[FFmpeg-trac] #5152(undetermined:reopened): Broken B frames while copying MPEG-2 ibp without recompression from some point
FFmpeg
trac at avcodec.org
Tue Jan 12 14:14:39 CET 2016
#5152: Broken B frames while copying MPEG-2 ibp without recompression from some
point
-------------------------------------+-------------------------------------
Reporter: | Owner:
Aleksandr_Slobodeniuk | Status: reopened
Type: defect | Component:
Priority: normal | undetermined
Version: git-master | Resolution:
Keywords: | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
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Comment (by cehoyos):
Replying to [comment:12 Aleksandr_Slobodeniuk]:
> 1) result must be from 3:00 to 3:24
This is impossible for {{{-vcodec copy}}} and the file you provided, and
this is not a deficiency of FFmpeg.
> 2) if you type (it's 25 frames)
>
> {{{
> ffmpeg -i result.mov %d.jpg
> }}}
> you'll see that
> - first 11 frames show 3:11 (because ffmpeg can't decode 11 b frames
because they are from the middle of the gop)
You have to use {{{-vsync 0}}} to avoid the command duplicating frames,
the eleven frames are not part of result.mov, the first available frame is
"3:11" and this is not related to FFmpeg but the format of the given input
file.
> - last 2 frames show 3:24 and 4:01 , 4:00 is missing (because it was not
read. 4:01 is I frame that goes before 4:00 in the file, and it was pulled
out with nullptr to avcodec_decode_video)
How should FFmpeg behave in your opinion?
--
Ticket URL: <https://trac.ffmpeg.org/ticket/5152#comment:13>
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