【音视频开发系列】QT 采集麦克风PCM并播放

[注] 调试前请先戴耳机，作为测试使用，没有项目的严谨，需要自调，适合做回声消除类似的测试用例

项目地址：https://github.com/dujingning/PcmCaptureAndPlay

1.创建 QT 项目
2.pro文件添加

QT       += multimedia

3添加类 .PcmCaptureAndPlay

①pcmcaptureandplay.h

/* * auth: dujingning * date: 2022.05.03 * licenst: MIT */

#ifndef PCMCAPTUREANDPLAY_H
#define PCMCAPTUREANDPLAY_H

#include <QThread>
#include <QDebug>
#include <QTimer>
#include <QFile>

#include <QAudio>
#include <QAudioFormat>
#include <QAudioInput>
#include <QAudioOutput>
#include <QIODevice>

class PcmCaptureAndPlay: public QThread
{
    
    Q_OBJECT

public:
    PcmCaptureAndPlay();

private: /* QT audio play */
    QAudioFormat qAudioFormat;
    QAudioOutput *out;
    QIODevice *audioIO;
    QTimer *audioPlayTimer;
    QThread *timerTHread;
    bool initQtAudioForPlay();

private: /* QT audio capture */
    QAudioFormat format;
    QAudioInput* audioInput;
    QIODevice *qIODevice;
    QFile file; 			// 可以输出到文件，咱不用，直接播
    bool initQtAudioForCapture();
private: /* QT audio capture */
    void audioCaptureAndPlay();

public slots:
    void onReadyRead(); /*采集并填充*/

public:
    void run();
};

#endif // PCMCAPTUREANDPLAY_H

② pcmcaptureandplay.cpp

#include "PcmCaptureAndPlay.h"

PcmCaptureAndPlay::PcmCaptureAndPlay()
{
    

}

bool PcmCaptureAndPlay::initQtAudioForPlay()
{
    
    qAudioFormat.setSampleRate(16000);
    qAudioFormat.setChannelCount(1);
    qAudioFormat.setSampleSize(16);
    qAudioFormat.setCodec("audio/pcm");
    qAudioFormat.setByteOrder(QAudioFormat::LittleEndian);
    qAudioFormat.setSampleType(QAudioFormat::SignedInt);

    out = new QAudioOutput(qAudioFormat);
    if (!out) {
    
        return false;
    }

    audioIO = out->start();
    return true;
}

bool PcmCaptureAndPlay::initQtAudioForCapture()
{
    
    qIODevice = nullptr;
    format.setSampleRate(16000);
    format.setChannelCount(1);      // 设定声道数目，mono(平声道)的声道数目是1；stero(立体声)的声道数目是2
    format.setSampleSize(16);       // 采样位深
    format.setCodec("audio/pcm");   // 设置唯一支持的codec
    format.setByteOrder(QAudioFormat::LittleEndian);
    format.setSampleType(QAudioFormat::SignedInt);

    QAudioDeviceInfo info = QAudioDeviceInfo::defaultInputDevice();
    if (!info.isFormatSupported(format))
    {
    
        format = info.nearestFormat(format);
    }

    file.setFileName("test.raw");
    file.open( QIODevice::WriteOnly | QIODevice::Truncate );

    audioInput = new QAudioInput(format, nullptr);
    qIODevice = audioInput->start(); // 这里可以直接写入到文件，咱不用直接就是播放 audioInput->start(file);

    if (qIODevice) {
    
        qDebug() << "device available";
        return true;
    }

    return false;
}

void PcmCaptureAndPlay::onReadyRead()
{
    
    qint64 len = 0, size = 4096;
    char buffer[4096]{
    0};

    len = qIODevice->read(buffer, size); //读取音频

    if (len <= 0) {
    
        return;
    }

    qDebug() << "read pcm size" << len;

    qint64 bufferPlay = out->periodSize();

    if (out->bytesFree() < bufferPlay) {
     //
        qDebug() << "play buffer not enough";
        return;
    }

    audioIO->write((const char*)(buffer),len);
}

void PcmCaptureAndPlay::audioCaptureAndPlay()
{
    
    initQtAudioForPlay(); // for play
    initQtAudioForCapture(); // for capture
    connect(qIODevice, SIGNAL(readyRead()), this, SLOT(onReadyRead()));
}

void PcmCaptureAndPlay::run()
{
    
    audioCaptureAndPlay();
    exec();
}

3.使用

    PcmCaptureAndPlay *PCAP = new PcmCaptureAndPlay;
    PCAP->start();