+            if (comp == 1 || comp == 2)
+                height = AV_CEIL_RSHIFT(canvas->height, desc->log2_chroma_h);
+            else
+                height = FFALIGN(canvas->height, 1 << desc->log2_chroma_h);
+
+            memset(canvas->data[plane], s->transparent_yuva[plane],
+                   height * canvas->linesize[plane]);
+        }
+    }
+
+    return 0;
+}
+
+/*
+ * Blend src1 (foreground) and src2 (background) into dest, in ARGB format.
+ * width, height are the dimensions of src1
+ * pos_x, pos_y is the position in src2 and in dest
+ */
+static void blend_alpha_argb(uint8_t *dest_data[4], int dest_linesize[4],
+                             const uint8_t *src1_data[4], int src1_linesize[4],
+                             const uint8_t *src2_data[4], int src2_linesize[4],
+                             int src2_step[4],
+                             int width, int height, int pos_x, int pos_y)
+{
+    for (int y = 0; y < height; y++) {
+        const uint8_t *src1 = src1_data[0] + y * src1_linesize[0];
+        const uint8_t *src2 = src2_data[0] + (y + pos_y) * src2_linesize[0] + pos_x * src2_step[0];
+        uint8_t       *dest = dest_data[0] + (y + pos_y) * dest_linesize[0] + pos_x * sizeof(uint32_t);
+        for (int x = 0; x < width; x++) {
+            int src1_alpha = src1[0];
+            int src2_alpha = src2[0];
+
+            if (src1_alpha == 255) {
+                memcpy(dest, src1, sizeof(uint32_t));
+            } else if (src1_alpha + src2_alpha == 0) {
+                memset(dest, 0, sizeof(uint32_t));
+            } else {
+                int tmp_alpha = src2_alpha - ROUNDED_DIV(src1_alpha * src2_alpha, 255);
+                int blend_alpha = src1_alpha + tmp_alpha;
+
+                dest[0] = blend_alpha;
+                dest[1] = ROUNDED_DIV(src1[1] * src1_alpha + src2[1] * tmp_alpha, blend_alpha);
+                dest[2] = ROUNDED_DIV(src1[2] * src1_alpha + src2[2] * tmp_alpha, blend_alpha);
+                dest[3] = ROUNDED_DIV(src1[3] * src1_alpha + src2[3] * tmp_alpha, blend_alpha);
+            }
+            src1 += sizeof(uint32_t);
+            src2 += src2_step[0];
+            dest += sizeof(uint32_t);
+        }
+    }
+}
+
+/*
+ * Blend src1 (foreground) and src2 (background) into dest, in YUVA format.
+ * width, height are the dimensions of src1
+ * pos_x, pos_y is the position in src2 and in dest
+ */
+static void blend_alpha_yuva(WebPContext *s,
+                             uint8_t *dest_data[4], int dest_linesize[4],
+                             const uint8_t *src1_data[4], int src1_linesize[4],
+                             int src1_format,
+                             const uint8_t *src2_data[4], int src2_linesize[4],
+                             int src2_step[4],
+                             int width, int height, int pos_x, int pos_y)
+{
+    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(src1_format);
+
+    int plane_y = desc->comp[0].plane;
+    int plane_u = desc->comp[1].plane;
+    int plane_v = desc->comp[2].plane;
+    int plane_a = desc->comp[3].plane;
+
+    // blend U & V planes first, because the later step may modify alpha plane
+    int w  = AV_CEIL_RSHIFT(width,  desc->log2_chroma_w);
+    int h  = AV_CEIL_RSHIFT(height, desc->log2_chroma_h);
+    int px = AV_CEIL_RSHIFT(pos_x,  desc->log2_chroma_w);
+    int py = AV_CEIL_RSHIFT(pos_y,  desc->log2_chroma_h);
+    int tile_w = 1 << desc->log2_chroma_w;
+    int tile_h = 1 << desc->log2_chroma_h;
+
+    for (int y = 0; y < h; y++) {
+        const uint8_t *src1_u = src1_data[plane_u] + y * src1_linesize[plane_u];
+        const uint8_t *src1_v = src1_data[plane_v] + y * src1_linesize[plane_v];
+        const uint8_t *src2_u = src2_data[plane_u] + (y + py) * src2_linesize[plane_u] + px * src2_step[plane_u];
+        const uint8_t *src2_v = src2_data[plane_v] + (y + py) * src2_linesize[plane_v] + px * src2_step[plane_v];
+        uint8_t       *dest_u = dest_data[plane_u] + (y + py) * dest_linesize[plane_u] + px;
+        uint8_t       *dest_v = dest_data[plane_v] + (y + py) * dest_linesize[plane_v] + px;
+        for (int x = 0; x < w; x++) {
+            // calculate the average alpha of the tile
+            int src1_alpha = 0;
+            int src2_alpha = 0;
+            for (int yy = 0; yy < tile_h; yy++) {
+                for (int xx = 0; xx < tile_w; xx++) {
+                    src1_alpha += src1_data[plane_a][(y * tile_h + yy) * src1_linesize[plane_a] +
+                                                     (x * tile_w + xx)];
+                    src2_alpha += src2_data[plane_a][((y + py) * tile_h + yy) * src2_linesize[plane_a] +
+                                                     ((x + px) * tile_w + xx) * src2_step[plane_a]];
+                }
+            }
+            src1_alpha = AV_CEIL_RSHIFT(src1_alpha, desc->log2_chroma_w + desc->log2_chroma_h);
+            src2_alpha = AV_CEIL_RSHIFT(src2_alpha, desc->log2_chroma_w + desc->log2_chroma_h);
+
+            if (src1_alpha == 255) {
+                *dest_u = *src1_u;
+                *dest_v = *src1_v;
+            } else if (src1_alpha + src2_alpha == 0) {
+                *dest_u = s->transparent_yuva[plane_u];
+                *dest_v = s->transparent_yuva[plane_v];
+            } else {
+                int tmp_alpha = src2_alpha - ROUNDED_DIV(src1_alpha * src2_alpha, 255);
+                int blend_alpha = src1_alpha + tmp_alpha;
+                *dest_u = ROUNDED_DIV(*src1_u * src1_alpha + *src2_u * tmp_alpha, blend_alpha);
+                *dest_v = ROUNDED_DIV(*src1_v * src1_alpha + *src2_v * tmp_alpha, blend_alpha);
+            }
+            src1_u++;
+            src1_v++;
+            src2_u += src2_step[plane_u];
+            src2_v += src2_step[plane_v];
+            dest_u++;
+            dest_v++;
+        }
+    }
+
+    // blend Y & A planes
+    for (int y = 0; y < height; y++) {
+        const uint8_t *src1_y = src1_data[plane_y] + y * src1_linesize[plane_y];
+        const uint8_t *src1_a = src1_data[plane_a] + y * src1_linesize[plane_a];
+        const uint8_t *src2_y = src2_data[plane_y] + (y + pos_y) * src2_linesize[plane_y] + pos_x * src2_step[plane_y];
+        const uint8_t *src2_a = src2_data[plane_a] + (y + pos_y) * src2_linesize[plane_a] + pos_x * src2_step[plane_a];
+        uint8_t       *dest_y = dest_data[plane_y] + (y + pos_y) * dest_linesize[plane_y] + pos_x;
+        uint8_t       *dest_a = dest_data[plane_a] + (y + pos_y) * dest_linesize[plane_a] + pos_x;
+        for (int x = 0; x < width; x++) {
+            int src1_alpha = *src1_a;
+            int src2_alpha = *src2_a;
+
+            if (src1_alpha == 255) {
+                *dest_y = *src1_y;
+                *dest_a = 255;
+            } else if (src1_alpha + src2_alpha == 0) {
+                *dest_y = s->transparent_yuva[plane_y];
+                *dest_a = 0;
+            } else {
+                int tmp_alpha = src2_alpha - ROUNDED_DIV(src1_alpha * src2_alpha, 255);
+                int blend_alpha = src1_alpha + tmp_alpha;
+                *dest_y = ROUNDED_DIV(*src1_y * src1_alpha + *src2_y * tmp_alpha, blend_alpha);
+                *dest_a = blend_alpha;
+            }
+            src1_y++;
+            src1_a++;
+            src2_y += src2_step[plane_y];
+            src2_a += src2_step[plane_a];
+            dest_y++;
+            dest_a++;
+        }
+    }
+}
+
+static int blend_frame_into_canvas(WebPContext *s)
+{
+    AVFrame *canvas = s->canvas_frame.f;
+    AVFrame *frame  = s->frame;
+    int ret;
+    int width, height;
+    int pos_x, pos_y;
+
+    ret = av_frame_copy_props(canvas, frame);
+    if (ret < 0)
+        return ret;
+
+    if ((s->anmf_flags & ANMF_BLENDING_METHOD) == ANMF_BLENDING_METHOD_OVERWRITE
+        || frame->format == AV_PIX_FMT_YUV420P) {
+        // do not blend, overwrite
+
+        if (canvas->format == AV_PIX_FMT_ARGB) {
+            width  = s->width;
+            height = s->height;
+            pos_x  = s->pos_x;
+            pos_y  = s->pos_y;
+
+            for (int y = 0; y < height; y++) {
+                const uint32_t *src = (uint32_t *) (frame->data[0] + y * frame->linesize[0]);
+                uint32_t *dst = (uint32_t *) (canvas->data[0] + (y + pos_y) * canvas->linesize[0]) + pos_x;
+                memcpy(dst, src, width * sizeof(uint32_t));
+            }
+        } else /* if (canvas->format == AV_PIX_FMT_YUVA420P) */ {
+            const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(frame->format);
+            int plane;
+
+            for (int comp = 0; comp < desc->nb_components; comp++) {
+                plane  = desc->comp[comp].plane;
+                width  = s->width;
+                height = s->height;
+                pos_x  = s->pos_x;
+                pos_y  = s->pos_y;
+                if (comp == 1 || comp == 2) {
+                    width  = AV_CEIL_RSHIFT(width,  desc->log2_chroma_w);
+                    height = AV_CEIL_RSHIFT(height, desc->log2_chroma_h);
+                    pos_x  = AV_CEIL_RSHIFT(pos_x,  desc->log2_chroma_w);
+                    pos_y  = AV_CEIL_RSHIFT(pos_y,  desc->log2_chroma_h);
+                }
+
+                for (int y = 0; y < height; y++) {
+                    const uint8_t *src = frame->data[plane] + y * frame->linesize[plane];
+                    uint8_t *dst = canvas->data[plane] + (y + pos_y) * canvas->linesize[plane] + pos_x;
+                    memcpy(dst, src, width);
+                }
+            }
+
+            if (desc->nb_components < 4) {
+                // frame does not have alpha, set alpha to 255
+                desc = av_pix_fmt_desc_get(canvas->format);
+                plane  = desc->comp[3].plane;
+                width  = s->width;
+                height = s->height;
+                pos_x  = s->pos_x;
+                pos_y  = s->pos_y;
+
+                for (int y = 0; y < height; y++) {
+                    uint8_t *dst = canvas->data[plane] + (y + pos_y) * canvas->linesize[plane] + pos_x;
+                    memset(dst, 255, width);
+                }
+            }
+        }
+    } else {
+        // alpha blending
+
+        if (canvas->format == AV_PIX_FMT_ARGB) {
+            int src2_step[4] = { sizeof(uint32_t) };
+            blend_alpha_argb(canvas->data, canvas->linesize,
+                             (const uint8_t **) frame->data, frame->linesize,
+                             (const uint8_t **) canvas->data, canvas->linesize,
+                             src2_step, s->width, s->height, s->pos_x, s->pos_y);
+        } else /* if (canvas->format == AV_PIX_FMT_YUVA420P) */ {
+            int src2_step[4] = { 1, 1, 1, 1 };
+            blend_alpha_yuva(s, canvas->data, canvas->linesize,
+                             (const uint8_t **) frame->data, frame->linesize,
+                             frame->format,
+                             (const uint8_t **) canvas->data, canvas->linesize,
+                             src2_step, s->width, s->height, s->pos_x, s->pos_y);
+        }
+    }
+
+    return 0;
+}
+
+static int copy_canvas_to_frame(WebPContext *s, AVFrame *frame, int key_frame)
+{
+    AVFrame *canvas = s->canvas_frame.f;
+    int ret;
+
+    // VP8 decoder changed the width and height in AVCodecContext.
+    // Change it back to the canvas size.
+    ret = ff_set_dimensions(s->avctx, canvas->width, canvas->height);
+    if (ret < 0)
+        return ret;
+
+    s->avctx->pix_fmt = canvas->format;
+    frame->format     = canvas->format;
+    frame->width      = canvas->width;
+    frame->height     = canvas->height;
+
+    ret = av_frame_get_buffer(frame, 0);
+    if (ret < 0)
+        return ret;
+
+    ret = av_frame_copy_props(frame, canvas);
+    if (ret < 0)
+        return ret;
+
+    // blend the canvas with the background color into the output frame
+    if (canvas->format == AV_PIX_FMT_ARGB) {
+        int src2_step[4] = { 0 };
+        const uint8_t *src2_data[4] = { &s->background_argb[0] };
+        blend_alpha_argb(frame->data, frame->linesize,
+                         (const uint8_t **) canvas->data, canvas->linesize,
+                         (const uint8_t **) src2_data, src2_step, src2_step,
+                         canvas->width, canvas->height, 0, 0);
+    } else /* if (canvas->format == AV_PIX_FMT_YUVA420P) */ {
+        int src2_step[4] = { 0, 0, 0, 0 };
+        blend_alpha_yuva(s, frame->data, frame->linesize,
+                         (const uint8_t **) canvas->data, canvas->linesize,
+                         canvas->format,
+                         s->background_data, src2_step, src2_step,
+                         canvas->width, canvas->height, 0, 0);
+    }
+
+    if (key_frame) {
+        frame->pict_type = AV_PICTURE_TYPE_I;
+    } else {
+        frame->pict_type = AV_PICTURE_TYPE_P;
+    }
+
+    return 0;
+}
+
+static int dispose_prev_frame_in_canvas(WebPContext *s)
+{
+    AVFrame *canvas = s->canvas_frame.f;
+    int width, height;
+    int pos_x, pos_y;
+
+    if ((s->prev_anmf_flags & ANMF_DISPOSAL_METHOD) == ANMF_DISPOSAL_METHOD_BACKGROUND) {
+        // dispose to background
+
+        if (canvas->format == AV_PIX_FMT_ARGB) {
+            width  = s->prev_width;
+            height = s->prev_height;
+            pos_x  = s->prev_pos_x;
+            pos_y  = s->prev_pos_y;
+
+            for (int y = 0; y < height; y++) {
+                uint32_t *dst = (uint32_t *) (canvas->data[0] + (y + pos_y) * canvas->linesize[0]) + pos_x;
+                memset(dst, 0, width * sizeof(uint32_t));
+            }
+        } else /* if (canvas->format == AV_PIX_FMT_YUVA420P) */ {
+            const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(canvas->format);
+            int plane;
+
+            for (int comp = 0; comp < desc->nb_components; comp++) {
+                plane  = desc->comp[comp].plane;
+                width  = s->prev_width;
+                height = s->prev_height;
+                pos_x  = s->prev_pos_x;
+                pos_y  = s->prev_pos_y;
+                if (comp == 1 || comp == 2) {
+                    width  = AV_CEIL_RSHIFT(width,  desc->log2_chroma_w);
+                    height = AV_CEIL_RSHIFT(height, desc->log2_chroma_h);
+                    pos_x  = AV_CEIL_RSHIFT(pos_x,  desc->log2_chroma_w);
+                    pos_y  = AV_CEIL_RSHIFT(pos_y,  desc->log2_chroma_h);
+                }
+
+                for (int y = 0; y < height; y++) {
+                    uint8_t *dst = canvas->data[plane] + (y + pos_y) * canvas->linesize[plane] + pos_x;
+                    memset(dst, s->transparent_yuva[plane], width);
+                }
+            }
+        }
+    }
+
+    return 0;
+}
+
+static int webp_decode_frame(AVCodecContext *avctx, AVFrame *p,
+                             int *got_frame, AVPacket *avpkt)
+{
+    WebPContext *s = avctx->priv_data;
+    int ret;
+    int key_frame = avpkt->flags & AV_PKT_FLAG_KEY;
+
+    for (int i = 0; i < avpkt->side_data_elems; ++i) {
+        if (avpkt->side_data[i].type == AV_PKT_DATA_NEW_EXTRADATA) {
+            ret = webp_decode_frame_common(avctx, avpkt->side_data[i].data,
+                                      avpkt->side_data[i].size,
+                                      got_frame, key_frame);
+            if (ret < 0)
+                goto end;
+        }
     }
 
-    return avpkt->size;
+    *got_frame   = 0;
+
+    if (key_frame) {
+        // The canvas is passed from one thread to another in a sequence
+        // starting with a key frame followed by non-key frames.
+        // The key frame reports progress 1,
+        // the N-th non-key frame awaits progress N = s->await_progress
+        // and reports progress N + 1.
+        s->await_progress = 0;
+    }
+
+    // reset the frame params
+    s->anmf_flags = 0;
+    s->width      = 0;
+    s->height     = 0;
+    s->pos_x      = 0;
+    s->pos_y      = 0;
+    s->has_alpha  = 0;
+
+    ret = webp_decode_frame_common(avctx, avpkt->data, avpkt->size, got_frame, key_frame);
+    if (ret < 0)
+        goto end;
+
+    if (*got_frame) {
+        if (!(s->vp8x_flags & VP8X_FLAG_ANIMATION)) {
+            // no animation, output the decoded frame
+            av_frame_move_ref(p, s->frame);
+        } else {
+            if (!key_frame) {
+                ff_thread_await_progress(&s->canvas_frame, s->await_progress, 0);
+
+                ret = dispose_prev_frame_in_canvas(s);
+                if (ret < 0)
+                    goto end;
+            }
+
+            ret = blend_frame_into_canvas(s);
+            if (ret < 0)
+                goto end;
+
+            ret = copy_canvas_to_frame(s, p, key_frame);
+            if (ret < 0)
+                goto end;
+
+            ff_thread_report_progress(&s->canvas_frame, s->await_progress + 1, 0);
+        }
+
+        p->pts = avpkt->pts;
+    }
+
+    ret = avpkt->size;
+
+end:
+    av_frame_unref(s->frame);
+    return ret;
 }
 
 static av_cold int webp_decode_init(AVCodecContext *avctx)
 {
     WebPContext *s = avctx->priv_data;
+    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(AV_PIX_FMT_YUVA420P);
 
+    s->avctx = avctx;
     s->pkt = av_packet_alloc();
-    if (!s->pkt)
+    s->canvas_frame.f = av_frame_alloc();
+    s->frame = av_frame_alloc();
+    if (!s->pkt || !s->canvas_frame.f || !s->frame) {
+        av_packet_free(&s->pkt);
+        av_frame_free(&s->canvas_frame.f);
+        av_frame_free(&s->frame);
         return AVERROR(ENOMEM);
+    }
+
+    // prepare data pointers for YUVA background
+    for (int i = 0; i < 4; i++)
+        s->background_data[i] = &s->background_yuva[i];
+
+    // convert transparent black from RGBA to YUVA
+    s->transparent_yuva[desc->comp[0].plane] = RGB_TO_Y_CCIR(0, 0, 0);
+    s->transparent_yuva[desc->comp[1].plane] = RGB_TO_U_CCIR(0, 0, 0, 0);
+    s->transparent_yuva[desc->comp[2].plane] = RGB_TO_V_CCIR(0, 0, 0, 0);
+    s->transparent_yuva[desc->comp[3].plane] = 0;
 
     return 0;
 }
@@ -1533,6 +2085,9 @@ static av_cold int webp_decode_close(AVCodecContext *avctx)
     WebPContext *s = avctx->priv_data;
 
     av_packet_free(&s->pkt);
+    ff_thread_release_ext_buffer(avctx, &s->canvas_frame);
+    av_frame_free(&s->canvas_frame.f);
+    av_frame_free(&s->frame);
 
     if (s->initialized)
         return ff_vp8_decode_free(avctx);
@@ -1540,15 +2095,56 @@ static av_cold int webp_decode_close(AVCodecContext *avctx)
     return 0;
 }
 
+static void webp_decode_flush(AVCodecContext *avctx)
+{
+    WebPContext *s = avctx->priv_data;
+
+    ff_thread_release_ext_buffer(avctx, &s->canvas_frame);
+}
+
+#if HAVE_THREADS
+static int webp_update_thread_context(AVCodecContext *dst, const AVCodecContext *src)
+{
+    WebPContext *wsrc = src->priv_data;
+    WebPContext *wdst = dst->priv_data;
+    int ret;
+
+    if (dst == src)
+        return 0;
+
+    ff_thread_release_ext_buffer(dst, &wdst->canvas_frame);
+    if (wsrc->canvas_frame.f->data[0] &&
+        (ret = ff_thread_ref_frame(&wdst->canvas_frame, &wsrc->canvas_frame)) < 0)
+        return ret;
+
+    wdst->vp8x_flags      = wsrc->vp8x_flags;
+    wdst->canvas_width    = wsrc->canvas_width;
+    wdst->canvas_height   = wsrc->canvas_height;
+    wdst->prev_anmf_flags = wsrc->anmf_flags;
+    wdst->prev_width      = wsrc->width;
+    wdst->prev_height     = wsrc->height;
+    wdst->prev_pos_x      = wsrc->pos_x;
+    wdst->prev_pos_y      = wsrc->pos_y;
+    wdst->await_progress  = wsrc->await_progress + 1;
+
+    memcpy(wdst->background_argb,  wsrc->background_argb,  sizeof(wsrc->background_argb));
+    memcpy(wdst->background_yuva,  wsrc->background_yuva,  sizeof(wsrc->background_yuva));
+
+    return 0;
+}
+#endif
+
 const FFCodec ff_webp_decoder = {
     .p.name         = "webp",
     CODEC_LONG_NAME("WebP image"),
     .p.type         = AVMEDIA_TYPE_VIDEO,
     .p.id           = AV_CODEC_ID_WEBP,
     .priv_data_size = sizeof(WebPContext),
+    UPDATE_THREAD_CONTEXT(webp_update_thread_context),
     .init           = webp_decode_init,
     FF_CODEC_DECODE_CB(webp_decode_frame),
     .close          = webp_decode_close,
+    .flush          = webp_decode_flush,
     .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_FRAME_THREADS,
-    .caps_internal  = FF_CODEC_CAP_ICC_PROFILES,
+    .caps_internal  = FF_CODEC_CAP_ICC_PROFILES | FF_CODEC_CAP_ALLOCATE_PROGRESS,
 };
-- 
2.37.1 (Apple Git-137.1)

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Re: [FFmpeg-devel] [PATCH v1 3/4] libavcodec/webp: add support for animated WebP decoding

[James Zern]

On Thu, Jun 8, 2023 at 7:21 AM Thilo Borgmann <thilo.borgmann@mail.de> wrote:
>
> From: Josef Zlomek <josef@pex.com>
>
> Fixes: 4907
>
> Adds support for decoding of animated WebP.
>
> The WebP decoder adds the animation related features according to the specs:
> https://developers.google.com/speed/webp/docs/riff_container#animation
> The frames of the animation may be smaller than the image canvas.
> Therefore, the frame is decoded to a temporary frame,
> then it is blended into the canvas, the canvas is copied to the output frame,
> and finally the frame is disposed from the canvas.
>
> The output to AV_PIX_FMT_YUVA420P/AV_PIX_FMT_YUV420P is still supported.
> The background color is specified only as BGRA in the WebP file
> so it is converted to YUVA if YUV formats are output.
>
> Signed-off-by: Josef Zlomek <josef@pex.com>
> ---
>  Changelog               |   1 +
>  libavcodec/codec_desc.c |   3 +-
>  libavcodec/version.h    |   2 +-
>  libavcodec/webp.c       | 714 ++++++++++++++++++++++++++++++++++++----
>  4 files changed, 658 insertions(+), 62 deletions(-)
>
> [...]
> +
> +            bytestream2_skip(&gb, 2); // loop count is ignored

TODO? APNG and GIF support looping and have -ignore_loop to control it.
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Re: [FFmpeg-devel] [PATCH v1 3/4] libavcodec/webp: add support for animated WebP decoding

[Thilo Borgmann]

Am 14.06.23 um 04:04 schrieb James Zern:
> On Thu, Jun 8, 2023 at 7:21 AM Thilo Borgmann <thilo.borgmann@mail.de> wrote:
>>
>> From: Josef Zlomek <josef@pex.com>
>>
>> Fixes: 4907
>>
>> Adds support for decoding of animated WebP.
>>
>> The WebP decoder adds the animation related features according to the specs:
>> https://developers.google.com/speed/webp/docs/riff_container#animation
>> The frames of the animation may be smaller than the image canvas.
>> Therefore, the frame is decoded to a temporary frame,
>> then it is blended into the canvas, the canvas is copied to the output frame,
>> and finally the frame is disposed from the canvas.
>>
>> The output to AV_PIX_FMT_YUVA420P/AV_PIX_FMT_YUV420P is still supported.
>> The background color is specified only as BGRA in the WebP file
>> so it is converted to YUVA if YUV formats are output.
>>
>> Signed-off-by: Josef Zlomek <josef@pex.com>
>> ---
>>   Changelog               |   1 +
>>   libavcodec/codec_desc.c |   3 +-
>>   libavcodec/version.h    |   2 +-
>>   libavcodec/webp.c       | 714 ++++++++++++++++++++++++++++++++++++----
>>   4 files changed, 658 insertions(+), 62 deletions(-)
>>
>> [...]
>> +
>> +            bytestream2_skip(&gb, 2); // loop count is ignored
> 
> TODO? APNG and GIF support looping and have -ignore_loop to control it.

Will look into this maybe supporting it in v2. Otherwise making it a TODO.

Thanks,
Thilo
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[FFmpeg-devel] [PATCH v1 4/4] avcodec/webp: make init_canvas_frame static

[Thilo Borgmann]

---
 libavcodec/webp.c | 143 +++++++++++++++++++++++-----------------------
 1 file changed, 71 insertions(+), 72 deletions(-)

diff --git a/libavcodec/webp.c b/libavcodec/webp.c
index bee43fcf19..d3e3f85dd3 100644
--- a/libavcodec/webp.c
+++ b/libavcodec/webp.c
@@ -1337,7 +1337,77 @@ static int vp8_lossy_decode_frame(AVCodecContext *avctx, AVFrame *p,
     }
     return ret;
 }
-int init_canvas_frame(WebPContext *s, int format, int key_frame);
+
+static int init_canvas_frame(WebPContext *s, int format, int key_frame)
+{
+    AVFrame *canvas = s->canvas_frame.f;
+    int height;
+    int ret;
+
+    // canvas is needed only for animation
+    if (!(s->vp8x_flags & VP8X_FLAG_ANIMATION))
+        return 0;
+
+    // avoid init for non-key frames whose format and size did not change
+    if (!key_frame &&
+        canvas->data[0] &&
+        canvas->format == format &&
+        canvas->width  == s->canvas_width &&
+        canvas->height == s->canvas_height)
+        return 0;
+
+    // canvas changes within IPPP sequences will loose thread sync
+    // because of the ThreadFrame reallocation and will wait forever
+    // so if frame-threading is used, forbid canvas changes and unlock
+    // previous frames
+    if (!key_frame && canvas->data[0]) {
+        if (s->avctx->thread_count > 1) {
+            av_log(s->avctx, AV_LOG_WARNING, "Canvas change detected. The output will be damaged. Use -threads 1 to try decoding with best effort.\n");
+            // unlock previous frames that have sent an _await() call
+            ff_thread_report_progress(&s->canvas_frame, INT_MAX, 0);
+            return AVERROR_PATCHWELCOME;
+        } else {
+            // warn for damaged frames
+            av_log(s->avctx, AV_LOG_WARNING, "Canvas change detected. The output will be damaged.\n");
+        }
+    }
+
+    s->avctx->pix_fmt = format;
+    canvas->format    = format;
+    canvas->width     = s->canvas_width;
+    canvas->height    = s->canvas_height;
+
+    // VP8 decoder changed the width and height in AVCodecContext.
+    // Change it back to the canvas size.
+    ret = ff_set_dimensions(s->avctx, s->canvas_width, s->canvas_height);
+    if (ret < 0)
+        return ret;
+
+    ff_thread_release_ext_buffer(s->avctx, &s->canvas_frame);
+    ret = ff_thread_get_ext_buffer(s->avctx, &s->canvas_frame, AV_GET_BUFFER_FLAG_REF);
+    if (ret < 0)
+        return ret;
+
+    if (canvas->format == AV_PIX_FMT_ARGB) {
+        height = canvas->height;
+        memset(canvas->data[0], 0, height * canvas->linesize[0]);
+    } else /* if (canvas->format == AV_PIX_FMT_YUVA420P) */ {
+        const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(canvas->format);
+        for (int comp = 0; comp < desc->nb_components; comp++) {
+            int plane = desc->comp[comp].plane;
+
+            if (comp == 1 || comp == 2)
+                height = AV_CEIL_RSHIFT(canvas->height, desc->log2_chroma_h);
+            else
+                height = FFALIGN(canvas->height, 1 << desc->log2_chroma_h);
+
+            memset(canvas->data[plane], s->transparent_yuva[plane],
+                   height * canvas->linesize[plane]);
+        }
+    }
+
+    return 0;
+}
 
 static int webp_decode_frame_common(AVCodecContext *avctx, uint8_t *data, int size,
                                int *got_frame, int key_frame)
@@ -1577,77 +1647,6 @@ exif_end:
     return size;
 }
 
-int init_canvas_frame(WebPContext *s, int format, int key_frame)
-{
-    AVFrame *canvas = s->canvas_frame.f;
-    int height;
-    int ret;
-
-    // canvas is needed only for animation
-    if (!(s->vp8x_flags & VP8X_FLAG_ANIMATION))
-        return 0;
-
-    // avoid init for non-key frames whose format and size did not change
-    if (!key_frame &&
-        canvas->data[0] &&
-        canvas->format == format &&
-        canvas->width  == s->canvas_width &&
-        canvas->height == s->canvas_height)
-        return 0;
-
-    // canvas changes within IPPP sequences will loose thread sync
-    // because of the ThreadFrame reallocation and will wait forever
-    // so if frame-threading is used, forbid canvas changes and unlock
-    // previous frames
-    if (!key_frame && canvas->data[0]) {
-        if (s->avctx->thread_count > 1) {
-            av_log(s->avctx, AV_LOG_WARNING, "Canvas change detected. The output will be damaged. Use -threads 1 to try decoding with best effort.\n");
-            // unlock previous frames that have sent an _await() call
-            ff_thread_report_progress(&s->canvas_frame, INT_MAX, 0);
-            return AVERROR_PATCHWELCOME;
-        } else {
-            // warn for damaged frames
-            av_log(s->avctx, AV_LOG_WARNING, "Canvas change detected. The output will be damaged.\n");
-        }
-    }
-
-    s->avctx->pix_fmt = format;
-    canvas->format    = format;
-    canvas->width     = s->canvas_width;
-    canvas->height    = s->canvas_height;
-
-    // VP8 decoder changed the width and height in AVCodecContext.
-    // Change it back to the canvas size.
-    ret = ff_set_dimensions(s->avctx, s->canvas_width, s->canvas_height);
-    if (ret < 0)
-        return ret;
-
-    ff_thread_release_ext_buffer(s->avctx, &s->canvas_frame);
-    ret = ff_thread_get_ext_buffer(s->avctx, &s->canvas_frame, AV_GET_BUFFER_FLAG_REF);
-    if (ret < 0)
-        return ret;
-
-    if (canvas->format == AV_PIX_FMT_ARGB) {
-        height = canvas->height;
-        memset(canvas->data[0], 0, height * canvas->linesize[0]);
-    } else /* if (canvas->format == AV_PIX_FMT_YUVA420P) */ {
-        const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(canvas->format);
-        for (int comp = 0; comp < desc->nb_components; comp++) {
-            int plane = desc->comp[comp].plane;
-
-            if (comp == 1 || comp == 2)
-                height = AV_CEIL_RSHIFT(canvas->height, desc->log2_chroma_h);
-            else
-                height = FFALIGN(canvas->height, 1 << desc->log2_chroma_h);
-
-            memset(canvas->data[plane], s->transparent_yuva[plane],
-                   height * canvas->linesize[plane]);
-        }
-    }
-
-    return 0;
-}
-
 /*
  * Blend src1 (foreground) and src2 (background) into dest, in ARGB format.
  * width, height are the dimensions of src1
-- 
2.37.1 (Apple Git-137.1)

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Re: [FFmpeg-devel] [PATCH v1 4/4] avcodec/webp: make init_canvas_frame static

[James Zern]

On Thu, Jun 8, 2023 at 7:21 AM Thilo Borgmann <thilo.borgmann@mail.de> wrote:
>
> ---
>  libavcodec/webp.c | 143 +++++++++++++++++++++++-----------------------
>  1 file changed, 71 insertions(+), 72 deletions(-)
>

lgtm.
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Re: [FFmpeg-devel] [PATCH v1 4/4] avcodec/webp: make init_canvas_frame static

[Andreas Rheinhardt]

Thilo Borgmann:
> ---
>  libavcodec/webp.c | 143 +++++++++++++++++++++++-----------------------
>  1 file changed, 71 insertions(+), 72 deletions(-)
> 
> diff --git a/libavcodec/webp.c b/libavcodec/webp.c
> index bee43fcf19..d3e3f85dd3 100644
> --- a/libavcodec/webp.c
> +++ b/libavcodec/webp.c
> @@ -1337,7 +1337,77 @@ static int vp8_lossy_decode_frame(AVCodecContext *avctx, AVFrame *p,
>      }
>      return ret;
>  }
> -int init_canvas_frame(WebPContext *s, int format, int key_frame);
> +
> +static int init_canvas_frame(WebPContext *s, int format, int key_frame)
> +{
> +    AVFrame *canvas = s->canvas_frame.f;
> +    int height;
> +    int ret;
> +
> +    // canvas is needed only for animation
> +    if (!(s->vp8x_flags & VP8X_FLAG_ANIMATION))
> +        return 0;
> +
> +    // avoid init for non-key frames whose format and size did not change
> +    if (!key_frame &&
> +        canvas->data[0] &&
> +        canvas->format == format &&
> +        canvas->width  == s->canvas_width &&
> +        canvas->height == s->canvas_height)
> +        return 0;
> +
> +    // canvas changes within IPPP sequences will loose thread sync
> +    // because of the ThreadFrame reallocation and will wait forever
> +    // so if frame-threading is used, forbid canvas changes and unlock
> +    // previous frames
> +    if (!key_frame && canvas->data[0]) {
> +        if (s->avctx->thread_count > 1) {
> +            av_log(s->avctx, AV_LOG_WARNING, "Canvas change detected. The output will be damaged. Use -threads 1 to try decoding with best effort.\n");
> +            // unlock previous frames that have sent an _await() call
> +            ff_thread_report_progress(&s->canvas_frame, INT_MAX, 0);
> +            return AVERROR_PATCHWELCOME;
> +        } else {
> +            // warn for damaged frames
> +            av_log(s->avctx, AV_LOG_WARNING, "Canvas change detected. The output will be damaged.\n");
> +        }
> +    }
> +
> +    s->avctx->pix_fmt = format;
> +    canvas->format    = format;
> +    canvas->width     = s->canvas_width;
> +    canvas->height    = s->canvas_height;
> +
> +    // VP8 decoder changed the width and height in AVCodecContext.
> +    // Change it back to the canvas size.
> +    ret = ff_set_dimensions(s->avctx, s->canvas_width, s->canvas_height);
> +    if (ret < 0)
> +        return ret;
> +
> +    ff_thread_release_ext_buffer(s->avctx, &s->canvas_frame);
> +    ret = ff_thread_get_ext_buffer(s->avctx, &s->canvas_frame, AV_GET_BUFFER_FLAG_REF);
> +    if (ret < 0)
> +        return ret;
> +
> +    if (canvas->format == AV_PIX_FMT_ARGB) {
> +        height = canvas->height;
> +        memset(canvas->data[0], 0, height * canvas->linesize[0]);
> +    } else /* if (canvas->format == AV_PIX_FMT_YUVA420P) */ {
> +        const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(canvas->format);
> +        for (int comp = 0; comp < desc->nb_components; comp++) {
> +            int plane = desc->comp[comp].plane;
> +
> +            if (comp == 1 || comp == 2)
> +                height = AV_CEIL_RSHIFT(canvas->height, desc->log2_chroma_h);
> +            else
> +                height = FFALIGN(canvas->height, 1 << desc->log2_chroma_h);
> +
> +            memset(canvas->data[plane], s->transparent_yuva[plane],
> +                   height * canvas->linesize[plane]);
> +        }
> +    }
> +
> +    return 0;
> +}
>  
>  static int webp_decode_frame_common(AVCodecContext *avctx, uint8_t *data, int size,
>                                 int *got_frame, int key_frame)
> @@ -1577,77 +1647,6 @@ exif_end:
>      return size;
>  }
>  
> -int init_canvas_frame(WebPContext *s, int format, int key_frame)
> -{
> -    AVFrame *canvas = s->canvas_frame.f;
> -    int height;
> -    int ret;
> -
> -    // canvas is needed only for animation
> -    if (!(s->vp8x_flags & VP8X_FLAG_ANIMATION))
> -        return 0;
> -
> -    // avoid init for non-key frames whose format and size did not change
> -    if (!key_frame &&
> -        canvas->data[0] &&
> -        canvas->format == format &&
> -        canvas->width  == s->canvas_width &&
> -        canvas->height == s->canvas_height)
> -        return 0;
> -
> -    // canvas changes within IPPP sequences will loose thread sync
> -    // because of the ThreadFrame reallocation and will wait forever
> -    // so if frame-threading is used, forbid canvas changes and unlock
> -    // previous frames
> -    if (!key_frame && canvas->data[0]) {
> -        if (s->avctx->thread_count > 1) {
> -            av_log(s->avctx, AV_LOG_WARNING, "Canvas change detected. The output will be damaged. Use -threads 1 to try decoding with best effort.\n");
> -            // unlock previous frames that have sent an _await() call
> -            ff_thread_report_progress(&s->canvas_frame, INT_MAX, 0);
> -            return AVERROR_PATCHWELCOME;
> -        } else {
> -            // warn for damaged frames
> -            av_log(s->avctx, AV_LOG_WARNING, "Canvas change detected. The output will be damaged.\n");
> -        }
> -    }
> -
> -    s->avctx->pix_fmt = format;
> -    canvas->format    = format;
> -    canvas->width     = s->canvas_width;
> -    canvas->height    = s->canvas_height;
> -
> -    // VP8 decoder changed the width and height in AVCodecContext.
> -    // Change it back to the canvas size.
> -    ret = ff_set_dimensions(s->avctx, s->canvas_width, s->canvas_height);
> -    if (ret < 0)
> -        return ret;
> -
> -    ff_thread_release_ext_buffer(s->avctx, &s->canvas_frame);
> -    ret = ff_thread_get_ext_buffer(s->avctx, &s->canvas_frame, AV_GET_BUFFER_FLAG_REF);
> -    if (ret < 0)
> -        return ret;
> -
> -    if (canvas->format == AV_PIX_FMT_ARGB) {
> -        height = canvas->height;
> -        memset(canvas->data[0], 0, height * canvas->linesize[0]);
> -    } else /* if (canvas->format == AV_PIX_FMT_YUVA420P) */ {
> -        const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(canvas->format);
> -        for (int comp = 0; comp < desc->nb_components; comp++) {
> -            int plane = desc->comp[comp].plane;
> -
> -            if (comp == 1 || comp == 2)
> -                height = AV_CEIL_RSHIFT(canvas->height, desc->log2_chroma_h);
> -            else
> -                height = FFALIGN(canvas->height, 1 << desc->log2_chroma_h);
> -
> -            memset(canvas->data[plane], s->transparent_yuva[plane],
> -                   height * canvas->linesize[plane]);
> -        }
> -    }
> -
> -    return 0;
> -}
> -
>  /*
>   * Blend src1 (foreground) and src2 (background) into dest, in ARGB format.
>   * width, height are the dimensions of src1

You add this function in the preceding patch. So why don't you do it
properly instead of fixing this up later?

- Andreas

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Re: [FFmpeg-devel] [PATCH v1 4/4] avcodec/webp: make init_canvas_frame static

[Thilo Borgmann]

Am 14.06.23 um 11:42 schrieb Andreas Rheinhardt:
> Thilo Borgmann:
>> ---
>>   libavcodec/webp.c | 143 +++++++++++++++++++++++-----------------------
>>   1 file changed, 71 insertions(+), 72 deletions(-)
>>
>> diff --git a/libavcodec/webp.c b/libavcodec/webp.c
>> index bee43fcf19..d3e3f85dd3 100644
>> --- a/libavcodec/webp.c
>> +++ b/libavcodec/webp.c
>> @@ -1337,7 +1337,77 @@ static int vp8_lossy_decode_frame(AVCodecContext *avctx, AVFrame *p,
>>       }
>>       return ret;
>>   }
>> -int init_canvas_frame(WebPContext *s, int format, int key_frame);
>> +
>> +static int init_canvas_frame(WebPContext *s, int format, int key_frame)
>> +{
>> +    AVFrame *canvas = s->canvas_frame.f;
>> +    int height;
>> +    int ret;
>> +
>> +    // canvas is needed only for animation
>> +    if (!(s->vp8x_flags & VP8X_FLAG_ANIMATION))
>> +        return 0;
>> +
>> +    // avoid init for non-key frames whose format and size did not change
>> +    if (!key_frame &&
>> +        canvas->data[0] &&
>> +        canvas->format == format &&
>> +        canvas->width  == s->canvas_width &&
>> +        canvas->height == s->canvas_height)
>> +        return 0;
>> +
>> +    // canvas changes within IPPP sequences will loose thread sync
>> +    // because of the ThreadFrame reallocation and will wait forever
>> +    // so if frame-threading is used, forbid canvas changes and unlock
>> +    // previous frames
>> +    if (!key_frame && canvas->data[0]) {
>> +        if (s->avctx->thread_count > 1) {
>> +            av_log(s->avctx, AV_LOG_WARNING, "Canvas change detected. The output will be damaged. Use -threads 1 to try decoding with best effort.\n");
>> +            // unlock previous frames that have sent an _await() call
>> +            ff_thread_report_progress(&s->canvas_frame, INT_MAX, 0);
>> +            return AVERROR_PATCHWELCOME;
>> +        } else {
>> +            // warn for damaged frames
>> +            av_log(s->avctx, AV_LOG_WARNING, "Canvas change detected. The output will be damaged.\n");
>> +        }
>> +    }
>> +
>> +    s->avctx->pix_fmt = format;
>> +    canvas->format    = format;
>> +    canvas->width     = s->canvas_width;
>> +    canvas->height    = s->canvas_height;
>> +
>> +    // VP8 decoder changed the width and height in AVCodecContext.
>> +    // Change it back to the canvas size.
>> +    ret = ff_set_dimensions(s->avctx, s->canvas_width, s->canvas_height);
>> +    if (ret < 0)
>> +        return ret;
>> +
>> +    ff_thread_release_ext_buffer(s->avctx, &s->canvas_frame);
>> +    ret = ff_thread_get_ext_buffer(s->avctx, &s->canvas_frame, AV_GET_BUFFER_FLAG_REF);
>> +    if (ret < 0)
>> +        return ret;
>> +
>> +    if (canvas->format == AV_PIX_FMT_ARGB) {
>> +        height = canvas->height;
>> +        memset(canvas->data[0], 0, height * canvas->linesize[0]);
>> +    } else /* if (canvas->format == AV_PIX_FMT_YUVA420P) */ {
>> +        const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(canvas->format);
>> +        for (int comp = 0; comp < desc->nb_components; comp++) {
>> +            int plane = desc->comp[comp].plane;
>> +
>> +            if (comp == 1 || comp == 2)
>> +                height = AV_CEIL_RSHIFT(canvas->height, desc->log2_chroma_h);
>> +            else
>> +                height = FFALIGN(canvas->height, 1 << desc->log2_chroma_h);
>> +
>> +            memset(canvas->data[plane], s->transparent_yuva[plane],
>> +                   height * canvas->linesize[plane]);
>> +        }
>> +    }
>> +
>> +    return 0;
>> +}
>>   
>>   static int webp_decode_frame_common(AVCodecContext *avctx, uint8_t *data, int size,
>>                                  int *got_frame, int key_frame)
>> @@ -1577,77 +1647,6 @@ exif_end:
>>       return size;
>>   }
>>   
>> -int init_canvas_frame(WebPContext *s, int format, int key_frame)
>> -{
>> -    AVFrame *canvas = s->canvas_frame.f;
>> -    int height;
>> -    int ret;
>> -
>> -    // canvas is needed only for animation
>> -    if (!(s->vp8x_flags & VP8X_FLAG_ANIMATION))
>> -        return 0;
>> -
>> -    // avoid init for non-key frames whose format and size did not change
>> -    if (!key_frame &&
>> -        canvas->data[0] &&
>> -        canvas->format == format &&
>> -        canvas->width  == s->canvas_width &&
>> -        canvas->height == s->canvas_height)
>> -        return 0;
>> -
>> -    // canvas changes within IPPP sequences will loose thread sync
>> -    // because of the ThreadFrame reallocation and will wait forever
>> -    // so if frame-threading is used, forbid canvas changes and unlock
>> -    // previous frames
>> -    if (!key_frame && canvas->data[0]) {
>> -        if (s->avctx->thread_count > 1) {
>> -            av_log(s->avctx, AV_LOG_WARNING, "Canvas change detected. The output will be damaged. Use -threads 1 to try decoding with best effort.\n");
>> -            // unlock previous frames that have sent an _await() call
>> -            ff_thread_report_progress(&s->canvas_frame, INT_MAX, 0);
>> -            return AVERROR_PATCHWELCOME;
>> -        } else {
>> -            // warn for damaged frames
>> -            av_log(s->avctx, AV_LOG_WARNING, "Canvas change detected. The output will be damaged.\n");
>> -        }
>> -    }
>> -
>> -    s->avctx->pix_fmt = format;
>> -    canvas->format    = format;
>> -    canvas->width     = s->canvas_width;
>> -    canvas->height    = s->canvas_height;
>> -
>> -    // VP8 decoder changed the width and height in AVCodecContext.
>> -    // Change it back to the canvas size.
>> -    ret = ff_set_dimensions(s->avctx, s->canvas_width, s->canvas_height);
>> -    if (ret < 0)
>> -        return ret;
>> -
>> -    ff_thread_release_ext_buffer(s->avctx, &s->canvas_frame);
>> -    ret = ff_thread_get_ext_buffer(s->avctx, &s->canvas_frame, AV_GET_BUFFER_FLAG_REF);
>> -    if (ret < 0)
>> -        return ret;
>> -
>> -    if (canvas->format == AV_PIX_FMT_ARGB) {
>> -        height = canvas->height;
>> -        memset(canvas->data[0], 0, height * canvas->linesize[0]);
>> -    } else /* if (canvas->format == AV_PIX_FMT_YUVA420P) */ {
>> -        const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(canvas->format);
>> -        for (int comp = 0; comp < desc->nb_components; comp++) {
>> -            int plane = desc->comp[comp].plane;
>> -
>> -            if (comp == 1 || comp == 2)
>> -                height = AV_CEIL_RSHIFT(canvas->height, desc->log2_chroma_h);
>> -            else
>> -                height = FFALIGN(canvas->height, 1 << desc->log2_chroma_h);
>> -
>> -            memset(canvas->data[plane], s->transparent_yuva[plane],
>> -                   height * canvas->linesize[plane]);
>> -        }
>> -    }
>> -
>> -    return 0;
>> -}
>> -
>>   /*
>>    * Blend src1 (foreground) and src2 (background) into dest, in ARGB format.
>>    * width, height are the dimensions of src1
> 
> You add this function in the preceding patch. So why don't you do it
> properly instead of fixing this up later?

Done for Anton's remark in the last iteration to make the patch reviewable.

webp_decode_frame() was renamed into webp_decode_frame_common() which makes 
patch 3/4 very unreadable as the - lines do not correspond to the + lines, 
making it very hard/impossible to review.

Moving init_canvas_frame() out of the way into another place in the file 
resolves this mangling up of the patch so that the changes in 
webp:decode_frame_common() become readable again.

I could totally stash patch 4/4 into 3/4 before pushing if you want the history 
less readable but cleaner.

Thanks,
Thilo
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Re: [FFmpeg-devel] [PATCH v1 0/4] webp: add support for animated WebP decoding

[James Zern]

On Thu, Jun 8, 2023 at 7:20 AM Thilo Borgmann <thilo.borgmann@mail.de> wrote:
>
> Follow-up to [1], the decoder only.
>
> In [1] we found a hanging sample. In frame-threading, this led to an
> infinite wait, damaged frames otherwise. So warn acordingly and do
> best-effort in single-thread mode.
>
> Also split into more patches to make reviewing easier.
>
> [1] http://ffmpeg.org/pipermail/ffmpeg-devel/2023-April/308965.html
>
> Josef Zlomek (1):
>   libavcodec/webp: add support for animated WebP decoding
>
> Thilo Borgmann (3):
>   avcodec/webp: move definitions into header
>   avcodec/webp_parser: parse each frame into one packet
>   avcodec/webp: make init_canvas_frame static
>
>  Changelog                |   1 +
>  libavcodec/codec_desc.c  |   3 +-
>  libavcodec/version.h     |   2 +-
>  libavcodec/webp.c        | 724 +++++++++++++++++++++++++++++++++++----
>  libavcodec/webp.h        |  55 +++
>  libavcodec/webp_parser.c | 132 ++++---
>  6 files changed, 800 insertions(+), 117 deletions(-)
>  create mode 100644 libavcodec/webp.h
>

This has a few rendering / framerate issues. I'll send you some samples.
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