/**
* 最簡單的基於FFmpeg的視訊播放器2(SDL升級版)
* Simplest FFmpeg Player 2(SDL Update)
*
* 雷霄驊 Lei Xiaohua
* [email protected]
* 中國傳媒大學/數字電視技術
* Communication University of China / Digital TV Technology
* http://blog.csdn.net/leixiaohua1020
*
* 第2版使用SDL2.0取代了第一版中的SDL1.2
* Version 2 use SDL 2.0 instead of SDL 1.2 in version 1.
*
* 本程式實現了視訊檔案的解碼和顯示(支援HEVC，H.264，MPEG2等)。
* 是最簡單的FFmpeg視訊解碼方面的教程。
* 通過學習本例子可以瞭解FFmpeg的解碼流程。
* 本版本中使用SDL訊息機制重新整理視訊畫面。
* This software is a simplest video player based on FFmpeg.
* Suitable for beginner of FFmpeg.
*
* 備註:
* 標準版在播放視訊的時候，畫面顯示使用延時40ms的方式。這麼做有兩個後果：
* （1）SDL彈出的視窗無法移動，一直顯示是忙碌狀態
* （2）畫面顯示並不是嚴格的40ms一幀，因為還沒有考慮解碼的時間。
* SU（SDL Update）版在視訊解碼的過程中，不再使用延時40ms的方式，而是建立了
* 一個執行緒，每隔40ms傳送一個自定義的訊息，告知主函式進行解碼顯示。這樣做之後：
* （1）SDL彈出的視窗可以移動了
* （2）畫面顯示是嚴格的40ms一幀
* Remark:
* Standard Version use's SDL_Delay() to control video's frame rate, it has 2
* disadvantages:
* (1)SDL's Screen can't be moved and always "Busy".
* (2)Frame rate can't be accurate because it doesn't consider the time consumed
* by avcodec_decode_video2()
* SU（SDL Update）Version solved 2 problems above. It create a thread to send SDL
* Event every 40ms to tell the main loop to decode and show video frames.
*/

#include <stdio.h>
#include "stdafx.h"
#define __STDC_CONSTANT_MACROS

#ifdef _WIN32
//Windows
extern "C"
{
#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"
#include "libswscale/swscale.h"
#include "SDL2/SDL.h"
};
#else
//Linux...
#ifdef __cplusplus
extern "C"
{
#endif
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>
#include <SDL2/SDL.h>
#ifdef __cplusplus
};
#endif
#endif

//Refresh Event
#define SFM_REFRESH_EVENT  (SDL_USEREVENT + 1)

#define SFM_BREAK_EVENT  (SDL_USEREVENT + 2)

int thread_exit = 0;
int thread_pause = 0;

int sfp_refresh_thread(void *opaque) {
	thread_exit = 0;
	thread_pause = 0;

	while (!thread_exit) {
		if (!thread_pause) {
			SDL_Event event;
			event.type = SFM_REFRESH_EVENT;
			SDL_PushEvent(&event); //傳送一個事件
		}
		SDL_Delay(40); //可用於調節播放速度
	}
	thread_exit = 0;
	thread_pause = 0;
	//Break
	SDL_Event event;
	event.type = SFM_BREAK_EVENT;
	SDL_PushEvent(&event);

	return 0;
}


int main(int argc, char* argv[])
{

	AVFormatContext	*pFormatCtx;
	int				i, videoindex;
	AVCodecContext	*pCodecCtx;
	AVCodec			*pCodec;
	AVFrame	*pFrame, *pFrameYUV;
	uint8_t *out_buffer;
	AVPacket *packet;
	int ret, got_picture;

	//------------SDL----------------
	int screen_w, screen_h;
	SDL_Window *screen;
	SDL_Renderer* sdlRenderer;
	SDL_Texture* sdlTexture;
	SDL_Rect sdlRect;
	SDL_Thread *video_tid;
	SDL_Event event;

	struct SwsContext *img_convert_ctx;

	//輸入檔案路徑
	char filepath[] = "Tai.mp4";

	av_register_all(); //註冊所有元件
	avformat_network_init(); //初始化網路
	pFormatCtx = avformat_alloc_context(); //初始化一個 AVFormatContext 

	if (avformat_open_input(&pFormatCtx, filepath, NULL, NULL) != 0) { //開啟輸入的視訊檔案
		printf("Couldn't open input stream.\n");
		return -1;
	}
	if (avformat_find_stream_info(pFormatCtx, NULL)<0) { //獲取視訊檔案資訊
		printf("Couldn't find stream information.\n");
		return -1;
	}
	videoindex = -1;
	for (i = 0; i<pFormatCtx->nb_streams; i++)
		if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
			videoindex = i;
			break;
		}
	if (videoindex == -1) {
		printf("Didn't find a video stream.\n");
		return -1;
	}
	pCodecCtx = pFormatCtx->streams[videoindex]->codec;
	pCodec = avcodec_find_decoder(pCodecCtx->codec_id); //查詢解碼器
	if (pCodec == NULL) {
		printf("Codec not found.\n");
		return -1;
	}
	if (avcodec_open2(pCodecCtx, pCodec, NULL)<0) { //開啟解碼器
		printf("Could not open codec.\n");
		return -1;
	}
	pFrame = av_frame_alloc();
	pFrameYUV = av_frame_alloc();
	out_buffer = (uint8_t *)av_malloc(avpicture_get_size(PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height));
	avpicture_fill((AVPicture *)pFrameYUV, out_buffer, PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height);
	packet = (AVPacket *)av_malloc(sizeof(AVPacket));

	//Output Info-----------------------------
	printf("---------------- File Information ---------------\n");
	av_dump_format(pFormatCtx, 0, filepath, 0);
	printf("-------------------------------------------------\n");

	img_convert_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt,
		pCodecCtx->width, pCodecCtx->height, PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL);

	//初始化 SDL 系統
	if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) {
		printf("Could not initialize SDL - %s\n", SDL_GetError());
		return -1;
	}
	//SDL 2.0 Support for multiple windows
	screen_w = pCodecCtx->width;
	screen_h = pCodecCtx->height;
	//建立視窗
	screen = SDL_CreateWindow("Simplest ffmpeg player's Window", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
		screen_w, screen_h, SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE);

	if (!screen) {
		printf("SDL: could not create window - exiting:%s\n", SDL_GetError());
		return -1;
	}
	//建立渲染器
	sdlRenderer = SDL_CreateRenderer(screen, -1, 0);
	//IYUV: Y + U + V  (3 planes)
	//YV12: Y + V + U  (3 planes)
	//建立紋理
	sdlTexture = SDL_CreateTexture(sdlRenderer, SDL_PIXELFORMAT_IYUV, SDL_TEXTUREACCESS_STREAMING, screen_w, screen_h);

	//建立一個執行緒
	video_tid = SDL_CreateThread(sfp_refresh_thread, NULL, NULL);
	//------------SDL End------------
	//Event Loop

	for (;;) {
		//Wait
		SDL_WaitEvent(&event);
		if (event.type == SFM_REFRESH_EVENT) {
			//------------------------------ 



			if (av_read_frame(pFormatCtx, packet) >= 0) { //讀取一幀壓縮資料
				if (packet->stream_index == videoindex) {
					ret = avcodec_decode_video2(pCodecCtx, pFrame, &got_picture, packet); //解碼一幀壓縮資料
					if (ret < 0) {
						printf("Decode Error.\n");
						return -1;
					}
					if (got_picture) {
						sws_scale(img_convert_ctx, (const uint8_t* const*)pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pFrameYUV->data, pFrameYUV->linesize);
						//SDL---------------------------
						//設定紋理的資料
						SDL_UpdateTexture(sdlTexture, NULL, pFrameYUV->data[0], pFrameYUV->linesize[0]);

						sdlRect.x = 0;
						sdlRect.y = 0;
						sdlRect.w = screen_w;
						sdlRect.h = screen_h;

						//清空紋理
						SDL_RenderClear(sdlRenderer);
						//SDL_RenderCopy( sdlRenderer, sdlTexture, &sdlRect, &sdlRect );  
						//將紋理的資料拷貝給渲染器
						SDL_RenderCopy(sdlRenderer, sdlTexture, NULL, NULL);
						//顯示
						SDL_RenderPresent(sdlRenderer);
						//SDL End-----------------------
					}
				}
				av_free_packet(packet);
			}
			else {
				//Exit Thread
				thread_exit = 1;
			}
		}
		else if (event.type == SDL_WINDOWEVENT) {
			//If Resize  
			SDL_GetWindowSize(screen, &screen_w, &screen_h);
		}
		else if (event.type == SDL_KEYDOWN) {
			//Pause
			if (event.key.keysym.sym == SDLK_SPACE)
				thread_pause = !thread_pause;
		}
		else if (event.type == SDL_QUIT) {
			thread_exit = 1;
		}
		else if (event.type == SFM_BREAK_EVENT) {
			break;
		}

	}

	sws_freeContext(img_convert_ctx);

	SDL_Quit();
	//--------------
	av_frame_free(&pFrameYUV);
	av_frame_free(&pFrame);
	avcodec_close(pCodecCtx);
	avformat_close_input(&pFormatCtx);

	return 0;
}
 

示例總結