[FFmpeg-devel] [PATCH v8 1/2] avcodec/pngenc: support writing iCCP chunks

[Niklas Haas <ffmpeg@haasn.xyz>]

From: Niklas Haas <git@haasn.dev>

We re-use the PNGEncContext.zstream for deflate-related operations.
Other than that, the code is pretty straightforward. Special care needs
to be taken to avoid writing more than 79 characters of the profile
description (the maximum supported).

To write the (dynamically sized) deflate-encoded data, we allocate extra
space in the packet and use that directly as a scratch buffer. Modify
png_write_chunk slightly to allow pre-writing the chunk contents like
this.

Also add a FATE transcode test to ensure that the ICC profile gets
encoded correctly.

Signed-off-by: Niklas Haas <git@haasn.dev>
---
 libavcodec/pngenc.c    | 84 +++++++++++++++++++++++++++++++++++++++++-
 tests/fate/image.mak   | 10 ++++-
 tests/ref/fate/png-icc | 43 +++++++++++++++++++++
 3 files changed, 133 insertions(+), 4 deletions(-)
 create mode 100644 tests/ref/fate/png-icc

diff --git a/libavcodec/pngenc.c b/libavcodec/pngenc.c
index f67f90cd14..47a5ede888 100644
--- a/libavcodec/pngenc.c
+++ b/libavcodec/pngenc.c
@@ -236,7 +236,8 @@ static void png_write_chunk(uint8_t **f, uint32_t tag,
     bytestream_put_be32(f, av_bswap32(tag));
     if (length > 0) {
         crc = av_crc(crc_table, crc, buf, length);
-        memcpy(*f, buf, length);
+        if (*f != buf)
+            memcpy(*f, buf, length);
         *f += length;
     }
     bytestream_put_be32(f, ~crc);
@@ -345,10 +346,53 @@ static int png_get_gama(enum AVColorTransferCharacteristic trc, uint8_t *buf)
     return 1;
 }
 
+static int png_write_iccp(PNGEncContext *s, const AVFrameSideData *sd)
+{
+    z_stream *const zstream = &s->zstream.zstream;
+    const AVDictionaryEntry *entry;
+    const char *name;
+    uint8_t *start, *buf;
+    int ret;
+
+    if (!sd || !sd->size)
+        return 0;
+    zstream->next_in  = sd->data;
+    zstream->avail_in = sd->size;
+
+    /* write the chunk contents first */
+    start = s->bytestream + 8; /* make room for iCCP tag + length */
+    buf = start;
+
+    /* profile description */
+    entry = av_dict_get(sd->metadata, "name", NULL, 0);
+    name = (entry && entry->value[0]) ? entry->value : "icc";
+    for (int i = 0;; i++) {
+        char c = (i == 79) ? 0 : name[i];
+        bytestream_put_byte(&buf, c);
+        if (!c)
+            break;
+    }
+
+    /* compression method and profile data */
+    bytestream_put_byte(&buf, 0);
+    zstream->next_out  = buf;
+    zstream->avail_out = s->bytestream_end - buf;
+    ret = deflate(zstream, Z_FINISH);
+    deflateReset(zstream);
+    if (ret != Z_STREAM_END)
+        return AVERROR_EXTERNAL;
+
+    /* rewind to the start and write the chunk header/crc */
+    png_write_chunk(&s->bytestream, MKTAG('i', 'C', 'C', 'P'), start,
+                    zstream->next_out - start);
+    return 0;
+}
+
 static int encode_headers(AVCodecContext *avctx, const AVFrame *pict)
 {
     AVFrameSideData *side_data;
     PNGEncContext *s = avctx->priv_data;
+    int ret;
 
     /* write png header */
     AV_WB32(s->buf, avctx->width);
@@ -401,7 +445,11 @@ static int encode_headers(AVCodecContext *avctx, const AVFrame *pict)
     if (png_get_gama(pict->color_trc, s->buf))
         png_write_chunk(&s->bytestream, MKTAG('g', 'A', 'M', 'A'), s->buf, 4);
 
-    /* put the palette if needed */
+    side_data = av_frame_get_side_data(pict, AV_FRAME_DATA_ICC_PROFILE);
+    if ((ret = png_write_iccp(s, side_data)))
+        return ret;
+
+    /* put the palette if needed, must be after colorspace information */
     if (s->color_type == PNG_COLOR_TYPE_PALETTE) {
         int has_alpha, alpha, i;
         unsigned int v;
@@ -525,6 +573,34 @@ the_end:
     return ret;
 }
 
+static int add_icc_profile_size(AVCodecContext *avctx, const AVFrame *pict,
+                                uint64_t *max_packet_size)
+{
+    PNGEncContext *s = avctx->priv_data;
+    const AVFrameSideData *sd;
+    const int hdr_size = 128;
+    uint64_t new_pkt_size;
+    uLong bound;
+
+    if (!pict)
+        return 0;
+    sd = av_frame_get_side_data(pict, AV_FRAME_DATA_ICC_PROFILE);
+    if (!sd || !sd->size)
+        return 0;
+    if (sd->size != (uLong) sd->size)
+        return AVERROR_INVALIDDATA;
+
+    bound = deflateBound(&s->zstream.zstream, sd->size);
+    if (bound > INT32_MAX - hdr_size)
+        return AVERROR_INVALIDDATA;
+
+    new_pkt_size = *max_packet_size + bound + hdr_size;
+    if (new_pkt_size < *max_packet_size)
+        return AVERROR_INVALIDDATA;
+    *max_packet_size = new_pkt_size;
+    return 0;
+}
+
 static int encode_png(AVCodecContext *avctx, AVPacket *pkt,
                       const AVFrame *pict, int *got_packet)
 {
@@ -541,6 +617,8 @@ static int encode_png(AVCodecContext *avctx, AVPacket *pkt,
             enc_row_size +
             12 * (((int64_t)enc_row_size + IOBUF_SIZE - 1) / IOBUF_SIZE) // IDAT * ceil(enc_row_size / IOBUF_SIZE)
         );
+    if ((ret = add_icc_profile_size(avctx, pict, &max_packet_size)))
+        return ret;
     ret = ff_alloc_packet(avctx, pkt, max_packet_size);
     if (ret < 0)
         return ret;
@@ -870,6 +948,8 @@ static int encode_apng(AVCodecContext *avctx, AVPacket *pkt,
             enc_row_size +
             (4 + 12) * (((int64_t)enc_row_size + IOBUF_SIZE - 1) / IOBUF_SIZE) // fdAT * ceil(enc_row_size / IOBUF_SIZE)
         );
+    if ((ret = add_icc_profile_size(avctx, pict, &max_packet_size)))
+        return ret;
     if (max_packet_size > INT_MAX)
         return AVERROR(ENOMEM);
 
diff --git a/tests/fate/image.mak b/tests/fate/image.mak
index 573d398915..c6374c7d8a 100644
--- a/tests/fate/image.mak
+++ b/tests/fate/image.mak
@@ -385,11 +385,15 @@ FATE_PNG_PROBE += fate-png-side-data
 fate-png-side-data: CMD = run ffprobe$(PROGSSUF)$(EXESUF) -show_frames \
     -i $(TARGET_SAMPLES)/png1/lena-int_rgb24.png
 
+FATE_PNG_TRANSCODE-$(call ENCDEC, PNG, IMAGE2) += fate-png-icc
+fate-png-icc: CMD = transcode png_pipe $(TARGET_SAMPLES)/png1/lena-int_rgb24.png image2 "-c png" "" "" "-show_frames"
+
 FATE_PNG-$(call DEMDEC, IMAGE2, PNG) += $(FATE_PNG)
 FATE_PNG_PROBE-$(call DEMDEC, IMAGE2, PNG) += $(FATE_PNG_PROBE)
 FATE_IMAGE += $(FATE_PNG-yes)
 FATE_IMAGE_PROBE += $(FATE_PNG_PROBE-yes)
-fate-png: $(FATE_PNG-yes) $(FATE_PNG_PROBE-yes)
+FATE_IMAGE_TRANSCODE += $(FATE_PNG_TRANSCODE-yes)
+fate-png: $(FATE_PNG-yes) $(FATE_PNG_PROBE-yes) $(FATE_PNG_TRANSCODE-yes)
 
 FATE_IMAGE-$(call DEMDEC, IMAGE2, PTX) += fate-ptx
 fate-ptx: CMD = framecrc -i $(TARGET_SAMPLES)/ptx/_113kw_pic.ptx -pix_fmt rgb24 -vf scale
@@ -551,8 +555,10 @@ fate-xbm: $(FATE_XBM-yes)
 
 FATE_IMAGE += $(FATE_IMAGE-yes)
 FATE_IMAGE_PROBE += $(FATE_IMAGE_PROBE-yes)
+FATE_IMAGE_TRANSCODE += $(FATE_IMAGE_TRANSCODE-yes)
 
 FATE_SAMPLES_FFMPEG += $(FATE_IMAGE)
 FATE_SAMPLES_FFPROBE += $(FATE_IMAGE_PROBE)
+FATE_SAMPLES_FFMPEG_FFPROBE += $(FATE_IMAGE_TRANSCODE)
 
-fate-image: $(FATE_IMAGE) $(FATE_IMAGE_PROBE)
+fate-image: $(FATE_IMAGE) $(FATE_IMAGE_PROBE) $(FATE_IMAGE_TRANSCODE)
diff --git a/tests/ref/fate/png-icc b/tests/ref/fate/png-icc
new file mode 100644
index 0000000000..542bb76f9a
--- /dev/null
+++ b/tests/ref/fate/png-icc
@@ -0,0 +1,43 @@
+a50d37a0e72bddea2fcbba6fb773e2a0 *tests/data/fate/png-icc.image2
+49397 tests/data/fate/png-icc.image2
+#tb 0: 1/25
+#media_type 0: video
+#codec_id 0: rawvideo
+#dimensions 0: 128x128
+#sar 0: 2835/2835
+0,          0,          0,        1,    49152, 0xe0013dee
+[FRAME]
+media_type=video
+stream_index=0
+key_frame=1
+pts=0
+pts_time=0.000000
+pkt_dts=0
+pkt_dts_time=0.000000
+best_effort_timestamp=0
+best_effort_timestamp_time=0.000000
+pkt_duration=1
+pkt_duration_time=0.040000
+pkt_pos=0
+pkt_size=49397
+width=128
+height=128
+pix_fmt=rgb24
+sample_aspect_ratio=1:1
+pict_type=I
+coded_picture_number=0
+display_picture_number=0
+interlaced_frame=0
+top_field_first=0
+repeat_pict=0
+color_range=pc
+color_space=unknown
+color_primaries=unknown
+color_transfer=unknown
+chroma_location=unspecified
+[SIDE_DATA]
+side_data_type=ICC profile
+name=Photoshop ICC profile
+size=3144
+[/SIDE_DATA]
+[/FRAME]
-- 
2.35.1

_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
https://ffmpeg.org/mailman/listinfo/ffmpeg-devel

To unsubscribe, visit link above, or email
ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".