Android的AEC和​​噪音抑制器无法在某些设备上运行

Question

在使用具有VoIP功能的Android Unity应用程序时，我们发现在某些设备（特别是Galaxy S6）上，麦克风会拾取扬声器输出的声音，导致大量静电，失真和回声。因此，我开始研究原生解决方案，以利用Android的一些AEC和NS功能。

我编写了以下测试平台，它在某些设备（例如Note 4）上运行良好。当同一个应用程序在Galaxy S6上运行时，就好像ARC和NS没有得到很好的应用。

public class MainActivity extends Activity
{
    private AudioRecord mAudioRecorder = null;
    private AudioTrack mStreamingPlayer = null;

    private Thread playbackThread = null;

    private boolean useVoip = true;

    int bufferSize;
    int chunkSize;

    private AutomaticGainControl agc;
    private NoiseSuppressor suppressor;
    private  AcousticEchoCanceler aec;

    private boolean manuallyAttachEffects = false;

    private void StartRecordingAudio()
    {
        int sampleRate = 44100;
        int channelConfig = AudioFormat.CHANNEL_IN_MONO;
        int audioFormat = AudioFormat.ENCODING_PCM_16BIT;

        chunkSize = AudioRecord.getMinBufferSize(sampleRate, channelConfig, audioFormat);
        bufferSize = chunkSize * 10;

        int audioSource = MediaRecorder.AudioSource.MIC;

        if ( useVoip && !manuallyAttachEffects )
        {
            audioSource = MediaRecorder.AudioSource.VOICE_COMMUNICATION;
        }

        mAudioRecorder = new AudioRecord( audioSource, 
                                        sampleRate,
                                        channelConfig,
                                        audioFormat,
                                        bufferSize );

        if ( useVoip && manuallyAttachEffects )
        {
            SetupVoipEffects( mAudioRecorder.getAudioSessionId() );
        }

        mAudioRecorder.startRecording();

        mStreamingPlayer = new AudioTrack(  AudioManager.STREAM_MUSIC,
                                            sampleRate,
                                            AudioFormat.CHANNEL_OUT_MONO,
                                            audioFormat,
                                            bufferSize,
                                            AudioTrack.MODE_STREAM );

        mStreamingPlayer.play();

        playbackThread = new Thread(new Runnable()
        {
            @Override
            public void run() {
                readAudioData();
            }

        });

        playbackThread.start();
    }

    private void readAudioData()
    {
        Thread thisThread = Thread.currentThread();

        byte[] buffer = new byte[chunkSize];

        while ( !thisThread.isInterrupted() )
        {
            if ( mAudioRecorder == null )
                break;

            int bytesRead = mAudioRecorder.read(buffer, 0, chunkSize);
            if ( bytesRead > 0 )
            {
                if ( mStreamingPlayer == null )
                    break;

                mStreamingPlayer.write(buffer, 0, chunkSize);   
            }
        }
    }

    private void SetupVoipEffects( int sessionId )
    {
        if(AutomaticGainControl.isAvailable())
        {
            agc = AutomaticGainControl.create( sessionId );
            Log.d(LOG_TAG, "AGC is " + (agc.getEnabled()?"enabled":"disabled"));

            if ( !agc.getEnabled() )
            {
                agc.setEnabled(true);
                Log.d(LOG_TAG, "AGC is " + (agc.getEnabled()?"enabled":"disabled" +" after trying to enable"));
            }
        }

        if(NoiseSuppressor.isAvailable())
        {
            suppressor = NoiseSuppressor.create( sessionId );
            Log.d(LOG_TAG, "NS is " + (suppressor.getEnabled()?"enabled":"disabled"));

            if ( !suppressor.getEnabled() )
            {
                suppressor.setEnabled(true);
                Log.d(LOG_TAG, "NS is " + (suppressor.getEnabled()?"enabled":"disabled" +" after trying to disable"));  
            }

        }
        if(AcousticEchoCanceler.isAvailable())
        {
            aec = AcousticEchoCanceler.create( sessionId );
            Log.d(LOG_TAG, "AEC is " + (aec.getEnabled()?"enabled":"disabled"));

            if ( !aec.getEnabled() )
            {
                aec.setEnabled(true);
                Log.d(LOG_TAG, "AEC is " + (aec.getEnabled()?"enabled":"disabled" +" after trying to disable"));
            }
        }
    }
}

我尝试过很多东西，例如使用VOICE_COMMUNICATION作为AudioRecord，使用MIC并手动创建NoiseSuppressor和AcousticEchoCanceller，禁用/启用NuPlayer / AwesomePlayer等等。这些设备显示支持并启用了AEC，但它似乎并没有发生。使用耳机或使用听筒而不是扬声器电话时问题完全消失（因此麦克风无法拾取扬声器声音）。我是否在这里忽略了一些巨大的东西，或者是否有可能会报告错误？

如果AEC和NS在其他设备上没有完美运行，我不会怀疑。

Answer 1

这是Android中的一个已知问题。硬件AEC不可靠，即使他们另有报告也没有大量硬件实现/支持。 我建议同时部署软件AEC和硬件AEC，以使您的软件更加稳定。唯一的问题是软件AEC不是那么容易正确完成，所以要做好大量测试的准备。