FFmpeg + SDL的視訊播放器的製作（5）

SDL函式

進階練習

視窗可以移動

視窗可以調整大小

/**
 * 最簡單的SDL2播放視訊的例子（SDL2播放RGB/YUV）
 * Simplest Video Play SDL2 (SDL2 play RGB/YUV) 
 *
 * 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
 *
 * 本程式使用SDL2播放RGB/YUV視訊畫素資料。SDL實際上是對底層繪圖
 * API（Direct3D，OpenGL）的封裝，使用起來明顯簡單于直接呼叫底層
 * API。
 *
 * This software plays RGB/YUV raw video data using SDL2.
 * SDL is a wrapper of low-level API (Direct3D, OpenGL).
 * Use SDL is much easier than directly call these low-level API.  
 */

#include <stdio.h>

extern "C"
{
#include "sdl/SDL.h"
};

const int bpp=12;

int screen_w=500,screen_h=500;
const int pixel_w=320,pixel_h=180;

unsigned char buffer[pixel_w*pixel_h*bpp/8];

//Refresh Event
#define REFRESH_EVENT  (SDL_USEREVENT + 1)//重新整理事件
//Break
#define BREAK_EVENT  (SDL_USEREVENT + 2)//退出事件

int thread_exit=0;//控制執行緒安全退出

//使得主迴圈main不再有延時，延時放到子執行緒中
int refresh_video(void *opaque){
	thread_exit=0;
	while (thread_exit==0) {
		SDL_Event event;//設定一個事件
		event.type = REFRESH_EVENT;//自定義事件，重新整理視訊的畫面
		SDL_PushEvent(&event);//發重新整理事件
		SDL_Delay(40);
	}
	thread_exit=0;
	//Break
	SDL_Event event;
	event.type = BREAK_EVENT;
	SDL_PushEvent(&event);
	return 0;
}

int main(int argc, char* argv[])
{
	if(SDL_Init(SDL_INIT_VIDEO)) {  
		printf( "Could not initialize SDL - %s\n", SDL_GetError()); 
		return -1;
	} 

	SDL_Window *screen; 
	//SDL 2.0 Support for multiple windows
	screen = SDL_CreateWindow("Simplest Video Play SDL2", 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;
	}
	SDL_Renderer* sdlRenderer = SDL_CreateRenderer(screen, -1, 0);  

	Uint32 pixformat=0;
	//IYUV: Y + U + V  (3 planes)
	//YV12: Y + V + U  (3 planes)
	pixformat= SDL_PIXELFORMAT_IYUV;  

	SDL_Texture* sdlTexture = SDL_CreateTexture(sdlRenderer,pixformat, SDL_TEXTUREACCESS_STREAMING,pixel_w,pixel_h);

	FILE *fp=NULL;
	fp=fopen("test_yuv420p_320x180.yuv","rb+");

	if(fp==NULL){
		printf("cannot open this file\n");
		return -1;
	}

	SDL_Rect sdlRect;  

	SDL_Thread *refresh_thread = SDL_CreateThread(refresh_video,NULL,NULL);//建立一個執行緒，refresh_video是一個函式
	SDL_Event event;//事件
	while(1){
		//Wait
		SDL_WaitEvent(&event);//程式執行到這，停在這兒，需要等待一個事件來響應程式
		if(event.type==REFRESH_EVENT){//接受到重新整理事件，自定義事件
			if (fread(buffer, 1, pixel_w*pixel_h*bpp/8, fp) != pixel_w*pixel_h*bpp/8){
				// Loop
				fseek(fp, 0, SEEK_SET);
				fread(buffer, 1, pixel_w*pixel_h*bpp/8, fp);
			}

			SDL_UpdateTexture( sdlTexture, NULL, buffer, pixel_w);  

			//FIX: If window is resize
			sdlRect.x = 0;  
			sdlRect.y = 0;  
			sdlRect.w = screen_w;  
			sdlRect.h = screen_h;  
			
			SDL_RenderClear( sdlRenderer );   
			SDL_RenderCopy( sdlRenderer, sdlTexture, NULL, &sdlRect);  
			SDL_RenderPresent( sdlRenderer );  
			
		}else if(event.type==SDL_WINDOWEVENT){//windows下自帶的事件。在來回拉伸視窗時候會觸發
			//If Resize
			//從SDL window中，獲得當前視窗的寬和高，下一次迴圈會設定sdlRect.w和sdlRect.h
			SDL_GetWindowSize(screen,&screen_w,&screen_h);
		}else if(event.type==SDL_QUIT){//退出事件
			thread_exit=1;
		}else if(event.type==BREAK_EVENT){
			break;
		}
	}
	SDL_Quit();
	return 0;
}