11.QT-ffmpeg+QAudioOutput實現音訊播放器
阿新 • • 發佈：2020-09-11
1.前言
由於QAudioOutput支援的輸入資料必須是原始資料,所以播放mp3,WAV,AAC等格式檔案,需要解封裝後才能支援播放.
而在QT中,提供了QMediaPlayer類可以支援解封裝,但是該類的解碼協議都是基於平臺的,如果平臺自身無法播放,那麼QMediaPlayer也無法播放.有興趣的朋友可以去試試.
所以接下來,我們使用ffmpeg+QAudioOutput來實現一個簡單的音訊播放器.
在此之前,需要學習:
- 2.AVFormatContext和AVInputFormat
- 3.AVPacket使用
- 4.FFMPEG-AVFrame
- 5.AVStream和AVCodecParameters
- 6.AVCodecContext和AVCodec
- 7.SwrContext音訊重取樣使用
- 8.ffmpeg-基礎常用知識
- 9.下載ffmpeg、使QT支援同時編譯32位和64位
- 10.QT-QAudioOutput類使用
#include "playthread.h"
playthread::playthread()
{
audio=NULL;
type = control_none;
}
bool playthread::initAudio(int SampleRate)
{
QAudioFormat format;
if(audio!=NULL)
return true;
format.setSampleRate(SampleRate); //設定取樣率
format.setChannelCount(2); //設定通道數
format.setSampleSize(16); //樣本資料16位
format.setCodec("audio/pcm"); //播出格式為pcm格式
format.setByteOrder(QAudioFormat::LittleEndian); //預設小端模式
format.setSampleType(QAudioFormat::UnSignedInt); //無符號整形數
QAudioDeviceInfo info(QAudioDeviceInfo::defaultOutputDevice()); //選擇預設輸出裝置
// foreach(int count,info.supportedChannelCounts())
// {
// qDebug()<<"輸出裝置支援的通道數:"<<count;
// }
// foreach(int count,info.supportedSampleRates())
// {
// qDebug()<<"輸出裝置支援的取樣率:"<<count;
// }
// foreach(int count,info.supportedSampleSizes())
// {
// qDebug()<<"輸出裝置支援的樣本資料位數:"<<count;
// }
if (!info.isFormatSupported(format))
{
qDebug()<<"輸出裝置不支援該格式，不能播放音訊";
return false;
}
audio = new QAudioOutput(format, this);
audio->setBufferSize(100000);
return true;
}
void playthread::play(QString filePath)
{
this->filePath = filePath;
type = control_play;
if(!this->isRunning())
{
this->start();
}
}
void playthread::stop()
{
if(this->isRunning())
{
type = control_stop;
}
}
void playthread::pause()
{
if(this->isRunning())
{
type = control_pause;
}
}
void playthread::resume()
{
if(this->isRunning())
{
type = control_resume;
}
}
void playthread::seek(int value)
{
if(this->isRunning())
{
seekMs = value;
type = control_seek;
}
}
void playthread::debugErr(QString prefix, int err) //根據錯誤編號獲取錯誤資訊並列印
{
char errbuf[512]={0};
av_strerror(err,errbuf,sizeof(errbuf));
qDebug()<<prefix<<":"<<errbuf;
emit ERROR(prefix+":"+errbuf);
}
bool playthread::runIsBreak() //處理控制,判斷是否需要停止
{
bool ret = false;
//處理播放暫停
if(type == control_pause)
{
while(type == control_pause)
{
audio->suspend();
msleep(500);
}
if(type == control_resume)
{
audio->resume();
}
}
if(type == control_play) //重新播放
{
ret = true;
if(audio->state()== QAudio::ActiveState)
audio->stop();
}
if(type == control_stop) //停止
{
ret = true;
if(audio->state()== QAudio::ActiveState)
audio->stop();
}
return ret;
}
void playthread::runPlay()
{
int ret;
int destMs,currentMs;
if(audio==NULL)
{
emit ERROR("輸出裝置不支援該格式，不能播放音訊");
return ;
}
//初始化網路庫 （可以開啟rtsp rtmp http 協議的流媒體視訊）
avformat_network_init();
AVFormatContext *pFmtCtx=NULL;
ret = avformat_open_input(&pFmtCtx, this->filePath.toLocal8Bit().data(),NULL, NULL) ; //開啟音視訊檔案並建立AVFormatContext結構體以及初始化.
if (ret!= 0)
{
debugErr("avformat_open_input",ret);
return ;
}
ret = avformat_find_stream_info(pFmtCtx, NULL); //初始化流資訊
if (ret!= 0)
{
debugErr("avformat_find_stream_info",ret);
return ;
}
int audioindex=-1;
audioindex = av_find_best_stream(pFmtCtx, AVMEDIA_TYPE_AUDIO, -1, -1, NULL, 0);
qDebug()<<"audioindex:"<<audioindex;
AVCodec *acodec = avcodec_find_decoder(pFmtCtx->streams[audioindex]->codecpar->codec_id);//獲取codec
AVCodecContext *acodecCtx = avcodec_alloc_context3(acodec); //構造AVCodecContext ,並將vcodec填入AVCodecContext中
avcodec_parameters_to_context(acodecCtx, pFmtCtx->streams[audioindex]->codecpar); //初始化AVCodecContext
ret = avcodec_open2(acodecCtx, NULL,NULL); //開啟解碼器,由於之前呼叫avcodec_alloc_context3(vcodec)初始化了vc,那麼codec(第2個引數)可以填NULL
if (ret!= 0)
{
debugErr("avcodec_open2",ret);
return ;
}
SwrContext *swrctx =NULL;
swrctx=swr_alloc_set_opts(swrctx, av_get_default_channel_layout(2),AV_SAMPLE_FMT_S16,44100,
acodecCtx->channel_layout, acodecCtx->sample_fmt,acodecCtx->sample_rate, NULL,NULL);
swr_init(swrctx);
destMs = av_q2d(pFmtCtx->streams[audioindex]->time_base)*1000*pFmtCtx->streams[audioindex]->duration;
qDebug()<<"位元速率:"<<acodecCtx->bit_rate;
qDebug()<<"格式:"<<acodecCtx->sample_fmt;
qDebug()<<"通道:"<<acodecCtx->channels;
qDebug()<<"取樣率:"<<acodecCtx->sample_rate;
qDebug()<<"時長:"<<destMs;
qDebug()<<"解碼器:"<<acodec->name;
AVPacket * packet =av_packet_alloc();
AVFrame *frame =av_frame_alloc();
audio->stop();
QIODevice*io = audio->start();
while(1)
{
if(runIsBreak())
break;
if(type == control_seek)
{
av_seek_frame(pFmtCtx, audioindex, seekMs/(double)1000/av_q2d(pFmtCtx->streams[audioindex]->time_base),AVSEEK_FLAG_BACKWARD);
type = control_none;
emit seekOk();
}
ret = av_read_frame(pFmtCtx, packet);
if (ret!= 0)
{
debugErr("av_read_frame",ret);
emit duration(destMs,destMs);
break ;
}
//解碼一幀資料
ret = avcodec_send_packet(acodecCtx, packet);
av_packet_unref(packet);
if (ret != 0)
{
debugErr("avcodec_send_packet",ret);
continue ;
}
if(packet->stream_index==audioindex)
{
while( avcodec_receive_frame(acodecCtx, frame) == 0)
{
if(runIsBreak())
break;
uint8_t *data[2] = { 0 };
int byteCnt=frame->nb_samples * 2 * 2;
unsigned char *pcm = new uint8_t[byteCnt]; //frame->nb_samples*2*2表示分配樣本資料量*兩通道*每通道2位元組大小
data[0] = pcm; //輸出格式為AV_SAMPLE_FMT_S16(packet型別),所以轉換後的LR兩通道都存在data[0]中
ret = swr_convert(swrctx,
data, frame->nb_samples, //輸出
(const uint8_t**)frame->data,frame->nb_samples ); //輸入
//將重取樣後的data資料傳送到輸出裝置,進行播放
while (audio->bytesFree() < byteCnt)
{
if(runIsBreak())
break;
msleep(10);
}
if(!runIsBreak())
io->write((const char *)pcm,byteCnt);
currentMs = av_q2d(pFmtCtx->streams[audioindex]->time_base)*1000*frame->pts;
//qDebug()<<"時長:"<<destMs<<currentMs;
emit duration(currentMs,destMs);
delete[] pcm;
}
}
}
//釋放記憶體
av_frame_free(&frame);
av_packet_free(&packet);
swr_free(&swrctx);
avcodec_free_context(&acodecCtx);
avformat_close_input(&pFmtCtx);
}
void playthread::run()
{
if(!initAudio(44100))
{
emit ERROR("輸出裝置不支援該格式，不能播放音訊");
}
while(1)
{
switch(type)
{
case control_none: msleep(100); break;
case control_play : type=control_none;runPlay(); break; //播放
default: type=control_none; break;
}
}
}
4.2 widget介面類
而在介面中要處理的就很簡單,widget.cpp如下所示:
#include "widget.h"
#include "ui_widget.h"
#include <QDebug>
Widget::Widget(QWidget *parent)
: QWidget(parent)
, ui(new Ui::Widget)
{
ui->setupUi(this);
this->setAcceptDrops(true);
thread = new playthread();
connect(thread,SIGNAL(duration(int,int)),this,SLOT(onDuration(int,int)));
connect(thread,SIGNAL(seekOk()),this,SLOT(onSeekOk()));
void duration(long currentMs,long destMs); //播放時長
thread->start();
sliderSeeking =false;
}
Widget::~Widget()
{
delete ui;
thread->stop();
}
void Widget::onSeekOk()
{
sliderSeeking=false;
}
void Widget::onDuration(int currentMs,int destMs) //時長
{
static int currentMs1=-1,destMs1=-1;
if(currentMs1==currentMs&&destMs1==destMs)
{
return;
}
currentMs1 = currentMs;
destMs1 = destMs;
qDebug()<<"onDuration："<<currentMs<<destMs<<sliderSeeking;
QString currentTime = QString("%1:%2:%3").arg(currentMs1/360000%60,2,10,QChar('0')).arg(currentMs1/6000%60,2,10,QChar('0')).arg(currentMs1/1000%60,2,10,QChar('0'));
QString destTime = QString("%1:%2:%3").arg(destMs1/360000%60,2,10,QChar('0')).arg(destMs1/6000%60,2,10,QChar('0')).arg(destMs1/1000%60,2,10,QChar('0'));
ui->label_duration->setText(currentTime+"/"+destTime);
if(!sliderSeeking) //未滑動
{
ui->slider->setMaximum(destMs);
ui->slider->setValue(currentMs);
}
}
void Widget::dragEnterEvent(QDragEnterEvent *event)
{
if(event->mimeData()->hasUrls()) //判斷拖的型別
{
event->acceptProposedAction();
}
else
{
event->ignore();
}
}
void Widget::dropEvent(QDropEvent *event)
{
if(event->mimeData()->hasUrls()) //判斷放的型別
{
QList<QUrl> List = event->mimeData()->urls();
if(List.length()!=0)
{
ui->line_audioPath->setText(List[0].toLocalFile());
}
}
else
{
event->ignore();
}
}
void Widget::on_btn_start_clicked()
{
sliderSeeking=false;
thread->play(ui->line_audioPath->text());
}
void Widget::on_btn_stop_clicked()
{
thread->stop();
}
void Widget::on_btn_pause_clicked()
{
thread->pause();
}
void Widget::on_btn_resume_clicked()
{
thread->resume();
}
void Widget::on_slider_sliderPressed()
{
sliderSeeking=true;
}
void Widget::on_slider_sliderReleased()
{
thread->seek(ui->slider->value());
}