通过命令行录音

ffmpeg -devices

Devices:
 D. = Demuxing supported
 .E = Muxing supported
 --
 D  avfoundation    AVFoundation input device
 D  lavfi           Libavfilter virtual input device
  E sdl,sdl2        SDL2 output device

查看avfoundation支持的设备

ffmpeg -f avfoundation -list_devices true -i ''

[AVFoundation indev @ 0x7f826452d700] AVFoundation video devices:
[AVFoundation indev @ 0x7f826452d700] [0] FaceTime高清摄像头（内建）
[AVFoundation indev @ 0x7f826452d700] [1] Capture screen 0
[AVFoundation indev @ 0x7f826452d700] [2] Capture screen 1
[AVFoundation indev @ 0x7f826452d700] [3] Capture screen 2
[AVFoundation indev @ 0x7f826452d700] AVFoundation audio devices:
[AVFoundation indev @ 0x7f826452d700] [0] Built-in Microphone

指定设备进行录音

# 在Mac上通过编号指定设备
ffmpeg -f avfoundation -i :0 out.wav
# :0表示使用0号音频设备
# 0:0表示使用0号视频设备和0号音频设备
ffplay out.wav

• 可以使用快捷键Ctrl + C终止录音
• 我这边的测试结果显示，默认的音频参数是：
  • Mac：48000Hz采样率、16位深度、2声道、1536Kbps比特率

录制视频和音频

ffmpeg -f avfoundation -i 0:0 out.mp4
ffplay out.mp4

查看参数

ffmpeg -devices -hide_banner

Devices:
 D. = Demuxing supported
 .E = Muxing supported
 --
 D  avfoundation    AVFoundation input device
 D  lavfi           Libavfilter virtual input device
  E sdl,sdl2        SDL2 output device
 D  x11grab         X11 screen capture, using XCB

• Demuxing supported D代表解复用器
• Muxing supported E表示复用器

image-20210325210301041

ffmpeg -h demuxer=avfoundation -hide_banner

Demuxer avfoundation [AVFoundation input device]:
AVFoundation indev AVOptions:
  -list_devices      <boolean>    .D........ list available devices (default false)
  -video_device_index <int>        .D........ select video device by index for devices with same name (starts at 0) (from -1 to INT_MAX) (default -1)
  -audio_device_index <int>        .D........ select audio device by index for devices with same name (starts at 0) (from -1 to INT_MAX) (default -1)
  -pixel_format      <pix_fmt>    .D........ set pixel format (default yuv420p)
  -framerate         <video_rate> .D........ set frame rate (default "ntsc")
  -video_size        <image_size> .D........ set video size
  -capture_cursor    <boolean>    .D........ capture the screen cursor (default false)
  -capture_mouse_clicks <boolean>    .D........ capture the screen mouse clicks (default false)
  -capture_raw_data  <boolean>    .D........ capture the raw data from device connection (default false)
  -drop_late_frames  <boolean>    .D........ drop frames that are available later than expected (default true)

ffmpeg -f avfoundation  -audio_device_index 0 -i ""
Input #0, avfoundation, from '':
  Duration: N/A, start: 42170.757098, bitrate: 2822 kb/s
    Stream #0:0: Audio: pcm_f32le, 44100 Hz, stereo, flt, 2822 kb/s
At least one output file must be specified

ffmpeg -f avfoundation  -video_device_index 0 -i ""


[avfoundation @ 0x7fafb100a200] Selected pixel format (yuv420p) is not supported by the input device.
[avfoundation @ 0x7fafb100a200] Supported pixel formats:
[avfoundation @ 0x7fafb100a200]   uyvy422
[avfoundation @ 0x7fafb100a200]   yuyv422
[avfoundation @ 0x7fafb100a200]   nv12
[avfoundation @ 0x7fafb100a200]   0rgb
[avfoundation @ 0x7fafb100a200]   bgr0
[avfoundation @ 0x7fafb100a200] Overriding selected pixel format to use uyvy422 instead.
Input #0, avfoundation, from '':
  Duration: N/A, start: 42259.834733, bitrate: N/A
    Stream #0:0: Video: rawvideo (UYVY / 0x59565955), uyvy422, 1280x720, 20 tbr, 1000k tbn, 1000k tbc