演示基于SDL2.0+FFmpeg的播放器

SDL是一个跨平台的渲染组件，眼下已经推出到2.0.3版本号，支持Win/Linux/OSX/Android。网上非常多介绍大多是基于SDL1.2版本号的，与2.0版本号有一定的区别，本文演示怎样用SDL2.0版本号播放视频（仅视频）。

SDL下载站点：http://libsdl.org

參考网址：http://blog.csdn.net/dawdo222/article/details/8692834

上代码：

// 演示怎样用SDL2进行播放
//可參考http://blog.csdn.net/dawdo222/article/details/8692834

#include "stdafx.h"
#include <stdio.h>
#include <tchar.h>
#include <io.h>
#include <direct.h>
#include <windows.h>

extern "C"
{
    // ffmpeg
#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"
#include "libswscale/swscale.h"
    // SDL
#include "SDL203include/SDL.h"
#include "SDL203include/SDL_thread.h"
};  

#pragma comment(lib,"../lib/avutil.lib")
#pragma comment(lib,"../lib/avcodec.lib")
#pragma comment(lib,"../lib/avformat.lib")
#pragma comment(lib,"../lib/swscale.lib")
#pragma comment(lib,"../lib/sdl2.lib")  

//把參数转换为utf8
void prepare_app_arguments2(int *argc_ptr, char ***argv_ptr)
{
	int i, nSize, newSize, buffsize;
	char *argv;
	char **argv2;
	wchar_t* lpWideCharStr;
	char* buf;
	char** win32_argv_utf8 = NULL;
	argv2 = *argv_ptr;

	buffsize = 0;
	/* determine the UTF-8 buffer size (including NULL-termination symbols) */
    for (i = 0; i < *argc_ptr; i++)
	{
		argv = argv2[i];
		nSize = MultiByteToWideChar(CP_ACP, 0, argv, strlen(argv)*sizeof(char), NULL, 0);
		lpWideCharStr = (wchar_t*)av_mallocz( (nSize+1) * sizeof(wchar_t));
		MultiByteToWideChar(CP_ACP, 0, argv, strlen(argv)*sizeof(wchar_t), lpWideCharStr, nSize);
        buffsize += WideCharToMultiByte(CP_UTF8, 0, lpWideCharStr, -1, NULL, 0, NULL, NULL);
		av_free(lpWideCharStr);
	}

    win32_argv_utf8 = (char**)av_mallocz(sizeof(char *) * (*argc_ptr + 1) + buffsize);

	for (i = 0; i < *argc_ptr; i++)
	{
		argv = argv2[i];
		nSize = MultiByteToWideChar(CP_ACP, 0, argv, strlen(argv)*sizeof(char), NULL, 0);
		lpWideCharStr = (wchar_t*)av_mallocz( (nSize+1) * sizeof(wchar_t));
		memset(lpWideCharStr, 0, (nSize+1)*sizeof(wchar_t));
		nSize = MultiByteToWideChar(CP_ACP, 0, argv, strlen(argv)*sizeof(wchar_t), lpWideCharStr, nSize);
		nSize =WideCharToMultiByte(CP_UTF8 ,0,lpWideCharStr,-1,NULL,0,NULL,NULL);
		buf = (char*)av_mallocz( (nSize+1) * sizeof(char));//new char[nSize+1];
		memset(buf, 0, nSize+1);
		newSize = WideCharToMultiByte(CP_UTF8 ,0,lpWideCharStr,-1,buf,nSize,NULL,NULL);
		av_free(lpWideCharStr);
		win32_argv_utf8[i] = buf;
	}
	*argc_ptr = *argc_ptr;
    *argv_ptr = win32_argv_utf8;
}

int _tmain(int argc, char* argv[])
{
	///////////////////////////////////////////////////////////////////////////////
    // ffmpeg
    // Register all formats and codecs
    av_register_all();  

    // Open video file
    AVFormatContext *pFormatCtx = NULL;
	prepare_app_arguments2(&argc, &argv);//转成UTF-8
    const char* filename = "d:\\clip\\avander2.mp4";//argv[1];
    if( avformat_open_input(&pFormatCtx, filename, NULL, NULL) != 0 ) {
        return -1; // Couldn't open file
    }  

    // Retrieve stream information
    if( avformat_find_stream_info(pFormatCtx, NULL) < 0 ) {
        return -1; // Couldn't find stream information
    }  

    // Dump information about file onto standard error
    av_dump_format(pFormatCtx, 0, filename, 0);
    // Find the first video stream
    int videoStream = -1;
    for(int i=0; i < pFormatCtx->nb_streams; i++) {
        if( pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO ) {
            videoStream = i;
            break;
        }
    }
    if( videoStream == -1) {
        return -1; // Didn't find a video stream
    }  

    // Get a pointer to the codec context for the video stream
    AVCodecContext * pCodecCtx = pFormatCtx->streams[videoStream]->codec;  

    // Find the decoder for the video stream
    AVCodec* pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
    if( pCodec == NULL ) {
        fprintf(stderr, "Unsupported codec!\n");
        return -1; // Codec not found
    }  

    // Open codec
    AVDictionary* optionsDict = NULL;
    if( avcodec_open2(pCodecCtx, pCodec, &optionsDict) < 0 ) {
        return -1; // Could not open codec
    }
	//源颜色格式
	AVPixelFormat src_fix_fmt = pCodecCtx->pix_fmt;	//AV_PIX_FMT_YUV420P
 	//目标颜色格式
	AVPixelFormat dst_fix_fmt = PIX_FMT_BGR24;//PIX_FMT_YUV420P
   // Allocate video frame
    AVFrame* pFrame = av_frame_alloc();
    AVFrame* pFrameYUV = av_frame_alloc();
    if( pFrameYUV == NULL ) {
        return -1;
    }  

    struct SwsContext* sws_ctx = sws_getContext(
        pCodecCtx->width,
        pCodecCtx->height,
        pCodecCtx->pix_fmt,
        pCodecCtx->width,
        pCodecCtx->height,
        dst_fix_fmt,//PIX_FMT_BGR24,//PIX_FMT_YUV420P,
        SWS_BILINEAR,
        NULL,
        NULL,
        NULL);  

    int numBytes = avpicture_get_size(
        dst_fix_fmt,//PIX_FMT_YUV420P,
        pCodecCtx->width,
        pCodecCtx->height);
    uint8_t* buffer = (uint8_t *)av_malloc( numBytes*sizeof(uint8_t) );  

    avpicture_fill((AVPicture *)pFrameYUV, buffer, dst_fix_fmt,//PIX_FMT_YUV420P,
        pCodecCtx->width, pCodecCtx->height);  

    // Read frames and save first five frames to disk
    SDL_Rect sdlRect;
    sdlRect.x = 0;
    sdlRect.y = 0;
    sdlRect.w = pCodecCtx->width;
    sdlRect.h = pCodecCtx->height;  

    //////////////////////////////////////////////////////
    // SDL
    if( SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER )) {
        fprintf(stderr, "Could not initialize SDL - %s\n", SDL_GetError());
        exit(1);
    }  

    SDL_Window* sdlWindow = SDL_CreateWindow("My Game Window",
        SDL_WINDOWPOS_UNDEFINED,
        SDL_WINDOWPOS_UNDEFINED,
        pCodecCtx->width,  pCodecCtx->height,
        0);
    if( !sdlWindow ) {
        fprintf(stderr, "SDL: could not set video mode - exiting\n");
        exit(1);
    }  

    SDL_Renderer* sdlRenderer = SDL_CreateRenderer(sdlWindow, -1, SDL_RENDERER_TARGETTEXTURE);  //原本第三个參数是0
    SDL_Texture* sdlTexture = SDL_CreateTexture(
        sdlRenderer,
        SDL_PIXELFORMAT_BGR24,//SDL_PIXELFORMAT_YV12,
        SDL_TEXTUREACCESS_STATIC,//SDL_TEXTUREACCESS_STREAMING,
        pCodecCtx->width,
        pCodecCtx->height);
	if(!sdlTexture)
		return -1;
	SDL_SetTextureBlendMode(sdlTexture,SDL_BLENDMODE_BLEND );

    AVPacket packet;
    SDL_Event event;
    while( av_read_frame(pFormatCtx, &packet) >= 0 ) {
        // Is this a packet from the video stream?
        if( packet.stream_index == videoStream ) {
            // Decode video frame
            int frameFinished;
            avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);  

            // Did we get a video frame?
            if( frameFinished ) {
                sws_scale(
                    sws_ctx,
                    (uint8_t const * const *)pFrame->data,
                    pFrame->linesize,
                    0,
                    pCodecCtx->height,
                    pFrameYUV->data,
                    pFrameYUV->linesize
                    );  

                SDL_UpdateTexture( sdlTexture, &sdlRect, pFrameYUV->data[0], pFrameYUV->linesize[0] );
                SDL_RenderClear( sdlRenderer );
                SDL_RenderCopy( sdlRenderer, sdlTexture, &sdlRect, &sdlRect );
                SDL_RenderPresent( sdlRenderer );
            }
            SDL_Delay(50);
        }  

        // Free the packet that was allocated by av_read_frame
        av_free_packet(&packet);
        SDL_PollEvent(&event);
        switch( event.type ) {
            case SDL_QUIT:
                SDL_Quit();
                exit(0);
                break;
            default:
                break;
        }  

    }  

    SDL_DestroyTexture(sdlTexture);  

    // Free the YUV frame
    av_free(pFrame);
    av_free(pFrameYUV);  

    // Close the codec
    avcodec_close(pCodecCtx);  

    // Close the video file
    avformat_close_input(&pFormatCtx);  

    return 0;
}

上述代码演示了怎样把视频帧转换为BGR24格式，然后用SDL的纹理函数渲染到屏幕上。

不完好的地方：没有音频部分，更没有视音频同步，播放帧率固定设为20帧/秒。