Tdarr-AudioEncode.js

const AUDIO_ENCODER="aac",
      AUDIO_CHANNEL=1,
      AUDIO_BITRATE="64k",
      AUDIO_SAMPLERATE="48k",
      AUDIO_LANG_TAG="und";

const PREFERRED_LANG_TAGS = ["jp", "en", "und"]

function appendAudioStream({
  args,
  streams,
  langTag,
  audioEncoder,
  wantedChannelCount,
  wantedBitrate,
  wantedSampleRate,
}){
  const audioStreams = streams.filter((stream) => stream.codec_type === 'audio')

  if (audioStreams.length === 0) {
    args.jobLog(`No audio streams found. Skipping \n`);
    return
  }

  var baseAudioStream = audioStreams.reduce(
    (selected, stream) => {
      // langTag: unmatch -> selected win
      if (!PREFERRED_LANG_TAGS.some((langTag) =>
          stream.tags?.language?.toLowerCase().includes(langTag) === true
      )) {
        return selected
      }

      // channel count
      if (selected.channels > stream.channels) {
        return selected
      }
      return stream

      // TODO: sample_rate, bitrate check
    },
    audioStreams[0],
  );

  // TODO: 既に変換したい音源があればスキップする

  const channelCount = Math.min(wantedChannelCount, baseAudioStream.channels),
        bitrate = wantedBitrate,
        sampleRate = wantedSampleRate;

  args.jobLog(`Adding ${langTag} stream in ${audioEncoder}, ${channelCount} channels \n`);

  // mark as removed for all audio stream
  audioStreams.forEach((stream) => { stream.removed = true });

  const streamCopy = JSON.parse(JSON.stringify(baseAudioStream))
  streamCopy.removed = false;
  streamCopy.index = streams.length;
  streamCopy.tags = {
    language: AUDIO_LANG_TAG,
  }

  streamCopy.outputArgs.push('-c:{outputIndex}', audioEncoder);
  streamCopy.outputArgs.push('-ac', `${channelCount}`);
  // if (enableBitrate)
  streamCopy.outputArgs.push(`-b:a:{outputTypeIndex}`, `${bitrate}`);
  // if (enableSamplerate)
  streamCopy.outputArgs.push('-ar', `${sampleRate}`);
  // -metadata:s:a:0 language=eng
  streamCopy.outputArgs.push('-metadata:s:a:{outputTypeIndex}', `language=${langTag}`)

  args.variables.ffmpegCommand.shouldProcess = true;

  streams.push(streamCopy);
}

module.exports = async (args) => {
  const { streams } = args.variables.ffmpegCommand;

  appendAudioStream({
    args,
    streams,
    langTag: AUDIO_LANG_TAG,
    audioEncoder: AUDIO_ENCODER,
    wantedChannelCount: AUDIO_CHANNEL,
    wantedBitrate: AUDIO_BITRATE,
    wantedSampleRate: AUDIO_SAMPLERATE,
  });

  return {
    outputFileObj: args.inputFileObj,
    outputNumber: 1,
    variables: args.variables,
  }
}