Linux Video

列出所有裝置

$ v4l2-ctl --list-devices

USB3.0 Camera (usb-0000:00:14.0-2):
        /dev/video1
        /dev/video2

Integrated Camera (usb-0000:00:1a.0-1.6):
        /dev/video0

列出所有的格式 

$ ffmpeg -f v4l2 -list_formats all -i /dev/video0 

[video4linux2,v4l2 @ 0x2007420] Raw       :   yuyv422 :     YUV 4:2:2 (YUYV) : 640x480 640x360 352x288 320x240 800x448 960x540 1280x720 424x240
[video4linux2,v4l2 @ 0x2007420] Compressed:     mjpeg :                MJPEG : 640x480 640x360 352x288 320x240 800x448 960x540 1280x720

$ ffmpeg -f v4l2 -list_formats all -i /dev/video1

[video4linux2,v4l2 @ 0x2113420] Raw       :   yuyv422 :     YUV 4:2:2 (YUYV) : 1280x720 2560x720 640x480 1280x480 320x240 960x540 640x240 848x480 320x180 424x240 640x360 800x600 1600x600 

$ ffmpeg -f v4l2 -list_formats all -i /dev/video2

[video4linux2,v4l2 @ 0xd20e60] Raw       :   yuyv422 :     YUV 4:2:2 (YUYV) : 320x480 160x240 

Ref

https://trac.ffmpeg.org/wiki/Capture/Webcam