[FFmpeg-devel] [PATCH 1/3] avcodec/sanm: ignore unknown codecs in FOBJs

[FFmpeg-devel] [PATCH 1/3] avcodec/sanm: ignore unknown codecs in FOBJs

[Manuel Lauss]

Don't error out, just ignore unknown codec numbers and pretend
decode succeeded.  This is useful for older LucasArts titles
which stack a lot of different FOBJs with different codecs into
a single frame.

Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
---
 libavcodec/sanm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavcodec/sanm.c b/libavcodec/sanm.c
index c30095ed32..37d2c915d4 100644
--- a/libavcodec/sanm.c
+++ b/libavcodec/sanm.c
@@ -1274,7 +1274,7 @@ static int process_frame_obj(SANMVideoContext *ctx)
         return old_codec48(ctx, w, h);
     default:
         avpriv_request_sample(ctx->avctx, "Subcodec %d", codec);
-        return AVERROR_PATCHWELCOME;
+        return 0;
     }
 }
 
-- 
2.48.1

_______________________________________________
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".

[FFmpeg-devel] [PATCH 2/3] avcodec/sanm: fobj left/top are signed

[Manuel Lauss]

The left and top parameters of an FOBJ are signed values.

Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
---
 libavcodec/sanm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavcodec/sanm.c b/libavcodec/sanm.c
index 37d2c915d4..0e7cd292d0 100644
--- a/libavcodec/sanm.c
+++ b/libavcodec/sanm.c
@@ -1238,8 +1238,8 @@ static int old_codec48(SANMVideoContext *ctx, int width, int height)
 static int process_frame_obj(SANMVideoContext *ctx)
 {
     uint16_t codec = bytestream2_get_le16u(&ctx->gb);
-    uint16_t left  = bytestream2_get_le16u(&ctx->gb);
-    uint16_t top   = bytestream2_get_le16u(&ctx->gb);
+    int16_t  left  = bytestream2_get_le16u(&ctx->gb);
+    int16_t  top   = bytestream2_get_le16u(&ctx->gb);
     uint16_t w     = bytestream2_get_le16u(&ctx->gb);
     uint16_t h     = bytestream2_get_le16u(&ctx->gb);
 
-- 
2.48.1

_______________________________________________
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".

[FFmpeg-devel] [PATCH 3/3] avcodec/sanm: add smush codec23 decoder

[Manuel Lauss]

This codec alternatingly skips and changes existing pixels.
A second 16bit parameter in the FOBJ header indicates how to do
the pixel changes: either by specifying a LUT in the codec datastream
or by adding a constant value to the pixel.

Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
---
Videos showing the before/after state (Rebel Assault II LEV09/09PLAY.SAN file)
http://mlau.at/ffmpeg_c23_before.mp4
http://mlau.at/ffmpeg_c23_after.mp4
notice the blue transparent forcefields.

 libavcodec/sanm.c | 62 +++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 60 insertions(+), 2 deletions(-)

diff --git a/libavcodec/sanm.c b/libavcodec/sanm.c
index 0e7cd292d0..fb055b61c7 100644
--- a/libavcodec/sanm.c
+++ b/libavcodec/sanm.c
@@ -292,6 +292,7 @@ typedef struct SANMVideoContext {
     int8_t p4x4glyphs[NGLYPHS][16];
     int8_t p8x8glyphs[NGLYPHS][64];
     uint8_t c47itbl[0x10000];
+    uint8_t c23lut[256];
 } SANMVideoContext;
 
 typedef struct SANMFrameHeader {
@@ -555,6 +556,58 @@ static int rle_decode(SANMVideoContext *ctx, uint8_t *dst, const int out_size)
     return 0;
 }
 
+static int old_codec23(SANMVideoContext *ctx, int top, int left, int width,
+                       int height, uint8_t param, uint16_t param2)
+{
+    const uint32_t maxpxo = ctx->width * ctx->pitch;
+    uint8_t *dst, lut[256], c;
+    int i, j, k, pc, sk;
+    int32_t pxoff;
+
+    if (param2 == 256) {
+        if (bytestream2_get_bytes_left(&ctx->gb) < 256)
+            return AVERROR_INVALIDDATA;
+        bytestream2_get_bufferu(&ctx->gb, ctx->c23lut, 256);
+    } else if (param2 < 256) {
+        for (i = 0; i < 256; i++)
+            lut[i] = (i + param2) & 0xff;
+    } else {
+        memcpy(lut, ctx->c23lut, 256);
+    }
+    if (bytestream2_get_bytes_left(&ctx->gb) < 1)
+        return 0;  /* some c23 frames just set up the LUT */
+
+    dst = (uint8_t *)ctx->frm0;
+    for (i = 0; i < height; i++) {
+        if (bytestream2_get_bytes_left(&ctx->gb) < 2)
+            return 0;
+        pxoff = left + ((top + i) * ctx->pitch);
+        k = bytestream2_get_le16u(&ctx->gb);
+        sk = 1;
+        pc = 0;
+        while (k > 0 && pc <= width) {
+            if (bytestream2_get_bytes_left(&ctx->gb) < 1)
+                return AVERROR_INVALIDDATA;
+            j = bytestream2_get_byteu(&ctx->gb);
+            if (sk) {
+                pxoff += j;
+                pc += j;
+            } else {
+                while (j--) {
+                    if (pxoff >=0 && pxoff < maxpxo) {
+                        c = *(dst + pxoff);
+                        *(dst + pxoff) = lut[c];
+                    }
+                    pxoff++;
+                    pc++;
+                }
+            }
+            sk ^= 1;
+        }
+    }
+    return 0;
+}
+
 static int old_codec1(SANMVideoContext *ctx, int top,
                       int left, int width, int height)
 {
@@ -1237,11 +1290,15 @@ static int old_codec48(SANMVideoContext *ctx, int width, int height)
 
 static int process_frame_obj(SANMVideoContext *ctx)
 {
-    uint16_t codec = bytestream2_get_le16u(&ctx->gb);
+    uint16_t parm2;
+    uint8_t  codec = bytestream2_get_byteu(&ctx->gb);
+    uint8_t  param = bytestream2_get_byteu(&ctx->gb);
     int16_t  left  = bytestream2_get_le16u(&ctx->gb);
     int16_t  top   = bytestream2_get_le16u(&ctx->gb);
     uint16_t w     = bytestream2_get_le16u(&ctx->gb);
     uint16_t h     = bytestream2_get_le16u(&ctx->gb);
+    bytestream2_skip(&ctx->gb, 2);
+    parm2 = bytestream2_get_le16u(&ctx->gb);
 
     if (!w || !h) {
         av_log(ctx->avctx, AV_LOG_ERROR, "Dimensions are invalid.\n");
@@ -1260,12 +1317,13 @@ static int process_frame_obj(SANMVideoContext *ctx)
             return AVERROR(ENOMEM);
         }
     }
-    bytestream2_skip(&ctx->gb, 4);
 
     switch (codec) {
     case 1:
     case 3:
         return old_codec1(ctx, top, left, w, h);
+    case 23:
+        return old_codec23(ctx, top, left, w, h, param, parm2);
     case 37:
         return old_codec37(ctx, top, left, w, h);
     case 47:
-- 
2.48.1

_______________________________________________
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".

Re: [FFmpeg-devel] [PATCH 1/3] avcodec/sanm: ignore unknown codecs in FOBJs

[Marton Balint]

On Mon, 10 Feb 2025, Manuel Lauss wrote:

> Don't error out, just ignore unknown codec numbers and pretend
> decode succeeded.  This is useful for older LucasArts titles
> which stack a lot of different FOBJs with different codecs into
> a single frame.
>
> Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
> ---
> libavcodec/sanm.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/libavcodec/sanm.c b/libavcodec/sanm.c
> index c30095ed32..37d2c915d4 100644
> --- a/libavcodec/sanm.c
> +++ b/libavcodec/sanm.c
> @@ -1274,7 +1274,7 @@ static int process_frame_obj(SANMVideoContext *ctx)
>         return old_codec48(ctx, w, h);
>     default:
>         avpriv_request_sample(ctx->avctx, "Subcodec %d", codec);
> -        return AVERROR_PATCHWELCOME;
> +        return 0;

But if there is an unsupported FOBJ code that means that the frame might 
be only partially decoded, right? So you should set AV_FRAME_FLAG_CORRUPT 
flag in AVFrame->flags, and still log the error, not silently ignore it.

Regards,
Marton


>     }
> }
>
> -- 
> 2.48.1
>
> _______________________________________________
> 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".
>
_______________________________________________
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".

Re: [FFmpeg-devel] [PATCH 1/3] avcodec/sanm: ignore unknown codecs in FOBJs

[Manuel Lauss]

Hi Marton!


Marton Balint <cus@passwd.hu> schrieb am Mo., 10. Feb. 2025, 20:42:

>
>
> On Mon, 10 Feb 2025, Manuel Lauss wrote:
>
> > Don't error out, just ignore unknown codec numbers and pretend
> > decode succeeded.  This is useful for older LucasArts titles
> > which stack a lot of different FOBJs with different codecs into
> > a single frame.
> >
> > Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
> > ---
> > libavcodec/sanm.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/libavcodec/sanm.c b/libavcodec/sanm.c
> > index c30095ed32..37d2c915d4 100644
> > --- a/libavcodec/sanm.c
> > +++ b/libavcodec/sanm.c
> > @@ -1274,7 +1274,7 @@ static int process_frame_obj(SANMVideoContext *ctx)
> >         return old_codec48(ctx, w, h);
> >     default:
> >         avpriv_request_sample(ctx->avctx, "Subcodec %d", codec);
> > -        return AVERROR_PATCHWELCOME;
> > +        return 0;
>
> But if there is an unsupported FOBJ code that means that the frame might
> be only partially decoded, right?


Thats how the game engine works as well: A FRME can have >=0 FOBJs, all of
them skippable based on game state.
An unchanged image buffer from the previous FRME is absolutely posssible.

So you should set AV_FRAME_FLAG_CORRUPT
> flag in AVFrame->flags, and still log the error, not silently ignore it.
>

It's not corrupt per se.
While working on codec 23, the other unsupported codecs in the test videos
stop the decoding before getting to the c23 fobj.

For a lot of Rebel Assault 2  videos this patch improves playback; nothing
changes for the ones that were already supported by ffmpeg.


Regards,
> Marton
>
>
> >     }
> > }
> >
> > --
> > 2.48.1
> >
> > _______________________________________________
> > 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".
> >
> _______________________________________________
> 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".
>
_______________________________________________
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".