播放器的音视频同步
播放器的音视频同步
文章分为以下几个部分：
1.音视频同步的原理
2.需要注意的地方
3.代码示例
音视频同步的原理
音频和视频即使按照固定的帧率去播放，但是由于机器运行速度或者解码效率等原因，可能会造成一定的偏差使音视频不能同步播放。
音视频同步的思路有3种：
1.参考一个外部时钟，将音频与视频同步至此时间。
2.以视频为基准，音频去同步视频的时间。
3.以音频为基准，视频去同步音频的时间。
第2种方式可能是每一个新手都会想到的方式，但是研究表明人对声音的变化比较敏感，但是对视觉变化不太敏感。所以频繁的去调整声音的播放会有些刺耳或者杂音影响用户体验，所以一般用第三种方式。
需要注意的地方
DTS：解码时间戳，告诉解码器packet的解码顺序。
PTS：显示时间戳，指示从packet中解码出来的数据的显示顺序。
这里我们在SDL的回调函数中解码出每一帧音频数据的时候，记录下音频的PTS，然后根据此PTS来决定是否显示视频。
代码示例
主线程：
mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include <QImage>
#include <QPaintEvent>
#include <QTimer>
#include "videoplayer/videoplayer.h"
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
protected:
void paintEvent(QPaintEvent *event);
private:
Ui::MainWindow *ui;
VideoPlayer *mPlayer; //播放线程
QImage mImage; //记录当前的图像
QTimer *mTimer; //定时器-获取当前视频时间
private slots:
void slotGetOneFrame(QImage img);
void slotTotalTimeChanged(qint64 uSec);
void slotSliderMoved(int value);
void slotTimerTimeOut();
void slotBtnClick();
};
#endif // MAINWINDOW_H
mainwindow.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QPainter>
#include <QPaintEvent>
#include <QFileDialog>
#include <QDebug>
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
av_register_all(); //初始化FFMPEG 调用了这个才能正常使用编码器和解码器
avformat_network_init(); //支持打开网络文件
if (SDL_Init(SDL_INIT_AUDIO)) {
fprintf(stderr,"Could not initialize SDL - %s. \n", SDL_GetError());
exit(1);
}
mPlayer = new VideoPlayer;
connect(mPlayer,SIGNAL(sig_GetOneFrame(QImage)),this,SLOT(slotGetOneFrame(QImage)));
connect(mPlayer,SIGNAL(sig_TotalTimeChanged(qint64)),this,SLOT(slotTotalTimeChanged(qint64)));
connect(mPlayer,SIGNAL(sig_StateChanged(VideoPlayer::PlayerState)),this,SLOT(slotStateChanged(VideoPlayer::PlayerState)));
mTimer = new QTimer; //定时器-获取当前视频时间
connect(mTimer,SIGNAL(timeout()),this,SLOT(slotTimerTimeOut()));
mTimer->setInterval(500);
connect(ui->pushButton_open,SIGNAL(clicked()),this,SLOT(slotBtnClick()));
connect(ui->pushButton_play,SIGNAL(clicked()),this,SLOT(slotBtnClick()));
connect(ui->pushButton_pause,SIGNAL(clicked()),this,SLOT(slotBtnClick()));
connect(ui->pushButton_stop,SIGNAL(clicked()),this,SLOT(slotBtnClick()));
connect(ui->horizontalSlider,SIGNAL(sliderMoved(int)),this,SLOT(slotSliderMoved(int)));
}
MainWindow::~MainWindow()
{
delete ui;
}
//每次update都会执行
void MainWindow::paintEvent(QPaintEvent *event)
{
QPainter painter(this);
painter.setBrush(Qt::black);
painter.drawRect(0, 0, this->width(), this->height()); //先画成黑色
if (mImage.size().width() <= 0) return;
///将图像按比例缩放成和窗口一样大小
QImage img = mImage.scaled(this->size(),Qt::KeepAspectRatio);
int x = this->width() - img.width();
int y = this->height() - img.height();
x /= 2;
y /= 2;
painter.drawImage(QPoint(x,y),img); //画出图像
}
//得到一帧图片响应的槽函数
void MainWindow::slotGetOneFrame(QImage img)
{
mImage = img;
update(); //调用update将执行 paintEvent函数
}
//获取到视频时长响应的槽函数
void MainWindow::slotTotalTimeChanged(qint64 uSec)
{
qint64 Sec = uSec/1000000;
ui->horizontalSlider->setRange(0,Sec);
// QString hStr = QString("00%1").arg(Sec/3600);
QString mStr = QString("00%1").arg(Sec/60);
QString sStr = QString("00%1").arg(Sec%60);
QString str = QString("%1:%2").arg(mStr.right(2)).arg(sStr.right(2));
ui->label_totaltime->setText(str);
}
//进度条移动的槽函数
void MainWindow::slotSliderMoved(int value)
{
if (QObject::sender() == ui->horizontalSlider)
{
mPlayer->seek((qint64)value * 1000000);
}
}
//计时器到点（每500ms）
void MainWindow::slotTimerTimeOut()
{
if (QObject::sender() == mTimer)
{
qint64 Sec = mPlayer->getCurrentTime();
ui->horizontalSlider->setValue(Sec);
// QString hStr = QString("00%1").arg(Sec/3600);
QString mStr = QString("00%1").arg(Sec/60);
QString sStr = QString("00%1").arg(Sec%60);
QString str = QString("%1:%2").arg(mStr.right(2)).arg(sStr.right(2));
ui->label_currenttime->setText(str);
}
}
//打开，播放，暂停，停止按钮
void MainWindow::slotBtnClick()
{
if (QObject::sender() == ui->pushButton_play)
{
mPlayer->play();
}
else if (QObject::sender() == ui->pushButton_pause)
{
mPlayer->pause();
}
else if (QObject::sender() == ui->pushButton_stop)
{
mPlayer->stop(true);
}
else if (QObject::sender() == ui->pushButton_open)
{
QString s = QFileDialog::getOpenFileName(
this, "选择要播放的文件",
"/",//初始目录
"视频文件 (*.flv *.rmvb *.avi *.MP4);; 所有文件 (*.*);; ");
if (!s.isEmpty())
{
s.replace("/","\\");
mPlayer->stop(true); //如果在播放则先停止
mPlayer->setFileName(s);
mTimer->start();
}
}
}
mainwindows.ui
处理音视频的线程：
videoplayer.h
#ifndef VIDEOPLAYER_H
#define VIDEOPLAYER_H
#include <QThread>
#include <QImage>
extern "C"
{
#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"
#include <libavutil/time.h>
#include "libavutil/pixfmt.h"
#include "libswscale/swscale.h"
#include "libswresample/swresample.h"
#include <SDL.h>
#include <SDL_audio.h>
#include <SDL_types.h>
#include <SDL_name.h>
#include <SDL_main.h>
#include <SDL_config.h>
}
typedef struct PacketQueue {
AVPacketList *first_pkt, *last_pkt;
int nb_packets;
int size;
SDL_mutex *mutex;
SDL_cond *cond;
} PacketQueue;
#define VIDEO_PICTURE_QUEUE_SIZE 1
#define AVCODEC_MAX_AUDIO_FRAME_SIZE 192000 // 1 second of 48khz 32bit audio
#define MAX_AUDIO_SIZE (25 * 16 * 1024)
#define MAX_VIDEO_SIZE (25 * 256 * 1024)
class VideoPlayer; //前置声明
typedef struct VideoState {
AVFormatContext *ic;
int videoStream, audioStream;
AVFrame *audio_frame;// 解码音频过程中的使用缓存
PacketQueue audioq;
AVStream *audio_st; //音频流
unsigned int audio_buf_size;
unsigned int audio_buf_index;
AVPacket audio_pkt;
uint8_t *audio_pkt_data;
int audio_pkt_size;
uint8_t *audio_buf;
DECLARE_ALIGNED(16,uint8_t,audio_buf2) [AVCODEC_MAX_AUDIO_FRAME_SIZE * 4];
enum AVSampleFormat audio_src_fmt;
enum AVSampleFormat audio_tgt_fmt;
int audio_src_channels;
int audio_tgt_channels;
int64_t audio_src_channel_layout;
int64_t audio_tgt_channel_layout;
int audio_src_freq;
int audio_tgt_freq;
struct SwrContext *swr_ctx; //用于解码后的音频格式转换
int audio_hw_buf_size;
double audio_clock; ///音频时钟
double video_clock; ///<pts of last decoded frame / predicted pts of next decoded frame
AVStream *video_st;
PacketQueue videoq;
/// 跳转相关的变量
int seek_req; //跳转标志
int64_t seek_pos; //跳转的位置 -- 微秒
int seek_flag_audio;//跳转标志 -- 用于音频线程中
int seek_flag_video;//跳转标志 -- 用于视频线程中
double seek_time; //跳转的时间(秒) 值和seek_pos是一样的
///播放控制相关
bool isPause; //暂停标志
bool quit; //停止
bool readFinished; //文件读取完毕
bool readThreadFinished;
bool videoThreadFinished;
SDL_Thread *video_tid; //视频线程id
SDL_AudioDeviceID audioID;
VideoPlayer *player; //记录下这个类的指针 主要用于在线程里面调用激发信号的函数
} VideoState;
class VideoPlayer : public QThread
{
Q_OBJECT
public:
enum PlayerState
{
Playing,
Pause,
Stop
};
explicit VideoPlayer();
~VideoPlayer();
bool setFileName(QString path);
bool play();
bool pause();
bool stop(bool isWait = false); //参数表示是否等待所有的线程执行完毕再返回
void seek(int64_t pos); //单位是微秒
int64_t getTotalTime(); //单位微秒
double getCurrentTime(); //单位秒
void disPlayVideo(QImage img);
signals:
void sig_GetOneFrame(QImage); //没获取到一帧图像 就发送此信号
void sig_StateChanged(VideoPlayer::PlayerState state);
void sig_TotalTimeChanged(qint64 uSec); //获取到视频时长的时候激发此信号
protected:
void run();
private:
QString mFileName;
VideoState mVideoState;
PlayerState mPlayerState; //播放状态
};
#endif // VIDEOPLAYER_H
videoplayer.cpp
#include "videoplayer.h"
#include <stdio.h>
#include <QDebug>
#define SDL_AUDIO_BUFFER_SIZE 1024
#define AVCODEC_MAX_AUDIO_FRAME_SIZE 192000 // 1 second of 48khz 32bit audio
#define FLUSH_DATA "FLUSH"
void packet_queue_init(PacketQueue *q) {
memset(q, 0, sizeof(PacketQueue));
q->mutex = SDL_CreateMutex();
q->cond = SDL_CreateCond();
q->size = 0;
q->nb_packets = 0;
q->first_pkt = NULL;
q->last_pkt = NULL;
}
int packet_queue_put(PacketQueue *q, AVPacket *pkt) {
AVPacketList *pkt1;
if (av_dup_packet(pkt) < 0) {
return -1;
}
pkt1 = (AVPacketList*)av_malloc(sizeof(AVPacketList));
if (!pkt1)
return -1;
pkt1->pkt = *pkt;
pkt1->next = NULL;
SDL_LockMutex(q->mutex);
if (!q->last_pkt)
q->first_pkt = pkt1;
else
q->last_pkt->next = pkt1;
q->last_pkt = pkt1;
q->nb_packets++;
q->size += pkt1->pkt.size;
SDL_CondSignal(q->cond);
SDL_UnlockMutex(q->mutex);
return 0;
}
static int packet_queue_get(PacketQueue *q, AVPacket *pkt, int block) {
AVPacketList *pkt1;
int ret;
SDL_LockMutex(q->mutex);
for (;;) {
pkt1 = q->first_pkt;
if (pkt1) {
q->first_pkt = pkt1->next;
if (!q->first_pkt)
q->last_pkt = NULL;
q->nb_packets--;
q->size -= pkt1->pkt.size;
*pkt = pkt1->pkt;
av_free(pkt1);
ret = 1;
break;
} else if (!block) {
ret = 0;
break;
} else {
SDL_CondWait(q->cond, q->mutex);
}
}
SDL_UnlockMutex(q->mutex);
return ret;
}
static void packet_queue_flush(PacketQueue *q)
{
AVPacketList *pkt, *pkt1;
SDL_LockMutex(q->mutex);
for(pkt = q->first_pkt; pkt != NULL; pkt = pkt1)
{
pkt1 = pkt->next;
if(pkt1->pkt.data != (uint8_t *)"FLUSH")
{
}
av_free_packet(&pkt->pkt);
av_freep(&pkt);
}
q->last_pkt = NULL;
q->first_pkt = NULL;
q->nb_packets = 0;
q->size = 0;
SDL_UnlockMutex(q->mutex);
}
static int audio_decode_frame(VideoState *is, double *pts_ptr)
{
int len1, len2, decoded_data_size;
AVPacket *pkt = &is->audio_pkt;
int got_frame = 0;
int64_t dec_channel_layout;
int wanted_nb_samples, resampled_data_size, n;
double pts;
for (;;) {
while (is->audio_pkt_size > 0) {
if (is->isPause == true) //判断暂停
{
SDL_Delay(10);
continue;
}
if (!is->audio_frame) {
if (!(is->audio_frame = avcodec_alloc_frame())) {
return AVERROR(ENOMEM);
}
} else
avcodec_get_frame_defaults(is->audio_frame);
len1 = avcodec_decode_audio4(is->audio_st->codec, is->audio_frame,
&got_frame, pkt);
if (len1 < 0) {
// error, skip the frame
is->audio_pkt_size = 0;
break;
}
is->audio_pkt_data += len1;
is->audio_pkt_size -= len1;
if (!got_frame)
continue;
/* 计算解码出来的桢需要的缓冲大小 */
decoded_data_size = av_samples_get_buffer_size(NULL,
is->audio_frame->channels, is->audio_frame->nb_samples,
(AVSampleFormat)is->audio_frame->format, 1);
dec_channel_layout =
(is->audio_frame->channel_layout
&& is->audio_frame->channels
== av_get_channel_layout_nb_channels(
is->audio_frame->channel_layout)) ?
is->audio_frame->channel_layout :
av_get_default_channel_layout(
is->audio_frame->channels);
wanted_nb_samples = is->audio_frame->nb_samples;
if (is->audio_frame->format != is->audio_src_fmt
|| dec_channel_layout != is->audio_src_channel_layout
|| is->audio_frame->sample_rate != is->audio_src_freq
|| (wanted_nb_samples != is->audio_frame->nb_samples
&& !is->swr_ctx)) {
if (is->swr_ctx)
swr_free(&is->swr_ctx);
is->swr_ctx = swr_alloc_set_opts(NULL,
is->audio_tgt_channel_layout, (AVSampleFormat)is->audio_tgt_fmt,
is->audio_tgt_freq, dec_channel_layout,
(AVSampleFormat)is->audio_frame->format, is->audio_frame->sample_rate,
0, NULL);
if (!is->swr_ctx || swr_init(is->swr_ctx) < 0) {
//fprintf(stderr,"swr_init() failed\n");
break;
}
is->audio_src_channel_layout = dec_channel_layout;
is->audio_src_channels = is->audio_st->codec->channels;
is->audio_src_freq = is->audio_st->codec->sample_rate;
is->audio_src_fmt = is->audio_st->codec->sample_fmt;
}
/* 这里我们可以对采样数进行调整，增加或者减少，一般可以用来做声画同步 */
if (is->swr_ctx) {
const uint8_t **in =
(const uint8_t **) is->audio_frame->extended_data;
uint8_t *out[] = { is->audio_buf2 };
if (wanted_nb_samples != is->audio_frame->nb_samples) {
if (swr_set_compensation(is->swr_ctx,
(wanted_nb_samples - is->audio_frame->nb_samples)
* is->audio_tgt_freq
/ is->audio_frame->sample_rate,
wanted_nb_samples * is->audio_tgt_freq
/ is->audio_frame->sample_rate) < 0) {
//fprintf(stderr,"swr_set_compensation() failed\n");
break;
}
}
len2 = swr_convert(is->swr_ctx, out,
sizeof(is->audio_buf2) / is->audio_tgt_channels
/ av_get_bytes_per_sample(is->audio_tgt_fmt),
in, is->audio_frame->nb_samples);
if (len2 < 0) {
//fprintf(stderr,"swr_convert() failed\n");
break;
}
if (len2
== sizeof(is->audio_buf2) / is->audio_tgt_channels
/ av_get_bytes_per_sample(is->audio_tgt_fmt)) {
//fprintf(stderr,"warning: audio buffer is probably too small\n");
swr_init(is->swr_ctx);
}
is->audio_buf = is->audio_buf2;
resampled_data_size = len2 * is->audio_tgt_channels
* av_get_bytes_per_sample(is->audio_tgt_fmt);
} else {
resampled_data_size = decoded_data_size;
is->audio_buf = is->audio_frame->data[0];
}
pts = is->audio_clock;
*pts_ptr = pts;
n = 2 * is->audio_st->codec->channels;
is->audio_clock += (double) resampled_data_size
/ (double) (n * is->audio_st->codec->sample_rate);
if (is->seek_flag_audio)
{
//发生了跳转 则跳过关键帧到目的时间的这几帧
if (is->audio_clock < is->seek_time)
{
break;
}
else
{
is->seek_flag_audio = 0;
}
}
// We have data, return it and come back for more later
return resampled_data_size;
}
if (is->isPause == true) //判断暂停
{
SDL_Delay(10);
continue;
}
if (pkt->data)
av_free_packet(pkt);
memset(pkt, 0, sizeof(*pkt));
if (is->quit)
return -1;
if (packet_queue_get(&is->audioq, pkt, 0) <= 0)
{
return -1;
}
//收到这个数据 说明刚刚执行过跳转 现在需要把解码器的数据 清除一下
if(strcmp((char*)pkt->data,FLUSH_DATA) == 0)
{
avcodec_flush_buffers(is->audio_st->codec);
av_free_packet(pkt);
continue;
}
is->audio_pkt_data = pkt->data;
is->audio_pkt_size = pkt->size;
/* if update, update the audio clock w/pts */
if (pkt->pts != AV_NOPTS_VALUE) {
is->audio_clock = av_q2d(is->audio_st->time_base) * pkt->pts;
}
}
return 0;
}
static void audio_callback(void *userdata, Uint8 *stream, int len) {
VideoState *is = (VideoState *) userdata;
int len1, audio_data_size;
double pts;
/* len是由SDL传入的SDL缓冲区的大小，如果这个缓冲未满，我们就一直往里填充数据 */
while (len > 0) {
/* audio_buf_index 和 audio_buf_size 标示我们自己用来放置解码出来的数据的缓冲区，*/
/* 这些数据待copy到SDL缓冲区， 当audio_buf_index >= audio_buf_size的时候意味着我*/
/* 们的缓冲为空，没有数据可供copy，这时候需要调用audio_decode_frame来解码出更
/* 多的桢数据 */
if (is->audio_buf_index >= is->audio_buf_size) {
audio_data_size = audio_decode_frame(is, &pts);
/* audio_data_size < 0 标示没能解码出数据，我们默认播放静音 */
if (audio_data_size < 0) {
/* silence */
is->audio_buf_size = 1024;
/* 清零，静音 */
if (is->audio_buf == NULL) return;
memset(is->audio_buf, 0, is->audio_buf_size);
} else {
is->audio_buf_size = audio_data_size;
}
is->audio_buf_index = 0;
}
/* 查看stream可用空间，决定一次copy多少数据，剩下的下次继续copy */
len1 = is->audio_buf_size - is->audio_buf_index;
if (len1 > len) {
len1 = len;
}
if (is->audio_buf == NULL) return;
memcpy(stream, (uint8_t *) is->audio_buf + is->audio_buf_index, len1);
// SDL_MixAudio(stream, (uint8_t * )is->audio_buf + is->audio_buf_index, len1, 50);
// SDL_MixAudioFormat(stream, (uint8_t * )is->audio_buf + is->audio_buf_index, AUDIO_S16SYS, len1, 50);
len -= len1;
stream += len1;
is->audio_buf_index += len1;
}
}
static double get_audio_clock(VideoState *is)
{
double pts;
int hw_buf_size, bytes_per_sec, n;
pts = is->audio_clock; /* maintained in the audio thread */
hw_buf_size = is->audio_buf_size - is->audio_buf_index;
bytes_per_sec = 0;
n = is->audio_st->codec->channels * 2;
if(is->audio_st)
{
bytes_per_sec = is->audio_st->codec->sample_rate * n;
}
if(bytes_per_sec)
{
pts -= (double)hw_buf_size / bytes_per_sec;
}
return pts;
}
static double synchronize_video(VideoState *is, AVFrame *src_frame, double pts) {
double frame_delay;
if (pts != 0) {
/* if we have pts, set video clock to it */
is->video_clock = pts;
} else {
/* if we aren't given a pts, set it to the clock */
pts = is->video_clock;
}
/* update the video clock */
frame_delay = av_q2d(is->video_st->codec->time_base);
/* if we are repeating a frame, adjust clock accordingly */
frame_delay += src_frame->repeat_pict * (frame_delay * 0.5);
is->video_clock += frame_delay;
return pts;
}
int audio_stream_component_open(VideoState *is, int stream_index)
{
AVFormatContext *ic = is->ic;
AVCodecContext *codecCtx;
AVCodec *codec;
SDL_AudioSpec wanted_spec, spec;
int64_t wanted_channel_layout = 0;
int wanted_nb_channels;
/* SDL支持的声道数为 1, 2, 4, 6 */
/* 后面我们会使用这个数组来纠正不支持的声道数目 */
const int next_nb_channels[] = { 0, 0, 1, 6, 2, 6, 4, 6 };
if (stream_index < 0 || stream_index >= ic->nb_streams) {
return -1;
}
codecCtx = ic->streams[stream_index]->codec;
wanted_nb_channels = codecCtx->channels;
if (!wanted_channel_layout
|| wanted_nb_channels
!= av_get_channel_layout_nb_channels(
wanted_channel_layout)) {
wanted_channel_layout = av_get_default_channel_layout(
wanted_nb_channels);
wanted_channel_layout &= ~AV_CH_LAYOUT_STEREO_DOWNMIX;
}
wanted_spec.channels = av_get_channel_layout_nb_channels(
wanted_channel_layout);
wanted_spec.freq = codecCtx->sample_rate;
if (wanted_spec.freq <= 0 || wanted_spec.channels <= 0) {
//fprintf(stderr,"Invalid sample rate or channel count!\n");
return -1;
}
wanted_spec.format = AUDIO_S16SYS; // 具体含义请查看“SDL宏定义”部分
wanted_spec.silence = 0; // 0指示静音
wanted_spec.samples = SDL_AUDIO_BUFFER_SIZE; // 自定义SDL缓冲区大小
wanted_spec.callback = audio_callback; // 音频解码的关键回调函数
wanted_spec.userdata = is; // 传给上面回调函数的外带数据
// SDL_AudioDeviceID audioID = 1;// = SDL_OpenAudioDevice("",0,&wanted_spec, &spec,1);
// int num = SDL_GetNumAudioDevices(0);
// for (int i=0;i<num;i++)
// {
// qDebug()<<SDL_GetAudioDeviceName(i,0);
// }
// /// 打开SDL播放设备 - 开始
// SDL_LockAudio();
// SDL_AudioSpec spec;
// SDL_AudioSpec wanted_spec;
// wanted_spec.freq = aCodecCtx->sample_rate;
// wanted_spec.format = AUDIO_S16SYS;
// wanted_spec.channels = aCodecCtx->channels;
// wanted_spec.silence = 0;
// wanted_spec.samples = SDL_AUDIO_BUFFER_SIZE;
// wanted_spec.callback = audio_callback;
// wanted_spec.userdata = &mVideoState;
// if(SDL_OpenAudio(&wanted_spec, &spec) < 0)
// {
// fprintf(stderr, "SDL_OpenAudio: %s\n", SDL_GetError());
// return;
// }
// SDL_UnlockAudio();
// SDL_PauseAudio(0);
// /// 打开SDL播放设备 - 结束
/* 打开音频设备，这里使用一个while来循环尝试打开不同的声道数(由上面 */
/* next_nb_channels数组指定）直到成功打开，或者全部失败 */
// while (SDL_OpenAudio(&wanted_spec, &spec) < 0) {
do {
is->audioID = SDL_OpenAudioDevice(SDL_GetAudioDeviceName(0,0),0,&wanted_spec, &spec,0);
// qDebug()<<"audioID"<<audioID;
// if (audioID >= 1) break;
fprintf(stderr,"SDL_OpenAudio (%d channels): %s\n",wanted_spec.channels, SDL_GetError());
qDebug()<<QString("SDL_OpenAudio (%1 channels): %2").arg(wanted_spec.channels).arg(SDL_GetError());
wanted_spec.channels = next_nb_channels[FFMIN(7, wanted_spec.channels)];
if (!wanted_spec.channels) {
fprintf(stderr,"No more channel combinations to tyu, audio open failed\n");
// return -1;
break;
}
wanted_channel_layout = av_get_default_channel_layout(
wanted_spec.channels);
}while(is->audioID == 0);
/* 检查实际使用的配置（保存在spec,由SDL_OpenAudio()填充） */
if (spec.format != AUDIO_S16SYS) {
fprintf(stderr,"SDL advised audio format %d is not supported!\n",spec.format);
return -1;
}
if (spec.channels != wanted_spec.channels) {
wanted_channel_layout = av_get_default_channel_layout(spec.channels);
if (!wanted_channel_layout) {
fprintf(stderr,"SDL advised channel count %d is not supported!\n",spec.channels);
return -1;
}
}
is->audio_hw_buf_size = spec.size;
/* 把设置好的参数保存到大结构中 */
is->audio_src_fmt = is->audio_tgt_fmt = AV_SAMPLE_FMT_S16;
is->audio_src_freq = is->audio_tgt_freq = spec.freq;
is->audio_src_channel_layout = is->audio_tgt_channel_layout =
wanted_channel_layout;
is->audio_src_channels = is->audio_tgt_channels = spec.channels;
codec = avcodec_find_decoder(codecCtx->codec_id);
if (!codec || (avcodec_open2(codecCtx, codec, NULL) < 0)) {
fprintf(stderr,"Unsupported codec!\n");
return -1;
}
ic->streams[stream_index]->discard = AVDISCARD_DEFAULT;
switch (codecCtx->codec_type) {
case AVMEDIA_TYPE_AUDIO:
// is->audioStream = stream_index;
is->audio_st = ic->streams[stream_index];
is->audio_buf_size = 0;
is->audio_buf_index = 0;
memset(&is->audio_pkt, 0, sizeof(is->audio_pkt));
packet_queue_init(&is->audioq);
// SDL_PauseAudio(0); // 开始播放静音
SDL_PauseAudioDevice(is->audioID,0);
break;
default:
break;
}
return 0;
}
int video_thread(void *arg)
{
VideoState *is = (VideoState *) arg;
AVPacket pkt1, *packet = &pkt1;
int ret, got_picture, numBytes;
double video_pts = 0; //当前视频的pts
double audio_pts = 0; //音频pts
///解码视频相关
AVFrame *pFrame, *pFrameRGB;
uint8_t *out_buffer_rgb; //解码后的rgb数据
struct SwsContext *img_convert_ctx; //用于解码后的视频格式转换
AVCodecContext *pCodecCtx = is->video_st->codec; //视频解码器
pFrame = av_frame_alloc();
pFrameRGB = av_frame_alloc();
///这里我们改成了 将解码后的YUV数据转换成RGB32
img_convert_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height,
pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height,
PIX_FMT_RGB32, SWS_BICUBIC, NULL, NULL, NULL);
numBytes = avpicture_get_size(PIX_FMT_RGB32, pCodecCtx->width,pCodecCtx->height);
out_buffer_rgb = (uint8_t *) av_malloc(numBytes * sizeof(uint8_t));
avpicture_fill((AVPicture *) pFrameRGB, out_buffer_rgb, PIX_FMT_RGB32,
pCodecCtx->width, pCodecCtx->height);
while(1)
{
if (is->quit)
{
break;
}
if (is->isPause == true) //判断暂停
{
SDL_Delay(10);
continue;
}
if (packet_queue_get(&is->videoq, packet, 0) <= 0)
{
if (is->readFinished)
{//队列里面没有数据了且读取完毕了
break;
}
else
{
SDL_Delay(1); //队列只是暂时没有数据而已
continue;
}
}
//收到这个数据 说明刚刚执行过跳转 现在需要把解码器的数据 清除一下
if(strcmp((char*)packet->data,FLUSH_DATA) == 0)
{
avcodec_flush_buffers(is->video_st->codec);
av_free_packet(packet);
continue;
}
ret = avcodec_decode_video2(pCodecCtx, pFrame, &got_picture,packet);
if (ret < 0) {
qDebug()<<"decode error.\n";
av_free_packet(packet);
continue;
}
if (packet->dts == AV_NOPTS_VALUE && pFrame->opaque&& *(uint64_t*) pFrame->opaque != AV_NOPTS_VALUE)
{
video_pts = *(uint64_t *) pFrame->opaque;
}
else if (packet->dts != AV_NOPTS_VALUE)
{
video_pts = packet->dts;
}
else
{
video_pts = 0;
}
video_pts *= av_q2d(is->video_st->time_base);
video_pts = synchronize_video(is, pFrame, video_pts);
if (is->seek_flag_video)
{
//发生了跳转 则跳过关键帧到目的时间的这几帧
if (video_pts < is->seek_time)
{
av_free_packet(packet);
continue;
}
else
{
is->seek_flag_video = 0;
}
}
while(1)
{
if (is->quit)
{
break;
}
audio_pts = is->audio_clock;
//主要是 跳转的时候 我们把video_clock设置成0了
//因此这里需要更新video_pts
//否则当从后面跳转到前面的时候 会卡在这里
video_pts = is->video_clock;
if (video_pts <= audio_pts) break;
int delayTime = (video_pts - audio_pts) * 1000;
delayTime = delayTime > 5 ? 5:delayTime;
SDL_Delay(delayTime);
}
if (got_picture) {
sws_scale(img_convert_ctx,
(uint8_t const * const *) pFrame->data,
pFrame->linesize, 0, pCodecCtx->height, pFrameRGB->data,
pFrameRGB->linesize);
//把这个RGB数据 用QImage加载
QImage tmpImg((uchar *)out_buffer_rgb,pCodecCtx->width,pCodecCtx->height,QImage::Format_RGB32);
QImage image = tmpImg.copy(); //把图像复制一份 传递给界面显示
is->player->disPlayVideo(image); //调用激发信号的函数
}
av_free_packet(packet);
}
av_free(pFrame);
av_free(pFrameRGB);
av_free(out_buffer_rgb);
if (!is->quit)
{
is->quit = true;
}
is->videoThreadFinished = true;
return 0;
}
VideoPlayer::VideoPlayer()
{
mPlayerState = Stop;
}
VideoPlayer::~VideoPlayer()
{
}
bool VideoPlayer::setFileName(QString path)
{
if (mPlayerState != Stop)
{
return false;
}
mFileName = path;
this->start(); //启动线程
mPlayerState = Playing;
return true;
}
bool VideoPlayer::play()
{
mVideoState.isPause = false;
if (mPlayerState != Pause)
{
return false;
}
mPlayerState = Playing;
emit sig_StateChanged(Playing);
return true;
}
bool VideoPlayer::pause()
{
mVideoState.isPause = true;
if (mPlayerState != Playing)
{
return false;
}
mPlayerState = Pause;
emit sig_StateChanged(Pause);
return true;
}
bool VideoPlayer::stop(bool isWait)
{
if (mPlayerState == Stop)
{
return false;
}
mVideoState.quit = 1;
if (isWait)
{
while(!mVideoState.readThreadFinished || !mVideoState.videoThreadFinished)
{
SDL_Delay(10);
}
}
///关闭SDL音频播放设备
if (mVideoState.audioID != 0)
{
SDL_LockAudio();
SDL_PauseAudioDevice(mVideoState.audioID,1);
SDL_UnlockAudio();
mVideoState.audioID = 0;
}
mPlayerState = Stop;
emit sig_StateChanged(Stop);
return true;
}
void VideoPlayer::seek(int64_t pos)
{
if(!mVideoState.seek_req)
{
mVideoState.seek_pos = pos;
mVideoState.seek_req = 1;
}
}
double VideoPlayer::getCurrentTime()
{
return mVideoState.audio_clock;
}
int64_t VideoPlayer::getTotalTime()
{
return mVideoState.ic->duration;
}
void VideoPlayer::disPlayVideo(QImage img)
{
emit sig_GetOneFrame(img); //发送信号
}
void VideoPlayer::run()
{
char file_path[1280] = {0};;
strcpy(file_path,mFileName.toUtf8().data());
memset(&mVideoState,0,sizeof(VideoState)); //为了安全起见 先将结构体的数据初始化成0了
VideoState *is = &mVideoState;
AVFormatContext *pFormatCtx;
AVCodecContext *pCodecCtx;
AVCodec *pCodec;
AVCodecContext *aCodecCtx;
AVCodec *aCodec;
int audioStream ,videoStream, i;
//Allocate an AVFormatContext.
pFormatCtx = avformat_alloc_context();
if (avformat_open_input(&pFormatCtx, file_path, NULL, NULL) != 0) {
printf("can't open the file. \n");
return;
}
if (avformat_find_stream_info(pFormatCtx, NULL) < 0) {
printf("Could't find stream infomation.\n");
return;
}
videoStream = -1;
audioStream = -1;
///循环查找视频中包含的流信息，
for (i = 0; i < pFormatCtx->nb_streams; i++) {
if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO)
{
videoStream = i;
}
if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_AUDIO && audioStream < 0)
{
audioStream = i;
}
}
///如果videoStream为-1 说明没有找到视频流
if (videoStream == -1) {
printf("Didn't find a video stream.\n");
return;
}
if (audioStream == -1) {
printf("Didn't find a audio stream.\n");
return;
}
is->ic = pFormatCtx;
is->videoStream = videoStream;
is->audioStream = audioStream;
emit sig_TotalTimeChanged(getTotalTime());
if (audioStream >= 0) {
/* 所有设置SDL音频流信息的步骤都在这个函数里完成 */
audio_stream_component_open(&mVideoState, audioStream);
}
///查找音频解码器
aCodecCtx = pFormatCtx->streams[audioStream]->codec;
aCodec = avcodec_find_decoder(aCodecCtx->codec_id);
if (aCodec == NULL) {
printf("ACodec not found.\n");
return;
}
///打开音频解码器
if (avcodec_open2(aCodecCtx, aCodec, NULL) < 0) {
printf("Could not open audio codec.\n");
return;
}
is->audio_st = pFormatCtx->streams[audioStream];
///查找视频解码器
pCodecCtx = pFormatCtx->streams[videoStream]->codec;
pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
if (pCodec == NULL) {
printf("PCodec not found.\n");
return;
}
///打开视频解码器
if (avcodec_open2(pCodecCtx, pCodec, NULL) < 0) {
printf("Could not open video codec.\n");
return;
}
is->video_st = pFormatCtx->streams[videoStream];
packet_queue_init(&is->videoq);
///创建一个线程专门用来解码视频
is->video_tid = SDL_CreateThread(video_thread, "video_thread", &mVideoState);
is->player = this;
// int y_size = pCodecCtx->width * pCodecCtx->height;
AVPacket *packet = (AVPacket *) malloc(sizeof(AVPacket)); //分配一个packet 用来存放读取的视频
// av_new_packet(packet, y_size); //av_read_frame 会给它分配空间 因此这里不需要了
av_dump_format(pFormatCtx, 0, file_path, 0); //输出视频信息
while (1)
{
if (is->quit) { //停止播放了
break;
}
if (is->seek_req)
{
int stream_index = -1;
int64_t seek_target = is->seek_pos;
if (is->videoStream >= 0)
stream_index = is->videoStream;
else if (is->audioStream >= 0)
stream_index = is->audioStream;
AVRational aVRational = {1, AV_TIME_BASE};
if (stream_index >= 0) {
seek_target = av_rescale_q(seek_target, aVRational,
pFormatCtx->streams[stream_index]->time_base);
}
if (av_seek_frame(is->ic, stream_index, seek_target, AVSEEK_FLAG_BACKWARD) < 0) {
fprintf(stderr, "%s: error while seeking\n",is->ic->filename);
} else {
if (is->audioStream >= 0) {
AVPacket *packet = (AVPacket *) malloc(sizeof(AVPacket)); //分配一个packet
av_new_packet(packet, 10);
strcpy((char*)packet->data,FLUSH_DATA);
packet_queue_flush(&is->audioq); //清除队列
packet_queue_put(&is->audioq, packet); //往队列中存入用来清除的包
}
if (is->videoStream >= 0) {
AVPacket *packet = (AVPacket *) malloc(sizeof(AVPacket)); //分配一个packet
av_new_packet(packet, 10);
strcpy((char*)packet->data,FLUSH_DATA);
packet_queue_flush(&is->videoq); //清除队列
packet_queue_put(&is->videoq, packet); //往队列中存入用来清除的包
is->video_clock = 0;
}
}
is->seek_req = 0;
is->seek_time = is->seek_pos / 1000000.0;
is->seek_flag_audio = 1;
is->seek_flag_video = 1;
}
//这里做了个限制 当队列里面的数据超过某个大小的时候 就暂停读取 防止一下子就把视频读完了，导致的空间分配不足
/* 这里audioq.size是指队列中的所有数据包带的音频数据的总量或者视频数据总量，并不是包的数量 */
//这个值可以稍微写大一些
if (is->audioq.size > MAX_AUDIO_SIZE || is->videoq.size > MAX_VIDEO_SIZE) {
SDL_Delay(10);
continue;
}
if (is->isPause == true)
{
SDL_Delay(10);
continue;
}
if (av_read_frame(pFormatCtx, packet) < 0)
{
is->readFinished = true;
if (is->quit)
{
break; //解码线程也执行完了 可以退出了
}
SDL_Delay(10);
continue;
}
if (packet->stream_index == videoStream)
{
packet_queue_put(&is->videoq, packet);
//这里我们将数据存入队列 因此不调用 av_free_packet 释放
}
else if( packet->stream_index == audioStream )
{
packet_queue_put(&is->audioq, packet);
//这里我们将数据存入队列 因此不调用 av_free_packet 释放
}
else
{
// Free the packet that was allocated by av_read_frame
av_free_packet(packet);
}
}
///文件读取结束 跳出循环的情况
///等待播放完毕
while (!is->quit) {
SDL_Delay(100);
}
stop();
avcodec_close(pCodecCtx);
avformat_close_input(&pFormatCtx);
is->readThreadFinished = true;
}
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