Android通过AudioTrack播放自定义声音 比如正弦波

直接上代码

代码来自于https://github.com/xiaoniu/PureTone

FMCW这种经常要自定义指定函数的声音，就可以改改函数就可以直接用这里用的是sin

public class SinWave {
    /** 正弦波的高度 2的8次方减1**/
    public static final int HEIGHT = 127;
    /** 2PI **/
    public static final double TWOPI = 2 * 3.1415;

    /**
     * 生成正弦波
     *
     * @param wave
     * @param waveLen
     *            每段正弦波的长度
     * @param length
     *            总长度
     * @return
     */
    public static byte[] sin(byte[] wave, int waveLen, int length) {
        for (int i = 0; i < length; i++) {
            wave[i] = (byte) (HEIGHT * (1 - Math.sin(TWOPI * ((i % waveLen) * 1.00 / waveLen))));
        }
        return wave;
    }
}

PlayThread

import android.media.AudioFormat;
import android.media.AudioManager;
import android.media.AudioTrack;

public class PlayThread extends Thread {
    public static final int RATE = 44100;
    AudioTrack mAudioTrack;
    public static boolean ISPLAYSOUND;

    /**
     * 总长度
     **/
    int length;
    /**
     * 一个正弦波的长度
     **/
    int waveLen;
    /**
     * 频率
     **/
    int Hz;
    /**
     * 正弦波
     **/
    byte[] wave;

    /**
     * 初始化
     * @param rate 频率
     */
    public PlayThread(int rate) {
        if (rate > 0) {
            Hz = rate;
            waveLen = RATE / Hz;
            length = waveLen * Hz;
            wave = new byte[RATE];
            mAudioTrack = new AudioTrack(AudioManager.STREAM_MUSIC, RATE,
                    AudioFormat.CHANNEL_CONFIGURATION_STEREO, // CHANNEL_CONFIGURATION_MONO,
                    AudioFormat.ENCODING_PCM_8BIT, length, AudioTrack.MODE_STREAM);
            ISPLAYSOUND = true;
            wave = SinWave.sin(wave, waveLen, length);
        } else {
            return;
        }

    }

    @Override
    public void run() {
        super.run();
        if (null != mAudioTrack)
            mAudioTrack.play();
        //一直播放
        while (ISPLAYSOUND) {
            mAudioTrack.write(wave, 0, length);
        }

    }

    /**
     * 设置左右声道，左声道时设置右声道音量为0，右声道设置左声道音量为0
     *
     * @param left  左声道
     * @param right 右声道
     */
    public void setChannel(boolean left, boolean right) {
        if (null != mAudioTrack) {
            mAudioTrack.setStereoVolume(left ? 1 : 0, right ? 1 : 0);
        }
    }

    //设置音量
    public void setVolume(float left, float right) {
        if (null != mAudioTrack) {
            mAudioTrack.setStereoVolume(left,right);
        }
    }

    public void stopPlay() {
        ISPLAYSOUND = false;
        releaseAudioTrack();
    }

    private void releaseAudioTrack() {
        if (null != mAudioTrack) {
            mAudioTrack.stop();
            mAudioTrack.release();
            mAudioTrack = null;
        }
    }
}

MainActivity

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.KeyEvent;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    private PlayThread mPlayThread;

    Button btnPlay;
    Button btnLeft;
    Button btnRight;
    Button btnStop;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btnPlay = (Button) findViewById(R.id.btn_play);
        btnLeft = (Button) findViewById(R.id.btn_left);
        btnRight = (Button) findViewById(R.id.btn_right);
        btnStop = (Button) findViewById(R.id.btn_stop);
        btnPlay.setOnClickListener(this);
        btnLeft.setOnClickListener(this);
        btnRight.setOnClickListener(this);
        btnStop.setOnClickListener(this);

    }


    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_BACK) {
            this.finish();
            if (null != mPlayThread) {
                mPlayThread.stopPlay();
                mPlayThread = null;
            }
        }
        return super.onKeyDown(keyCode, event);
    }

    @Override
    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.btn_play:
                playSound(true, true);
                break;
            case R.id.btn_left:
                playSound(true, false);
                break;
            case R.id.btn_right:
                playSound(false, true);
                break;
            case R.id.btn_stop:
                if (null != mPlayThread) {
                    mPlayThread.stopPlay();
                    mPlayThread = null;
                }
                break;
        }
    }

    private void playSound(boolean left, boolean right) {
        if (null != mPlayThread) {
            mPlayThread.stopPlay();
            mPlayThread = null;
        }
        mPlayThread = new PlayThread(2);
        mPlayThread.setChannel(left, right);
        mPlayThread.start();
    }
}

XML

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
    <Button
        android:id="@+id/btn_play"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="双声道播放" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <Button
            android:id="@+id/btn_left"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="左声道播放" />

        <Button
            android:id="@+id/btn_right"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="右声道播放" />
    </LinearLayout>
    <Button
        android:id="@+id/btn_stop"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="停止播放" />
</LinearLayout>

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