1. ffmpeg -devices -loglevel quiet
显示ffmpeg支持的设备，通常用于查看ffmpeg支持的硬件设备，比如Cuda、Atalas
2. 输出
Devices: D. = Demuxing supported .E = Muxing supported
DE alsa ALSA audio output
E caca caca (color ASCII art) output device
DE fbdev Linux framebuffer
D iec61883 libiec61883 (new DV1394) A/V input device
D jack JACK Audio Connection Kit
D kmsgrab KMS screen capture
D lavfi Libavfilter virtual input device
D libcdio
D libdc1394 dc1394 v.2 A/V grab
D openal OpenAL audio capture device
E opengl OpenGL output
DE oss OSS (Open Sound System) playback
DE pulse Pulse audio output
E sdl,sdl2 SDL2 output device
DE sndio sndio audio playback
DE video4linux2,v4l2 Video4Linux2 output device
D x11grab X11 screen capture, using XCB
E xv XV (XVideo) output device
3. 说明
输出选项中带D，表示支持该格式的解码；带E，表示支持该格式的编码。
