Question

我试图从drangers指南（学校）学习ffmpeg，我有一个mac所以我做的第一件事就是使用Macports并获得ffmpeg和sdl ......

现在当我试图编译文件代码时，编译器没有识别标题...... 所以我在编译时使用了-I on gnu，并且还给了＆＃34;整个/路径/名称...＆＃34;到标题，但我总是在一些标题丢失时得到错误...

下面我将把代码与我的更正。

我也试过包含我收到错误的所有标题但是总有另一个标题，编译器无法找到

我尝试了gnu（在控制台上）和xcode。

// 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 -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 "/opt/local/include/libavcodec/avcodec.h"
#include "/opt/local/include/libavformat/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;
}

Answer 1

回到更简单的包含，例如：

#include "avcodec.h"

使用gcc或clang或任何编译器时，编译器使用符号表示添加include目录，如：

gcc tutorial01.c -o tut -I/opt/local/include -lavformat -lavcodec -lz -lavutil -lm

（我承认，我不知道这些是否是正确的-l参数，但一般原则适用。使用

-I/path/to/dir

添加包含目录路径。）

等等。

使用带有c程序的ffmpeg头文件

1 个答案: