[FFmpeg-devel] [PATCH] flac: add GIF image support

[leo60228]

The FLAC specification requires GIF images to contain their number of
colors. While I can't find a specific reference to that effect, I'm
assuming that's why GIF images were previously unsupported. This was
implemented by just writing AVPALETTE_COUNT for paletted images.
---
 Changelog             |  1 +
 libavformat/flacenc.c | 10 ++++++----
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/Changelog b/Changelog
index e8ee74775e..3ff783c61d 100644
--- a/Changelog
+++ b/Changelog
@@ -61,6 +61,7 @@ version <next>:
 - shear filter
 - kirsch filter
 - colortemperature filter
+- GIF support in FLAC
 
 
 version 4.3:
diff --git a/libavformat/flacenc.c b/libavformat/flacenc.c
index 1c983486aa..c156d13b14 100644
--- a/libavformat/flacenc.c
+++ b/libavformat/flacenc.c
@@ -151,11 +151,16 @@ static int flac_write_picture(struct AVFormatContext *s, AVPacket *pkt)
 
     avio_wb32(pb, st->codecpar->width);
     avio_wb32(pb, st->codecpar->height);
+
     if ((pixdesc = av_pix_fmt_desc_get(st->codecpar->format)))
         avio_wb32(pb, av_get_bits_per_pixel(pixdesc));
     else
         avio_wb32(pb, 0);
-    avio_wb32(pb, 0);
+
+    if (st->codecpar->format == AV_PIX_FMT_PAL8)
+        avio_wb32(pb, AVPALETTE_COUNT);
+    else
+        avio_wb32(pb, 0);
 
     avio_wb32(pb, pkt->size);
     avio_write(pb, pkt->data, pkt->size);
@@ -218,9 +223,6 @@ static int flac_init(struct AVFormatContext *s)
             if (!(st->disposition & AV_DISPOSITION_ATTACHED_PIC)) {
                 av_log(s, AV_LOG_WARNING, "Video stream #%d is not an attached picture. Ignoring\n", i);
                 continue;
-            } else if (st->codecpar->codec_id == AV_CODEC_ID_GIF) {
-                av_log(s, AV_LOG_ERROR, "GIF image support is not implemented.\n");
-                return AVERROR_PATCHWELCOME;
             } else if (!c->write_header) {
                 av_log(s, AV_LOG_ERROR, "Can't write attached pictures without a header.\n");
                 return AVERROR(EINVAL);
-- 
2.28.0