main入口函数

初始化

变量、缓存区、SDL窗口初始化等

int main(int argc, char **argv)
{int flags;VideoState *is;
//    av_log_set_level(AV_LOG_TRACE);init_dynload();av_log_set_flags(AV_LOG_SKIP_REPEATED);parse_loglevel(argc, argv, options);/// av_log_set_level(AV_LOG_DEBUG);/* register all codecs, demux and protocols */
#if CONFIG_AVDEVICEavdevice_register_all();
#endifavformat_network_init();init_opts();signal(SIGINT , sigterm_handler); /* Interrupt (ANSI).    */signal(SIGTERM, sigterm_handler); /* Termination (ANSI).  */show_banner(argc, argv, options);parse_options(NULL, argc, argv, options, opt_input_file);if (!input_filename) {show_usage();av_log(NULL, AV_LOG_FATAL, "An input file must be specified\n");av_log(NULL, AV_LOG_FATAL,"Use -h to get full help or, even better, run 'man %s'\n", program_name);exit(1);}/* 是否显示视频 */if (display_disable) {video_disable = 1;}flags = SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER;/* 是否运行音频 */if (audio_disable)flags &= ~SDL_INIT_AUDIO;else {/* Try to work around an occasional ALSA buffer underflow issue when the* period size is NPOT due to ALSA resampling by forcing the buffer size. */if (!SDL_getenv("SDL_AUDIO_ALSA_SET_BUFFER_SIZE"))SDL_setenv("SDL_AUDIO_ALSA_SET_BUFFER_SIZE","1", 1);}if (display_disable)flags &= ~SDL_INIT_VIDEO;if (SDL_Init (flags)) {av_log(NULL, AV_LOG_FATAL, "Could not initialize SDL - %s\n", SDL_GetError());av_log(NULL, AV_LOG_FATAL, "(Did you set the DISPLAY variable?)\n");exit(1);}SDL_EventState(SDL_SYSWMEVENT, SDL_IGNORE);SDL_EventState(SDL_USEREVENT, SDL_IGNORE);av_init_packet(&flush_pkt);				// 初始化flush_packetflush_pkt.data = (uint8_t *)&flush_pkt; // 初始化为数据指向自己本身if (!display_disable) {int flags = SDL_WINDOW_HIDDEN;if (alwaysontop)
#if SDL_VERSION_ATLEAST(2,0,5)flags |= SDL_WINDOW_ALWAYS_ON_TOP;
#elseav_log(NULL, AV_LOG_WARNING, "Your SDL version doesn't support SDL_WINDOW_ALWAYS_ON_TOP. Feature will be inactive.\n");
#endifif (borderless)flags |= SDL_WINDOW_BORDERLESS;elseflags |= SDL_WINDOW_RESIZABLE;window = SDL_CreateWindow(program_name, SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, default_width, default_height, flags);SDL_SetHint(SDL_HINT_RENDER_SCALE_QUALITY, "linear");if (window) {renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);if (!renderer) {av_log(NULL, AV_LOG_WARNING, "Failed to initialize a hardware accelerated renderer: %s\n", SDL_GetError());renderer = SDL_CreateRenderer(window, -1, 0);}if (renderer) {if (!SDL_GetRendererInfo(renderer, &renderer_info))av_log(NULL, AV_LOG_VERBOSE, "Initialized %s renderer.\n", renderer_info.name);}}if (!window || !renderer || !renderer_info.num_texture_formats) {av_log(NULL, AV_LOG_FATAL, "Failed to create window or renderer: %s", SDL_GetError());do_exit(NULL);}}

开始播放

启动线程：解复用，解码，播放等线程都在stream_open中启动

	is = stream_open(input_filename, file_iformat);if (!is) {av_log(NULL, AV_LOG_FATAL, "Failed to initialize VideoState!\n");do_exit(NULL);}

事件响应机制

播放、暂停、快进、快退等操作

	/* 事件响应 */event_loop(is);/* never returns */return 0;
}