Opened 19 months ago

Closed 15 months ago

#11494 closed defect (fixed)

Encoding to ffv1 produces broken bitstream for specific sample with specific settings

Reported by: Damian Höster Owned by:
Priority: normal Component: avformat
Version: unspecified Keywords:
Cc: Blocked By:
Blocking: Reproduced by developer: no
Analyzed by developer: no

Description

How to reproduce:
Download br2049-00006.mkv from here: ​https://mega.nz/file/UCw1AQ7D#-oQ_Hcob_VByBC-KSqvJ2xuV7GZkvkCJ-XOrU00zQeg
Reencode like this:
ffmpeg -i br2049-00006.mkv -vcodec ffv1 -pass 1 -coder 1 -context 1 -slices 24 -f null /dev/null && ffmpeg -i br2049-00006.mkv -vcodec ffv1 -pass 2 -coder 1 -context 1 -slices 24 broken-ffv1.mkv
Then try to decode.
I get errors like these:

[ffv1 @ 0x57b2744be500] CRC mismatch F9B52803!

[vist#0:0/ffv1 @ 0x57b2744dec00] [dec:ffv1 @ 0x57b2744e0f40] Error while opening decoder: Invalid data found when processing input

ffmpeg version N-118655-g696ea1c223
on Arch Linux

Change History (1)

comment:1 by mkver, 15 months ago

Component: avcodec → avformat
Resolution: → fixed
Status: new → closed

Fixed in 92e310eb82e04713e55d248b65c22f0eb95afada.
The encoded file is actually fine; a FFmpeg with the above commit can handle it.

(When I wrote 92e310eb82e04713e55d248b65c22f0eb95afada, I thought that it could only break files encoded using slicecrc mode 2 which is currently experimental. Yet I was wrong: This bug made the decoder read the slicecrc mode as two for your file, although the encoder only used one.)

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