[SOLVED]use ffmpeg read impossible with sdpo video

[LaurentDelaon]

Hi everybody,

Under ubuntu18.04 I read a usbcam with Sdpo Video uvcpf_BGR24 ans 480x640.
The device is an usbcam  is /dev/video6 and /dev/video7.
It's works i can read it.

If I duplicate this device like this  :

Code: Pascal  [Select][+][-]

1. //via loopback create video 2 3 4
2. sudo modprobe  v4l2loopback devices=4 exclusive_caps=1:
3. // duplicate video6 to video2
4. ffmpeg -f video4linux2 -i /dev/video6 -codec copy -f v4l2 /dev/video2
5.  

Now i cannot read /dev/video2 wich is the same as video6...
Same problem with another camera.

Seem due to metadata which are in video7 ?
How can I solve this ?
Thank's for your help.
Regards.

[LaurentDelaon]

Hi,

the solution is to modify the  sdpo lib lig=32:

Code: Pascal  [Select][+][-]

1. const
2.   VIDEO_BUFFERS = 3;

The last value buffer is 4. This value 3 work fine with the direct device said video0 but not with copy device video2 as describe.
Set to 3 solve the problem in each case. Maybe a zero based index.
(don't forget to stop

Code: Pascal  [Select][+][-]

1. ffmpeg -f video4linux2 -i /dev/video6 -codec copy -f v4l2 /dev/video2

for testing direct video0 access...)

regard
Laurent.