VoiceEngine中与录音和播放相关的头文件有五个，如下表所示：
头文件
包含的类
说明
voe_base.h
VoiceEngineObserver
VoiceEngine
VoEBase
1.默认使用G.711通过RTP进行全双工的VoIP会话 2.初始化和终止 3.通过文件和回调函数跟踪信息 4.多通道支持（比如混合，发送到多个目的端） 5.如果想支持G.711外的编码，需要VoECodec
voe_errors.h
无
一些VoiceEngine相关错误的定义
voe_file.h
VoEFile
1.音频播放
2.音频录制
3.音频转换
voe_hardware.h
VoEHardware
1.管理音频设备
2.获取设备信息
3.采样率设置
voe_volume_control.h
VoEVolumeControl
1.扬声器音量控制
2.麦克风音量控制
3.非线性语音电平控制
4.静音
5.音量放大
一.环境WebRTC版本：2016.6.22，详见 WebRTC学习之二：编译
Qt版本：Qt5.7.0 VS2015
需要安装Microsoft DirectX SDK (June 2010)，否则链接的时候会报：
LNK2019:无法解析的外部符号_MoInitMediaType@8,该符号在......
LNK2019:无法解析的外部符号_MoFreeMediaType@8,该符号在......
LNK2019:无法解析的外部符号_IID_IMediaBuffer
LNK2019:无法解析的外部符号_IID_IMediaObject
LNK2019:无法解析的外部符号_CLSID_CWMAudioAEC
如下图所示：
二.实现
mainwindow.h
#ifndef MAINWINDOW_H #define MAINWINDOW_H #include <QMainWindow> #include "myobserver.h" #include "webrtc/voice_engine/include/voe_base.h" #include "webrtc/voice_engine/include/voe_errors.h" #include "webrtc/voice_engine/include/voe_file.h" #include "webrtc/voice_engine/include/voe_hardware.h" #include "webrtc/voice_engine/include/voe_volume_control.h" using namespace webrtc; namespace Ui { class MainWindow; } class MainWindow : public QMainWindow { Q_OBJECT public: explicit MainWindow(QWidget *parent = 0); ~MainWindow(); private: void creatVoiceEngine(); int initialVoiceEngine(); int setDevice(); void setChannel(); int getMicrophoneVolumeValue(); int getSpeakerVolumeValue(); int unInitialVoiceEngine(); private: Ui::MainWindow *ui; MyObserver myObserver; int error; int audioChannel; VoiceEngine* ptrVoEngine; VoEBase* ptrVoEBase; VoEVolumeControl* ptrVoEVolumeControl; VoEFile* ptrVoEFile; VoEHardware* ptrVoEHardware; private slots: void on_pushButtonRecording_clicked(); void on_pushButtonPlayout_clicked(); void slotSetMicrophoneVolumeValue(int value); void slotSetSpeakerVolumeValue(int value); }; #endif // MAINWINDOW_Hmainwindow.cpp
#include "mainwindow.h" #include "ui_mainwindow.h" #include <QDebug> MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent), ui(new Ui::MainWindow), error(0), audioChannel(0), ptrVoEngine(NULL), ptrVoEBase(NULL), ptrVoEVolumeControl(NULL), ptrVoEFile(NULL), ptrVoEHardware(NULL) { ui->setupUi(this); creatVoiceEngine(); initialVoiceEngine(); setDevice(); setChannel(); connect(ui->horizontalSliderMicrophoneVolume,SIGNAL(valueChanged(int)),this,SLOT(slotSetMicrophoneVolumeValue(int))); connect(ui->horizontalSliderSpeakerVolume,SIGNAL(valueChanged(int)),this,SLOT(slotSetSpeakerVolumeValue(int))); int vol=getMicrophoneVolumeValue(); ui->horizontalSliderMicrophoneVolume->setValue(vol); ui->lineEditMicrophoneVolumeValue->setText(QString::number(vol)); vol=getSpeakerVolumeValue(); ui->horizontalSliderSpeakerVolume->setValue(vol); ui->lineEditSpeakerVolumeValue->setText(QString::number(vol)); } MainWindow::~MainWindow() { delete ui; unInitialVoiceEngine(); } void MainWindow::creatVoiceEngine() { ptrVoEngine = VoiceEngine::Create(); ptrVoEBase = VoEBase::GetInterface(ptrVoEngine); ptrVoEVolumeControl = VoEVolumeControl::GetInterface(ptrVoEngine); ptrVoEFile = VoEFile::GetInterface(ptrVoEngine); ptrVoEHardware = VoEHardware::GetInterface(ptrVoEngine); } int MainWindow::initialVoiceEngine() { error = ptrVoEBase->Init(); if (error != 0) { qDebug()<<"ERROR in VoEBase::Init"; return error; } error = ptrVoEBase->RegisterVoiceEngineObserver(myObserver); if (error != 0) { qDebug()<<"ERROR in VoEBase:;RegisterVoiceEngineObserver"; return error; } char temp[1024]; error = ptrVoEBase->GetVersion(temp); if (error != 0) { qDebug()<<"ERROR in VoEBase::GetVersion"; return error; } ui->lineEditVersion->setText(QString(temp)); return 100; } int MainWindow::unInitialVoiceEngine() { //Stop Playout error = ptrVoEBase->StopPlayout(audioChannel); if (error != 0) { qDebug()<<"ERROR in VoEBase::StopPlayout"; return error; } error = ptrVoEFile->StopPlayingFileLocally(audioChannel); if (error != 0) { qDebug()<<"ERROR in VoEFile::StopPlayingFileLocally"; return error; } //Stop Record error = ptrVoEFile->StopRecordingMicrophone(); if (error != 0) { qDebug()<<"ERROR in VoEFile::StopRecordingMicrophone"; return error; } //Delete Channel error = ptrVoEBase->DeleteChannel(audioChannel); if (error != 0) { qDebug()<<"ERROR in VoEBase::DeleteChannel"; return error; } //DeRegister observer ptrVoEBase->DeRegisterVoiceEngineObserver(); error = ptrVoEBase->Terminate(); if (error != 0) { qDebug()<<"ERROR in VoEBase::Terminate"; return error; } if(ptrVoEBase) { ptrVoEBase->Release(); } if(ptrVoEVolumeControl) { ptrVoEVolumeControl->Release(); } if(ptrVoEFile) { ptrVoEFile->Release(); } if(ptrVoEHardware) { ptrVoEHardware->Release(); } bool flag = VoiceEngine::Delete(ptrVoEngine); if (!flag) { qDebug()<<"ERROR in VoiceEngine::Delete"; return -1; } return 100; } int MainWindow::setDevice() { int rNum(-1), pNum(-1); error = ptrVoEHardware->GetNumOfRecordingDevices(rNum); if (error != 0) { qDebug()<<"ERROR in VoEHardware::GetNumOfRecordingDevices"; return error; } error = ptrVoEHardware->GetNumOfPlayoutDevices(pNum); if (error != 0) { qDebug()<<"ERROR in VoEHardware::GetNumOfPlayoutDevices"; return error; } char name[128] = { 0 }; char guid[128] = { 0 }; for (int j = 0; j < rNum; ++j) { error = ptrVoEHardware->GetRecordingDeviceName(j, name, guid); if (error != 0) { qDebug()<<"ERROR in VoEHardware::GetRecordingDeviceName"; return error; } ui->comboBoxRecordingDevice->addItem(QString(name)); } for (int j = 0; j < pNum; ++j) { error = ptrVoEHardware->GetPlayoutDeviceName(j, name, guid); if (error != 0) { qDebug()<<"ERROR in VoEHardware::GetPlayoutDeviceName"; return error; } ui->comboBoxPlayoutDevice->addItem(QString(name)); } error = ptrVoEHardware->SetRecordingDevice(ui->comboBoxRecordingDevice->currentIndex()); if (error != 0) { qDebug()<<"ERROR in VoEHardware::SetRecordingDevice"; return error; } error = ptrVoEHardware->SetPlayoutDevice(ui->comboBoxPlayoutDevice->currentIndex()); if (error != 0) { qDebug()<<"ERROR in VoEHardware::SetPlayoutDevice"; return error; } return 100; } void MainWindow::setChannel() { audioChannel = ptrVoEBase->CreateChannel(); if (audioChannel < 0) { qDebug()<<"ERROR in VoEBase::CreateChannel"; } error = ptrVoEBase->StartPlayout(audioChannel); if(error != 0) { qDebug()<<"ERROR in VoEBase::StartPlayout"; } } int MainWindow::getMicrophoneVolumeValue() { unsigned int vol = 999; error = ptrVoEVolumeControl->GetMicVolume(vol); if (error != 0) { qDebug()<<"ERROR in VoEVolume::GetMicVolume"; return 0; } if ((vol > 255) || (vol < 0)) { qDebug()<<"ERROR in GetMicVolume"; return 0; } return vol; } int MainWindow::getSpeakerVolumeValue() { unsigned int vol = 999; error = ptrVoEVolumeControl->GetSpeakerVolume(vol); if (error != 0) { qDebug()<<"ERROR in VoEVolume::GetSpeakerVolume"; return 0; } if ((vol > 255) || (vol < 0)) { qDebug()<<"ERROR in GetSpeakerVolume"; return 0; } return vol; } void MainWindow::on_pushButtonRecording_clicked() { static bool flag=true; if(flag) { //录制麦克风的音频，默认采样率是8000HZ error = ptrVoEFile->StartRecordingMicrophone("RecordingMicrophone.pcm"); if (error != 0) { qDebug()<<"ERROR in VoEFile::StartRecordingMicrophone"; } else { ui->pushButtonRecording->setText(QStringLiteral("停止录音")); } } else { error = ptrVoEFile->StopRecordingMicrophone(); if (error != 0) { qDebug()<<"ERROR in VoEFile::StopRecordingMicrophone"; } else { ui->pushButtonRecording->setText(QStringLiteral("开始录音")); } } flag=!flag; } void MainWindow::on_pushButtonPlayout_clicked() { static bool flag=true; if(flag) { error = ptrVoEFile->StartPlayingFileLocally(audioChannel,"RecordingMicrophone.pcm"); if (error != 0) { qDebug()<<"ERROR in VoEFile::StartPlayingFileLocally"; } else { ui->pushButtonPlayout->setText(QStringLiteral("停止播放")); } } else { error = ptrVoEFile->StopPlayingFileLocally(audioChannel); if (error != 0) { qDebug()<<"ERROR in VoEFile::StopPlayingFileLocally"; } else { ui->pushButtonPlayout->setText(QStringLiteral("开始播放")); } } flag=!flag; } void MainWindow::slotSetMicrophoneVolumeValue(int value) { error = ptrVoEVolumeControl->SetMicVolume(value); if (error != 0) { qDebug()<<"ERROR in VoEVolume::SetMicVolume"; } else { ui->lineEditMicrophoneVolumeValue->setText(QString::number(value)); } } void MainWindow::slotSetSpeakerVolumeValue(int value) { error = ptrVoEVolumeControl->SetSpeakerVolume(value); if (error != 0) { qDebug()<<"ERROR in VoEVolume::SetSpeakerVolume"; } else { ui->lineEditSpeakerVolumeValue->setText(QString::number(value)); } }三.效果
通过“录音音量”滑块可以实时调节录音的音量大小（0—255）。
通过“播放音量”滑块可以调节播放的音量大小（0—255），类似音乐播放器的音量调节，这里只是调节本软件的音量，而不是调节音频设备的音量。
源码链接：见http://blog.csdn.net/caoshangpa/article/details/53446916的评论
