multiple input camera & ffmpeg

[wacek5]

Hello

I`ve Composite video cards BT878 PICO 2000 , with 4 inputs. In my system BT878 PICO 2000 is /dev/video1
How to set command-line to tranmite stream from input 4 on /dev/video1:
ffmpeg -f v4l2 -i /dev/video1 -r 2 -f flv rtmp://localhost/myapp --> in this case there is no streaming, I don`t know how to set input number in the command-line

thx