How to reduce the size to 5.17 KiB/s?

[jasonrichdarmawan]

The issue

My goal is to send a data array with size 5.17 KiB/s to a WebSocket.

I have not tried it yet, currently I tried to save the audio to a file. I use RNSaveAudio to save the audio file. I also use react-native-fs to get the app's folder path.

My expected result is the file should be around 5 - 6 kB for 1 seconds of audio.

My actual result is: 8236 bytes for 93 milliseconds (roughly 0,093 seconds) of audio. I tried to change the sampleRate to 8000. I found the data size to be 2 - 3 times larger compared to Opus Voice with bit rate 5.17 KiB/s and sampling rate 8 kHz.

TL:DR

Steps to reproduce:

1. Add listener

  let audioInt16: number[] = [];
  let listener;

  React.useEffect(() => {
    // eslint-disable-next-line react-hooks/exhaustive-deps
    listener = Recording.addRecordingEventListener((data: number[]) => {
      console.log('record', data.length);
      // eslint-disable-next-line react-hooks/exhaustive-deps
      audioInt16 = audioInt16.concat(data);
    });

    return () => {
      listener.remove();
    };
  });

2. Record audio

  const startAsync = async () => {
    await PermissionsAndroid.requestMultiple([
      PermissionsAndroid.PERMISSIONS.RECORD_AUDIO,
    ]);

    Recording.init({
      bufferSize: 4096,
      sampleRate: 44100,
      bitsPerChannel: 16,
      channelsPerFrame: 1,
    });

    Recording.start();
  };

3. Save audio

  const saveAudio = async () => {
    const promise = await RNSaveAudio.saveWav(path, audioInt16);
    console.log('save audio', promise, path);
  };

4. Play audio

  const playAudio = () => {
    if (player.canPrepare || player.canPlay) {
      player.prepare((err) => {
        if (err) {
          console.log(err);
        }
        console.log('play audio', player.duration);
        player.play();
      });
    }
  };