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lavf/movenc: Use a dynamic buffer when writing the mfra box 

When doing streamed output, with e.g. +dash, if the mfra box ended
up being larger than the AVIOContext write buffer, the (unchecked)
seeking back to update the box size would silently fail and produce
an invalid mfra box.

This is similar to how other boxes are written in fragmented mode.

Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>
This commit is contained in:
Derek Buitenhuis 2020-06-23 16:05:18 +01:00
parent fdead2a31a
commit d5247fb1da
1 changed files with 26 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

38
libavformat/movenc.c
View File

@ -4798,28 +4798,40 @@ static int mov_write_tfra_tag(AVIOContext *pb, MOVTrack *track)
static int mov_write_mfra_tag(AVIOContext *pb, MOVMuxContext *mov)
{
int64_t pos = avio_tell(pb);
int i;
AVIOContext *mfra_pb;
int i, ret, sz;
uint8_t *buf;
avio_wb32(pb, 0); /* size placeholder */
ffio_wfourcc(pb, "mfra");
ret = avio_open_dyn_buf(&mfra_pb);
if (ret < 0)
return ret;
avio_wb32(mfra_pb, 0); /* size placeholder */
ffio_wfourcc(mfra_pb, "mfra");
/* An empty mfra atom is enough to indicate to the publishing point that
* the stream has ended. */
if (mov->flags & FF_MOV_FLAG_ISML)
return update_size(pb, pos);
goto done_mfra;
for (i = 0; i < mov->nb_streams; i++) {
MOVTrack *track = &mov->tracks[i];
if (track->nb_frag_info)
mov_write_tfra_tag(pb, track);
mov_write_tfra_tag(mfra_pb, track);
}
avio_wb32(pb, 16);
ffio_wfourcc(pb, "mfro");
avio_wb32(pb, 0); /* version + flags */
avio_wb32(pb, avio_tell(pb) + 4 - pos);
avio_wb32(mfra_pb, 16);
ffio_wfourcc(mfra_pb, "mfro");
avio_wb32(mfra_pb, 0); /* version + flags */
avio_wb32(mfra_pb, avio_tell(mfra_pb) + 4);
return update_size(pb, pos);
done_mfra:
sz = update_size(mfra_pb, 0);
ret = avio_get_dyn_buf(mfra_pb, &buf);
avio_write(pb, buf, ret);
ffio_free_dyn_buf(&mfra_pb);
return sz;
}
static int mov_write_mdat_tag(AVIOContext *pb, MOVMuxContext *mov)
@ -6987,7 +6999,9 @@ static int mov_write_trailer(AVFormatContext *s)
}
if (!(mov->flags & FF_MOV_FLAG_SKIP_TRAILER)) {
avio_write_marker(s->pb, AV_NOPTS_VALUE, AVIO_DATA_MARKER_TRAILER);
mov_write_mfra_tag(pb, mov);
res = mov_write_mfra_tag(pb, mov);
if (res < 0)
return res;
}
}