speex是音频编解码库，speexdsp是附加的音频DSP库，是音频降噪库，也有回声抑制和自动增益控制功能，即通常说的音频3A算法。
现在音频编解码大部分都是使用opus库，很少使用speex进行音频编解码，但还是会使用speexdsp库的3A算法对音频数据进行处理。
本例是在ubuntu环境下，C/C++语言，使用Qt进行测试。
speexdsp库编译
源码下载：https://github.com/xiph/speexdsp/tags
我下载的版本：speexdsp-SpeexDSP-1.2.1.zip，解压缩。
编译步骤：
cd speexdsp-SpeexDSP-1.2.1/
./autogen.sh
#./autogen.sh: 11: autoreconf: not found报错，安装依赖
sudo apt-get install -y autoconf automake libtool
./configure --prefix=${BUILD_LIBS} --disable-oggtest
make
make install
在家目录的build_libs/文件夹下生成include头文件，和libspeexdsp.a静态库，libspeexdsp.so动态库。
使用speexdsp做音频去噪声demo
在Qt环境下测试，使用wav文件作为音频输入，把处理后的音频数据输出到本地wav文件，回声消除使用在语音通话场景，本例只给出接口样例。
把编译好的include和lib文件夹拷贝到过程目录下，pro文件添加如下内容：
INCLUDEPATH += $$PWD/include
LIBS += -L$$PWD/lib -lspeexdsp -ldl
chwRtcAec.h
#ifndef chwAUDIOPROC_chwRtcAec_H_
#define chwAUDIOPROC_chwRtcAec_H_
#include <stdint.h>
#include <stdlib.h>
typedef struct{
void *session;
void (*init)(void* session, int32_t sampleRate, int32_t pchannel,int32_t pframeSize,int32_t echopath);
void (*closeAec)(void* session);
void (*echoCapture)(void* session,short *rec, short *out);
void (*preprocessRun)(void* session,short *pcm);
void (*echoStateReset)(void* session);
void (*echoPlayback)(void* session,short *play);
void (*echoCancellation)(void* session,const short *rec, const short *play,
short *out);
}chwRtcAec;
#define chw_delete(a) {if( (a)) {delete (a); (a) = NULL;}}
#define chw_deleteA(a) {if( (a)) {delete[] (a); (a) = NULL;}}
#define chw_free(a) {if( (a)) {free((a)); (a) = NULL;}}
#ifdef __cplusplus
extern "C"{
#endif
void chw_rtcaec_init(void* context, int32_t sampleRate, int32_t pchannel,int32_t pframeSize,int32_t echopath);
void chw_rtcaec_preprocess_run(void* context,short *pcm);
void chw_create_rtcaec(chwRtcAec* aec);
void chw_destroy_rtcaec(chwRtcAec* aec);
#ifdef __cplusplus
}
#endif
#endif /* chwAUDIOPROC_chwAECSPEEX_H_ */
chwRtcAec.c
#include "chwRtcAec.h"
#include <speex/speex_echo.h>
#include <speex/speex_preprocess.h>
#include <stdio.h>
#include <string.h>
typedef struct chwRtcAec{
int32_t channel;
int32_t frameSize;
int32_t sampleRate;
int32_t echoPath;
SpeexEchoState *state;
SpeexPreprocessState *preprocState;
}chwRtcAecContext;
///m_aec->session,16000,1,320,10
void chw_rtcaec_init(void* context, int32_t sampleRate, int32_t pchannel,int32_t pframeSize,int32_t echopath)
{
if(context==NULL) return;
chwRtcAecContext* aec=(chwRtcAecContext*)context;
aec->frameSize = pframeSize;
aec->sampleRate = sampleRate;
aec->channel = pchannel;
aec->echoPath=echopath;
int32_t frame_size = aec->frameSize;//(aec->frameSizeInMS * aec->sampleRate * 1.0) / 1000;
int32_t filter_length = aec->frameSize * aec->echoPath;//20;//30;//aec->echoPath;//(aec->frameSizeInMS * aec->sampleRate * 1.0) / 1000;
/** 创建一个新的多通道回波取消器状态
* @param frame_size 一次要处理的样本数(应对应10-20 ms)
* @param filter_length 要取消的回波样本数（一般应对应100-500 ms）
* @param aec->channel 麦克风通道数
* @param aec->channel 扬声器通道数
* @return 新创建的回波取消器状态
*/
if(!aec->state) aec->state = speex_echo_state_init_mc(frame_size, filter_length, aec->channel,aec->channel);
//frame_size *= 2; // length read each time
/** 将创建一个新的预处理状态。您必须为每个已处理的通道创建一个状态。
* @param frame_size 一次要处理的样品数（应对应10-20 ms）。必须为：与用于剩余回声消除的回波消除器的值相同。
* @param sampling_rate 用于输入的采样率。
* @return 返回新创建的预处理器状态
*/
if(!aec->preprocState) aec->preprocState = speex_preprocess_state_init(frame_size, aec->sampleRate);
speex_echo_ctl(aec->state, SPEEX_ECHO_SET_SAMPLING_RATE, &aec->sampleRate);//设置采样率
speex_preprocess_ctl(aec->preprocState, SPEEX_PREPROCESS_SET_ECHO_STATE,aec->state);//设置相应的回波消除器状态，以便可进行残余回波抑制（无残余回波抑制时为NULL）
int32_t i = 1;
//speex_preprocess_ctl(aec->preprocState, SPEEX_PREPROCESS_SET_VAD, &i);
int32_t noiseSuppress = -25;
i = 1;
speex_preprocess_ctl(aec->preprocState, SPEEX_PREPROCESS_SET_DENOISE, &i);//设置预处理器去噪状态
speex_preprocess_ctl(aec->preprocState, SPEEX_PREPROCESS_SET_NOISE_SUPPRESS, &noiseSuppress);//设置噪声的最大衰减，单位为dB（负数）
i=0;
speex_preprocess_ctl(aec->preprocState, SPEEX_PREPROCESS_SET_AGC, &i);//设置预处理器自动增益控制状态
i=sampleRate;
speex_preprocess_ctl(aec->preprocState, SPEEX_PREPROCESS_SET_AGC_LEVEL, &i);//设置预处理器自动增益控制级别（浮动）
i=0;
speex_preprocess_ctl(aec->preprocState, SPEEX_PREPROCESS_SET_DEREVERB, &i);//设置预处理器dereverb状态
float f=.0;
speex_preprocess_ctl(aec->preprocState, SPEEX_PREPROCESS_SET_DEREVERB_DECAY, &f);//设置预处理器dereverb decay
f=.0;
speex_preprocess_ctl(aec->preprocState, SPEEX_PREPROCESS_SET_DEREVERB_LEVEL, &f);//设置EverB级别的预处理器
}
void chw_rtcaec_close(void* context){
if(context==NULL) return;
chwRtcAecContext* aec=(chwRtcAecContext*)context;
if(aec->state) speex_echo_state_destroy(aec->state);//销毁回声消除状态
if(aec->preprocState) speex_preprocess_state_destroy(aec->preprocState);//销毁预处理器状态
aec->state = NULL;
aec->preprocState = NULL;
}
void chw_rtcaec_echo_capture(void* context,short *rec, short *out) {
if(context==NULL) return;
chwRtcAecContext* aec=(chwRtcAecContext*)context;
/** 使用内部回放缓冲区执行回声取消，这会延迟两帧
* 来解释大多数声卡引入的延迟（但它可能是关闭的！）
* @param aec->state 回声消除器状态
* @param rec 麦克风信号（近端+远端回声）
* @param out 返回去除回声的近端信号
*/
if(aec->state) speex_echo_capture(aec->state, rec, out);
}
void chw_rtcaec_preprocess_run(void* context,short *pcm)
{
if(context==NULL) return;
chwRtcAecContext* aec=(chwRtcAecContext*)context;
/** 对帧进行预处理
* @param aec->preprocState 预处理器状态
* @param Pcm 音频样本向量（进和出）。必须与在speex_preprocess_state_init()中指定的大小相同。
* @return 语音业务的Bool值（1表示语音，0表示噪音/静音），仅当VAD打开时使用。
*/
if(aec->preprocState) speex_preprocess_run(aec->preprocState, pcm);
}
void chw_rtcaec_echo_state_reset(void* context) {
if(context==NULL) return;
chwRtcAecContext* aec=(chwRtcAecContext*)context;
/** 将回声取消器重置到其原始状态
* @param aec->state 回声消除状态
*/
if(aec->state) speex_echo_state_reset(aec->state);
}
void chw_rtcaec_echo_playback(void* context,short *play) {
if(context==NULL) return;
chwRtcAecContext* aec=(chwRtcAecContext*)context;
/** 让回声取消器知道一个帧刚刚排队到声卡上
* @param aec->state 回声消除状态
* @param play 信号播放到扬声器（从远端接收）
*/
if(aec->state) speex_echo_playback(aec->state, play);
}
void chw_rtcaec_echo_cancellation(void* context,const short *rec, const short *play,
short *out) {
if(context==NULL) return;
chwRtcAecContext* aec=(chwRtcAecContext*)context;
/** 根据发送到扬声器的音频执行回声取消帧(没有添加延迟以此形式播放）
* @param aec->state 回声消除状态
* @param rec 来至麦克风的信号（近端+远端回声）
* @param play 信号播放到扬声器（从远端接收）
* @param out 返回消除回声的近端信号
*/
if(aec->state) speex_echo_cancellation(aec->state, rec, play, out);
}
void chw_create_rtcaec(chwRtcAec* aec){
if(aec==NULL) return;
aec->session=(chwRtcAecContext*)calloc(sizeof(chwRtcAecContext),1);
aec->init=chw_rtcaec_init;
aec->closeAec=chw_rtcaec_close;
aec->echoCancellation=chw_rtcaec_echo_cancellation;
aec->echoCapture=chw_rtcaec_echo_capture;
aec->echoPlayback=chw_rtcaec_echo_playback;
aec->echoStateReset=chw_rtcaec_echo_state_reset;
aec->preprocessRun=chw_rtcaec_preprocess_run;
}
void chw_destroy_rtcaec(chwRtcAec* aec){
if(aec==NULL) return;
chw_rtcaec_close((chwRtcAecContext*)aec->session);
chw_free(aec->session);
}
qt调用示例：
#include "spxmainwindow.h"
#include "ui_spxmainwindow.h"
#include <QFile>
#define HEADLEN 44
#define SAMPLE_RATE (48000)
#define SAMPLES_PER_FRAME (1024)
#define FRAME_SIZE (SAMPLES_PER_FRAME * 1000/ SAMPLE_RATE)
#define FRAME_BYTES (SAMPLES_PER_FRAME)
spxMainWindow::spxMainWindow(QWidget *parent)
: QMainWindow(parent)
, ui(new Ui::spxMainWindow)
{
ui->setupUi(this);
pcm=new short[4096/2];
m_aec = NULL;
m_aec=(chwRtcAec*)calloc(sizeof(chwRtcAec),1);
chw_create_rtcaec(m_aec);
chw_rtcaec_init(m_aec->session,44100,1,1024,10);//注意传参的采样率、帧大小、通道数一定要和采集时一致
dealAudio();
}
spxMainWindow::~spxMainWindow()
{
chw_destroy_rtcaec(m_aec);
chw_free(m_aec);
chw_deleteA(pcm);
delete ui;
}
//消除噪声处理，以wav文件为例
void spxMainWindow::dealAudio()
{
size_t len = 0;
QFile inFile, outFile;
inFile.setFileName("./test.wav");
outFile.setFileName("./outtest.wav");
char headBuf[HEADLEN];
char dataBuf[FRAME_BYTES * 2];
QByteArray readBuf;
if(inFile.open(QIODevice::ReadOnly))
inFile.read(headBuf,HEADLEN);//wav头部
if(outFile.open(QIODevice::WriteOnly))
outFile.write(headBuf,HEADLEN);
while(inFile.atEnd() == false)
{
len = inFile.read(dataBuf,SAMPLES_PER_FRAME);
if(len == 0) break;
chw_rtcaec_preprocess_run(m_aec->session,(short*)dataBuf);
outFile.write(dataBuf,SAMPLES_PER_FRAME);
}
inFile.flush();
inFile.close();
outFile.flush();
outFile.close();
}
//回声消除，播放对方音频后调用
void spxMainWindow::dealEchoPlay(short* pbuf,int32_t plen)
{
if(m_aec) m_aec->echoPlayback(m_aec->session,pbuf);
}
//回声采样和去噪，采集本端音频后，编码前调用
void spxMainWindow::putEchoBuffer( uint8_t *pBuffer,int32_t plen)
{
if (m_aec)
{
m_aec->echoCapture(m_aec->session, (short*) pBuffer, pcm);
m_aec->preprocessRun(m_aec->session, pcm);
m_audioFrame.data = (uint8_t*)pcm;
m_audioFrame.len = plen;
// m_resample.resample(m_resample.context,&m_audioFrame);
}
}
报错记录
使用回声消除时报如下几个警告：
waining:no playback frame available(your application is buggy and/or got xruns)，#ifndef DISABLE_WARNINGS
warning: Had to discard a playback frame (your application is buggy and/or got xruns)
warning: Auto-filling the buffer (your application is buggy and/or got xruns)
基本不影响业务，看着不顺眼的可以修改libspeexdsp源码里的os_support.h文件，在里面添加下面定义，不打印WARNINGS信息，重新编译即可。
#define DISABLE_WARNINGS