[FFmpeg-trac] #2305(avdevice:new): v4l2 user control configuration mechanism

FFmpeg trac at avcodec.org
Mon Sep 13 19:31:34 EEST 2021


#2305: v4l2 user control configuration mechanism
-------------------------------------+------------------------------------
             Reporter:  Adam Clarke  |                    Owner:  (none)
                 Type:  enhancement  |                   Status:  new
             Priority:  wish         |                Component:  avdevice
              Version:  git-master   |               Resolution:
             Keywords:  v4l2         |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+------------------------------------
Comment (by John Boiles):

 +1 it'd be nice for either ffmpeg to have full control over v4l2 devices
 or no control at all. Perhaps there could be a new ffmpeg flag to tell it
 to not change v4l2 settings.

 As it is currently, you may need to specify some settings twice -- once
 because sometimes v4l2 needs to switch to the right pixelformat before it
 can use pixelformat-related controls, then again for ffmpeg so that ffmpeg
 doesn't switch your settings around. E.g.:

 {{{
 v4l2-ctl -d /dev/video0 -v pixelformat=H264,width=1920,height=1080
 v4l2-ctl -d /dev/video0 -c
 video_bitrate_mode=1,video_bitrate=2000000,h264_profile=0,h264_i_frame_period=60
 v4l2-ctl -d /dev/video0 -p 30
 ffmpeg -pix_fmt h264 -video_size 1920x1080 -i /dev/video0 ....
 }}}
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/2305#comment:7>
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