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• 24kHz audio file problem : unsupported bitrate 64000

  28 novembre 2018, par R. Vait

  I use alexa audio tags a lot. I know that now audio tags support 24kHz audio files so tried converting my audio files from 16kHz. I used the provided command in the docs to do so :

  ffmpeg -i  -ac 2 -codec:a libmp3lame -b:a 48k -ar 24000 

  But when I try to play this file, I get an invalid response error, saying : Error: The audio is of an unsupported bitrate 64000. By looking into file details I clearly see, that bitrate is 48kbps and sample rate is 24kHz. I don’t see any value where it would say 64 or anything close to it.

  If I encode my file back to 16kHz it plays fine again.

  It seems that there is a problem with this command, because if I encode my files using audacity, they work with 24kHz. I still would prefer to use ffmpeg, because I need to encode a lot of files.

  I am asking, not about file format, format is correct. I need files in 24kHz sample rate and that is what causes issues. I saw another question about similar problem and others having the discussion there about sample rates, but no one was able to encode file to be 24kHz using ffmpeg.

  Did anyone had any luck on encoding files to 24kHz using ffmpeg ?

• Transcode video with php ffmpeg library

  27 juin 2019, par dev

  I need to upload video in 3 formate/resolution as 360p, 480p, 720p.

  After some research i got to know that some paid service are there like Amazone Elastic Transcoder . But i want to do with open source so i found FFMPEG.

  Also i want to upload video on Amazon s3 after transcode and video are in big size like video may contain 1GB size.

  I got php library for FFMPEG Library Link

  I have installed ffmpeg and it successfully generate new video. But i cannot figure out that how can i generate different formate/resolution as 360p, 480p, 720p.

  My sample Code is

          error_reporting(E_ALL);
  
          ini_set('display_errors', 1);
  
  
  
          require 'vendor/autoload.php';
  
  
  
          //$ffmpeg = FFMpeg\FFMpeg::create();
  
          $video = $ffmpeg->open('assets/small.mp4');
  
          $video
  
              ->filters()
  
              ->resize(new FFMpeg\Coordinate\Dimension(320, 240))
  
              ->synchronize();
  
          $video
  
              ->frame(FFMpeg\Coordinate\TimeCode::fromSeconds(2))
  
              ->save('assets/frame.jpg');
  
  
  
          $format = new FFMpeg\Format\Video\X264();
  
          $format->setAudioCodec("libmp3lame");
  
  
  
          $video->save($format, 'assets/new.mp4');

  Can anyone suggest me any way that how can i achieve this ??

• Can you think of a reason why windows might not enable audio if noone is logged in ?

  3 juillet 2017, par Caius Jard

  I’m having a bizarre problem with some virtual servers created to record podcasts. They run on amazon AWS as windows server 2012 instances and a small c# app tells FFMPEG to do the heavy lifting of capturing from the virtual screen and reading from the virtual sound card (Virtual Audio Cable : https://en.wikipedia.org/wiki/Virtual_Audio_Cable) via DirectShow filters

  The problem I have is if I leave the machine to do its stuff unattended, the recordings are sometimes silent. If I log in via VNC and watch it doing its stuff the audio is recorded just fine. All other aspects of the test op are the same, and the virtual machine is shut down between successive recordings so each one should theoretically be a clean slate. The app runs under a logged in session (hence the use of VNC rather than RDP)

  I’m now wondering if there is some optimisation of the windows sound engine whereby it doesn’t bother playing audio if it thinks noone is listening. The confusing thing to me is that not every virtual machine suffers these problems ; some of them record fine (and they’re all created from the same seed virtual hard disk image) in unattended mode

  I’m asking this question with the aim of getting together a list of things I can check/look into/debug.. I don’t have much knowledge of how MME/DirectSound/WASAPI work internally...