The branch, master has been updated
via 36896af64a9ecf6835758186e7161a2e954c364d (commit)
from a45d30a67579f00926525ffd23c7a6b5470d77a0 (commit)
- Log -----------------------------------------------------------------
commit 36896af64a9ecf6835758186e7161a2e954c364d
Author: Martin Storsjö <[email protected]>
AuthorDate: Fri Jun 27 15:11:13 2025 +0300
Commit: Martin Storsjö <[email protected]>
CommitDate: Thu Oct 16 18:58:54 2025 +0000
movenc: Make the hybrid_fragmented mode more robust
Write the moov tag at the end first, before overwriting the mdat size
at the start of the file.
In case writing the final moov box fails (e.g. due to being out
of disk), we haven't broken the initial moov box yet.
Thus if writing stops between these steps, we could end up with
a file with two moov boxes - which arguably is more feasible to
recover from, than from a file with no moov boxes at all.
diff --git a/libavformat/movenc.c b/libavformat/movenc.c
index b76d56dac4..cd66a39518 100644
--- a/libavformat/movenc.c
+++ b/libavformat/movenc.c
@@ -8546,6 +8546,28 @@ static int shift_data(AVFormatContext *s)
return ff_format_shift_data(s, mov->reserved_header_pos, moov_size);
}
+static void mov_write_mdat_size(AVFormatContext *s)
+{
+ MOVMuxContext *mov = s->priv_data;
+ AVIOContext *pb = s->pb;
+
+ /* Write size of mdat tag */
+ if (mov->mdat_size + 8 <= UINT32_MAX) {
+ avio_seek(pb, mov->mdat_pos, SEEK_SET);
+ avio_wb32(pb, mov->mdat_size + 8);
+ if (mov->flags & FF_MOV_FLAG_HYBRID_FRAGMENTED)
+ ffio_wfourcc(pb, "mdat"); // overwrite the original moov into a
mdat
+ } else {
+ /* overwrite 'wide' placeholder atom */
+ avio_seek(pb, mov->mdat_pos - 8, SEEK_SET);
+ /* special value: real atom size will be 64 bit value after
+ * tag field */
+ avio_wb32(pb, 1);
+ ffio_wfourcc(pb, "mdat");
+ avio_wb64(pb, mov->mdat_size + 16);
+ }
+}
+
static int mov_write_trailer(AVFormatContext *s)
{
MOVMuxContext *mov = s->priv_data;
@@ -8605,21 +8627,9 @@ static int mov_write_trailer(AVFormatContext *s)
moov_pos = avio_tell(pb);
- /* Write size of mdat tag */
- if (mov->mdat_size + 8 <= UINT32_MAX) {
- avio_seek(pb, mov->mdat_pos, SEEK_SET);
- avio_wb32(pb, mov->mdat_size + 8);
- if (mov->flags & FF_MOV_FLAG_HYBRID_FRAGMENTED)
- ffio_wfourcc(pb, "mdat"); // overwrite the original moov into
a mdat
- } else {
- /* overwrite 'wide' placeholder atom */
- avio_seek(pb, mov->mdat_pos - 8, SEEK_SET);
- /* special value: real atom size will be 64 bit value after
- * tag field */
- avio_wb32(pb, 1);
- ffio_wfourcc(pb, "mdat");
- avio_wb64(pb, mov->mdat_size + 16);
- }
+ if (!(mov->flags & FF_MOV_FLAG_HYBRID_FRAGMENTED))
+ mov_write_mdat_size(s);
+
avio_seek(pb, mov->reserved_moov_size > 0 ? mov->reserved_header_pos :
moov_pos, SEEK_SET);
if (mov->flags & FF_MOV_FLAG_FASTSTART) {
@@ -8647,6 +8657,15 @@ static int mov_write_trailer(AVFormatContext *s)
if ((res = mov_write_moov_tag(pb, mov, s)) < 0)
return res;
}
+
+ if (mov->flags & FF_MOV_FLAG_HYBRID_FRAGMENTED) {
+ // With hybrid fragmentation, only write the mdat size (hiding
+ // the original moov and all the fragments within the mdat)
+ // after we've successfully written the complete moov, to avoid
+ // risk for an unreadable file if writing the final moov fails.
+ mov_write_mdat_size(s);
+ }
+
res = 0;
} else {
mov_auto_flush_fragment(s, 1);
-----------------------------------------------------------------------
Summary of changes:
libavformat/movenc.c | 49 ++++++++++++++++++++++++++++++++++---------------
1 file changed, 34 insertions(+), 15 deletions(-)
hooks/post-receive
--
_______________________________________________
ffmpeg-cvslog mailing list -- [email protected]
To unsubscribe send an email to [email protected]
