[FFmpeg-trac] #1387(undetermined:new): v4l2 uses wrong (default) parameters

FFmpeg trac at avcodec.org
Sat Mar 9 22:18:31 CET 2013

#1387: v4l2 uses wrong (default) parameters
             Reporter:  burek        |                    Owner:
                 Type:  defect       |                   Status:  new
             Priority:  normal       |                Component:
              Version:  unspecified  |  undetermined
             Keywords:  v4l2         |               Resolution:
             Blocking:               |               Blocked By:
Analyzed by developer:  0            |  Reproduced by developer:  0

Comment (by dronus):

 The bug is still there. -pixel_format is needed to set the pixel format
 again already selected by v4l2-ctl before.

 And for the worse, this will in turn reset some other settings done by
 v4l2-ctl. For example, exposure mode is changed on some cameras. It seems
 that the format decision is assumed to take place prior to the other
 settings. The format can only be changed in close state, while the
 controls can be changed while capturing. So it may be incorrect to change
 the pixel format by ffmpeg without the ability to reapply the control

 I suggest either add a full control interface, or remove the pixel format
 setup from v4l2.c and just honor what was set by tools like v4l2-ctl

 Adding an control interface is the issue of
 https://ffmpeg.org/trac/ffmpeg/ticket/2305 too.

Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/1387#comment:5>
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