// tutorial01.c// Code based on a tutorial by Martin Bohme (boehme@inb.uni-luebeckREMOVETHIS.de)// 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 -lavutil -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.#include <avcodec.h>#include <avformat.h>#include <stdio.h>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;  int             i, videoStream;  AVCodecContext  *pCodecCtx;  AVCodec         *pCodec;  AVFrame         *pFrame;   AVFrame         *pFrameRGB;  AVPacket        packet;  int             frameFinished;  int             numBytes;  uint8_t         *buffer;    if(argc < 2) {    printf("Please provide a movie file\n");    return -1;  }  // Register all formats and codecs  av_register_all();    // Open video file  if(av_open_input_file(&pFormatCtx, argv[1], NULL, 0, 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  dump_format(pFormatCtx, 0, argv[1], 0);    // Find the first video stream  videoStream=-1;  for(i=0; i<pFormatCtx->nb_streams; i++)    if(pFormatCtx->streams[i]->codec->codec_type==CODEC_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_video(pCodecCtx, pFrame, &frameFinished, 			   packet.data, packet.size);            // Did we get a video frame?      if(frameFinished) {	// Convert the image from its native format to RGB	img_convert((AVPicture *)pFrameRGB, PIX_FMT_RGB24,                     (AVPicture*)pFrame, pCodecCtx->pix_fmt, pCodecCtx->width,                     pCodecCtx->height);		// Save the frame to disk	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);    // Close the codec  avcodec_close(pCodecCtx);    // Close the video file  av_close_input_file(pFormatCtx);    return 0;}