這篇文章要結合
https://blog.csdn.net/qq_15255121/article/details/117327999?spm=1001.2014.3001.5501來看
音視訊同步要用到時間戳。
時間戳的類型：
PTS：presentation timestamp 展示時間戳
DTS：Decoding timestamp 解碼時間戳
存在這兩個時間戳的主要原因是因為存在I B P幀。導緻展示順序和解碼順序不一緻。
I 幀 關鍵幀
P幀 向前參考幀
B幀 前後參考幀
具體可以參考https://blog.csdn.net/qq_15255121/article/details/115494817
從哪裡擷取到PTS
AVPacket中擷取PTS
AVFrame中擷取PTS。音視訊同步我們一般使用解碼後的PTS。
時間基（顧名思義就是時間的刻度）
tbr 幀率 如果tbr為25，那麼時間基就是1/25秒
tbn time base of stream
tbc time base of codec
PTS如何轉化為真正的時間呢？（pts可以了解為多少個目前的時間刻度）
av_q2d就是将時間基轉為每個刻度是多少秒。
PTS=PTS * av_q2d(video_stream->time_base)
音視訊同步的方式
視訊同步到音頻
音頻同步到視訊
音頻和視訊都同步到系統時鐘
我們要想同步，必須有一個基礎時鐘。這個基礎時鐘既可以是視訊，也可是音頻，還可以是系統時間。
我們這裡用音頻作為基礎時間。音頻時間的計算方式
is->audio_clock += (double)data_size /(double)(out_channel * av_get_bytes_per_sample(out_format) * is->audio_ctx->sample_rate);
data_size 是每幀資料的資料大小
out_channel * av_get_bytes_per_sample(out_format) * is->audio_ctx->sample_rate 計算出的是音頻裝置1秒中要處理的資料。聲道數 * 每個樣本的位元組數 * 采樣率
那麼(double)data_size /(double)(out_channel * av_get_bytes_per_sample(out_format) * is->audio_ctx->sample_rate) 得到的結果是處理這個資料需要多少時間。
通過
is->audio_clock += (double)data_size /(double)(out_channel * av_get_bytes_per_sample(out_format) * is->audio_ctx->sample_rate);
計算出is->audio_clock就是處理了目前音頻資料後的音頻時鐘。
擷取音頻時鐘：
double get_audio_clock(VideoState *is) {
double pts;
int hw_buf_size;
int bytes_per_sec;//每秒處理的資料數
pts = is->audio_clock; /* maintained in the audio thread */
hw_buf_size = is->audio_buf_size - is->audio_buf_index;
bytes_per_sec = 0;
if(is->audio_st) {
bytes_per_sec = is->audio_ctx->sample_rate * out_channel * av_get_bytes_per_sample(out_format);
}
if(bytes_per_sec) {
pts -= (double)hw_buf_size / bytes_per_sec;
}
return pts;
}
由于is->audio_clock代表的是播放了目前音頻資料的時鐘，是以擷取目前時鐘要減掉未播放的資料占用的時間。
視訊渲染要參考音頻的時鐘
視訊的初始時間我們在解複用的第一幀時标記為目前系統時間
int stream_component_open(VideoState *is, int stream_index)
{
.......
switch (codecCtx->codec_type)
{
case AVMEDIA_TYPE_AUDIO:
........
break;
case AVMEDIA_TYPE_VIDEO:
is->video_st = pFormatCtx->streams[stream_index];
is->video_ctx = codecCtx;
is->frame_timer = (double)av_gettime()/1000000.0;
is->frame_last_delay = 40e-3;
packet_queue_init(&is->videoq);
is->video_tid = SDL_CreateThread(video_thread, "video_thread", is);
is->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,
out_pix_foramt,
SWS_BILINEAR,
NULL, NULL, NULL);
break;
default:
break;
}
return 0;
}
is->frame_timer = (double)av_gettime()/1000000.0; 用目前時間初始化了基礎時間
我們要知道下一幀視訊幀的渲染時間，就必須知道下一幀視訊幀的pts。
。。。。。。。
AVFrame best_effort_timestamp 預測下一幀最佳pts
pts *= av_q2d(is->video_st->time_base);會計算出視訊渲染的具體時間
渲染代碼
以音頻作為基礎時鐘，視訊就要和音頻的時鐘實時對比。如果目前視訊幀的渲染時刻小于音頻時鐘，視訊幀要立即顯示或者丢棄。如果目前幀的渲染時刻大于音頻時鐘，那麼我們就要延遲一段時間，使得延遲後的視訊時刻大于等于音頻時鐘。
void video_refresh_timer(void *userdata)
{
。。。。。。
vp = &is->pictq[is->pictq_rindex];
delay = vp->pts - is->frame_last_pts;
// av_log(NULL, AV_LOG_INFO, "video_refresh_timer vp->pts=%f is->frame_last_pts=%f delay=%f\n", vp->pts, is->frame_last_pts, delay);
if(delay <= 0 || delay >= 1.0){
delay = is->frame_last_delay;
}
is->frame_last_delay = delay;
is->frame_last_pts = vp->pts;
ref_clock = get_audio_clock(is); //擷取參考時鐘，目前音頻的播放時間
diff = vp->pts - ref_clock;
// av_log(NULL, AV_LOG_INFO, "video_refresh_timer ref_clock=%f, diff=%f\n", ref_clock, diff);
sync_threshold = (delay > AV_SYNC_THRESHOLD)?delay:AV_SYNC_THRESHOLD;
if(fabs(diff) < AV_NOSYNC_THRESHOLD){
if(diff <= -sync_threshold){
delay = 0;
}else if(diff >= sync_threshold){
delay = 2 * delay;
}
}
// av_log(NULL, AV_LOG_INFO, "video_refresh_timer delay=%f, is->frame_timer=%f\n", delay, is->frame_timer);
is->frame_timer += delay;
double current_time = av_gettime()/1000000.0;
// av_log(NULL, AV_LOG_INFO, "video_refresh_timer 11111 is->frame_timer=%f, current_time=%f\n", is->frame_timer, current_time);
actual_delay = is->frame_timer - current_time;//av_gettime得到的是微妙
// av_log(NULL, AV_LOG_INFO, "video_refresh_timer 222222 actual_delay=%f\n", actual_delay);
if(actual_delay < AV_SYNC_THRESHOLD ){
actual_delay = AV_SYNC_THRESHOLD;
}
/* Now, normally here goes a ton of code
about timing, etc. we're just going to
guess at a delay for now. You can
increase and decrease this value and hard code
the timing - but I don't suggest that ;)
We'll learn how to do it for real later.
*/
schedule_refresh(is, actual_delay * 1000 + 0.5);
/* show the picture! */
video_display(is);
。。。。。。
}
1、先計算出目前幀需要播放多長時間，vp->pts下一幀播放時刻， is->frame_last_pts目前幀的播放時刻
delay = vp->pts - is->frame_last_pts;
2、擷取目前音頻時鐘
ref_clock = get_audio_clock(is); //擷取參考時鐘，目前音頻的播放時刻
3、下一幀視訊幀和音頻幀內插補點計算
diff = vp->pts - ref_clock;
4、計算目前視訊幀播放時間的門檻值
sync_threshold = (delay > AV_SYNC_THRESHOLD)?delay:AV_SYNC_THRESHOLD;
從這裡可以知道目前視訊幀最少也要播放AV_SYNC_THRESHOLD 10ms
5、第3步計算的內插補點
if(fabs(diff) < AV_NOSYNC_THRESHOLD){
if(diff - sync_threshold <= 0){
delay = 0;
}else if(diff >= sync_threshold){
delay = 2 * delay;
}
}
如果小于計算出的播放門檻值，那麼說明目前視訊如果按照delay來播放，還沒有播放完畢就要播放下一幀。是以我們要将delay指派為0
如果內插補點大于我們計算的門檻值，那麼我們就要遲一點渲染下一幀。是以也就有了 delay = 2 * delay;
6、計算真正的下一幀渲染時間
is->frame_timer += delay; //下一幀渲染的時間
double current_time = av_gettime()/1000000.0;
actual_delay = is->frame_timer - current_time; //計算出和目前時間相比要多長時間後開始渲染
if(actual_delay < AV_SYNC_THRESHOLD ){
actual_delay = AV_SYNC_THRESHOLD;
}
schedule_refresh(is, actual_delay * 1000 + 0.5);
這樣我們就把音視訊同步給完成了
下面是完整的代碼
#include <stdio.h>
#include <assert.h>
#include <math.h>
#include <SDL2/SDL.h>
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>
#include <libswresample/swresample.h>
#include <libavutil/samplefmt.h>
#include <libavutil/imgutils.h>
#include <libavutil/mem.h>
#include <libavutil/time.h>
#define MAX_AUDIO_FRAME_SIZE 192000
#define MAX_AUDIOQ_SIZE (5 * 16 * 1024)
#define MAX_VIDEOQ_SIZE (5 * 256 * 1024)
#define FF_REFRESH_EVENT SDL_USEREVENT
#define FF_QUIT_EVENT SDL_USEREVENT + 1
#define REFRESH_TIME 45
#define VIDEO_PICTURE_QUEUE_SIZE 1
#define AV_SYNC_THRESHOLD 0.01
#define AV_NOSYNC_THRESHOLD 10.0
static enum AVPixelFormat out_yuv_foramt = AV_PIX_FMT_YUV420P;
typedef struct PacketQueue
{
AVPacketList *first_pkt, *last_pkt;
int nb_packets;
int size;
SDL_mutex *mutex;
SDL_cond *cond;
int total;
int end;
int useCout;
int flash;
} PacketQueue;
typedef struct VideoPicture
{
AVFrame *yuv_frame;
int width, height;
int allocated;
double pts; //目前視訊幀的pts
} VideoPicture;
typedef struct VideoState
{
char filename[1024];
AVFormatContext *pFormatCtx;
int videoStream, audioStream;
//audio
AVStream *audio_st;
AVCodecContext *audio_ctx;
PacketQueue audioq;
uint8_t audio_buf[(MAX_AUDIO_FRAME_SIZE * 3) / 2];
unsigned int audio_buf_size;
unsigned int audio_buf_index;
struct SwrContext *audio_swr_ctx;
//video
AVStream *video_st;
AVCodecContext *video_ctx;
PacketQueue videoq;
struct SwsContext *sws_ctx;
VideoPicture pictq[VIDEO_PICTURE_QUEUE_SIZE];
int pictq_size, pictq_rindex, pictq_windex;
//for thread
SDL_mutex *pictq_mutex;
SDL_cond *pictq_cond;
SDL_Thread *parse_tid;
SDL_Thread *video_tid;
double audio_clock; //音頻播放的時間
double video_clock; //下一幀視訊播放的時間
double frame_timer; //下一次渲染要回調的時間是多少
double frame_last_pts; //上一次視訊幀的PTS
double frame_last_delay;//上一次視訊幀增加的delay
int quit;
} VideoState;
//SDL_mutex *texture_mutex;
SDL_Window *win;
SDL_Renderer *renderer;
SDL_Texture *texture;
VideoState *global_video_state;
static Uint8 out_channel = 2;
static enum AVSampleFormat out_format = AV_SAMPLE_FMT_S16;
static int out_nb_samples = 0; //一般情況下輸入音頻的采樣個數要等于輸出音頻的采樣個數
static int out_sample_rate = 0;
static enum AVPixelFormat out_pix_foramt = AV_PIX_FMT_YUV420P;
void packet_queue_init(PacketQueue *q)
{
memset(q, 0, sizeof(PacketQueue));
q->mutex = SDL_CreateMutex();
q->cond = SDL_CreateCond();
}
int packet_queue_put(PacketQueue *q, AVPacket *srcpkt)
{
AVPacket *pkt = av_packet_alloc();
AVPacketList *pkt1;
if (av_packet_ref(pkt, srcpkt) < 0)
{
return -1;
}
pkt1 = 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;
//fprintf(stderr, "enqueue, packets:%d, send cond signal\n", q->nb_packets);
SDL_CondSignal(q->cond);
SDL_UnlockMutex(q->mutex);
return 0;
}
int packet_queue_get(PacketQueue *q, AVPacket *pkt, int block)
{
AVPacketList *pkt1;
int ret;
SDL_LockMutex(q->mutex);
for (;;)
{
if (global_video_state->quit)
{
fprintf(stderr, "quit from queue_get\n");
ret = -1;
break;
}
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 if (!(q->end))
{
fprintf(stderr, "queue is empty, so wait a moment and wait a cond signal\n");
SDL_CondWait(q->cond, q->mutex);
}
else
{
ret = -1;
break;
}
}
SDL_UnlockMutex(q->mutex);
return ret;
}
int audio_decode_frame(VideoState *is, uint8_t *audio_buf, int buf_size, double *pts_ptr)
{
static AVPacket pkt;
static uint8_t *audio_pkt_data = NULL;
static int audio_pkt_size = 0;
static AVFrame frame;
int data_size = 0;
int ret = 0;
av_init_packet(&pkt);
pkt.data = NULL;
pkt.size = 0;
int index = 0;
uint64_t out_channel_layout = AV_CH_LAYOUT_STEREO;
frame.channels = is->audio_ctx->channels;
frame.format = is->audio_ctx->sample_fmt;
frame.nb_samples = is->audio_ctx->frame_size;
av_frame_get_buffer(&frame, 0);
double pts;
int n;
for (;;)
{
if (pkt.data)
av_packet_unref(&pkt);
if (is->quit)
{
return -1;
}
ret = avcodec_receive_frame(is->audio_ctx, &frame);
if (ret == 0)
{
goto __SWR_DATA;
}
if (packet_queue_get(&(is->audioq), &pkt, 1) < 0)
{
if (is->audioq.flash)
{
goto __RECEIVE;
}
av_log(NULL, AV_LOG_ERROR, "flash audio\n");
is->audioq.flash = 1;
ret = avcodec_send_packet(is->audio_ctx, NULL);
if (ret < 0)
{
return -1;
}
goto __RECEIVE;
}
++(is->audioq.useCout);
ret = avcodec_send_packet(is->audio_ctx, &pkt);
if (ret < 0)
{
ret = -1;
printf("decode error");
av_packet_unref(&pkt);
return -1;
}
if (pkt.data)
{
av_packet_unref(&pkt);
}
__RECEIVE:
index = 0;
ret = avcodec_receive_frame(is->audio_ctx, &frame);
if (ret < 0)
{
return ret;
}
__SWR_DATA:
data_size = av_get_bytes_per_sample(out_format) * out_channel * out_nb_samples;
swr_convert(is->audio_swr_ctx,
&audio_buf,
out_nb_samples,
(const uint8_t **)frame.data,
frame.nb_samples);
pts = is->audio_clock;
*pts_ptr = pts;
is->audio_clock += (double)data_size /(double)(out_channel * av_get_bytes_per_sample(out_format) * is->audio_ctx->sample_rate);
return data_size;
}
}
void audio_callback(void *userdata, Uint8 *stream, int len)
{
VideoState *is = (VideoState *)userdata;
int len1, audio_size;
double pts;
SDL_memset(stream, 0, len);
while (len > 0)
{
if (is->audio_buf_index >= is->audio_buf_size)
{
/* We have already sent all our data; get more */
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
{
is->audio_buf_size = audio_size;
}
is->audio_buf_index = 0;
}
len1 = is->audio_buf_size - is->audio_buf_index;
// fprintf(stderr, "stream addr:%p, audio_buf_index:%d, audio_buf_size:%d, len1:%d, len:%d\n",
// stream,
// is->audio_buf_index,
// is->audio_buf_size,
// len1,
// len);
if (len1 > len)
len1 = len;
SDL_MixAudio(stream, (uint8_t *)is->audio_buf + is->audio_buf_index, len1, SDL_MIX_MAXVOLUME);
len -= len1;
stream += len1;
is->audio_buf_index += len1;
}
}
static Uint32 sdl_refresh_timer_cb(Uint32 interval, void *opaque)
{
SDL_Event event;
event.type = FF_REFRESH_EVENT;
event.user.data1 = opaque;
SDL_PushEvent(&event);
return 0; /* 0 means stop timer */
}
static void schedule_refresh(VideoState *is, int delay)
{
// av_log(NULL, AV_LOG_INFO, "schedule_refresh delay=%d\n", delay);
SDL_AddTimer(delay, sdl_refresh_timer_cb, is);
}
void video_display(VideoState *is)
{
SDL_Rect rect;
VideoPicture *vp;
float aspect_ratio;
int w, h, x, y;
int i;
vp = &is->pictq[is->pictq_rindex];
if (vp->yuv_frame)
{
if (is->video_ctx->sample_aspect_ratio.num == 0)
{
aspect_ratio = 0;
}
else
{
aspect_ratio = av_q2d(is->video_ctx->sample_aspect_ratio) *
is->video_ctx->width / is->video_ctx->height;
}
if (aspect_ratio <= 0.0)
{
aspect_ratio = (float)is->video_ctx->width /
(float)is->video_ctx->height;
}
// size_t buffer_size = av_image_get_buffer_size(AV_PIX_FMT_YUV420P, 960, 540, 32);
// uint8_t *buffer = malloc(buffer_size);
// int y_size = 960 * 540;
// memcpy(buffer, vp->yuv_frame->data[0], y_size);
// memcpy(buffer + y_size, vp->yuv_frame->data[1], y_size / 4);
// memcpy(buffer + y_size + y_size / 4, vp->yuv_frame->data[2], y_size / 4);
SDL_UpdateYUVTexture(texture, NULL,
vp->yuv_frame->data[0], vp->yuv_frame->linesize[0],
vp->yuv_frame->data[1], vp->yuv_frame->linesize[1],
vp->yuv_frame->data[2], vp->yuv_frame->linesize[2]);
// SDL_UpdateTexture(texture, NULL, buffer, 960);
rect.x = 0;
rect.y = 0;
rect.w = is->video_ctx->width;
rect.h = is->video_ctx->height;
//SDL_LockMutex(texture_mutex);
SDL_RenderClear(renderer);
SDL_RenderCopy(renderer, texture, NULL, &rect);
SDL_RenderPresent(renderer);
//SDL_UnlockMutex(texture_mutex);
}
}
double get_audio_clock(VideoState *is) {
double pts;
int hw_buf_size;
int bytes_per_sec;//每秒處理的資料數
pts = is->audio_clock; /* maintained in the audio thread */
hw_buf_size = is->audio_buf_size - is->audio_buf_index;
bytes_per_sec = 0;
if(is->audio_st) {
bytes_per_sec = is->audio_ctx->sample_rate * out_channel * av_get_bytes_per_sample(out_format);
}
if(bytes_per_sec) {
pts -= (double)hw_buf_size / bytes_per_sec;
}
return pts;
}
void video_refresh_timer(void *userdata)
{
VideoState *is = (VideoState *)userdata;
VideoPicture *vp;
double actual_delay, delay, sync_threshold, ref_clock, diff;
if (is->video_st)
{
if (is->pictq_size == 0)
{
schedule_refresh(is, 1); //if the queue is empty, so we shoud be as fast as checking queue of picture
}
else
{
vp = &is->pictq[is->pictq_rindex];
delay = vp->pts - is->frame_last_pts;
// av_log(NULL, AV_LOG_INFO, "video_refresh_timer vp->pts=%f is->frame_last_pts=%f delay=%f\n", vp->pts, is->frame_last_pts, delay);
if(delay <= 0 || delay >= 1.0){
delay = is->frame_last_delay;
}
is->frame_last_delay = delay;
is->frame_last_pts = vp->pts;
ref_clock = get_audio_clock(is); //擷取參考時鐘，目前音頻的播放時間
diff = vp->pts - ref_clock;
// av_log(NULL, AV_LOG_INFO, "video_refresh_timer ref_clock=%f, diff=%f\n", ref_clock, diff);
sync_threshold = (delay > AV_SYNC_THRESHOLD)?delay:AV_SYNC_THRESHOLD;
if(fabs(diff) < AV_NOSYNC_THRESHOLD){
if(diff - sync_threshold <= 0){
delay = 0;
}else if(diff >= sync_threshold){
delay = 2 * delay;
}
}
// av_log(NULL, AV_LOG_INFO, "video_refresh_timer delay=%f, is->frame_timer=%f\n", delay, is->frame_timer);
is->frame_timer += delay;
double current_time = av_gettime()/1000000.0;
// av_log(NULL, AV_LOG_INFO, "video_refresh_timer 11111 is->frame_timer=%f, current_time=%f\n", is->frame_timer, current_time);
actual_delay = is->frame_timer - current_time;//av_gettime得到的是微妙
// av_log(NULL, AV_LOG_INFO, "video_refresh_timer 222222 actual_delay=%f\n", actual_delay);
if(actual_delay < AV_SYNC_THRESHOLD ){
actual_delay = AV_SYNC_THRESHOLD;
}
av_log(NULL, AV_LOG_INFO, "video_refresh_timer actual_delay=%f ms\n", actual_delay * 1000 + 0.5);
/* Now, normally here goes a ton of code
about timing, etc. we're just going to
guess at a delay for now. You can
increase and decrease this value and hard code
the timing - but I don't suggest that ;)
We'll learn how to do it for real later.
*/
schedule_refresh(is, 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);
}
}
void alloc_picture(void *userdata)
{
VideoState *is = (VideoState *)userdata;
VideoPicture *vp;
vp = &is->pictq[is->pictq_windex];
if (vp->yuv_frame)
{ //free space if vp->pict is not NULL
av_frame_free(&(vp->yuv_frame));
free(vp->yuv_frame);
}
// Allocate a place to put our YUV image on that screen
//SDL_LockMutex(texture_mutex);
vp->yuv_frame = av_frame_alloc();
vp->yuv_frame->width = is->video_ctx->width;
vp->yuv_frame->height = is->video_ctx->height;
vp->yuv_frame->format = out_yuv_foramt;
av_frame_get_buffer(vp->yuv_frame, 32);
vp->width = is->video_ctx->width;
vp->height = is->video_ctx->height;
vp->allocated = 1;
}
int queue_picture(VideoState *is, AVFrame *pFrame, double pts)
{
VideoPicture *vp;
int dst_pix_fmt;
AVPicture pict;
/* 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)
{
fprintf(stderr, "quit from queue_picture....\n");
return -1;
}
// windex is set to 0 initially
vp = &is->pictq[is->pictq_windex];
/*
fprintf(stderr, "vp.width=%d, vp.height=%d, video_ctx.width=%d, video_ctx.height=%d\n",
vp->width,
vp->height,
is->video_ctx->width,
is->video_ctx->height);
*/
/* allocate or resize the buffer! */
if (!vp->yuv_frame ||
vp->width != is->video_ctx->width ||
vp->height != is->video_ctx->height)
{
vp->allocated = 0;
alloc_picture(is);
if (is->quit)
{
fprintf(stderr, "quit from queue_picture2....\n");
return -1;
}
}
/* We have a place to put our picture on the queue */
if (vp->yuv_frame)
{
vp->pts=pts;
// Convert the image into YUV format that SDL uses
sws_scale(is->sws_ctx,
(uint8_t const *const *)pFrame->data,
pFrame->linesize,
0,
is->video_ctx->height,
vp->yuv_frame->data,
vp->yuv_frame->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;
}
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_ctx->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 video_thread(void *arg)
{
VideoState *is = (VideoState *)arg;
static AVPacket pkt;
static AVFrame pFrame;
int ret = 0;
av_init_packet(&pkt);
pkt.data = NULL;
pkt.size = 0;
double pts = 0;
for (;;)
{
if (pkt.data)
av_packet_unref(&pkt);
if (packet_queue_get(&is->videoq, &pkt, 1) < 0)
{
if (is->videoq.flash)
{
goto __RECEIVE;
}
av_log(NULL, AV_LOG_ERROR, "flash audio\n");
is->videoq.flash = 1;
ret = avcodec_send_packet(is->video_ctx, NULL);
if (ret < 0)
{
goto __ERROR;
}
goto __RECEIVE;
}
pts = 0;
ret = avcodec_send_packet(is->video_ctx, &pkt);
if (ret != 0)
{
printf("decode error");
goto __ERROR;
}
__RECEIVE:
ret = avcodec_receive_frame(is->video_ctx, &pFrame);
if (ret != 0)
{
continue;
}
pts = pFrame.best_effort_timestamp;
if(pts == AV_NOPTS_VALUE){
pts = 0;
}
pts *= av_q2d(is->video_st->time_base);
pts = synchronize_video(is, &pFrame, pts);
ret = queue_picture(is, &pFrame, pts);
if (ret < 0)
{
goto __ERROR;
}
}
__ERROR:
if (pkt.data)
{
av_packet_unref(&pkt);
}
return ret;
}
int stream_component_open(VideoState *is, int stream_index)
{
int64_t in_channel_layout, out_channel_layout;
AVFormatContext *pFormatCtx = is->pFormatCtx;
AVCodecContext *codecCtx = NULL;
AVCodec *codec = NULL;
SDL_AudioSpec wanted_spec, spec;
AVCodecParameters *codec_par = NULL;
if (stream_index < 0 || stream_index >= pFormatCtx->nb_streams)
{
return -1;
}
codec_par = pFormatCtx->streams[stream_index]->codecpar;
if (stream_index == is->audioStream)
{
out_nb_samples = codec_par->frame_size;
out_sample_rate = codec_par->sample_rate;
}
codec = avcodec_find_decoder(codec_par->codec_id);
codecCtx = avcodec_alloc_context3(codec);
avcodec_parameters_to_context(codecCtx, codec_par);
if (!codec)
{
fprintf(stderr, "Unsupported codec!\n");
return -1;
}
if (codecCtx->codec_type == AVMEDIA_TYPE_AUDIO)
{
// Set audio settings from codec info
wanted_spec.freq = codecCtx->sample_rate;
wanted_spec.format = AUDIO_S16SYS;
wanted_spec.channels = out_channel;
wanted_spec.silence = 0;
wanted_spec.samples = out_nb_samples;
wanted_spec.callback = audio_callback;
wanted_spec.userdata = is;
if (SDL_OpenAudio(&wanted_spec, &spec) < 0)
{
fprintf(stderr, "SDL_OpenAudio: %s\n", SDL_GetError());
return -1;
}
}
if (avcodec_open2(codecCtx, codec, NULL) < 0)
{
fprintf(stderr, "Unsupported codec!\n");
return -1;
}
switch (codecCtx->codec_type)
{
case AVMEDIA_TYPE_AUDIO:
is->audio_st = pFormatCtx->streams[stream_index];
is->audio_ctx = codecCtx;
is->audio_buf_size = 0;
is->audio_buf_index = 0;
packet_queue_init(&is->audioq);
SDL_PauseAudio(0);
//Out Audio Param
uint64_t out_channel_layout = av_get_default_channel_layout(out_channel);
//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);
struct SwrContext *audio_convert_ctx = NULL;
audio_convert_ctx = swr_alloc();
if (!audio_convert_ctx)
{
printf("Failed to swr_alloc\n");
return -1;
}
swr_alloc_set_opts(audio_convert_ctx,
out_channel_layout,
out_format,
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\n",
// out_channel_layout,
// out_format,
// 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;
break;
case AVMEDIA_TYPE_VIDEO:
is->video_st = pFormatCtx->streams[stream_index];
is->video_ctx = codecCtx;
is->frame_timer = (double)av_gettime()/1000000.0;
is->frame_last_delay = 40e-3;
packet_queue_init(&is->videoq);
is->video_tid = SDL_CreateThread(video_thread, "video_thread", is);
is->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,
out_pix_foramt,
SWS_BILINEAR,
NULL, NULL, NULL);
break;
default:
break;
}
return 0;
}
int decode_thread(void *arg)
{
VideoState *is = arg;
AVPacket packet;
av_init_packet(&packet);
packet.data = NULL;
packet.size = 0;
if (is->audioStream >= 0)
{
stream_component_open(is, is->audioStream);
}
if (is->videoStream >= 0)
{
stream_component_open(is, is->videoStream);
}
fprintf(stderr, "video context: width=%d, height=%d\n", is->video_ctx->width, is->video_ctx->height);
// main decode loop
for (;;)
{
if (is->quit)
{
SDL_CondSignal(is->videoq.cond);
SDL_CondSignal(is->audioq.cond);
break;
}
// seek stuff goes here
if (is->audioq.size > MAX_AUDIOQ_SIZE ||
is->videoq.size > MAX_VIDEOQ_SIZE)
{
SDL_Delay(10);
continue;
}
int ret = av_read_frame(is->pFormatCtx, &packet);
// fprintf(stderr, "av_read_frame, ret :%s\n", av_err2str(ret));
if (ret < 0)
{
break;
}
// Is this a packet from the video stream?
if (packet.stream_index == is->videoStream)
{
packet_queue_put(&is->videoq, &packet);
++(is->videoq.total);
// fprintf(stderr, "put video queue, size :%d\n", is->videoq.total);
}
else if (packet.stream_index == is->audioStream)
{
packet_queue_put(&is->audioq, &packet);
++(is->audioq.total);
// fprintf(stderr, "put audio queue, size :%d\n", is->audioq.total);
}
av_packet_unref(&packet);
}
is->audioq.end = 1;
is->videoq.end = 1;
/* 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;
}
int init_VideoState(VideoState *is)
{
Uint32 pixformat;
AVFormatContext *pFormatCtx = NULL;
AVPacket pkt1, *packet = &pkt1;
int i;
is->videoStream = -1;
is->audioStream = -1;
global_video_state = is;
// Open video file
if (avformat_open_input(&pFormatCtx, is->filename, NULL, NULL) != 0)
return -1; // Couldn't open file
is->pFormatCtx = pFormatCtx;
// Retrieve stream information
if (avformat_find_stream_info(pFormatCtx, NULL) < 0)
return -1; // Couldn't find stream information
// Dump information about file onto standard error
av_dump_format(pFormatCtx, 0, is->filename, 0);
// Find the first video stream
is->videoStream = av_find_best_stream(pFormatCtx, AVMEDIA_TYPE_VIDEO, -1, -1, NULL, -1);
is->audioStream = av_find_best_stream(pFormatCtx, AVMEDIA_TYPE_AUDIO, -1, -1, NULL, -1);
if (is->videoStream < 0 || is->audioStream < 0)
{
av_log(NULL, AV_LOG_ERROR, "%s: could not open codecs\n", is->filename);
return -1;
}
return 0;
}
int main(int argc, char *argv[])
{
int ret = -1;
SDL_Event event;
VideoState *is;
if (argc < 2)
{
fprintf(stderr, "Usage: test <file>\n");
exit(1);
}
av_log_set_level(AV_LOG_INFO);
//big struct, it's core
is = av_mallocz(sizeof(VideoState));
// Register all formats and codecs
if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER))
{
fprintf(stderr, "Could not initialize SDL - %s\n", SDL_GetError());
exit(1);
}
//texture_mutex = SDL_CreateMutex();
memcpy(is->filename, argv[1], sizeof(is->filename));
is->pictq_mutex = SDL_CreateMutex();
is->pictq_cond = SDL_CreateCond();
ret = init_VideoState(is);
if (ret < 0)
{
goto __FAIL;
}
AVCodecParameters *video_paramters = is->pFormatCtx->streams[is->videoStream]->codecpar;
win = SDL_CreateWindow("Media Player",
SDL_WINDOWPOS_UNDEFINED,
SDL_WINDOWPOS_UNDEFINED,
video_paramters->width,
video_paramters->height,
SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE);
renderer = SDL_CreateRenderer(win, -1, 0);
texture = SDL_CreateTexture(renderer,
SDL_PIXELFORMAT_IYUV,
SDL_TEXTUREACCESS_STREAMING,
video_paramters->width,
video_paramters->height);
//set timer
schedule_refresh(is, 40);
is->parse_tid = SDL_CreateThread(decode_thread, "decode_thread", is);
if (!is->parse_tid)
{
av_free(is);
goto __FAIL;
}
for (;;)
{
SDL_WaitEvent(&event);
switch (event.type)
{
case FF_QUIT_EVENT:
case SDL_QUIT:
fprintf(stderr, "receive a QUIT event: %d\n", event.type);
is->quit = 1;
SDL_CondSignal(is->audioq.cond);
SDL_CondSignal(is->pictq_cond);
goto __QUIT;
break;
case FF_REFRESH_EVENT:
//fprintf(stderr, "receive a refresh event: %d\n", event.type);
video_refresh_timer(event.user.data1);
break;
default:
break;
}
}
__QUIT:
ret = 0;
__FAIL:
SDL_Delay(20);
SDL_Quit();
if (is)
{
if (is->audio_swr_ctx)
{
swr_close(is->audio_swr_ctx);
swr_free(&(is->audio_swr_ctx));
}
if (is->sws_ctx)
{
sws_freeContext(is->sws_ctx);
}
if (is->audio_ctx)
{
avcodec_free_context(&is->audio_ctx);
}
if (is->video_ctx)
{
avcodec_free_context(&is->video_ctx);
}
if (is->pFormatCtx)
{
avformat_close_input(&(is->pFormatCtx));
avformat_free_context(is->pFormatCtx);
}
}
return ret;
}
![FFmpeg視訊解碼為YUV像素資料檔案[圖]](data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACwAAAAAAQABAAACAkQBADs=)