How to aggregate two webcams side by side into a single video device ?

Linux.tar.gz · 07-19-2021, 05:16 AM

Hi,

I'd like to mix the video streams from two webcams (same model) into one single stream, i.e. having two 800x600 /dev/video0 and /dev/video1, create a fake 1600x600 /dev/video2 that I can use like a normal webcam.
I searched for a v4l way to do that, but without success.

Regards.

Mike_Walsh · 07-19-2021, 06:56 AM

Are we talking here about the two 'streams' displaying side-by-side?

If you're looking for a command-line solution involving v4l/v4l2/ffmpeg, etc, I can't help with that. Hate using the terminal, except for troubleshooting.....always been more of a GUI man myself.

The only software I know of that will allow this kind of thing is webcam/security monitoring stuff. Take a look at Xeoma; the free version will allow display of up to 4 streams simultaneously.

May help, may not. Others can doubtless help with the command-line stuff; I expect there IS a way to do what you want.

Mike.

teckk · 07-19-2021, 07:46 AM

Quote:

I'd like to mix the video streams from two webcams

Vertical stack

Code:

ffplay -f lavfi -i "movie=file1.mp4,crop=800:600:0:0[v0];movie=file2.mp4,scale=800:-1,crop=800:600:0:0[v1];[v0][v1]vstack"

Horizontal stack

Code:

ffplay -f lavfi -i "movie=file1.mp4,crop=800:600:0:0[h0];movie=file2.mp4,scale=800:-1,crop=800:600:0:0[h1];[h0][h1]hstack"

And I am going to do a little test to see if that works ok. I'll use a video that I happen to have here.

Code:

ffmpeg -ss 00:03:00 -t 00:03:30 -i MyVid.mp4 -c:a copy -c:v copy test1.mp4
ffmpeg -ss 00:06:00 -t 00:06:30 -i MyVid.mp4 -c:a copy -c:v copy test2.mp4

Play both videos, in the same window.

Code:

ffplay -f lavfi -i "movie=test1.mp4,crop=1920:1080:0:0[v0];movie=test2.mp4,scale=1920:-1,crop=1920:1080:0:0[v1];[v0][v1]vstack"

ffplay -f lavfi -i "movie=test1.mp4,crop=1920:1080:0:0[h0];movie=test2.mp4,scale=1920:-1,crop=1920:1080:0:0[h1];[h0][h1]hstack"

Screenshots of videos playing.

Code:

curl -F'file=@shot1.jpg' https://0x0.st
https://0x0.st/-VuN.jpg

curl -F'file=@shot2.jpg' https://0x0.st
https://0x0.st/-Vuq.jpg

https://0x0.st/-VuN.jpg
https://0x0.st/-Vuq.jpg

Linux.tar.gz · 07-19-2021, 08:31 AM

Thanks, but I'd like to export two webcams in a /dev/videoX in order to use it in some videoconferencing software.

TenTenths · 07-19-2021, 09:09 AM

A quick read suggests that Snowmix might do what you're looking for: https://snowmix.sourceforge.io/