[FFmpeg-user] non-monotonous DTS in output stream

[cedric.dewijs at telfort.nl]

>----Origineel Bericht----
>Van : ceffmpeg at gmail.com
>Datum : 18/05/2018 10:05
>Aan : ffmpeg-user at ffmpeg.org
>Onderwerp : Re: [FFmpeg-user] non-monotonous DTS in output stream
>
>2018-05-17 14:57 GMT+02:00, cedric.dewijs at telfort.nl <cedric.dewijs at telfort.nl>:
>> Hi All,
>> I am capturing mjpeg frames from my webcam connected to a bananapi, running
>> armbian. The resulting video file is choppy when played with mplayer and
>> VLC, and in the console I see the following messages.
>
>If the camera provides constant frame rate, you can use the mjpg container.
>
>Carl Eugen
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I Carl,

I've tried, but there are a lot of frames missing in the resulting video file. I have captured the image of a stopwatch with my webcam, and I see the seconds go way faster than they should. I used the official 4.0 version of the source:

ffmpeg-4.0$ ./ffmpeg -fflags +igndts -f v4l2 -input_format mjpeg -s 1280x720 -i /dev/video0 -pix_fmt nv12 -c:v copy output.mjpeg
ffmpeg version 4.0 Copyright (c) 2000-2018 the FFmpeg developers
  built with gcc 5.4.0 (Ubuntu/Linaro 5.4.0-6ubuntu1~16.04.9) 20160609
  configuration: --prefix=/usr --enable-nonfree --enable-gpl --enable-version3 --enable-vdpau --enable-libx264 --enable-libmp3lame --enable-libpulse --enable-libv4l2
  libavutil      56. 14.100 / 56. 14.100
  libavcodec     58. 18.100 / 58. 18.100
  libavformat    58. 12.100 / 58. 12.100
  libavdevice    58.  3.100 / 58.  3.100
  libavfilter     7. 16.100 /  7. 16.100
  libswscale      5.  1.100 /  5.  1.100
  libswresample   3.  1.100 /  3.  1.100
  libpostproc    55.  1.100 / 55.  1.100
Input #0, video4linux2,v4l2, from '/dev/video0':
  Duration: N/A, start: 71259.463599, bitrate: N/A
    Stream #0:0: Video: mjpeg, yuvj422p(pc, bt470bg/unknown/unknown), 1280x720, 30 fps, 30 tbr, 1000k tbn, 1000k tbc
Output #0, mjpeg, to 'output.mjpeg':
  Metadata:
    encoder         : Lavf58.12.100
    Stream #0:0: Video: mjpeg, yuvj422p(pc, bt470bg/unknown/unknown), 1280x720, q=2-31, 30 fps, 30 tbr, 1000k tbn, 1000k tbc
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
Press [q] to stop, [?] for help
frame=   16 fps=0.0 q=-1.0 size=    2048kB time=00:00:00.49 bitrate=33559.2kbitsframe=   31 fps= 31 q=-1.0 size=    4864kB time=00:00:00.99 bitrate=39854.6kbitsframe=   46 fps= 31 q=-1.0 size=    7680kB time=00:00:01.49 bitrate=41953.0kbitsframe=   61 fps= 30 q=-1.0 size=   10496kB time=00:00:01.99 bitrate=43001.2kbitsframe=   76 fps= 30 q=-1.0 size=   13312kB time=00:00:02.49 bitrate=43629.2kbitsframe=   91 fps= 30 q=-1.0 size=   16128kB time=00:00:02.99 bitrate=44049.9kbitsframe=  106 fps= 30 q=-1.0 size=   18944kB time=00:00:03.49 bitrate=44349.5kbitsframe=  121 fps= 30 q=-1.0 size=   21760kB time=00:00:03.99 bitrate=44575.2kbitsframe=  136 fps= 30 q=-1.0 size=   24576kB time=00:00:04.49

s/s speed=0.907x    
video:381272kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.000000%
Exiting normally, received signal 2.

Cheers,
Cedric