stream to twitch and youtube RTMP destinations using FFmpeg

ffmpeg.js

  const ffmpeg = child_process.spawn('ffmpeg', [
    // the input
    '-i',
    '-',

    // video codec config: low latency, adaptive bitrate, 
    // list of presets: https://trac.ffmpeg.org/wiki/Encode/H.264
    // tune zerolatency is good for fast encoding and low-latency streaming
    // g:v 60 ==> https://www.reddit.com/r/ffmpeg/comments/redaa2/while_livestreaming_to_youtube_using_ffmpeg_i_get/
    '-c:v',
    'libx264',
    '-preset',
    'veryfast',
    '-tune',
    'zerolatency',
    '-g:v',
    '60',

    // audio codec config: 2 channels of audio, audio sampling rate of 44100, bitrate 64 kbits
    '-c:a',
    'aac',
    '-strict',
    '-2',
    '-ar',
    '44100',
    '-b:a',
    '64k',

    //force to overwrite
    // this is probably not needed
    '-y',

    // used for audio sync
    '-use_wallclock_as_timestamps',
    '1',
    '-async',
    '1',

    // output to twitch's RTMP server in an flv container
    '-f',
    'flv',
    twitchRtmpUrl,

    // video codec config: low latency, adaptive bitrate
    '-c:v',
    'libx264',
    '-preset',
    'veryfast',
    '-tune',
    'zerolatency',

    // audio codec config
    '-c:a',
    'aac',
    '-strict',
    '-2',
    '-ar',
    '44100',
    '-b:a',
    '64k',

    //force to overwrite
    '-y',

    // used for audio sync
    '-use_wallclock_as_timestamps',
    '1',
    '-async',
    '1',

    // output to youtube's RTMP server in an flv container
    '-f',
    'flv',
    youtubeRtmpUrl
  ])