android-project/app/src/main/java/org/libsdl/app/SDLAudioManager.java

package org.libsdl.app;

import android.media.*;
import android.util.Log;

public class SDLAudioManager
{
    protected static final String TAG = "SDLAudio";

    protected static AudioTrack mAudioTrack;
    protected static AudioRecord mAudioRecord;

    public static void initialize() {
        mAudioTrack = null;
        mAudioRecord = null;
    }

    // Audio

    /**
     * This method is called by SDL using JNI.
     */
    public static int audioOpen(int sampleRate, boolean is16Bit, boolean isStereo, int desiredFrames) {
        int channelConfig = isStereo ? AudioFormat.CHANNEL_CONFIGURATION_STEREO : AudioFormat.CHANNEL_CONFIGURATION_MONO;
        int audioFormat = is16Bit ? AudioFormat.ENCODING_PCM_16BIT : AudioFormat.ENCODING_PCM_8BIT;
        int frameSize = (isStereo ? 2 : 1) * (is16Bit ? 2 : 1);

        Log.v(TAG, "SDL audio: wanted " + (isStereo ? "stereo" : "mono") + " " + (is16Bit ? "16-bit" : "8-bit") + " " + (sampleRate / 1000f) + "kHz, " + desiredFrames + " frames buffer");

        // Let the user pick a larger buffer if they really want -- but ye
        // gods they probably shouldn't, the minimums are horrifyingly high
        // latency already
        desiredFrames = Math.max(desiredFrames, (AudioTrack.getMinBufferSize(sampleRate, channelConfig, audioFormat) + frameSize - 1) / frameSize);

        if (mAudioTrack == null) {
            mAudioTrack = new AudioTrack(AudioManager.STREAM_MUSIC, sampleRate,
                    channelConfig, audioFormat, desiredFrames * frameSize, AudioTrack.MODE_STREAM);

            // Instantiating AudioTrack can "succeed" without an exception and the track may still be invalid
            // Ref: https://android.googlesource.com/platform/frameworks/base/+/refs/heads/master/media/java/android/media/AudioTrack.java
            // Ref: http://developer.android.com/reference/android/media/AudioTrack.html#getState()

            if (mAudioTrack.getState() != AudioTrack.STATE_INITIALIZED) {
                Log.e(TAG, "Failed during initialization of Audio Track");
                mAudioTrack = null;
                return -1;
            }

            mAudioTrack.play();
        }

        Log.v(TAG, "SDL audio: got " + ((mAudioTrack.getChannelCount() >= 2) ? "stereo" : "mono") + " " + ((mAudioTrack.getAudioFormat() == AudioFormat.ENCODING_PCM_16BIT) ? "16-bit" : "8-bit") + " " + (mAudioTrack.getSampleRate() / 1000f) + "kHz, " + desiredFrames + " frames buffer");

        return 0;
    }

    /**
     * This method is called by SDL using JNI.
     */
    public static void audioWriteShortBuffer(short[] buffer) {
        if (mAudioTrack == null) {
            Log.e(TAG, "Attempted to make audio call with uninitialized audio!");
            return;
        }

        for (int i = 0; i < buffer.length; ) {
            int result = mAudioTrack.write(buffer, i, buffer.length - i);
            if (result > 0) {
                i += result;
            } else if (result == 0) {
                try {
                    Thread.sleep(1);
                } catch(InterruptedException e) {
                    // Nom nom
                }
            } else {
                Log.w(TAG, "SDL audio: error return from write(short)");
                return;
            }
        }
    }

    /**
     * This method is called by SDL using JNI.
     */
    public static void audioWriteByteBuffer(byte[] buffer) {
        if (mAudioTrack == null) {
            Log.e(TAG, "Attempted to make audio call with uninitialized audio!");
            return;
        }
        
        for (int i = 0; i < buffer.length; ) {
            int result = mAudioTrack.write(buffer, i, buffer.length - i);
            if (result > 0) {
                i += result;
            } else if (result == 0) {
                try {
                    Thread.sleep(1);
                } catch(InterruptedException e) {
                    // Nom nom
                }
            } else {
                Log.w(TAG, "SDL audio: error return from write(byte)");
                return;
            }
        }
    }

    /**
     * This method is called by SDL using JNI.
     */
    public static int captureOpen(int sampleRate, boolean is16Bit, boolean isStereo, int desiredFrames) {
        int channelConfig = isStereo ? AudioFormat.CHANNEL_CONFIGURATION_STEREO : AudioFormat.CHANNEL_CONFIGURATION_MONO;
        int audioFormat = is16Bit ? AudioFormat.ENCODING_PCM_16BIT : AudioFormat.ENCODING_PCM_8BIT;
        int frameSize = (isStereo ? 2 : 1) * (is16Bit ? 2 : 1);

        Log.v(TAG, "SDL capture: wanted " + (isStereo ? "stereo" : "mono") + " " + (is16Bit ? "16-bit" : "8-bit") + " " + (sampleRate / 1000f) + "kHz, " + desiredFrames + " frames buffer");

        // Let the user pick a larger buffer if they really want -- but ye
        // gods they probably shouldn't, the minimums are horrifyingly high
        // latency already
        desiredFrames = Math.max(desiredFrames, (AudioRecord.getMinBufferSize(sampleRate, channelConfig, audioFormat) + frameSize - 1) / frameSize);

        if (mAudioRecord == null) {
            mAudioRecord = new AudioRecord(MediaRecorder.AudioSource.DEFAULT, sampleRate,
                    channelConfig, audioFormat, desiredFrames * frameSize);

            // see notes about AudioTrack state in audioOpen(), above. Probably also applies here.
            if (mAudioRecord.getState() != AudioRecord.STATE_INITIALIZED) {
                Log.e(TAG, "Failed during initialization of AudioRecord");
                mAudioRecord.release();
                mAudioRecord = null;
                return -1;
            }

            mAudioRecord.startRecording();
        }

        Log.v(TAG, "SDL capture: got " + ((mAudioRecord.getChannelCount() >= 2) ? "stereo" : "mono") + " " + ((mAudioRecord.getAudioFormat() == AudioFormat.ENCODING_PCM_16BIT) ? "16-bit" : "8-bit") + " " + (mAudioRecord.getSampleRate() / 1000f) + "kHz, " + desiredFrames + " frames buffer");

        return 0;
    }

    /** This method is called by SDL using JNI. */
    public static int captureReadShortBuffer(short[] buffer, boolean blocking) {
        // !!! FIXME: this is available in API Level 23. Until then, we always block.  :(
        //return mAudioRecord.read(buffer, 0, buffer.length, blocking ? AudioRecord.READ_BLOCKING : AudioRecord.READ_NON_BLOCKING);
        return mAudioRecord.read(buffer, 0, buffer.length);
    }

    /** This method is called by SDL using JNI. */
    public static int captureReadByteBuffer(byte[] buffer, boolean blocking) {
        // !!! FIXME: this is available in API Level 23. Until then, we always block.  :(
        //return mAudioRecord.read(buffer, 0, buffer.length, blocking ? AudioRecord.READ_BLOCKING : AudioRecord.READ_NON_BLOCKING);
        return mAudioRecord.read(buffer, 0, buffer.length);
    }


    /** This method is called by SDL using JNI. */
    public static void audioClose() {
        if (mAudioTrack != null) {
            mAudioTrack.stop();
            mAudioTrack.release();
            mAudioTrack = null;
        }
    }

    /** This method is called by SDL using JNI. */
    public static void captureClose() {
        if (mAudioRecord != null) {
            mAudioRecord.stop();
            mAudioRecord.release();
            mAudioRecord = null;
        }
    }

    public static native int nativeSetupJNI();
}