[vlc-commits] [Git][videolan/vlc][master] 2 commits: codec: avcodec: handle per-frame palette changes

[Steve Lhomme (@robUx4)]

Steve Lhomme pushed to branch master at VideoLAN / VLC


Commits:
81612520 by Tristan Matthews at 2026-06-16T12:21:30+00:00
codec: avcodec: handle per-frame palette changes

Previously we were only ever using the initial palette, whereas e.g. mpv and
ffmpeg correctly handle per-frame palette updates.

- - - - -
6805e458 by Tristan Matthews at 2026-06-16T12:21:30+00:00
swscale: allow for per-frame palette changes

Fixes #24859 and #25017

- - - - -


2 changed files:

- modules/codec/avcodec/video.c
- modules/video_chroma/swscale.c


Changes:

=====================================
modules/codec/avcodec/video.c
=====================================
@@ -1667,6 +1667,14 @@ static int DecodeBlock( decoder_t *p_dec, block_t **pp_block )
             }
         }
 
+        /* The palette can change on any frame; avcodec exposes the current one
+         * in frame->data[1]. The fmt_out palette and the chroma converter are
+         * only set up once (on the first frame above), so refresh the output
+         * picture's own palette every frame to keep the colors up-to-date. */
+        if( p_context->pix_fmt == AV_PIX_FMT_PAL8 && frame->data[1] != NULL
+         && p_pic->format.p_palette != NULL )
+            lavc_Frame8PaletteCopy( p_pic->format.p_palette, frame->data[1] );
+
         p_pic->date = i_pts;
         /* Hack to force display of still pictures */
         p_pic->b_force = p_sys->b_first_frame;


=====================================
modules/video_chroma/swscale.c
=====================================
@@ -673,9 +673,10 @@ static void Convert( filter_t *p_filter, struct SwsContext *ctx,
                p_src, i_plane_count, b_swap_uvi );
     if( p_filter->fmt_in.video.i_chroma == VLC_CODEC_RGBP )
     {
-        if( p_filter->fmt_in.video.p_palette )
+        /* The palette may change every picture, that's why we check it here. */
+        const video_palette_t *p_palette = p_src->format.p_palette;
+        if( p_palette )
         {
-            const video_palette_t *p_palette = p_filter->fmt_in.video.p_palette;
             static_assert(sizeof(p_palette->palette) == AVPALETTE_SIZE,
                           "Palette size mismatch between vlc and libavutil");
             uint8_t *dstp = palette;



View it on GitLab: https://code.videolan.org/videolan/vlc/-/compare/3c4953e746e19df5df04e4af36ebd17b2b73ce94...6805e4584e6bafa77dd22f26049ea0cd49a7c17a

-- 
View it on GitLab: https://code.videolan.org/videolan/vlc/-/compare/3c4953e746e19df5df04e4af36ebd17b2b73ce94...6805e4584e6bafa77dd22f26049ea0cd49a7c17a
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