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• How to save data of packet.data in ffmpeg using c language ?

  10 juin 2015, par patrick

  I’m try to build an app in c that extract audio from video and save it as audio file. I write the below code. I’m able to extract the audio but now the problem is how to save it. Thanks in advance.

  My code is :

  int main(int argc, char *argv[]) {
  
  AVFormatContext *pFormatCtx = NULL;
  
  int             i;
  
  AVCodecContext  *pCodecCtx = NULL;
  
  AVCodec         *pCodec = NULL;
  
  AVFrame         *pFrame = NULL; 
  
  AVPacket        packet;
  
  
  
  AVDictionary    *optionsDict = NULL;
  
  
  
  if(argc < 2) {
  
  printf("Please provide a movie file\n");
  
  return -1;
  
  }
  
  av_register_all();
  
  if(avformat_open_input(&pFormatCtx, argv[1], NULL, NULL)!=0)
  
  return -1; 
  
  
  
  if(avformat_find_stream_info(pFormatCtx, NULL)<0)
  
  return -1; 
  
  
  
  av_dump_format(pFormatCtx, 0, argv[1], 0);
  
  
  
  int audioStream=-1;
  
  for(i=0; inb_streams; i++)
  
      if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_AUDIO) {
  
          audioStream=i;
  
          break;
  
      }
  
  if(audioStream==-1)
  
  return -1; 
  
  
  
  pCodecCtx=pFormatCtx->streams[audioStream]->codec;
  
  
  
  pCodec=avcodec_find_decoder(pCodecCtx->codec_id);
  
  if(pCodec==NULL) {
  
      fprintf(stderr, "Unsupported codec!\n");
  
      return -1; // Codec not found
  
  }
  
  
  
  if(avcodec_open2(pCodecCtx, pCodec, &optionsDict)<0)
  
  return -1; 
  
  
  
  pFrame=avcodec_alloc_frame();
  
  packet.data = NULL;
  
  packet.size = 0;
  
  
  
  while(av_read_frame(pFormatCtx, &packet)>=0) {
  
      int got_frame = 0;
  
      int ret = avcodec_decode_audio4(pCodecCtx, pFrame, &got_frame, &packet);
  
      if(got_frame && packet.stream_index==audioStream) {
  
          //save result but how???
  
      }
  
      av_free_packet(&packet);
  
  }
  
  av_free(pFrame);
  
  avcodec_close(pCodecCtx);
  
  avformat_close_input(&pFormatCtx);
  
  return 0;
  
  }

• Android-How to pass back frames from FFmpeg back to Android

  23 octobre 2013, par yarin

  It is an architecture question-i am really interesting about the answer

  I building an app with following goals :

  1.record video with effect in real time(using FFmpeg)

  2.display the customized video in real time for the user while he recording

  So,after 1 month of working...i decide to remember that goal number 2 is worth to thinking about :)
  I have a ready skeleton app that record video with effect in real time.
  but i have to preview this customized frame back to the user.

  My options (and this is my question) :

  1.Each frame that pass from onPreviewFrame(byte[] video_frame_data, Camera camera) to ffmpeg with JNI to encode-will sending back to android through the same JNI after i apply the effects(i mean : onPreviewFrame->JNI to FFMPEG->immediately apply effect->send the costumed frame back to android side for display->encode the costumed frame).

  Advantages : it is look like is the most easy to use.

  Disadvantages : use the JNI twice or the passing back the frame could consume time(i really don't now if it really big price to pay,cuz it is only byte array or int array per frame to send to android side)

  2.I heard about openGL on ndk,but i think that the surface it self created on the android side-so is it really going to be better ?
  i prefer to use other surface that i using now in java

  3.Create an video player on FFmpeg to preview each customized frame in real time.

  Thank for your helping,i hope that the first solution is available and not consume to much expensive time in terms of real time processing

• ffmpeg : how to save h264 raw data as mp4 file

  15 avril 2016, par monkid

  I encode h264 data by libavcodec.
  ex.

  while (1) {
  
    ...
  
    avcodec_encode_video(pEnc->pCtx, OutBuf, ENC_OUTSIZE, pEnc->pYUVFrame);
  
    ...
  
  }

  If I directly save OutBuf data as a .264 file, it can`t be play by player. Now I want to save OutBuf

  as a mp4 file. Anyone know how to do this by ffmpeg lib ? thanks.