Screen cast and capture video cam and show both on screen using ffmpeg?

Question

I'm using the following command to capture my screen cast and laptop video camera at the same time. Video from the cameraappears in a smallish window in bottom right of the screen cast.This works, however there is a snag; I can't see the video ofmyself on screen while I'm recording and I want to be ableto see myself in the bottom right window so I can be sure Ialign myself with the camera. How can I do this? ffmpeg -f alsa -i default \\ -f x11grab -s `xdpyinfo | grep 'dimensions:'|awk '{print $2}'` -r 25 \\ -i :0.0 -f video4linux2 \\ -i /dev/video0 -filter_complex '[2:v]scale=380:-1[cam];[1:v][cam]overlay=W-w-8:H-h-8' \\ -c:a flac \\ -qscale 0 screen_and_video_grab.mkv

Answer 1

You almost had it.

This command overlays camera video input 1 onto the desktop video input 0 and saves it to a file. It then sends over only video 1 input to ffplay to display the preview.

For this to work well, ffmpeg expects a file format. And for it to work fast, you also have to specify audio and video codec.

Just be sure to move your preview out of the way to a second screen.

fmpeg -f x11grab -framerate 25 -video_size 1366x768 -i :0.0+0,0 \

-f v4l2 -framerate 25 -video_size 640x480 -i /dev/video0 \

-filter_complex "[1:v]scale=320:-1[cam];[0:v][cam]overlay=W-w-10:H-h-10" \

-c:a flac -qscale 0 output.mkv \

-f matroska -map 1:v -c:v copy -c:a copy pipe:1 | ffplay -i pipe:0

If you want to use fancy shorthand, you can use the - symbol instead of pipe, like this:

fmpeg -f x11grab -framerate 25 -video_size 1366x768 -i :0.0+0,0 \

-f v4l2 -framerate 25 -video_size 640x480 -i /dev/video0 \

-filter_complex "[1:v]scale=320:-1[cam];[0:v][cam]overlay=W-w-10:H-h-10" \

-c:a flac -qscale 0 output.mkv \

-f matroska -map 1:v -c:v copy -c:a copy - | ffplay -i -