SDL+FFmpeg库实现音视频同步功能

#include "define.h" #include "SDL_Wraper.h" #include "datequeue.h" #include "parser_stream.h" #include "callback.h" #include "thread.h" double get_audio_clock(VideoState *is) { double pts; int hw_buf_size, bytes_per_sec, n; pts = is->audio_clock; 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; } return pts; } //定时发送事件 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); SDL_Delay(40); return 0; } //添加一个定时器 static void schedule_refresh(VideoState *is, int delay) { SDL_AddTimer(delay, sdl_refresh_timer_cb, is); } void video_refresh_timer(void *userdata) { VideoState *is = (VideoState *)userdata; AVFrame *vp; int64_t delay, sync_threshold, ref_clock; double actual_delay; if (is->video_st) { if (is->pictq_size == 0) { schedule_refresh(is, 1); } else { vp = &is->pictq[is->pictq_rindex]; delay = vp->pts - is->frame_last_pts; //存储pts和delay下次使用 is->frame_last_delay = delay; is->frame_last_pts = vp->pts; //获取音频延迟时间 ref_clock = get_audio_clock(is); double diff = vp->pts * av_q2d(is->video_st->time_base) - ref_clock; /* Skip or repeat the frame. Take delay into account FFPlay still doesn't "know if this is the best guess." */ 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; } } is->frame_timer += delay * av_q2d(is->video_st->time_base); //计算真正的延迟时间 actual_delay = is->frame_timer - (av_gettime() / 1000000.0); if (actual_delay < 0.010) { actual_delay = 0.010; } //std::cout << actual_delay << "frame_timer" << is->frame_timer << std::endl; schedule_refresh(is, (int)(actual_delay * 1000 + 0.5)); //显示视频帧 video_display(is); //刷新视频信息，为下次刷新做准备 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); } } int main(int argc, char *argv[]) { int ret = -1; SDL_Event event; if (argc < 2) { printf("Usage: command <file>\n"); return ret; } //初始化SDL InitSDL(); //初始化各种变量 g_state = (VideoState*)av_mallocz(sizeof(VideoState)); g_state->pictq_mutex = SDL_CreateMutex(); g_state->pictq_cond = SDL_CreateCond(); memcpy(g_state->filename, argv[1], sizeof(g_state->filename)); //解封装的线程 g_state->parse_tid = SDL_CreateThread(demux_thread, "demux_thread", g_state); if (!g_state->parse_tid) { av_free(g_state); goto __FAIL; } while (!g_state->video_ctx) { SDL_Delay(10); } //创建窗口渲染视频,在子线程里面创建会阻塞主线程的时间循环 win = SDL_CreateWindow("Feifei Player", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, g_state->video_ctx->width, g_state->video_ctx->height, SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE); renderer = SDL_CreateRenderer(win, -1, 0); texture = SDL_CreateTexture(renderer, SDL_PIXELFORMAT_IYUV, SDL_TEXTUREACCESS_STREAMING, g_state->video_ctx->width, g_state->video_ctx->height); schedule_refresh(g_state, 40); while (1) { SDL_WaitEvent(&event); switch (event.type) { case FF_QUIT_EVENT: case SDL_QUIT: g_state->quit = 1; goto __QUIT; break; case FF_REFRESH_EVENT: video_refresh_timer(event.user.data1); break; default: break; } } __QUIT: ret = 0; __FAIL: SDL_Quit(); return ret; }