ffmpeg(1)环境搭建+tutorial01.c

环境搭建

1）将ffmpeg-20121125-git-26c531c-win32-shared\bin加入到环境变量中。

2）将SDL-1.2.15\include，ffmpeg-20121125-git-26c531c-win32-dev\include加入到工程中，如图示：

3）在附加依赖库中添加如下lib文件

SDL.lib
SDLmain.lib
avcodec.lib
avformat.lib
avdevice.lib
avfilter.lib
avutil.lib
swscale.lib
swresample.lib
postproc.lib

4）导入tutorial01.c工程

 

// tutorial01.c
// Code based on a tutorial by Martin Bohme ([email protected])
// Tested on Gentoo, CVS version 5/01/07 compiled with GCC 4.1.1

// A small sample program that shows how to use libavformat and libavcodec to
// read video from a file.
//
// Use
//
// gcc -o tutorial01 tutorial01.c -lavformat -lavcodec -lz
//
// to build (assuming libavformat and libavcodec are correctly installed
// your system).
//
// Run using
//
// tutorial01 myvideofile.mpg
//
// to write the first five frames from "myvideofile.mpg" to disk in PPM
// format.
extern "C"
{
#include <libavcodec\avcodec.h>
#include <libavformat\avformat.h>
//******************************************************************************
#include <libavutil/avstring.h>
#include <libswscale/swscale.h>
//*********************************************************************************

}
#include <stdio.h>
#include <math.h>
#include <iostream>
using namespace std ;
void SaveFrame(AVFrame *pFrame, int width, int height, int iFrame) {
	FILE *pFile;
	char szFilename[32];
	int  y;
  
	// Open file
	sprintf(szFilename, "frame%d.ppm", iFrame);
	pFile=fopen(szFilename, "wb");
	if(pFile==NULL)
		return;

	// Write header
	fprintf(pFile, "P6\n%d %d\n255\n", width, height);

	// Write pixel data
	for(y=0; y<height; y++)
		fwrite(pFrame->data[0]+y*pFrame->linesize[0], 1, width*3, pFile);

	// Close file
	fclose(pFile);
}

int main(int argc, char *argv[]) {
	AVFormatContext *pFormatCtx = avformat_alloc_context();//！！！这一句没有加后面部分时会有错误，会在执行avformat_open_input函数报错
	int             i, videoStream;
	AVCodecContext  *pCodecCtx;
	AVCodec         *pCodec;
	AVFrame         *pFrame; 
	AVFrame         *pFrameRGB;
	AVPacket        packet;
	int             frameFinished;
	int             numBytes;
	uint8_t         *buffer;
    struct SwsContext *img_convert_ctx;
	const char * filename="c:\\1.mp4";

	// Register all formats and codecs
	av_register_all();
 
	// Open video file
	if(avformat_open_input(&pFormatCtx, filename, NULL, NULL)!=0)
		return -1; // Couldn't open file

	// Retrieve stream information
	if(av_find_stream_info(pFormatCtx)<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
	videoStream=-1;
	for(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
		pCodecCtx=pFormatCtx->streams[videoStream]->codec;

		// Find the decoder for the video stream
		pCodec=avcodec_find_decoder(pCodecCtx->codec_id);
		if(pCodec==NULL) {
			fprintf(stderr, "Unsupported codec!\n");
			return -1; // Codec not found
		}
		// Open codec
		if(avcodec_open(pCodecCtx, pCodec)<0)
			return -1; // Could not open codec

		// Allocate video frame
		pFrame=avcodec_alloc_frame();

		// Allocate an AVFrame structure
		pFrameRGB=avcodec_alloc_frame();
		if(pFrameRGB==NULL)
			return -1;

		// Determine required buffer size and allocate buffer
		numBytes=avpicture_get_size(PIX_FMT_RGB24, pCodecCtx->width,
			pCodecCtx->height);
		buffer=(uint8_t *)av_malloc(numBytes*sizeof(uint8_t));

		// Assign appropriate parts of buffer to image planes in pFrameRGB
		// Note that pFrameRGB is an AVFrame, but AVFrame is a superset
		// of AVPicture
		avpicture_fill((AVPicture *)pFrameRGB, buffer, PIX_FMT_RGB24,
			pCodecCtx->width, pCodecCtx->height);

		// Read frames and save first five frames to disk		
		i=0;
		while(av_read_frame(pFormatCtx, &packet)>=0) 
		{  
			// Is this a packet from the video stream?
			if(packet.stream_index==videoStream)
			{
				// Decode video frame
				avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);

				// Did we get a video frame?
				if(frameFinished)
				{	
					img_convert_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height, PIX_FMT_RGB565,SWS_BILINEAR, NULL, NULL, NULL); 
					if (img_convert_ctx == NULL)  
					{  
						fprintf(stderr, "Cannot initialize the conversion context/n");  
						exit(1);  
					}  
					sws_scale(img_convert_ctx,(const uint8_t* const*)pFrame->data,pFrame->linesize,0,pCodecCtx->height,pFrameRGB->data,pFrameRGB->linesize);
					if(++i<=5)
						SaveFrame(pFrameRGB, pCodecCtx->width, pCodecCtx->height, i);
					}
			}
		}
		// Free the packet that was allocated by av_read_frame
		av_free_packet(&packet);

		// Free the RGB image
		av_free(buffer);
		av_free(pFrameRGB);

		// Free the YUV frame
		av_free(pFrame);

		// Free the SwsContext
		sws_freeContext(img_convert_ctx);

		// Close the codec
		avcodec_close(pCodecCtx);
		return 0;
}

总结：

1）调试时，朋友给的代码，很多错误，所以还是从官网自己下载比较好，另外，这个是最新版本的，ffmpeg修改了很多接口

2）tutorial01提供了很好的操作视频的基本方法，只要你处理视频，就必须使用这些方法。

下面对tutorial2进行调试，当然这些基本的只是练手和熟悉ffmpeg，最终还是为了自己的编解码和小型播放器