Android AudioRecord不会初始化

Question

我正在尝试实现一个监听麦克风输入(特别是呼吸)的应用程序,并根据它提供数据.我正在使用Android类AudioRecord,在尝试实例化AudioRecord时,我得到了三个错误.

AudioRecord: AudioFlinger could not create record track, status: -1
AudioRecord-JNI: Error creating AudioRecord instance: initialization check failed with status -1.
android.media.AudioRecord: Error code -20 when initializing native AudioRecord object.

我发现这个优秀的线程:AudioRecord对象没有初始化

我从已接受的答案中借用了代码,尝试所有采样率,音频格式和通道配置以尝试解决问题,但它没有帮助,我得到了所有设置的上述错误.我还根据线程中的一个答案在几个地方添加了对AudioRecord.release()的调用,但它没有任何区别.

这是我的代码:

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

public class SoundMeter {

private AudioRecord ar = null;
private int minSize;
private static int[] mSampleRates = new int[] { 8000, 11025, 22050, 32000, 44100 };

public boolean start() {
    ar = findAudioRecord();
    if(ar != null){
        ar.startRecording();
        return true;
    }
    else{
        Log.e("SoundMeter", "ERROR, could not create audio recorder");
        return false;
    }
}

public void stop() {
    if (ar != null) {
        ar.stop();
        ar.release();
    }
}

public double getAmplitude() {
    short[] buffer = new short[minSize];
    ar.read(buffer, 0, minSize);
    int max = 0;
    for (short s : buffer)
    {
        if (Math.abs(s) > max)
        {
            max = Math.abs(s);
        }
    }
    return max;
}

public AudioRecord findAudioRecord() {
    for (int rate : mSampleRates) {
        for (short audioFormat : new short[] { AudioFormat.ENCODING_PCM_8BIT, AudioFormat.ENCODING_PCM_16BIT, AudioFormat.ENCODING_PCM_FLOAT }) {
            for (short channelConfig : new short[] { AudioFormat.CHANNEL_IN_MONO, AudioFormat.CHANNEL_IN_STEREO }) {
                try {
                    Log.d("SoundMeter", "Attempting rate " + rate + "Hz, bits: " + audioFormat + ", channel: " + channelConfig);
                    int bufferSize = AudioRecord.getMinBufferSize(rate, channelConfig, audioFormat);

                    if (bufferSize != AudioRecord.ERROR_BAD_VALUE) {
                        // check if we can instantiate and have a success
                        Log.d("SoundMeter", "Found a supported bufferSize, attempting to instantiate");
                        AudioRecord recorder = new AudioRecord(MediaRecorder.AudioSource.DEFAULT, rate, channelConfig, audioFormat, bufferSize);

                        if (recorder.getState() == AudioRecord.STATE_INITIALIZED){
                            minSize = bufferSize;
                            return recorder;
                        }
                        else
                            recorder.release();
                    }
                } catch (Exception e) {
                    Log.e("SoundMeter", rate + " Exception, keep trying.", e);
                }
            }
        }
    }
    return null;
}

}

我也加了

<uses-permission android:name="android.permission.RECORD_AUDIO"/>

根据上面提到的线程中的其他答案之一,标记到我的清单文件,作为清单标记的子项和应用程序标记的兄弟.我在添加此标记后重建了该项目.

这些是我在搜索问题时找到的解决方案,但不幸的是,它们似乎并没有为我做到这一点.我正在调试我的Nexus 5手机(不是模拟器).调用AudioRecord的构造函数时会出现这些错误.我已经多次重启我的手机试图释放麦克风,但无济于事.该项目基于Android 4.4,我的手机目前运行的是Android 6.0.1.

非常感谢我可以尝试的其他一些提示,我可能错过了什么.谢谢!

Answer 1

我自己找到了答案.它与权限有关.

问题是我在手机上运行API版本23(Android 6.0.1),它不再仅使用清单文件来处理权限.从版本23开始,将在运行时授予权限.我添加了一个确保在运行时请求权限的方法,当我在手机上允许它一次时,它就可以了.

private void requestRecordAudioPermission() {
    //check API version, do nothing if API version < 23!
    int currentapiVersion = android.os.Build.VERSION.SDK_INT;
    if (currentapiVersion > android.os.Build.VERSION_CODES.LOLLIPOP){

        if (ContextCompat.checkSelfPermission(this, Manifest.permission.RECORD_AUDIO) != PackageManager.PERMISSION_GRANTED) {

            // Should we show an explanation?
            if (ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.RECORD_AUDIO)) {

                // Show an expanation to the user *asynchronously* -- don't block
                // this thread waiting for the user's response! After the user
                // sees the explanation, try again to request the permission.

            } else {

                // No explanation needed, we can request the permission.

                ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.RECORD_AUDIO}, 1);
            }
        }
    }
}

@Override
public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {
    switch (requestCode) {
        case 1: {
            // If request is cancelled, the result arrays are empty.
            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {

                // permission was granted, yay! Do the
                // contacts-related task you need to do.
                Log.d("Activity", "Granted!");

            } else {

                // permission denied, boo! Disable the
                // functionality that depends on this permission.
                Log.d("Activity", "Denied!");
                finish();
            }
            return;
        }

        // other 'case' lines to check for other
        // permissions this app might request
    }
}

然后,在创建AudioRecord之前,从主活动中的onCreate()方法调用requestRecordAudioPermission().