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最簡單的基於FFmpeg的視訊播放器系列文章列表：

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本文補充記錄《最簡單的基於FFMPEG+SDL的視訊播放器》中的兩個例子：FFmpeg視訊解碼器和SDL畫素資料播放器。這兩個部分是從視訊播放器中拆分出來的兩個例子。FFmpeg視訊解碼器實現了視訊資料到YUV資料的解碼，而SDL畫素資料播放器實現了YUV資料的顯示。簡而言之，原先的FFmpeg+SDL視訊播放器實現了：

視訊資料->YUV->顯示器

FFmpeg視訊解碼器實現了：

視訊資料->YUV

SDL畫素資料播放器實現了：

FFmpeg視訊解碼器

原始碼

/**
 * 最簡單的基於FFmpeg的視訊解碼器
 * Simplest FFmpeg Decoder
 *
 * 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
 *
 *
 * 本程式實現了視訊檔案解碼為YUV資料。它使用了libavcodec和
 * libavformat。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。
 * This software is a simplest decoder based on FFmpeg.
 * It decodes video to YUV pixel data.
 * It uses libavcodec and libavformat.
 * Suitable for beginner of FFmpeg.
 *
 */



#include <stdio.h>

#define __STDC_CONSTANT_MACROS

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


int main(int argc, char* argv[])
{
	AVFormatContext	*pFormatCtx;
	int				i, videoindex;
	AVCodecContext	*pCodecCtx;
	AVCodec			*pCodec;
	AVFrame	*pFrame,*pFrameYUV;
	unsigned char *out_buffer;
	AVPacket *packet;
	int y_size;
	int ret, got_picture;
	struct SwsContext *img_convert_ctx;

	char filepath[]="Titanic.mkv";

	FILE *fp_yuv=fopen("output.yuv","wb+");  

	av_register_all();
	avformat_network_init();
	pFormatCtx = avformat_alloc_context();

	if(avformat_open_input(&pFormatCtx,filepath,NULL,NULL)!=0){
		printf("Couldn't open input stream.\n");
		return -1;
	}
	if(avformat_find_stream_info(pFormatCtx,NULL)<0){
		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);
	if(pCodec==NULL){
		printf("Codec not found.\n");
		return -1;
	}
	if(avcodec_open2(pCodecCtx, pCodec,NULL)<0){
		printf("Could not open codec.\n");
		return -1;
	}
	
	pFrame=av_frame_alloc();
	pFrameYUV=av_frame_alloc();
	out_buffer=(unsigned char *)av_malloc(av_image_get_buffer_size(AV_PIX_FMT_YUV420P,  pCodecCtx->width, pCodecCtx->height,1));
	av_image_fill_arrays(pFrameYUV->data, pFrameYUV->linesize,out_buffer,
		AV_PIX_FMT_YUV420P,pCodecCtx->width, pCodecCtx->height,1);

	
	
	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, AV_PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL); 

	while(av_read_frame(pFormatCtx, packet)>=0){
		if(packet->stream_index==videoindex){
			ret = avcodec_decode_video2(pCodecCtx, pFrame, &got_picture, packet);
			if(ret < 0){
				printf("Decode Error.\n");
				return -1;
			}
			if(got_picture){
				sws_scale(img_convert_ctx, (const unsigned char* const*)pFrame->data, pFrame->linesize, 0, pCodecCtx->height, 
					pFrameYUV->data, pFrameYUV->linesize);

				y_size=pCodecCtx->width*pCodecCtx->height;  
				fwrite(pFrameYUV->data[0],1,y_size,fp_yuv);    //Y 
				fwrite(pFrameYUV->data[1],1,y_size/4,fp_yuv);  //U
				fwrite(pFrameYUV->data[2],1,y_size/4,fp_yuv);  //V
				printf("Succeed to decode 1 frame!\n");

			}
		}
		av_free_packet(packet);
	}
	//flush decoder
	//FIX: Flush Frames remained in Codec
	while (1) {
		ret = avcodec_decode_video2(pCodecCtx, pFrame, &got_picture, packet);
		if (ret < 0)
			break;
		if (!got_picture)
			break;
		sws_scale(img_convert_ctx, (const unsigned char* const*)pFrame->data, pFrame->linesize, 0, pCodecCtx->height, 
			pFrameYUV->data, pFrameYUV->linesize);

		int y_size=pCodecCtx->width*pCodecCtx->height;  
		fwrite(pFrameYUV->data[0],1,y_size,fp_yuv);    //Y 
		fwrite(pFrameYUV->data[1],1,y_size/4,fp_yuv);  //U
		fwrite(pFrameYUV->data[2],1,y_size/4,fp_yuv);  //V

		printf("Flush Decoder: Succeed to decode 1 frame!\n");
	}

	sws_freeContext(img_convert_ctx);

    fclose(fp_yuv);

	av_frame_free(&pFrameYUV);
	av_frame_free(&pFrame);
	avcodec_close(pCodecCtx);
	avformat_close_input(&pFormatCtx);

	return 0;
}
 

執行結果

SDL畫素資料播放器

原始碼

/**
 * 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。
 *
 * 函式呼叫步驟如下: 
 *
 * [初始化]
 * SDL_Init(): 初始化SDL。
 * SDL_CreateWindow(): 建立視窗（Window）。
 * SDL_CreateRenderer(): 基於視窗建立渲染器（Render）。
 * SDL_CreateTexture(): 建立紋理（Texture）。
 *
 * [迴圈渲染資料]
 * SDL_UpdateTexture(): 設定紋理的資料。
 * SDL_RenderCopy(): 紋理複製給渲染器。
 * SDL_RenderPresent(): 顯示。
 *
 * 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.  
 *
 * The process is shown as follows:
 *
 * [Init]
 * SDL_Init(): Init SDL.
 * SDL_CreateWindow(): Create a Window.
 * SDL_CreateRenderer(): Create a Render.
 * SDL_CreateTexture(): Create a Texture.
 *
 * [Loop to Render data]
 * SDL_UpdateTexture(): Set Texture's data.
 * SDL_RenderCopy(): Copy Texture to Render.
 * SDL_RenderPresent(): Show.
 */

#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)

#define BREAK_EVENT  (SDL_USEREVENT + 2)

int thread_exit=0;

int refresh_video(void *opaque){
	thread_exit=0;
	while (!thread_exit) {
		SDL_Event event;
		event.type = REFRESH_EVENT;
		SDL_PushEvent(&event);
		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);
	SDL_Event event;
	while(1){
		//Wait
		SDL_WaitEvent(&event);
		if(event.type==REFRESH_EVENT){
			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){
			//If Resize
			SDL_GetWindowSize(screen,&screen_w,&screen_h);
		}else if(event.type==SDL_QUIT){
			thread_exit=1;
		}else if(event.type==BREAK_EVENT){
			break;
		}
	}
	SDL_Quit();
	return 0;
}
 

執行結果

下載

專案主頁

simplest_ffmpeg_player：標準版，FFmpeg學習的開始。
simplest_ffmpeg_player_su：SU（SDL Update）版，加入了簡單的SDL的Event。
simplest_ffmpeg_decoder：一個包含了封裝格式處理功能的解碼器。使用了libavcodec和libavformat。
simplest_ffmpeg_decoder_pure：一個純淨的解碼器。只使用libavcodec（沒有使用libavformat）。
simplest_video_play_sdl2：使用SDL2播放YUV的例子。
simplest_ffmpeg_helloworld：輸出FFmpeg類庫的資訊。