Android AEC不会产生有用的声音

Question

我正在为一个VoIP应用程序做一些声学回声消除实验，声音让我抓狂。我想做的很简单:我之前录过一个声音。现在我将播放该声音，并在播放时录制另一个声音，这是全双工VoIP场景的真实情况。我用MedaiPlayer播放声音，用MediaRecorder录制新声音。下面是类的完整代码，修改自Android SoundRecorder样本。重要的是，mPlayer.setAudioStreamType (AudioManager.MODE_IN_COMMUNICATION);Android的文档说"在通信音频模式下。"建立语音/视频聊天或VoIP通话mRecorder.setAudioSource (MediaRecorder.AudioSource.VOICE_COMMUNICATION);Android的文档说"麦克风音频源调谐语音通信，如VoIP。例如，如果可用，它将利用回声消除或自动增益控制。如果没有应用语音处理，它的行为就像默认一样。"这是很有希望的。但如果我播放扬声器发出的任何声音，我几乎什么也录不到，或者只有奇怪的声音。由于我是新用户，我无法附加录音的声波，但第一个是正常的录音，有正常的声波。第二次录音是播放第一次录音时的录音，几乎什么都没有，没有声波。如果扬声器中有任何活动，Android似乎会关闭麦克风。我尝试了MediaRecorder和MediaPlayer的不同可能性，但没有用。在Android中实现声学回声消除的正确方法是什么?我尝试在索尼Tablet S上使用Android 3.0 SDK进行开发。提前谢谢。

package com.kadir.sample;
import android.app.Activity;
import android.widget.LinearLayout;
import android.widget.Toast;
import android.os.Bundle;
import android.os.Environment;
import android.view.ViewGroup;
import android.widget.Button;
import android.view.View;
import android.content.Context;
import android.util.Log;
import android.media.AudioManager;
import android.media.MediaRecorder;
import android.media.MediaPlayer;
import java.io.IOException;

public class AudioRecordTest extends Activity
{
    private static final String LOG_TAG = "AudioRecordTest";
    private static String mFileName = null;
    private static String mFileNameConst = null;
    private RecordButton mRecordButton = null;
    private MediaRecorder mRecorder = null;
    private PlayButton   mPlayButton = null;
    private MediaPlayer   mPlayer = null;
    private PlayConstButton mPlayConstButton = null;
    private void onRecord(boolean start) {
        if (start) {
            startRecording();
        } else {
            stopRecording();
        }
    }
    private void onPlay(boolean start) {
        if (start) {
            startPlaying();
        } else {
            stopPlaying();
        }
    }
    private void onPlayConst(boolean start) {
        if (start) {
            startConstPlaying();
        } else {
            stopConstPlaying();
        }
    }
    private void startPlaying() {
        mPlayer = new MediaPlayer();
        try {
            mPlayer.setDataSource(mFileName);
            mPlayer.prepare();
            mPlayer.start();
        } catch (IOException e) {
            Toast.makeText(this, "prepare() failed", Toast.LENGTH_LONG).show();
            Log.e(LOG_TAG, "prepare() failed");
        }
    }
    private void stopPlaying() {
        mPlayer.release();
        mPlayer = null;
    }
    private void startConstPlaying() {
        mPlayer = new MediaPlayer();
        try {
            mPlayer.setDataSource(mFileNameConst);
            mPlayer.setAudioStreamType(AudioManager.MODE_IN_COMMUNICATION);
            mPlayer.prepare();
            mPlayer.start();
        } catch (IOException e) {
            Toast.makeText(this, "prepare() failed", Toast.LENGTH_LONG).show();
            Log.e(LOG_TAG, "prepare() failed");
    }
}
private void stopConstPlaying() {
        mPlayer.release();
        mPlayer = null;
    }
    private void startRecording() {
        mRecorder = new MediaRecorder();
        mRecorder.setAudioSource(MediaRecorder.AudioSource.VOICE_COMMUNICATION);
        mRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
        mRecorder.setOutputFile(mFileName);
        mRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
        try {
            mRecorder.prepare();
        } catch (IOException e) {
            Toast.makeText(this, "startRecording() failed", Toast.LENGTH_LONG).show();
            Log.e(LOG_TAG, "prepare() failed");
        }
        mRecorder.start();
    }
    private void stopRecording() {
        mRecorder.stop();
        mRecorder.release();
        mRecorder = null;
    }
    class RecordButton extends Button {
        boolean mStartRecording = true;
        OnClickListener clicker = new OnClickListener() {
            public void onClick(View v) {
                onRecord(mStartRecording);
                if (mStartRecording) {
                    setText("Stop recording");
                } else {
                    setText("Start recording");
                }
                mStartRecording = !mStartRecording;
            }
        };
        public RecordButton(Context ctx) {
            super(ctx);
            setText("Start recording");
            setOnClickListener(clicker);
        }
    }
    class PlayButton extends Button {
        boolean mStartPlaying = true;
        OnClickListener clicker = new OnClickListener() {
            public void onClick(View v) {
                onPlay(mStartPlaying);
                if (mStartPlaying) {
                    setText("Stop playing");
                } else {
                    setText("Start playing");
                }
                mStartPlaying = !mStartPlaying;
            }
        };
        public PlayButton(Context ctx) {
            super(ctx);
            setText("Start playing");
            setOnClickListener(clicker);
        }
    }
    class PlayConstButton extends Button {
        boolean mStartPlaying = true;
        OnClickListener clicker = new OnClickListener() {
            public void onClick(View v) {
                onPlayConst(mStartPlaying);
                if (mStartPlaying) {
                    setText("Stop Constant playing");
                } else {
                    setText("Start Constant playing");
                }
                mStartPlaying = !mStartPlaying;
            }
        };
        public PlayConstButton(Context ctx) {
            super(ctx);
            setText("Start Constant playing");
            setOnClickListener(clicker);
        }
    }
    public AudioRecordTest() {
        mFileName = Environment.getExternalStorageDirectory().getAbsolutePath();
        mFileName += "/audiorecordtest.3gp";
        mFileNameConst = Environment.getExternalStorageDirectory().getAbsolutePath();
        mFileNameConst += "/constant.3gp";
    }
    @Override
    public void onCreate(Bundle icicle) {
        super.onCreate(icicle);
        LinearLayout ll = new LinearLayout(this);
        mRecordButton = new RecordButton(this);
        ll.addView(mRecordButton,
            new LinearLayout.LayoutParams(
                ViewGroup.LayoutParams.WRAP_CONTENT,
                ViewGroup.LayoutParams.WRAP_CONTENT,
                0));
        mPlayButton = new PlayButton(this);
        ll.addView(mPlayButton,
            new LinearLayout.LayoutParams(
                ViewGroup.LayoutParams.WRAP_CONTENT,
                ViewGroup.LayoutParams.WRAP_CONTENT,
                0));
        mPlayConstButton = new PlayConstButton(this);
        ll.addView(mPlayConstButton,
            new LinearLayout.LayoutParams(
                ViewGroup.LayoutParams.WRAP_CONTENT,
                ViewGroup.LayoutParams.WRAP_CONTENT,
                0));
        setContentView(ll);
    }
    @Override
    public void onPause() {
        super.onPause();
        if (mRecorder != null) {
            mRecorder.release();
            mRecorder = null;
        }
        if (mPlayer != null) {
            mPlayer.release();
            mPlayer = null;
        }
    }
}

更新:我做了如下的研究:我改变MediaRecorder和MediaPlayer参数。对于每个值，我自己录制，在录制过程中，我开始另一个播放。然后完成录音，听我刚刚录的。对于MediaRecorder，我尝试了这些值:MediaRecorder.AudioSource.DEFAULT MediaRecorder.AudioSource。麦克风、MediaRecorder.AudioSource.VOICE_CALL MediaRecorder.AudioSource.VOICE_COMMUNICATION、MediaRecorder.AudioSource.VOICE_DOWNLINK MediaRecorder.AudioSource.VOICE_RECOGNITION MediaRecorder.AudioSource.VOICE_UPLINK对于MediaPlayer，我尝试了这些值:AudioManager。MODE_NORMAL、AudioManager.MODE_CURRENT AudioManager.MODE_IN_CALL AudioManager.MODE_IN_COMMUNICATION,AudioManager.STREAM_VOICE_CALL AudioManager.STREAM_MUSIC。但无论我怎么尝试，我总是要么安静，要么纯粹的噪音。我认为MediaRecorder和MediaPlayer类对于VoIP是不够的。对于像我这样的初学者来说，Android的音响系统有点奇怪。

Answer 1

我部分明白了。我使用的是安装了Android 3.2系统的索尼Tablet S。我在安装了Android 2.3的Archos 70上尝试了同样的程序。当我一边录制一边播放另一个东西时，两种声音都会被记录下来。这意味着我有一个声音可以应用AEC。在索尼，录音只是噪音。现在有两种可能性:要么索尼Tablet S有麦克风实现的问题(顺便说一下，GTalk在索尼上工作得很好，但它可以在Android上实现的特殊的东西)，要么Android 3.2有麦克风实现的问题。

Answer 2

Android中的Echo取消功能在很多情况下都不是很有效。我认为这与长回声尾有关。我知道有第三方算法可以解决这个问题。谷歌回声消除软件，并验证该软件是否支持长回声尾

Answer 3

为什么在流媒体应用程序中使用MediaRecorder ?使用AudioRecorder代替。

我目前正在玩一个类似的用例，AudioRecorder工作完美无瑕。