音视频同步代码
#include<stdio.h>
#include<assert.h>
#include<math.h>
#include<SDL.h>
#include<libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>
#include<libswresample/swresample.h>
// compatibility with newer API
#if LIBAVCODEC_VERSION_INT < AV_VERSION_INT(55,28,1)
#define av_frame_alloc avcodec_alloc_frame
#define av_frame_free avcodec_free_frame
#endif
#define SDL_AUDIO_BUFFER_SIZE1024
#define MAX_AUDIO_FRAME_SIZE 192000 //channels(2) * data_size(2) * sample_rate(48000)
#define MAX_AUDIOQ_SIZE (5*16*1024)
#define MAX_VIDEOQ_SIZE (5*256*1024)
#define AV_SYNC_THRESHOLD0.01
#define AV_NOSYNC_THRESHOLD10.0
#define SAMPLE_CORRECTION_PERCENT_MAX10
#define AUDIO_DIFF_AVG_NB20
#define FF_REFRESH_EVENT (SDL_USEREVENT)
#define FF_QUIT_EVENT (SDL_USEREVENT +1)
#define VIDEO_PICTURE_QUEUE_SIZE1
#define DEFAULT_AV_SYNC_TYPE AV_SYNC_AUDIO_MASTER//AV_SYNC_VIDEO_MASTER
typedef struct PacketQueue {
AVPacketList *first_pkt, *last_pkt;
intnb_packets;
intsize;
SDL_mutex *mutex;
SDL_cond *cond;
} PacketQueue;
typedef struct VideoPicture {
AVPicture *bmp;
int width, height; /* source height & width */
intallocated;
doublepts;
} VideoPicture;
typedef struct VideoState {
//multi-media file
//多媒体文件的名字
char filename[1024];
//多媒体文件上下文
AVFormatContext *pFormatCtx;
//音频 视频流
int videoStream, audioStream;
//sync
int av_sync_type;
double external_clock;/* external clock base */
int64_t external_clock_time;
double audio_diff_cum;/* used for AV difference average computation */
double audio_diff_avg_coef;
double audio_diff_threshold;
int audio_diff_avg_count;
//记录当前音频播放的时间
double audio_clock;
//下次要回掉的时间值是多少
double frame_timer;
//上一次播放的视频帧的pds
double frame_last_pts;
//上一次播放的视频帧 增加的delay时间
double frame_last_delay;
//记录视频下一帧将要播放的pts时间
double video_clock;///
double video_current_pts;///
int64_t video_current_pts_time; ///
//audio
//音频流
AVStream *audio_st;
//音频上下文
AVCodecContext *audio_ctx;
//音频队列
PacketQueue audioq;
//解码后的音频缓冲区
uint8_t audio_buf[(MAX_AUDIO_FRAME_SIZE *3) /2];
//缓冲区大小
unsignedint audio_buf_size;
//使用了多少字节
unsignedint audio_buf_index;
//解码后的音频帧
AVFrame audio_frame;
//解码之前的音频包
AVPacket audio_pkt;
//解码之前数据的指针
uint8_t *audio_pkt_data;
//解码之前数据的大小
int audio_pkt_size;
int audio_hw_buf_size;
//video
//视频流
AVStream *video_st;
//视频上下文
AVCodecContext *video_ctx;
//视频流队列
PacketQueue videoq;
structSwsContext*video_sws_ctx;
//音频重采样上下文
//打开音频设备的时候给音频设备设置了固定参数。采样率多少 通道数 采样大小
//多媒体文件各种各样的大小 放到音频设备统一的播放出来 我们需要进行重采样
//将我们所有的多媒体格式 重采样到 打开音频设备的时候给音频设备设置了固定参数
structSwrContext*audio_swr_ctx;
//解码后的视频
VideoPicture pictq[VIDEO_PICTURE_QUEUE_SIZE];
//pictq_size 解码后的视频大小 pictq_rindex 取视频帧的位置 pictq_windex存放视频帧所在位置
int pictq_size, pictq_rindex, pictq_windex;
//视频帧队列锁
SDL_mutex *pictq_mutex;
SDL_cond *pictq_cond;
//解复用线程
SDL_Thread *parse_tid;
//视频解码线程
SDL_Thread *video_tid;
//结束窗口 退出事件
int quit;
} VideoState;
SDL_mutex *text_mutex;
SDL_Window *win = NULL;
SDL_Renderer *renderer;
SDL_Texture *texture;
enum {
AV_SYNC_AUDIO_MASTER,
AV_SYNC_VIDEO_MASTER,
AV_SYNC_EXTERNAL_MASTER,
};
staticintscreen_left= SDL_WINDOWPOS_CENTERED;
staticintscreen_top= SDL_WINDOWPOS_CENTERED;
static int screen_width = 0;
static int screen_height = 0;
static int resize = 1;
FILE *yuvfd = NULL;
FILE *audiofd = NULL;
/* Since we only have one decoding thread, the Big Struct
can be global in case we need it. */
VideoState *global_video_state;
voidpacket_queue_init(PacketQueue *q) {
memset(q,0,sizeof(PacketQueue));
q->mutex = SDL_CreateMutex();
q->cond = SDL_CreateCond();
}
//入队函数 第一个是队列指针 第二个是插入元素的Packet
intpacket_queue_put(PacketQueue *q, AVPacket *pkt) {
AVPacketList *pkt1;
if(av_dup_packet(pkt) <0) {
return-1;
}
//分配一个元素
pkt1 = av_malloc(sizeof(AVPacketList));
if(!pkt1)
return-1;
pkt1->pkt = *pkt;
pkt1->next =NULL;
//加锁
SDL_LockMutex(q->mutex);
//空队列
if(!q->last_pkt)
q->first_pkt = pkt1;
else
q->last_pkt->next = pkt1;
q->last_pkt = pkt1;
//整个队列元素增加
q->nb_packets++;
//队列的大小
q->size += pkt1->pkt.size;
//入队成功 发一个信号 等待的线程进入
//SDL_CondSignal 解锁 发信号 在加锁
SDL_CondSignal(q->cond);
SDL_UnlockMutex(q->mutex);
return 0;
}
//出队 block代表阻塞还是非阻塞
intpacket_queue_get(PacketQueue *q, AVPacket *pkt,intblock)
{
AVPacketList *pkt1;
intret;
//加锁
SDL_LockMutex(q->mutex);
for(;;) {
if(global_video_state->quit) {
ret = -1;
break;
}
//拿到队列头取
pkt1 = q->first_pkt;
if(pkt1) {//头摔出来
q->first_pkt = pkt1->next;
if(!q->first_pkt)//队列为空
q->last_pkt =NULL;
q->nb_packets--;//队列数量--
q->size -= pkt1->pkt.size;//队列大小
*pkt = pkt1->pkt;//获得的pkt
av_free(pkt1);
ret =1;
break;
}elseif(!block) {
ret =0;
break;
}else {// 没有数据 那么等待
//🧵解锁 等待 加锁
SDL_CondWait(q->cond, q->mutex);
}
}
SDL_UnlockMutex(q->mutex);
returnret;
}
doubleget_audio_clock(VideoState *is) {
doublepts;
inthw_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_ctx->channels *2;
if(is->audio_st) {
bytes_per_sec = is->audio_ctx->sample_rate * n;
}
if(bytes_per_sec) {
pts -= (double)hw_buf_size / bytes_per_sec;
}
returnpts;
}
doubleget_video_clock(VideoState *is) {
doubledelta;
delta = (av_gettime() - is->video_current_pts_time) /1000000.0;
returnis->video_current_pts + delta;
}
doubleget_external_clock(VideoState *is) {
returnav_gettime() /1000000.0;
}
doubleget_master_clock(VideoState *is) {
//get_video_clock 拿到正在播放音频的时间
if(is->av_sync_type == AV_SYNC_VIDEO_MASTER) {
returnget_video_clock(is);
}elseif(is->av_sync_type == AV_SYNC_AUDIO_MASTER) {
returnget_audio_clock(is);
}else{
returnget_external_clock(is);
}
}
/* Add or subtract samples to get a better sync, return new
audio buffer size */
intsynchronize_audio(VideoState *is,short*samples,
intsamples_size,doublepts) {
intn;
doubleref_clock;
n =2* is->audio_ctx->channels;
if(is->av_sync_type != AV_SYNC_AUDIO_MASTER) {
doublediff, avg_diff;
intwanted_size, min_size, max_size/*, nb_samples */;
ref_clock = get_master_clock(is);
//我们要展示视频帧还是不要展示
diff = get_audio_clock(is) - ref_clock;
if(diff < AV_NOSYNC_THRESHOLD) {//超过阀值
// accumulate the diffs
is->audio_diff_cum = diff + is->audio_diff_avg_coef
* is->audio_diff_cum;
if(is->audio_diff_avg_count < AUDIO_DIFF_AVG_NB) {
is->audio_diff_avg_count++;
}else{
avg_diff = is->audio_diff_cum * (1.0- is->audio_diff_avg_coef);
if(fabs(avg_diff) >= is->audio_diff_threshold) {
wanted_size = samples_size + ((int)(diff * is->audio_ctx->sample_rate) * n);
min_size = samples_size * ((100- SAMPLE_CORRECTION_PERCENT_MAX) /100);
max_size = samples_size * ((100+ SAMPLE_CORRECTION_PERCENT_MAX) /100);
if(wanted_size < min_size) {
wanted_size = min_size;
}elseif(wanted_size > max_size) {
wanted_size = max_size;
}
if(wanted_size < samples_size) {
/* remove samples */
samples_size = wanted_size;
}elseif(wanted_size > samples_size) {
uint8_t *samples_end, *q;
intnb;
/* add samples by copying final sample*/
nb = (samples_size - wanted_size);
samples_end = (uint8_t *)samples + samples_size - n;
q = samples_end + n;
while(nb >0) {
memcpy(q, samples_end, n);
q += n;
nb -= n;
}
samples_size = wanted_size;
}
}
}
}else{
/* difference is TOO big; reset diff stuff */
is->audio_diff_avg_count =0;
is->audio_diff_cum =0;
}
}
returnsamples_size;
}
intaudio_decode_frame(VideoState *is, uint8_t *audio_buf,intbuf_size,double*pts_ptr) {
intlen1, data_size =0;
AVPacket *pkt = &is->audio_pkt;
doublepts;
intn;
for(;;) {
//音频流还有数据
while(is->audio_pkt_size >0) {
intgot_frame =0;
//解码
len1 = avcodec_decode_audio4(is->audio_ctx, &is->audio_frame, &got_frame, pkt);
if(len1 <0) {//出错
/* if error, skip frame */
is->audio_pkt_size =0;
break;
}
data_size =0;
if(got_frame) {
/*
data_size = av_samples_get_buffer_size(NULL,
is->audio_ctx->channels,
is->audio_frame.nb_samples,
is->audio_ctx->sample_fmt,
1);
*/
data_size =2* is->audio_frame.nb_samples *2;
assert(data_size <= buf_size);
//进行重采样
swr_convert(is->audio_swr_ctx,
&audio_buf,
MAX_AUDIO_FRAME_SIZE*3/2,
(constuint8_t **)is->audio_frame.data,
is->audio_frame.nb_samples);
fwrite(audio_buf,1, data_size, audiofd);
//memcpy(audio_buf, is->audio_frame.data[0], data_size);
}
is->audio_pkt_data += len1;
is->audio_pkt_size -= len1;
if(data_size <=0) {
/* No data yet, get more frames */
continue;
}
pts = is->audio_clock;
*pts_ptr = pts;
n =2* is->audio_ctx->channels;
is->audio_clock += (double)data_size /
(double)(n * is->audio_ctx->sample_rate);
/* We have data, return it and come back for more later */
returndata_size;
}
if(pkt->data)
av_free_packet(pkt);
if(is->quit) {
return-1;
}
/* next packet */
//音频队列中取出包
if(packet_queue_get(&is->audioq, pkt,1) <0) {
return-1;
}
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;
}
}
}
voidaudio_callback(void*userdata, Uint8 *stream,intlen) {
VideoState *is = (VideoState *)userdata;
intlen1, audio_size;
doublepts;
SDL_memset(stream,0, len);
while(len >0) {
//现在索取的数据 大于audio_buf_size 说明 缓冲区没有数据
if(is->audio_buf_index >= is->audio_buf_size) {
/* We have already sent all our data; get more */
//解码
audio_size = audio_decode_frame(is, is->audio_buf,sizeof(is->audio_buf), &pts);
if(audio_size <0) {
/* If error, output silence */
is->audio_buf_size =1024*2*2;
memset(is->audio_buf,0, is->audio_buf_size);
}else{
audio_size = synchronize_audio(is, (int16_t *)is->audio_buf,
audio_size, pts);
is->audio_buf_size = audio_size;
}
is->audio_buf_index =0;
}
// 解码后的长度
len1 = is->audio_buf_size - is->audio_buf_index;
if(len1 > len) //解码后的长度和 声卡需要的长度比较
len1 = len;
//扔给声卡
SDL_MixAudio(stream,(uint8_t *)is->audio_buf + is->audio_buf_index, len1, SDL_MIX_MAXVOLUME);
//memcpy(stream, (uint8_t *)is->audio_buf + is->audio_buf_index, len1);
len -= len1;
stream += len1;
is->audio_buf_index += len1;
}
}
staticUint32sdl_refresh_timer_cb(Uint32 interval,void*opaque) {
SDL_Event event;
//发送事件
event.type = FF_REFRESH_EVENT;
event.user.data1 = opaque;
SDL_PushEvent(&event);
return 0; /* 0 means stop timer */
}
/* schedule a video refresh in 'delay' ms */
staticvoidschedule_refresh(VideoState *is,intdelay) {
SDL_AddTimer(delay, sdl_refresh_timer_cb, is);
}
voidvideo_display(VideoState *is) {
SDL_Rect rect;
VideoPicture *vp;
floataspect_ratio;
intw, h, x, y;
inti;
if(screen_width && resize){
SDL_SetWindowSize(win, screen_width, screen_height);
SDL_SetWindowPosition(win, screen_left, screen_top);
SDL_ShowWindow(win);
//IYUV: Y + U + V (3 planes)
//YV12: Y + V + U (3 planes)
Uint32 pixformat= SDL_PIXELFORMAT_IYUV;
//create texture for render
texture = SDL_CreateTexture(renderer,
pixformat,
SDL_TEXTUREACCESS_STREAMING,
screen_width,
screen_height);
resize =0;
}
vp = &is->pictq[is->pictq_rindex];
if(vp->bmp) {
//解码后的视频帧放入纹理中去
SDL_UpdateYUVTexture( texture,NULL,
vp->bmp->data[0], vp->bmp->linesize[0],
vp->bmp->data[1], vp->bmp->linesize[1],
vp->bmp->data[2], vp->bmp->linesize[2]);
rect.x =0;
rect.y =0;
rect.w = is->video_ctx->width;
rect.h = is->video_ctx->height;
SDL_LockMutex(text_mutex);
//刷一下屏
SDL_RenderClear( renderer );
//
SDL_RenderCopy( renderer, texture,NULL, &rect);
SDL_RenderPresent( renderer );
SDL_UnlockMutex(text_mutex);
}
}
//隔多长时间刷新
void video_refresh_timer(void *userdata) {
VideoState *is = (VideoState *)userdata;
VideoPicture *vp;
doubleactual_delay, delay, sync_threshold, ref_clock, diff;
if(is->video_st) {
//解码后是否有数据
if(is->pictq_size ==0) {
//没有数据 就1ms 不停的查询是否有数据了
schedule_refresh(is,1);
//fprintf(stderr, "no picture in the queue!!!\n");
}else{
//fprintf(stderr, "get picture from queue!!!\n");
//解码后队列拿到视频帧
vp = &is->pictq[is->pictq_rindex];
is->video_current_pts = vp->pts;
is->video_current_pts_time = av_gettime();
delay = vp->pts - is->frame_last_pts;/* the pts from last time */
//大于1s
if(delay <=0|| delay >=1.0) {
/* if incorrect delay, use previous one */
//上一次delay时间
delay = is->frame_last_delay;
}
/* save for next time */
is->frame_last_delay = delay;
is->frame_last_pts = vp->pts;
/* update delay to sync to audio if not master source */
if(is->av_sync_type != AV_SYNC_VIDEO_MASTER) {
ref_clock = get_master_clock(is);
diff = vp->pts - ref_clock;
/* Skip or repeat the frame. Take delay into account
FFPlay still doesn't "know if this is the best guess." */
//同步阀值
sync_threshold = (delay > AV_SYNC_THRESHOLD) ? delay : AV_SYNC_THRESHOLD;
if(fabs(diff) < AV_NOSYNC_THRESHOLD) {
if(diff <= -sync_threshold) {//阀值小于sync_threshold 视频时间是在音频时间之前
delay =0;//立马展示
}elseif(diff >= sync_threshold) {//视频展示的时间还没到 等待时间加长
delay =2* delay;
}
}
}//音频的每一个包是10ms
// 加上系统时间
is->frame_timer += delay;
/* computer the REAL delay */
//真正等待时间
actual_delay = is->frame_timer - (av_gettime() /1000000.0);
if(actual_delay <0.010) {//小于10ms就等待10ms
/* Really it should skip the picture instead */
actual_delay =0.010;
}
//下一次渲染的时间
schedule_refresh(is, (int)(actual_delay *1000+0.5));
/* show the picture! */
video_display(is);
/* update queue for next picture! */
if(++is->pictq_rindex == VIDEO_PICTURE_QUEUE_SIZE) {
is->pictq_rindex =0;
}
SDL_LockMutex(is->pictq_mutex);
is->pictq_size--;
SDL_CondSignal(is->pictq_cond);
SDL_UnlockMutex(is->pictq_mutex);
}
}else{
schedule_refresh(is,100);
}
}
voidalloc_picture(void*userdata) {
intret;
VideoState *is = (VideoState *)userdata;
VideoPicture *vp;
vp = &is->pictq[is->pictq_windex];
if(vp->bmp) {
// we already have one make another, bigger/smaller
avpicture_free(vp->bmp);
free(vp->bmp);
vp->bmp =NULL;
}
// Allocate a place to put our YUV image on that screen
SDL_LockMutex(text_mutex);
vp->bmp = (AVPicture*)malloc(sizeof(AVPicture));
ret = avpicture_alloc(vp->bmp, AV_PIX_FMT_YUV420P, is->video_ctx->width, is->video_ctx->height);
if(ret <0) {
fprintf(stderr,"Could not allocate temporary picture: %s\n", av_err2str(ret));
}
SDL_UnlockMutex(text_mutex);
vp->width = is->video_ctx->width;
vp->height = is->video_ctx->height;
vp->allocated =1;
}
intqueue_picture(VideoState *is, AVFrame *pFrame,doublepts) {
VideoPicture *vp;
/* wait until we have space for a new pic */
SDL_LockMutex(is->pictq_mutex);
while(is->pictq_size >= VIDEO_PICTURE_QUEUE_SIZE &&
!is->quit) {
SDL_CondWait(is->pictq_cond, is->pictq_mutex);
}
SDL_UnlockMutex(is->pictq_mutex);
if(is->quit)
return-1;
// windex is set to 0 initially
vp = &is->pictq[is->pictq_windex];
/* allocate or resize the buffer! */
if(!vp->bmp ||
vp->width != is->video_ctx->width ||
vp->height != is->video_ctx->height) {
vp->allocated =0;
alloc_picture(is);
if(is->quit) {
return-1;
}
}
/* We have a place to put our picture on the queue */
if(vp->bmp) {
//
vp->pts = pts;
// Convert the image into YUV format that SDL uses
sws_scale(is->video_sws_ctx, (uint8_tconst*const*)pFrame->data,
pFrame->linesize,0, is->video_ctx->height,
vp->bmp->data, vp->bmp->linesize);
/* now we inform our display thread that we have a pic ready */
if(++is->pictq_windex == VIDEO_PICTURE_QUEUE_SIZE) {
is->pictq_windex =0;
}
SDL_LockMutex(is->pictq_mutex);
is->pictq_size++;
SDL_UnlockMutex(is->pictq_mutex);
}
return 0;
}
doublesynchronize_video(VideoState *is, AVFrame *src_frame,doublepts) {
doubleframe_delay;
if(pts !=0) {
/* if we have pts, set video clock to it */
//更新video_clock
is->video_clock = pts;
}else{
/* if we aren't given a pts, set it to the clock */
//使用上一次的
pts = is->video_clock;
}
/* update the video clock */
//
frame_delay = av_q2d(is->video_ctx->time_base);
/* if we are repeating a frame, adjust clock accordingly */
//解码后的视频帧 这个帧要重复的播放
frame_delay += src_frame->repeat_pict * (frame_delay *0.5);
//下一帧的pts
is->video_clock += frame_delay;
returnpts;
}
//视频解码线程
int decode_video_thread(void *arg) {
VideoState *is = (VideoState *)arg;
AVPacket pkt1, *packet = &pkt1;
intframeFinished;
AVFrame *pFrame;
doublepts;
pFrame = av_frame_alloc();
for(;;) {
//视频队列中取出视频包
if(packet_queue_get(&is->videoq, packet,1) <0) {
// means we quit getting packets
break;
}
pts =0;
// Decode video frame
//解码
avcodec_decode_video2(is->video_ctx, pFrame, &frameFinished, packet);
if((pts = av_frame_get_best_effort_timestamp(pFrame)) != AV_NOPTS_VALUE) {
}else{
pts =0;
}
//时间机换算成s
pts *= av_q2d(is->video_st->time_base);
// Did we get a video frame?
//解码成功后
if(frameFinished) {
pts = synchronize_video(is, pFrame, pts);
//解码后的视频帧队列中
if(queue_picture(is, pFrame, pts) <0) {
break;
}
}
av_free_packet(packet);
}
av_frame_free(&pFrame);
return 0;
}
//stream_index 哪路流
intstream_component_open(VideoState *is,intstream_index) {
AVFormatContext *pFormatCtx = is->pFormatCtx;
AVCodecContext *codecCtx =NULL;
AVCodec *codec =NULL;
SDL_AudioSpec wanted_spec, spec;
if(stream_index <0|| stream_index >= pFormatCtx->nb_streams) {
return-1;
}
codecCtx = avcodec_alloc_context3(NULL);
//得到编码上下文
intret = avcodec_parameters_to_context(codecCtx, pFormatCtx->streams[stream_index]->codecpar);
if(ret <0)
return-1;
// 解码器
codec = avcodec_find_decoder(codecCtx->codec_id);
if(!codec) {
fprintf(stderr,"Unsupported codec!\n");
return-1;
}
//音频
if(codecCtx->codec_type == AVMEDIA_TYPE_AUDIO) {
//打开音频设备
// Set audio settings from codec info
//音频采样率
wanted_spec.freq = codecCtx->sample_rate;
//采样格式
wanted_spec.format = AUDIO_S16SYS;
wanted_spec.channels =2;//codecCtx->channels;
//禁默音
wanted_spec.silence =0;
//采样的个数 每秒中可以多少个数
wanted_spec.samples = SDL_AUDIO_BUFFER_SIZE;
wanted_spec.callback = audio_callback;
wanted_spec.userdata = is;
fprintf(stderr,"wanted spec: channels:%d, sample_fmt:%d, sample_rate:%d \n",
2, AUDIO_S16SYS, codecCtx->sample_rate);
//打开解码器
if(SDL_OpenAudio(&wanted_spec, &spec) <0) {
fprintf(stderr,"SDL_OpenAudio: %s\n", SDL_GetError());
return-1;
}
is->audio_hw_buf_size = spec.size;
}
if(avcodec_open2(codecCtx, codec,NULL) <0) {
fprintf(stderr,"Unsupported codec!\n");
return-1;
}
switch(codecCtx->codec_type) {
caseAVMEDIA_TYPE_AUDIO:
//音频流index
is->audioStream = stream_index;
//具体音频流
is->audio_st = pFormatCtx->streams[stream_index];
//编解码上下文
is->audio_ctx = codecCtx;
//音频buf_size
is->audio_buf_size =0;
// 我们使用了多少
is->audio_buf_index =0;
//音频包
memset(&is->audio_pkt,0,sizeof(is->audio_pkt));
//音频队列初始化
packet_queue_init(&is->audioq);
//Out Audio Param
uint64_t out_channel_layout=AV_CH_LAYOUT_STEREO;
//AAC:1024 MP3:1152
intout_nb_samples= is->audio_ctx->frame_size;
//AVSampleFormat out_sample_fmt = AV_SAMPLE_FMT_S16;
intout_sample_rate=is->audio_ctx->sample_rate;
intout_channels=av_get_channel_layout_nb_channels(out_channel_layout);
//Out Buffer Size
/*
int out_buffer_size=av_samples_get_buffer_size(NULL,
out_channels,
out_nb_samples,
AV_SAMPLE_FMT_S16,
1);
*/
//uint8_t *out_buffer=(uint8_t *)av_malloc(MAX_AUDIO_FRAME_SIZE*2);
int64_t in_channel_layout=av_get_default_channel_layout(is->audio_ctx->channels);
//音频重采样上下文
structSwrContext *audio_convert_ctx;
audio_convert_ctx = swr_alloc();
swr_alloc_set_opts(audio_convert_ctx,
out_channel_layout,
AV_SAMPLE_FMT_S16,
out_sample_rate,
in_channel_layout,
is->audio_ctx->sample_fmt,
is->audio_ctx->sample_rate,
0,
NULL);
fprintf(stderr,"swr opts: out_channel_layout:%lld, out_sample_fmt:%d, out_sample_rate:%d, in_channel_layout:%lld, in_sample_fmt:%d, in_sample_rate:%d",
out_channel_layout, AV_SAMPLE_FMT_S16, out_sample_rate, in_channel_layout, is->audio_ctx->sample_fmt, is->audio_ctx->sample_rate);
swr_init(audio_convert_ctx);
is->audio_swr_ctx = audio_convert_ctx;
//播放音频
SDL_PauseAudio(0);
break;
caseAVMEDIA_TYPE_VIDEO:
is->videoStream = stream_index;
//具体流
is->video_st = pFormatCtx->streams[stream_index];
//视频解码上下文
is->video_ctx = codecCtx;
//获取系统时间换算成s av_gettime微s
is->frame_timer = (double)av_gettime() /1000000.0;
is->frame_last_delay =40e-3;
is->video_current_pts_time = av_gettime();
//视频的队列
packet_queue_init(&is->videoq);
//视频裁剪上下文
is->video_sws_ctx = sws_getContext(is->video_ctx->width, is->video_ctx->height,
is->video_ctx->pix_fmt, is->video_ctx->width,
is->video_ctx->height, AV_PIX_FMT_YUV420P,
SWS_BILINEAR,NULL,NULL,NULL
);
//创建线程
is->video_tid = SDL_CreateThread(decode_video_thread,"decode_video_thread", is);
break;
default:
break;
}
}
int demux_thread(void *arg) {
interr_code;
charerrors[1024] = {0,};
intw, h;
VideoState *is = (VideoState *)arg;
AVFormatContext *pFormatCtx =NULL;
AVPacket pkt1, *packet = &pkt1;
intvideo_index = -1;
intaudio_index = -1;
inti;
is->videoStream=-1;
is->audioStream=-1;
global_video_state = is;
/* open input file, and allocate format context */
//真正打开多媒体文件
if((err_code=avformat_open_input(&pFormatCtx, is->filename,NULL,NULL)) <0) {
av_strerror(err_code, errors,1024);
fprintf(stderr,"Could not open source file %s, %d(%s)\n", is->filename, err_code, errors);
return-1;
}
is->pFormatCtx = pFormatCtx;
// Retrieve stream information
//查找流相关的信息
if(avformat_find_stream_info(pFormatCtx,NULL)<0)
return -1; // Couldn't find stream information
// Dump information about file onto standard error
//将多媒体文件信息dump出来
av_dump_format(pFormatCtx,0, is->filename,0);
// Find the first video stream
for(i=0; inb_streams; i++) {
if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO &&
video_index <0) {
video_index=i;
}
if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_AUDIO &&
audio_index <0) {
audio_index=i;
}
}
if(audio_index >=0) {
//设置其音频相关参数
stream_component_open(is, audio_index);
}
if(video_index >=0) {
stream_component_open(is, video_index);
}
//音频和视频是否都是ok
if(is->videoStream <0|| is->audioStream <0) {
fprintf(stderr,"%s: could not open codecs\n", is->filename);
gotofail;
}
screen_width = is->video_ctx->width;
screen_height = is->video_ctx->height;
// main decode loop
for(;;) {
if(is->quit) {
break;
}
// seek stuff goes here
if(is->audioq.size > MAX_AUDIOQ_SIZE ||
is->videoq.size > MAX_VIDEOQ_SIZE) {
SDL_Delay(10);
continue;
}
//解复用
if(av_read_frame(is->pFormatCtx, packet) <0) {
if(is->pFormatCtx->pb->error ==0) {
SDL_Delay(100); /* no error; wait for user input */
continue;
}else{
break;
}
}
// Is this a packet from the video stream?
//读取的是视频
if(packet->stream_index == is->videoStream) {
// 放入视频队列
packet_queue_put(&is->videoq, packet);
}elseif(packet->stream_index == is->audioStream) {
// 放入音频队列去
packet_queue_put(&is->audioq, packet);
}else{
av_free_packet(packet);
}
}
/* all done - wait for it */
while(!is->quit) {
SDL_Delay(100);
}
fail:
if(1){
SDL_Event event;
event.type = FF_QUIT_EVENT;
event.user.data1 = is;
SDL_PushEvent(&event);
}
return 0;
}
intmain(intargc,char*argv[]) {
SDL_Event event;
//播放器 音频视频都保存在这个结构体里面
VideoState *is;
//核心结构体分配空间
is = av_mallocz(sizeof(VideoState));
if(argc <2) {
fprintf(stderr,"Usage: test <file>\n");
exit(1);
}
yuvfd = fopen("testout.yuv","wb+");
audiofd = fopen("testout.pcm","wb+");
// Register all formats and codecs
av_register_all();
if(SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) {
fprintf(stderr,"Could not initialize SDL - %s\n", SDL_GetError());
exit(1);
}
//creat window from SDL
win = SDL_CreateWindow("Media Player",
100,
100,
640,480,
//is->video_ctx->width, is->video_ctx->height,
SDL_WINDOW_RESIZABLE);
if(!win) {
fprintf(stderr,"\nSDL: could not set video mode:%s - exiting\n", SDL_GetError());
exit(1);
}
renderer = SDL_CreateRenderer(win, -1,0);
text_mutex = SDL_CreateMutex();
av_strlcpy(is->filename, argv[1],sizeof(is->filename));
//解码视频队列创建一个锁
is->pictq_mutex = SDL_CreateMutex();
//解码视频队列创建一个信号量
is->pictq_cond = SDL_CreateCond();
//set timer 40ms回掉一次一帧 视频渲染
schedule_refresh(is,40);
is->av_sync_type = DEFAULT_AV_SYNC_TYPE;
//创建一个解复用线程
is->parse_tid = SDL_CreateThread(demux_thread,"demux_thread", is);
if(!is->parse_tid) {
av_free(is);
return-1;
}
for(;;) {
//等待事件
SDL_WaitEvent(&event);
switch(event.type) {
caseFF_QUIT_EVENT:
caseSDL_QUIT:
is->quit =1;
SDL_Quit();
return0;
break;
caseFF_REFRESH_EVENT:
video_refresh_timer(event.user.data1);
break;
default:
break;
}
}
fclose(yuvfd);
fclose(audiofd);
return 0;
}
