FFMpeg提取视频帧

提取视频帧，并以bmp格式保存到本地。

#include 
#include  
#include 
#include 
  
extern "C"  
{  
	#include "libavcodec/avcodec.h"	
	#include "libavformat/avformat.h"
	#include "libavdevice/avdevice.h"
	#include "libavfilter/avfilter.h"
	#include "libswscale/swscale.h"
	#include "libswresample/swresample.h"
	#include "libavutil/avutil.h"
}  
   
#pragma comment(lib, "avcodec.lib") 
#pragma comment(lib, "avformat.lib") 
#pragma comment(lib, "avdevice.lib") 
#pragma comment(lib, "avfilter.lib")
#pragma comment(lib, "swscale.lib")
#pragma comment(lib, "swresample.lib")
#pragma comment(lib, "avutil.lib")

//______________
//定义BMP文件头 



#ifndef _WINGDI_  
#define _WINGDI_  
typedef struct tagBITMAPFILEHEADER {  
	WORD    bfType;   
	DWORD   bfSize;   
	WORD    bfReserved1;   
	WORD    bfReserved2;   
	DWORD   bfOffBits;   
} BITMAPFILEHEADER, FAR *LPBITMAPFILEHEADER, *PBITMAPFILEHEADER;     

typedef struct tagBITMAPINFOHEADER{   
	DWORD      biSize;   
	LONG       biWidth;   
	LONG       biHeight;   
	WORD       biPlanes;   
	WORD       biBitCount;   
	DWORD      biCompression;   
	DWORD      biSizeImage;   
	LONG       biXPelsPerMeter;   
	LONG       biYPelsPerMeter;   
	DWORD      biClrUsed;   
	DWORD      biClrImportant;  
} BITMAPINFOHEADER, FAR *LPBITMAPINFOHEADER, *PBITMAPINFOHEADER;    
#endif    
//保存BMP文件的函数  
void SaveAsBMP (AVFrame *pFrameRGB, int width, int height, int index, int bpp)  
{   char buf[5] = {0};   //bmp头   
BITMAPFILEHEADER bmpheader;   
BITMAPINFOHEADER bmpinfo;   
FILE *fp;    
char *filename = new char[255];  //文件存放路径，根据自己的修改   
sprintf_s(filename,255,"%s_%d.bmp","C:/test",index);  
if ( (fp=fopen(filename,"wb+")) == NULL )   {    
	printf ("open file failed!\n");      
	return;  
 }     
	bmpheader.bfType = 0x4d42;  
	bmpheader.bfReserved1 = 0;  
	bmpheader.bfReserved2 = 0;    
	bmpheader.bfOffBits = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER);  
	bmpheader.bfSize = bmpheader.bfOffBits + width*height*bpp/8;    
	bmpinfo.biSize = sizeof(BITMAPINFOHEADER);   
	bmpinfo.biWidth = width;   
	bmpinfo.biHeight = height;   
	bmpinfo.biPlanes = 1;   
	bmpinfo.biBitCount = bpp;   
	bmpinfo.biCompression = BI_RGB;    
	bmpinfo.biSizeImage = (width*bpp+31)/32*4*height;   
	bmpinfo.biXPelsPerMeter = 100;   
	bmpinfo.biYPelsPerMeter = 100;   
	bmpinfo.biClrUsed = 0;   
	bmpinfo.biClrImportant = 0;     
	fwrite (&bmpheader, sizeof(bmpheader), 1, fp);   
	fwrite (&bmpinfo, sizeof(bmpinfo), 1, fp);    
	fwrite (pFrameRGB->data[0], width*height*bpp/8, 1, fp);   
	fclose(fp);  
}








int main ()  
{  
	printf("%d\n", avcodec_version()); 
	
	unsigned int i = 0, videoStream = -1;
	AVFormatContext *pFormatCtx;
	AVCodecContext *pCodecCtx;
	AVCodec *pCodec;
	AVFrame *pFrame,*pFrameRGB;
	struct SwsContext *pSwsCtx;
	const char *filename = "C:/test.mp4";
	int frameFinished;
	int PictureSize;
	AVPacket packet;
	uint8_t *buf;


	//注册解码器
	av_register_all();
	avformat_network_init();
	pFormatCtx = avformat_alloc_context();
	

	//AVInputFormat *pInputFormt = av_find_input_format("dshow");
	if(avformat_open_input(&pFormatCtx,filename,NULL,NULL)!=0){
		printf("%s\n","failed");
	}
	//获取视频流信息
	if(avformat_find_stream_info(pFormatCtx,NULL)<0){
		printf("%s\n","couldn`t find stream info");
	}
	
	//获取视频数据
	for(int i=0;inb_streams;i++)
		
		if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO){
			videoStream = i ;
		}
		
		if(videoStream == -1){
			printf("%s\n","find video stream failed");
			exit(1);	
		}
		pCodecCtx = pFormatCtx->streams[videoStream]->codec;
		pCodec = avcodec_find_decoder(pCodecCtx->codec_id);

		if(pCodec ==NULL){
			printf("%d\n","avcode find decoder failed!");
			exit(1);
		}
		//打开解码器
		if(avcodec_open2(pCodecCtx,pCodec,NULL)<0){
			printf("avcode open failed!\n");
			exit(1);
		}

		//为每帧图像分配内存
		pFrame = av_frame_alloc();
		pFrameRGB = av_frame_alloc();

		if(pFrame==NULL||pFrameRGB==NULL){
			printf("av frame alloc failed!\n");
			exit(1);
		}
		//获得帧图大小
		PictureSize = avpicture_get_size(AV_PIX_FMT_BGR24,pCodecCtx->width,pCodecCtx->height);
		buf = (uint8_t*)av_malloc(PictureSize);
		if(buf ==NULL){
			printf("av malloc failed!\n");
			exit(1);
		}
		
		avpicture_fill((AVPicture *)pFrameRGB,buf,AV_PIX_FMT_BGR24,pCodecCtx->width,pCodecCtx->height);
		//设置图像转换上下文
		pSwsCtx = sws_getContext(pCodecCtx->width,pCodecCtx->height,pCodecCtx->pix_fmt,pCodecCtx->width,pCodecCtx->height,AV_PIX_FMT_BGR24,SWS_BICUBIC,NULL,NULL,NULL);
		i = 0;
		
		while(av_read_frame(pFormatCtx,&packet)>=0){
			if(packet.stream_index==videoStream){
				//真正的解码
				avcodec_decode_video2(pCodecCtx,pFrame,&frameFinished,&packet);
				if(frameFinished){
					//饭庄图像，否则是上下颠倒的
					pFrame->data[0]+=pFrame->linesize[0]*(pCodecCtx->height-1);
					pFrame->linesize[0]*=-1;
					pFrame->data[1]+=pFrame->linesize[1]*(pCodecCtx->height/2-1);
					pFrame->linesize[1]*=-1;
					pFrame->data[2]+=pFrame->linesize[2]*(pCodecCtx->header_bits/2-1);
					pFrame->linesize[2]*=-1;

					//转换图像格式，将解压出来的YUV420P的图像转换为BRG24的图像
					sws_scale(pSwsCtx,pFrame->data,pFrame->linesize,0,pCodecCtx->height,pFrameRGB->data,pFrameRGB->linesize);
					//保存为bmp图
					SaveAsBMP(pFrameRGB,pCodecCtx->width,pCodecCtx->height,i,24);
					i++;
				}
				av_free_packet(&packet);
			}
		}
		sws_freeContext(pSwsCtx);
		av_free(pFrame);
		av_free(pFrameRGB);
		avcodec_close(pCodecCtx);
		avformat_close_input(&pFormatCtx);
		return 0;
	}