[FFmpeg-devel] [PATCH] mov: do not mark timed thumbnail tracks as attached picture

[wm4]

The AV_DISPOSITION_ATTACHED_PIC flag is meant only for exporting a
static picture (such as embedded cover art) as pseudo video track. The
requirement is that there is exactly 1 packet, and that normal demuxing
does not return it (otherwise avformat_queue_attached_pictures() would
add it a second time). It should never used on actual video tracks that
return packets when demuxing.

I considered keeping the current behavior if there is exactly 1 frame
(according to nb_index_entries), but that would require additional work
to make sure avformat_queue_attached_pictures() does not add it a second
time, so I didn't bother.

Reverts part of 697400eac07c0614f6b9f2e7615563982dbcbe4a and fixes
regressions with certain API users with such mp4 files.
---
 libavformat/mov.c | 18 +-----------------
 1 file changed, 1 insertion(+), 17 deletions(-)

diff --git a/libavformat/mov.c b/libavformat/mov.c
index 22faecfc17..f74be03359 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -6335,23 +6335,7 @@ static void mov_read_chapters(AVFormatContext *s)
         cur_pos = avio_tell(sc->pb);
 
         if (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
-            st->disposition |= AV_DISPOSITION_ATTACHED_PIC | AV_DISPOSITION_TIMED_THUMBNAILS;
-            if (st->nb_index_entries) {
-                // Retrieve the first frame, if possible
-                AVPacket pkt;
-                AVIndexEntry *sample = &st->index_entries[0];
-                if (avio_seek(sc->pb, sample->pos, SEEK_SET) != sample->pos) {
-                    av_log(s, AV_LOG_ERROR, "Failed to retrieve first frame\n");
-                    goto finish;
-                }
-
-                if (av_get_packet(sc->pb, &pkt, sample->size) < 0)
-                    goto finish;
-
-                st->attached_pic              = pkt;
-                st->attached_pic.stream_index = st->index;
-                st->attached_pic.flags       |= AV_PKT_FLAG_KEY;
-            }
+            st->disposition |= AV_DISPOSITION_TIMED_THUMBNAILS;
         } else {
             st->codecpar->codec_type = AVMEDIA_TYPE_DATA;
             st->codecpar->codec_id = AV_CODEC_ID_BIN_DATA;
-- 
2.15.1