**** dogfoot note ****

ffmpeg 을 이용한 비디오 파일에서 첫 다섯개의 프레임 이미지 추출 예제..

makefile

all:
	gcc ./test.c -I/c/Temp/ffmpeg_win65/include -L/c/Temp/ffmpeg_win64/lib -lavformat -lavcodec -lswscale -lavutil -lswresample -lz -lbcrypt -lole32 -lMfplat -ltiff -liconv -llzma -lws2_32 -lSecur32 -lbz2 -lstrmiids

test.c

#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>

#include <stdio.h>

// compatibility with newer API
#if LIBAVCODEC_VERSION_INT < AV_VERSION_INT(55,28,1)
#define av_frame_alloc avcodec_alloc_frame
#define av_frame_free avcodec_free_frame
#endif

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[]) {
  // Initalizing these to NULL prevents segfaults!
  AVFormatContext   *pFormatCtx = NULL;
  int               i, videoStream;
  AVCodecContext    *pCodecCtxOrig = NULL;
  AVCodecContext    *pCodecCtx = NULL;
  AVCodec           *pCodec = NULL;
  AVFrame           *pFrame = NULL;
  AVFrame           *pFrameRGB = NULL;
  AVPacket          packet;
  int               frameFinished;
  int               numBytes;
  uint8_t           *buffer = NULL;
  struct SwsContext *sws_ctx = NULL;

  if(argc < 2) {
    printf("Please provide a movie file\n");
    return -1;
  }
  // Register all formats and codecs
  av_register_all();
  
  // Open video file
  if(avformat_open_input(&pFormatCtx, argv[1], 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, 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==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
  pCodecCtxOrig=pFormatCtx->streams[videoStream]->codec;
  // Find the decoder for the video stream
  pCodec=avcodec_find_decoder(pCodecCtxOrig->codec_id);
  if(pCodec==NULL) {
    fprintf(stderr, "Unsupported codec!\n");
    return -1; // Codec not found
  }
  // Copy context
  pCodecCtx = avcodec_alloc_context3(pCodec);
  if(avcodec_copy_context(pCodecCtx, pCodecCtxOrig) != 0) {
    fprintf(stderr, "Couldn't copy codec context");
    return -1; // Error copying codec context
  }

  // Open codec
  if(avcodec_open2(pCodecCtx, pCodec, NULL)<0)
    return -1; // Could not open codec
  
  // Allocate video frame
  pFrame=av_frame_alloc();
  
  // Allocate an AVFrame structure
  pFrameRGB=av_frame_alloc();
  if(pFrameRGB==NULL)
    return -1;

  // Determine required buffer size and allocate buffer
  numBytes=avpicture_get_size(AV_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, AV_PIX_FMT_RGB24,
     pCodecCtx->width, pCodecCtx->height);
  
  // initialize SWS context for software scaling
  sws_ctx = sws_getContext(pCodecCtx->width,
         pCodecCtx->height,
         pCodecCtx->pix_fmt,
         pCodecCtx->width,
         pCodecCtx->height,
         AV_PIX_FMT_RGB24,
         SWS_BILINEAR,
         NULL,
         NULL,
         NULL
         );

  // 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) {
			  //avcodec_align_dimensions2 (pCodecCtx, &pCodecCtx->width, &pCodecCtx->height, pFrameRGB->linesize);

			  // Convert the image from its native format to RGB
			  sws_scale(sws_ctx, (uint8_t const * const *)pFrame->data,
					  pFrame->linesize, 0, pCodecCtx->height,
					  pFrameRGB->data, pFrameRGB->linesize);

			  // 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_frame_free(&pFrameRGB);
  
  // Free the YUV frame
  av_frame_free(&pFrame);
  
  // Close the codecs
  avcodec_close(pCodecCtx);
  avcodec_close(pCodecCtxOrig);

  // Close the video file
  avformat_close_input(&pFormatCtx);
  
  return 0;
}

Tagged with: ffmpeg

Categorized as: Programming