[FFmpeg-trac] #4030(undetermined:new): V4L2 recording results in invalid data & buffer still owned errors

FFmpeg trac at avcodec.org
Wed Oct 15 09:43:29 CEST 2014

#4030: V4L2 recording results in invalid data & buffer still owned errors
             Reporter:  thender      |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:               |                  Version:
  undetermined                       |  unspecified
             Keywords:  v4l2 buffer  |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
 Summary of the bug:

 If I try to record from a magewell USB3 V4L2 capture device, it works the
 first time. However, the 2nd time I try to record from it, I will receive
 this error. Occasionally capture will die in the middle of a recording
 with this same error.

 How to reproduce:

 Run this with a USB3 magewell v4l2 dongle.

 ffmpeg -f v4l2 -framerate 60 -s 1920x1080 -i /dev/video1 -f alsa -i
 pulse -c:v libx264 -crf 0 -preset ultrafast -c:a pcm_s16le outfile3.mkv

 Stop the recording, then run it again. It won't work.

 To confirm the issue is isolated to ffmpeg, try using cvlc and it will
 work. You can use this command as many times as you please and it will
 always record just fine, and never freeze in the middle of a recording.

 cvlc v4l2:// :v4l2-dev=/dev/video1 :v4l2-width=1920 :v4l2-height=1080
 --input-slave pulse:// --sout

 The problem is that CVLC does not allow me to set an input framerate,
 which is functionality I need, so that I do not stress the CPU too much
 recording at 60 FPS.

 ffmpeg version 2.27
 built on ... Gentoo Linux

Ticket URL: <https://trac.ffmpeg.org/ticket/4030>
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