[FFmpeg-cvslog] avformat/flacenc: Only update streaminfo if it has changed

Andreas Rheinhardt git at videolan.org
Sat Apr 18 02:53:02 EEST 2020

ffmpeg | branch: master | Andreas Rheinhardt <andreas.rheinhardt at gmail.com> | Sun Apr 12 17:49:30 2020 +0200| [9311ece7d30f846b8f61398321f0d48c19ae2f50] | committer: Andreas Rheinhardt

avformat/flacenc: Only update streaminfo if it has changed

An AVStream's codecpar is supposed to be filled by the caller before
avformat_write_header(); if the CodecParameters change, the caller
should signal this via packet side data, but not touch the AVStream's

The FLAC muxer checks for packet side data containing updated extradata,
yet if nothing has arrived by the time the trailer is written, the
already written extradata is overwritten by the very same extradata
again, unless the output is unseekable, in which case a warning that the
FLAC header can't be rewritten is emitted.

This commit changes this by only trying to rewrite the extradata if a
new streaminfo arrived via packet side data. Only then is a warning
emitted in case the output is unseekable.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=9311ece7d30f846b8f61398321f0d48c19ae2f50

 libavformat/flacenc.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/libavformat/flacenc.c b/libavformat/flacenc.c
index 1aae0c97e0..42c1efec54 100644
--- a/libavformat/flacenc.c
+++ b/libavformat/flacenc.c
@@ -331,8 +331,6 @@ static int flac_write_trailer(struct AVFormatContext *s)
     AVIOContext *pb = s->pb;
     int64_t file_size;
     FlacMuxerContext *c = s->priv_data;
-    uint8_t *streaminfo = c->streaminfo ? c->streaminfo :
-                                          s->streams[c->audio_stream_idx]->codecpar->extradata;
     if (c->waiting_pics) {
         av_log(s, AV_LOG_WARNING, "No packets were sent for some of the "
@@ -340,14 +338,14 @@ static int flac_write_trailer(struct AVFormatContext *s)
-    if (!c->write_header || !streaminfo)
+    if (!c->write_header || !c->streaminfo)
         return 0;
     if (pb->seekable & AVIO_SEEKABLE_NORMAL) {
         /* rewrite the STREAMINFO header block data */
         file_size = avio_tell(pb);
         avio_seek(pb, 8, SEEK_SET);
-        avio_write(pb, streaminfo, FLAC_STREAMINFO_SIZE);
+        avio_write(pb, c->streaminfo, FLAC_STREAMINFO_SIZE);
         avio_seek(pb, file_size, SEEK_SET);
     } else {
         av_log(s, AV_LOG_WARNING, "unable to rewrite FLAC header.\n");

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