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android - Speex 回声消除配置

转载 作者:塔克拉玛干 更新时间:2023-11-02 21:05:51 28 4
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我正在使用其 AudioRecord 和 AudioTrack 类以及通过 NDK 的 Speex 来制作一个 Android 到 Android VoIP(扬声器)应用程序来进行回声消除。我能够成功地传入 Speex 的 speex_echo_cancellation() 函数并从中检索数据,但回声仍然存在。

这里是录音/发送和接收/播放音频的相关android线程代码:

//constructor
public MyThread(DatagramSocket socket, int frameSize, int filterLength){
this.socket = socket;
nativeMethod_initEchoState(frameSize, filterLength);
}

public void run(){

short[] audioShorts, recvShorts, recordedShorts, filteredShorts;
byte[] audioBytes, recvBytes;
int shortsRead;
DatagramPacket packet;

//initialize recorder and player
int samplingRate = 8000;
int managerBufferSize = 2000;
AudioTrack player = new AudioTrack(AudioManager.STREAM_MUSIC, samplingRate, AudioFormat.CHANNEL_OUT_MONO, AudioFormat.ENCODING_PCM_16BIT, managerBufferSize, AudioTrack.MODE_STREAM);
recorder = new AudioRecord(MediaRecorder.AudioSource.MIC, samplingRate, AudioFormat.CHANNEL_IN_MONO, AudioFormat.ENCODING_PCM_16BIT, managerBufferSize);
recorder.startRecording();
player.play();

//record first packet
audioShorts = new short[1000];
shortsRead = recorder.read(audioShorts, 0, audioShorts.length);

//convert shorts to bytes to send
audioBytes = new byte[shortsRead*2];
ByteBuffer.wrap(audioBytes).order(ByteOrder.LITTLE_ENDIAN).asShortBuffer().put(audioShorts);

//send bytes
packet = new DatagramPacket(audioBytes, audioBytes.length);
socket.send(packet);

while (!this.isInterrupted()){

//recieve packet/bytes (received audio data should have echo cancelled already)
recvBytes = new byte[2000];
packet = new DatagramPacket(recvBytes, recvBytes.length);
socket.receive(packet);

//convert bytes to shorts
recvShorts = new short[packet.getLength()/2];
ByteBuffer.wrap(packet.getData(), 0, packet.getLength()).order(ByteOrder.LITTLE_ENDIAN).asShortBuffer().get(recvShorts);

//play shorts
player.write(recvShorts, 0, recvShorts.length);

//record shorts
recordedShorts = new short[1000];
shortsRead = recorder.read(recordedShorts, 0, recordedShorts.length);

//send played and recorded shorts into speex,
//returning audio data with the echo removed
filteredShorts = nativeMethod_speexEchoCancel(recordedShorts, recvShorts);

//convert filtered shorts to bytes
audioBytes = new byte[shortsRead*2];
ByteBuffer.wrap(audioBytes).order(ByteOrder.LITTLE_ENDIAN).asShortBuffer().put(filteredShorts);

//send off bytes
packet = new DatagramPacket(audioBytes, audioBytes.length);
socket.send(packet);

}//end of while loop

}

这里是相关的 NDK/JNI 代码:

void nativeMethod_initEchoState(JNIEnv *env, jobject jobj, jint frameSize, jint filterLength){
echo_state = speex_echo_state_init(frameSize, filterLength);
}

jshortArray nativeMethod_speexEchoCancel(JNIEnv *env, jobject jObj, jshortArray input_frame, jshortArray echo_frame){

//create native shorts from java shorts
jshort *native_input_frame = (*env)->GetShortArrayElements(env, input_frame, NULL);
jshort *native_echo_frame = (*env)->GetShortArrayElements(env, echo_frame, NULL);

//allocate memory for output data
jint length = (*env)->GetArrayLength(env, input_frame);
jshortArray temp = (*env)->NewShortArray(env, length);
jshort *native_output_frame = (*env)->GetShortArrayElements(env, temp, 0);

//call echo cancellation
speex_echo_cancellation(echo_state, native_input_frame, native_echo_frame, native_output_frame);

//convert native output to java layer output
jshortArray output_shorts = (*env)->NewShortArray(env, length);
(*env)->SetShortArrayRegion(env, output_shorts, 0, length, native_output_frame);

//cleanup and return
(*env)->ReleaseShortArrayElements(env, input_frame, native_input_frame, 0);
(*env)->ReleaseShortArrayElements(env, echo_frame, native_echo_frame, 0);
(*env)->ReleaseShortArrayElements(env, temp, native_output_frame, 0);
return output_shorts;
}

这些代码运行良好,音频数据肯定正在从 android 到 android 发送/接收/处理/播放。给定 8000 Hz 的音频采样率和 2000bytes/1000shorts 的数据包大小,我发现需要 1000 的 frameSize 才能使播放的音频流畅。 filterLength 的大部分值(根据 Speex 文档也称为尾长度)将运行,但似乎对回声消除没有影响。

是否有人对 AEC 有足够的了解,可以为我提供一些实现或配置 Speex 的指导?感谢阅读。

最佳答案

您的代码是正确的,但在 native 代码中缺少一些东西,我修改了 init 方法并在回声消除后添加了 speex 预处理,然后您的代码运行良好(我在 windows 中试过)这是 native 代码

#include <jni.h>
#include "speex/speex_echo.h"
#include "speex/speex_preprocess.h"
#include "EchoCanceller_jniHeader.h"
SpeexEchoState *st;
SpeexPreprocessState *den;

JNIEXPORT void JNICALL Java_speex_EchoCanceller_open
(JNIEnv *env, jobject jObj, jint jSampleRate, jint jBufSize, jint jTotalSize)
{
//init
int sampleRate=jSampleRate;
st = speex_echo_state_init(jBufSize, jTotalSize);
den = speex_preprocess_state_init(jBufSize, sampleRate);
speex_echo_ctl(st, SPEEX_ECHO_SET_SAMPLING_RATE, &sampleRate);
speex_preprocess_ctl(den, SPEEX_PREPROCESS_SET_ECHO_STATE, st);
}

JNIEXPORT jshortArray JNICALL Java_speex_EchoCanceller_process
(JNIEnv * env, jobject jObj, jshortArray input_frame, jshortArray echo_frame)
{
//create native shorts from java shorts
jshort *native_input_frame = (*env)->GetShortArrayElements(env, input_frame, NULL);
jshort *native_echo_frame = (*env)->GetShortArrayElements(env, echo_frame, NULL);

//allocate memory for output data
jint length = (*env)->GetArrayLength(env, input_frame);
jshortArray temp = (*env)->NewShortArray(env, length);
jshort *native_output_frame = (*env)->GetShortArrayElements(env, temp, 0);

//call echo cancellation
speex_echo_cancellation(st, native_input_frame, native_echo_frame, native_output_frame);
//preprocess output frame
speex_preprocess_run(den, native_output_frame);

//convert native output to java layer output
jshortArray output_shorts = (*env)->NewShortArray(env, length);
(*env)->SetShortArrayRegion(env, output_shorts, 0, length, native_output_frame);

//cleanup and return
(*env)->ReleaseShortArrayElements(env, input_frame, native_input_frame, 0);
(*env)->ReleaseShortArrayElements(env, echo_frame, native_echo_frame, 0);
(*env)->ReleaseShortArrayElements(env, temp, native_output_frame, 0);

return output_shorts;
}

JNIEXPORT void JNICALL Java_speex_EchoCanceller_close
(JNIEnv *env, jobject jObj)
{
//close
speex_echo_state_destroy(st);
speex_preprocess_state_destroy(den);
}

您可以在 speex 库的源代码 (http://www.speex.org/downloads/) 中找到有用的示例,例如编码、解码、回声消除

关于android - Speex 回声消除配置,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/12748277/

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