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響應式pos機源碼
初始化
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初始化主要在main里面，主要做了如下幾件事：
1. SDL_Init，主要是SDL_INIT_VIDEO的?持2. SDL_CreateWindow，創建主窗?3. SDL_CreateRender，基于主窗?創建renderer，?于渲染輸出。4. stream_open5. event_loop，播放控制事件響應循環，但也負責了video顯示輸出。
video_refresh()
/* called to display each frame *//* 非暫停或強制刷新的時候，循環調用video_refresh */static void video_refresh(void *opaque, double *remaining_time){ VideoState *is = opaque; double time; Frame *sp, *sp2; if (!is->paused && get_master_sync_type(is) == AV_SYNC_EXTERNAL_CLOCK && is->realtime) check_external_clock_speed(is); if (!display_disable && is->show_mode != SHOW_MODE_VIDEO && is->audio_st) { time = av_gettime_relative() / 1000000.0; if (is->force_refresh || is->last_vis_time + rdftspeed < time) { video_display(is); is->last_vis_time = time; } *remaining_time = FFMIN(*remaining_time, is->last_vis_time + rdftspeed - time); } if (is->video_st) {retry: if (frame_queue_nb_remaining(&is->pictq) == 0) {// 幀隊列是否為空 // nothing to do, no picture to display in the queue // 什么都不做，隊列中沒有圖像可顯示 } else { // 重點是音視頻同步 double last_duration, duration, delay; Frame *vp, *lastvp; /* dequeue the picture */ // 從隊列取出上一個Frame lastvp = frame_queue_peek_last(&is->pictq);//讀取上一幀 vp = frame_queue_peek(&is->pictq); // 讀取待顯示幀 // lastvp 上一幀(正在顯示的幀) // vp 等待顯示的幀 if (vp->serial != is->videoq.serial) { // 如果不是最新的播放序列，則將其出隊列，以盡快讀取最新序列的幀 frame_queue_next(&is->pictq); goto retry; } if (lastvp->serial != vp->serial) { // 新的播放序列重置當前時間 is->frame_timer = av_gettime_relative() / 1000000.0; } if (is->paused) { goto display; printf("視頻暫停is->paused"); } /* compute nominal last_duration */ //lastvp上一幀，vp當前幀 ，nextvp下一幀 //last_duration 計算上一幀應顯示的時長 last_duration = vp_duration(is, lastvp, vp); // 經過compute_target_delay方法，計算出待顯示幀vp需要等待的時間 // 如果以video同步，則delay直接等于last_duration。 // 如果以audio或外部時鐘同步，則需要比對主時鐘調整待顯示幀vp要等待的時間。 delay = compute_target_delay(last_duration, is); time= av_gettime_relative()/1000000.0; // is->frame_timer 實際上就是上一幀lastvp的播放時間, // is->frame_timer + delay 是待顯示幀vp該播放的時間 if (time < is->frame_timer + delay) { //判斷是否繼續顯示上一幀 // 當前系統時刻還未到達上一幀的結束時刻，那么還應該繼續顯示上一幀。 // 計算出最小等待時間 *remaining_time = FFMIN(is->frame_timer + delay - time, *remaining_time); goto display; } // 走到這一步，說明已經到了或過了該顯示的時間，待顯示幀vp的狀態變更為當前要顯示的幀 is->frame_timer += delay; // 更新當前幀播放的時間 if (delay > 0 && time - is->frame_timer > AV_SYNC_THRESHOLD_MAX) { is->frame_timer = time; //如果和系統時間差距太大，就糾正為系統時間 } SDL_LockMutex(is->pictq.mutex); if (!isnan(vp->pts)) update_video_pts(is, vp->pts, vp->pos, vp->serial); // 更新video時鐘 SDL_UnlockMutex(is->pictq.mutex); //丟幀邏輯 if (frame_queue_nb_remaining(&is->pictq) > 1) {//有nextvp才會檢測是否該丟幀 Frame *nextvp = frame_queue_peek_next(&is->pictq); duration = vp_duration(is, vp, nextvp); if(!is->step // 非逐幀模式才檢測是否需要丟幀 is->step==1 為逐幀播放 && (framedrop>0 || // cpu解幀過慢 (framedrop && get_master_sync_type(is) != AV_SYNC_VIDEO_MASTER)) // 非視頻同步方式 && time > is->frame_timer + duration // 確實落后了一幀數據 ) { printf("%s(%d) dif:%lfs, drop frame\", __FUNCTION__, __LINE__, (is->frame_timer + duration) - time); is->frame_drops_late++; // 統計丟幀情況 frame_queue_next(&is->pictq); // 這里實現真正的丟幀 //(這里不能直接while丟幀，因為很可能audio clock重新對時了，這樣delay值需要重新計算) goto retry; //回到函數開始位置，繼續重試 } } if (is->subtitle_st) { while (frame_queue_nb_remaining(&is->subpq) > 0) { sp = frame_queue_peek(&is->subpq); if (frame_queue_nb_remaining(&is->subpq) > 1) sp2 = frame_queue_peek_next(&is->subpq); else sp2 = NULL; if (sp->serial != is->subtitleq.serial || (is->vidclk.pts > (sp->pts + ((float) sp->sub.end_display_time / 1000))) || (sp2 && is->vidclk.pts > (sp2->pts + ((float) sp2->sub.start_display_time / 1000)))) { if (sp->uploaded) { int i; for (i = 0; i < sp->sub.num_rects; i++) { AVSubtitleRect *sub_rect = sp->sub.rects[i]; uint8_t *pixels; int pitch, j; if (!SDL_LockTexture(is->sub_texture, (SDL_Rect *)sub_rect, (void **)&pixels, &pitch)) { for (j = 0; j < sub_rect->h; j++, pixels += pitch) memset(pixels, 0, sub_rect->w << 2); SDL_UnlockTexture(is->sub_texture); } } } frame_queue_next(&is->subpq); } else { break; } } } frame_queue_next(&is->pictq); // 當前vp幀出隊列 is->force_refresh = 1; /* 說明需要刷新視頻幀 */ if (is->step && !is->paused) stream_toggle_pause(is); }display: /* display picture */ if (!display_disable && is->force_refresh && is->show_mode == SHOW_MODE_VIDEO && is->pictq.rindex_shown) video_display(is); // 重點是顯示 } is->force_refresh = 0; if (show_status) { static int64_t last_time; int64_t cur_time; int aqsize, vqsize, sqsize; double av_diff; cur_time = av_gettime_relative(); if (!last_time || (cur_time - last_time) >= 30000) { aqsize = 0; vqsize = 0; sqsize = 0; if (is->audio_st) aqsize = is->audioq.size; if (is->video_st) vqsize = is->videoq.size; if (is->subtitle_st) sqsize = is->subtitleq.size; av_diff = 0; if (is->audio_st && is->video_st) av_diff = get_clock(&is->audclk) - get_clock(&is->vidclk); else if (is->video_st) av_diff = get_master_clock(is) - get_clock(&is->vidclk); else if (is->audio_st) av_diff = get_master_clock(is) - get_clock(&is->audclk); av_log(NULL, AV_LOG_INFO, "%7.2f %s:%7.3f fd=M aq=]KB vq=]KB sq=]B f=%"PRId64"/%"PRId64" \", get_master_clock(is), (is->audio_st && is->video_st) ? "A-V" : (is->video_st ? "M-V" : (is->audio_st ? "M-A" : " ")), av_diff, is->frame_drops_early + is->frame_drops_late, aqsize / 1024, vqsize / 1024, sqsize, is->video_st ? is->viddec.avctx->pts_correction_num_faulty_dts : 0, is->video_st ? is->viddec.avctx->pts_correction_num_faulty_pts : 0); fflush(stdout); last_time = cur_time; } }}
video_image_display()
static void video_image_display(VideoState *is){ Frame *vp; Frame *sp = NULL; SDL_Rect rect; // keep_last的作用就出來了,我們是有調用frame_queue_next, 但最近出隊列的幀并沒有真正銷毀 // 所以這里可以讀取出來顯示 vp = frame_queue_peek_last(&is->pictq); if (is->subtitle_st) { if (frame_queue_nb_remaining(&is->subpq) > 0) { sp = frame_queue_peek(&is->subpq); if (vp->pts >= sp->pts + ((float) sp->sub.start_display_time / 1000)) { if (!sp->uploaded) { uint8_t* pixels[4]; int pitch[4]; int i; if (!sp->width="360px",height="auto" />
convert_ctx = sws_getCachedContext(is->sub_convert_ctx, sub_rect->w, sub_rect->h, AV_PIX_FMT_PAL8, sub_rect->w, sub_rect->h, AV_PIX_FMT_BGRA, 0, NULL, NULL, NULL); if (!is->sub_convert_ctx) { av_log(NULL, AV_LOG_FATAL, "Cannot initialize the conversion context\"); return; } if (!SDL_LockTexture(is->sub_texture, (SDL_Rect *)sub_rect, (void **)pixels, pitch)) { sws_scale(is->sub_convert_ctx, (const uint8_t * const *)sub_rect->data, sub_rect->linesize, 0, sub_rect->h, pixels, pitch); SDL_UnlockTexture(is->sub_texture); } } sp->uploaded = 1; } } else sp = NULL; } } //將幀寬高按照sar最大適配到窗口，并通過rect返回視頻幀在窗口的顯示位置和寬高 calculate_display_rect(&rect, is->xleft, is->ytop, is->width="360px",height="auto" />以上就是關于響應式pos機源碼,ffplay源碼分析06 的知識，后面我們會繼續為大家整理關于響應式pos機源碼的知識，希望能夠幫助到大家！
