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• FFMPEG compression - Piping vs File [on hold]

  27 avril 2014, par raaj

  Good Day,

  I have written an application that uses the V4L2 driver to capture H264 Raw frames from a C920. The bytes are output into stdout, and can be piped to a file or any program

  What I am trying to do is this :

  ./capture | ffmpeg -f h264 -i - -b 500000 -vcodec copy out.mp4

  The idea is to capture a raw video and convert it to an mp4 file on the fly. It works perfectly, however, the bit rate compression is never applied. It ends up with a file the same size as the raw file (since the camera outputs a compressed h264 file but in raw frames already)

  However, if I was to do this instead

  ./cature > input.raw

  ffmpeg -i out.mp4 -b 500000 output.mp4

  Now, it compresses the file down to a reasonable size. Is there a reason for this ? My only current solution right now is to use an alternative like gstreamer (which has issues with h264) or to figure out the ffmpeg API and see if I can add some code to make it do compression on the frames on the fly.

• Detect if FFmpeg is running or has stopped running

  21 février 2013, par asprin

  I'm using C to scan a directory which contains frames extracted by ffmpeg. Now in the event that the last file is reached during the scan, I need to check for two conditions :

  1. It's the last file as the video duration is over.
  2. It's the last file as ffmpeg terminated abruptly and is no longer able to populate the directory

  My C program workflow is like :

  while(<there exists="exists" files="files" in="in" the="the" directory="directory">)
  
  {
  
     // iterate over them and do something with each frame
  
  }
  
  
  
  // coming out of the loop means no more files available...so I need a if condition
  
  if(<check if="if" ffmpeg="ffmpeg" is="is" stopped="stopped">) // &lt;-- need to know what to put inside the condition
  
  {
  
     // start it again
  
  }
  
  else
  
  {
  
    // video is over, nothing more left to do
  
  }
  
  </check></there>

  I'm thinking I can do this using Process ID of ffmpeg, but how would I get that info ? Any other alternative way of checking if ffpmeg has stopped ?

  Some metadata

  OS : Windows 7
  IDE : Dev C++
  Language Used : C

• Mp3 file not showing in any media player after creating through ffmpeg

  4 mai 2019, par Aashit Shah

  Mp3 file not showing in any application after the mp3 file is saved . After 15 odd minutes it is automatically shown . if i manually change the name from file manager it will be instantly shown . How to solve this problem .

  Uri uri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
  
              String[] projection = {
  
                      MediaStore.Audio.Media.TITLE,
  
                      MediaStore.Audio.Media.DATA,
  
                      MediaStore.Audio.Media.DISPLAY_NAME,
  
                      MediaStore.Audio.Media.DURATION,
  
                      MediaStore.Audio.Media.ALBUM_ID
  
              };
  
              String sortOrder =  MediaStore.Audio.Media.DISPLAY_NAME
  
              Cursor c = getContentResolver().query(uri,projection,null,null,sortOrder);
  
              if(c.moveToFirst())
  
              {
  
                  do {
  
                      String title = c.getString(c.getColumnIndex(MediaStore.Audio.Media.TITLE));
  
                      String data = c.getString(c.getColumnIndex(MediaStore.Audio.Media.DATA));
  
                      String name = c.getString(c.getColumnIndex(MediaStore.Audio.Media.DISPLAY_NAME));
  
                      String duration = c.getString(c.getColumnIndex(MediaStore.Audio.Media.DURATION));
  
                      String albumid= c.getString(c.getColumnIndex(MediaStore.Audio.Media.ALBUM_ID));
  
                      Songs song = new Songs(title,data,name,duration,albumid);
  
                      songs.add(song);
  
                      title1.add(name);
  
                  }while (c.moveToNext());
  
              }

  Output file path :

   Environment.getExternalStorageDirectory()+ "/Trim"+".mp3";

  This is my command :

  "-y","-ss", start,"-i", input_path,"-t", end,"-metadata","title=Trim","-acodec", "copy","-preset", "ultrafast",output_path