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Video capture on Linux

Capture cards

If you have issues with this card (dmesg yelling that it's a model with the generic USB PVID), you need either to reload the kernel module with modprobe em28xx card=64, or adding options em28xx card64 to /etc/modprobe.d/easycap-em28xx.conf, but this will screw with other capture cards using the eMPIA em28xx controllers.

Input Works?
S-Video Yes, OOB, in color (input=0)
Composite Yes, OOB, (input=1)
Audio Muted by default, need to be unmuted with v4lctl

Remarks:

  • All settings need to be preset with v4lctl, setting format and framerate with ffmpeg will fail with the following error: ioctl(VIDIOC_S_PARM): Inappropriate ioctl for device em28xx.
  • Signal integrity is satisfactory, no specific remarks to add.

Monitoring video signal

You can do this in realtime using the following commands:

Display NTSC:

ffmpeg -f v4l2 -standard NTSC -video_size ntsc -framerate ntsc -i /dev/video2 -f alsa -i hw:1,0 -vcodec ayuv -acodec copy -map 0:0 -map 1:0 -f avi pipe:1 | ffplay -

Display PAL:

ffmpeg -f v4l2 -standard PAL -video_size pal -framerate pal -i /dev/video2 -f alsa -i hw:1,0 -vcodec ayuv -acodec copy -map 0:0 -map 1:0 -f avi pipe:1 | ffplay -

If your card doesn't support VIDIOC_S_PARM ioctls:

ffmpeg -f v4l2 -i /dev/video2 -f alsa -i hw:1,0 -vcodec ayuv -acodec copy -map 0:0 -map 1:0 -f avi pipe:1 | ffplay -
docs/vidcap.1652782289.txt.gz · Last modified: 2022/05/17 12:11 by root

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