Re: [FFmpeg-trac] #6905(undetermined:closed): When copying video from .avi to .mp4, frames have incorrect pts values

[FFmpeg]

#6905: When copying video from .avi to .mp4, frames have incorrect pts values
-+-
 Reporter:  Misaki   |Owner:
 Type:  defect   |   Status:  closed
 Priority:  normal   |Component:
  Version:  git-master   |  undetermined
 Keywords:   |   Resolution:
 Blocking:   |  needs_more_info
Analyzed by developer:  0|   Blocked By:
 |  Reproduced by developer:  0
-+-

Comment (by Misaki):

 I didn't know about that option, but it does not make a difference. The
 warning messages '[mp4 @ 0x5569f707bea0] Timestamps are unset in a packet
 for stream 0. This is deprecated and will stop working in the future. Fix
 your code to set the timestamps properly' and '[mp4 @ 0x5569f707bea0] pts
 has no value' x30 for the test file are still there, and timestamps in the
 output file are the same as without the option.

 Reproducing is easy, just copy the video stream in any avi with B-frames
 to mp4 format. Confirming that the output is such that it will stutter in
 Chrome, even though it has almost no problems in most players, is more
 difficult, and that's where it helps to start with an mp4 so you can see
 that the start and end files are clearly different.

 Symptom is that if examined with ffprobe, a stutter-prone file will have
 same dts as pts with -show_packets, while normal mp4s have same with
 -show_frames.

--
Ticket URL: 
FFmpeg 
FFmpeg issue tracker
___
FFmpeg-trac mailing list
FFmpeg-trac@avcodec.org
http://ffmpeg.org/mailman/listinfo/ffmpeg-trac

Re: [FFmpeg-trac] #6905(undetermined:closed): When copying video from .avi to .mp4, frames have incorrect pts values

[FFmpeg]

#6905: When copying video from .avi to .mp4, frames have incorrect pts values
-+-
 Reporter:  Misaki   |Owner:
 Type:  defect   |   Status:  closed
 Priority:  normal   |Component:
  Version:  git-master   |  undetermined
 Keywords:   |   Resolution:
 Blocking:   |  needs_more_info
Analyzed by developer:  0|   Blocked By:
 |  Reproduced by developer:  0
-+-

Comment (by cehoyos):

 Replying to [comment:5 Misaki]:
 > Mpeg4 streams work the same way.
 Then please explain how to reproduce and reopen.

 Does `-fflags +genpts` make a difference?

--
Ticket URL: 
FFmpeg 
FFmpeg issue tracker
___
FFmpeg-trac mailing list
FFmpeg-trac@avcodec.org
http://ffmpeg.org/mailman/listinfo/ffmpeg-trac

Re: [FFmpeg-trac] #6905(undetermined:closed): When copying video from .avi to .mp4, frames have incorrect pts values

[FFmpeg]

#6905: When copying video from .avi to .mp4, frames have incorrect pts values
-+-
 Reporter:  Misaki   |Owner:
 Type:  defect   |   Status:  closed
 Priority:  normal   |Component:
  Version:  git-master   |  undetermined
 Keywords:   |   Resolution:
 Blocking:   |  needs_more_info
Analyzed by developer:  0|   Blocked By:
 |  Reproduced by developer:  0
-+-

Comment (by Misaki):

 The workaround, MP4Box, stopped working on episode 6 when the encoder
 switched from XVID to DX50. The resulting file was half the size and had
 lots of missing frames (and pts not matching dts for frames). Playback was
 fine for the first 12 seconds, with no missing frames.

 Copying using ffmpeg starting at 13 seconds to another avi, and then
 copying that to mp4 using MP4Box, led to good output. Two videos had been
 combined, with different encoding parameters. For the original, MP4Box
 indicated 'Has B-Frames (8 max consecutive B-VOPs)'. For the video
 starting at the keyframe before 13 sec, it said 'Has B-Frames (2 max
 consecutive B-VOPs)'. (no packed bitstream.)

 This information is for anyone trying to get this to work when ffmpeg is
 bugged.

--
Ticket URL: 
FFmpeg 
FFmpeg issue tracker
___
FFmpeg-trac mailing list
FFmpeg-trac@avcodec.org
http://ffmpeg.org/mailman/listinfo/ffmpeg-trac

Re: [FFmpeg-trac] #6905(undetermined:closed): When copying video from .avi to .mp4, frames have incorrect pts values

[FFmpeg]

#6905: When copying video from .avi to .mp4, frames have incorrect pts values
-+-
 Reporter:  Misaki   |Owner:
 Type:  defect   |   Status:  closed
 Priority:  normal   |Component:
  Version:  git-master   |  undetermined
 Keywords:   |   Resolution:
 Blocking:   |  needs_more_info
Analyzed by developer:  0|   Blocked By:
 |  Reproduced by developer:  0
-+-

Comment (by Misaki):

 Mpeg4 streams work the same way. The reasons for using h.264 were that I
 was sure it would lead to B-pyramids and unpredictable frame order, and
 also that it would work in browsers like Chrome on Linux so verifying an
 error would be easier.

 As I said, MP4Box does it correctly. I don't know how accurate ffprobe is,
 but if it is accurate, then ffmpeg just needs to generate pts's for a
 frame that are the same as the dts's that already exist for that frame,
 when converting an avi to mp4.

 There's also the issue of timestamps being bumped up when converting to
 and from avi; in a 30-fps file this isn't noticeable, but at 1 fps it was
 more so. Although the packet dts as reported by ffprobe started from 0,
 the frames' pkt_dts_time starts at 2 for the ordered-frames.avi file
 (pkt_dts=4). Even if .avi can't have negative timestamps, could still
 start at 0 instead of higher than that. The original mp4 does start at 0
 dts and pts for frames.

--
Ticket URL: 
FFmpeg 
FFmpeg issue tracker
___
FFmpeg-trac mailing list
FFmpeg-trac@avcodec.org
http://ffmpeg.org/mailman/listinfo/ffmpeg-trac

Re: [FFmpeg-trac] #6905(undetermined:closed): When copying video from .avi to .mp4, frames have incorrect pts values

[FFmpeg]

#6905: When copying video from .avi to .mp4, frames have incorrect pts values
-+-
 Reporter:  Misaki   |Owner:
 Type:  defect   |   Status:  closed
 Priority:  normal   |Component:
  Version:  git-master   |  undetermined
 Keywords:   |   Resolution:
 Blocking:   |  needs_more_info
Analyzed by developer:  0|   Blocked By:
 |  Reproduced by developer:  0
-+-
Changes (by cehoyos):

 * status:  new => closed
 * resolution:   => needs_more_info


Comment:

 I suggest we shorten this discussion: H.264 timestamps are not always
 correct with FFmpeg, this is a known limitation, it is apparently very
 difficult to fix, several tickets exist.
 H.264 in avi may have issues, this may be unrelated though.

--
Ticket URL: 
FFmpeg 
FFmpeg issue tracker
___
FFmpeg-trac mailing list
FFmpeg-trac@avcodec.org
http://ffmpeg.org/mailman/listinfo/ffmpeg-trac