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。