RNLiveAudioStreamModule.java

package com.imxiqi.rnliveaudiostream;

import android.media.AudioFormat;
import android.media.AudioRecord;
import android.media.MediaRecorder.AudioSource;
import android.util.Base64;
import android.util.Log;

import com.facebook.react.bridge.Promise;
import com.facebook.react.bridge.ReactApplicationContext;
import com.facebook.react.bridge.ReactContextBaseJavaModule;
import com.facebook.react.bridge.ReactMethod;
import com.facebook.react.bridge.ReadableMap;
import com.facebook.react.modules.core.DeviceEventManagerModule;

import java.lang.Math;

public class RNLiveAudioStreamModule extends ReactContextBaseJavaModule {

    private final ReactApplicationContext reactContext;
    private DeviceEventManagerModule.RCTDeviceEventEmitter eventEmitter;

    private int sampleRateInHz;
    private int channelConfig;
    private int audioFormat;
    private int audioSource;

    private AudioRecord recorder;
    private int bufferSize;
    private boolean isRecording;

    public RNLiveAudioStreamModule(ReactApplicationContext reactContext) {
        super(reactContext);
        this.reactContext = reactContext;
    }

    @Override
    public String getName() {
        return "RNLiveAudioStream";
    }

    @ReactMethod
    public void init(ReadableMap options) {
        sampleRateInHz = 44100;
        if (options.hasKey("sampleRate")) {
            sampleRateInHz = options.getInt("sampleRate");
        }

        channelConfig = AudioFormat.CHANNEL_IN_MONO;
        if (options.hasKey("channels")) {
            if (options.getInt("channels") == 2) {
                channelConfig = AudioFormat.CHANNEL_IN_STEREO;
            }
        }

        audioFormat = AudioFormat.ENCODING_PCM_16BIT;
        if (options.hasKey("bitsPerSample")) {
            if (options.getInt("bitsPerSample") == 8) {
                audioFormat = AudioFormat.ENCODING_PCM_8BIT;
            }
        }

        audioSource = AudioSource.VOICE_RECOGNITION;
        if (options.hasKey("audioSource")) {
            audioSource = options.getInt("audioSource");
        }

        isRecording = false;
        eventEmitter = reactContext.getJSModule(DeviceEventManagerModule.RCTDeviceEventEmitter.class);

        bufferSize = AudioRecord.getMinBufferSize(sampleRateInHz, channelConfig, audioFormat);

        if (options.hasKey("bufferSize")) {
            bufferSize = Math.max(bufferSize, options.getInt("bufferSize"));
        }

        int recordingBufferSize = bufferSize * 3;
        recorder = new AudioRecord(audioSource, sampleRateInHz, channelConfig, audioFormat, recordingBufferSize);
    }

    @ReactMethod
    public void start() {
        isRecording = true;
        recorder.startRecording();

        Thread recordingThread = new Thread(new Runnable() {
            public void run() {
                try {
                    int bytesRead;
                    int count = 0;
                    String base64Data;
                    byte[] buffer = new byte[bufferSize];

                    while (isRecording) {
                        bytesRead = recorder.read(buffer, 0, buffer.length);

                        // skip first 2 buffers to eliminate "click sound"
                        if (bytesRead > 0 && ++count > 2) {
                            base64Data = Base64.encodeToString(buffer, Base64.NO_WRAP);
                            eventEmitter.emit("data", base64Data);
                        }
                    }
                    recorder.stop();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });

        recordingThread.start();
    }

    @ReactMethod
    public void stop(Promise promise) {
        isRecording = false;
    }

    @ReactMethod
    public void addListener(String eventName) {
        // Keep: Required for RN built in Event Emitter Calls.
    }

    @ReactMethod
    public void removeListeners(Integer count) {
        // Keep: Required for RN built in Event Emitter Calls.
    }
}