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

[FFmpeg]

#4030: V4L2 recording results in invalid data & buffer still owned errors
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             Reporter:  thender     |                    Owner:  holden
                 Type:  defect      |                   Status:  open
             Priority:  normal      |                Component:  avdevice
              Version:  git-master  |               Resolution:
             Keywords:  v4l2        |               Blocked By:
             Blocking:              |  Reproduced by developer:  0
Analyzed by developer:  1           |
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Comment (by holden):

 Replying to [comment:22 corco]:

 > The issue doesn't affect every kernel. I don't have any problem with my
 Centos 3.10.0 kernel, but the problem was reported and confirmed on Ubuntu
 14.04 3.16.0 kernel. So the issue may be with the V4L2 driver, but FFmpeg
 is the only one to complain about it; gstreamer and VLC are fine.

 Yes, probably something changed in the v4l2 driver with recent kernels.

 > I tested the 0001-lavd-v4l2-print-buffer-flags-in-case-of-error.patch
 from holden and was pleased to see that it fixed the problem, albeit a
 rather harmless error message at the beginning. Is there any chance to
 apply the patch to upstream?

 That patch only modified a message to include the flags of the buffer that
 gave an error, so I doubt it can actually fix the problem. Nonetheless, I
 sent it upstream anyway and it was integrated. Maybe you meant the other
 patch (0001-lavd-v4l2-produce-a-0-byte-packet-when-a-dequeued-bu.patch)?

 > If you're interested in investigating the issue, I could provide SSH to
 the ubuntu machine.

 Yes, if we can't solve it easily that might help, thanks.

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Ticket URL: <https://trac.ffmpeg.org/ticket/4030#comment:23>
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