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• Import a ffprobe json metadata file into a video file

  26 avril 2020, par CMH

  I've used ffprobe to export the metadata from a video file as a JSON file (metadata.json) and then removed several chapters from the JSON metadata file using jq metadata_clean.json.

  



  I'm now looking for a way to import the JSON metadata file (metadata_clean.json) back into the video file.

  



  I've looked at ffmpeg but it appears to only accept its own standard metadata file format.

  



  Any suggestions appreciated, thanks.

  


• FFMPEG - How to save audio stream detached from video to file whithout transcoding

  15 septembre 2015, par Tony Than

  I try to use fwrite() to save audio stream. But, generated file can not be opened.
  At the same time, I also try to use av_frame_write() to write packet. But, it can not write.
  Please help me with this problem. How to write audio stream without transcoding....

  /* open the input file with generic avformat function */
  
  err = avformat_open_input(input_format_context, filename, NULL, NULL);
  
  if (err < 0) {
  
      return err;
  
  }
  
  
  
  /* If not enough info to get the stream parameters, we decode the
  
     first frames to get it. (used in mpeg case for example) */
  
  ret = avformat_find_stream_info(*input_format_context, 0);
  
  if (ret < 0) {
  
      av_log(NULL, AV_LOG_FATAL, "%s: could not find codec parameters\n", filename);
  
      return ret;
  
  }
  
  
  
  /* dump the file content */
  
  av_dump_format(*input_format_context, 0, filename, 0);
  
  
  
  for (size_t i = 0; i < (*input_format_context)->nb_streams; i++) {
  
      AVStream *st = (*input_format_context)->streams[i];
  
      if (st->codec->codec_type == AVMEDIA_TYPE_AUDIO) {
  
          FILE *file = NULL;
  
          file = fopen("C:\\Users\\MyPC\\Downloads\\test.aac", "wb");
  
          AVPacket reading_packet;
  
          av_init_packet(&reading_packet);
  
          while (av_read_frame(*input_format_context, &reading_packet) == 0) {
  
              if (reading_packet.stream_index == (int) i) {
  
              fwrite(reading_packet.data, 1, reading_packet.size, file);
  
              }
  
              av_free_packet(&reading_packet);   
  
          }
  
          fclose(file);
  
  
  
          return 0;
  
      }
  
  }

• Converting mp4 to ogg file format results in a large file

  26 avril 2014, par parags

  I have a MP4 file of 83MB (converted from MOV of about 772MB using FFMPEG).
  For the file to be playable from all browsers from HTML5 video tag, I am converting the MP4 to OGG, again using FFMPEG command

  ffmpeg -i object-creation.mp4 -acodec libvorbis -vcodec libtheora -q:v 5 -q:a 5 object-creation-3.ogg

  The result of the above command is a very large OGG file of around 500 MB. I would certainly not want to upload such huge files to Amazon S3 (which I am using for storage, and distribution).

  Is there something I am missing here ? Is the file not compressed enough ?

  Is it possible to have the resultant file of somewhat manageable size like 80-100 MB without any appreciable loss in quality over what is seen in MP4 format ? Why is it that even the source file is 83MB, the resultant file is too big in comparison ?

  Thanks
  Parag