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• Downloading, transcoding, then streaming on the fly with VLC

  12 avril 2012, par Alexis K

  I need to download a file from a web service the immediatley extract the audio, then transcode it, then stream it out.

  When I use :

  vlc.exe URL :sout=#transcode{acodec=mp3,ab=128,channels=2,samplerate=44100}:http{dst=:8080/audio.mp3}

  it is really choppy when I listen to it on the other computer. What is strange also is that for some YouTube links, the above works well, but for others it dosen't work well. I am not sure why this is.

  However, when I download the audio first, then stream it out, like this
  vlc.exe "song.mp3" :sout=#transcode{acodec=mp3,ab=128,channels=2,samplerate=44100}:http{dst=:8080/audio.mp3}

  it works well. The issue is I can't always download the song before hand (long pod casts or internet radio...).

  Is there a command or VLC optimization that I can use to help remedy this situation ? Or another program that would be good ?

• Android - Decoding via a pipe will not work : Could not find an ffmpeg binary for your system

  28 août 2017, par Daniele

  I’m trying to use TarsosDSP for real time pitch shifting on Android.

  This is my code :

  Uri song;
  
  // initialized in another method
  
  
  
  double rate = 1.0;
  
          RateTransposer rateTransposer;
  
          AudioDispatcher dispatcher;
  
          WaveformSimilarityBasedOverlapAdd wsola;
  
  
  
          dispatcher = AudioDispatcherFactory.fromPipe(getRealPathFromUri(song), 44100, 5000, 2500);
  
          rateTransposer = new RateTransposer(rate);
  
          wsola = new WaveformSimilarityBasedOverlapAdd(WaveformSimilarityBasedOverlapAdd.Parameters
  
                  .musicDefaults(rate, 44100));
  
  
  
          wsola.setDispatcher(dispatcher);
  
          dispatcher.addAudioProcessor(wsola);
  
          dispatcher.addAudioProcessor(rateTransposer);
  
          dispatcher.addAudioProcessor(new AndroidAudioPlayer(dispatcher.getFormat()));
  
          dispatcher.setZeroPadFirstBuffer(true);
  
          dispatcher.setZeroPadLastBuffer(true);

  I get an error here

  dispatcher = AudioDispatcherFactory.fromPipe(getRealPathFromUri(song), 44100, 5000, 2500);

  Decoding via a pipe will not work : Could not find an ffmpeg binary for
  your system

  Why does this happen and how should I fix it ?

  EDIT :

  As far as I was able to understand it’s because ffmpeg isn’t integrated within the app. I looked for a guide here on SO but I couldn’t find any updated one. Using NDK r15c and FFmpeg 3.3.3

• Adding audio to an OpenCV video

  21 février 2019, par pcrunn

  I’m trying to make a script that automates the process of making a video and i’m stuck on the part that i add the audio, I’m not sure if i’ll need to use ffmpeg for that and if so, i’m not sure how to use it the proper way to work with OpenCV (Which I use for rendering the video).

  Thanks for your time, Here is my current code (that I found from a website)

  # Creating the video... The worst part. Literally
  
  
  
  width = 1920
  
  height = 1080
  
  FPS = 30
  
  length = 0
  
  
  
  for song in songs:
  
      length+=song.info.length
  
  
  
  length = int(length)
  
  
  
  fourcc = VideoWriter_fourcc(*'MP42')
  
  video = VideoWriter('result.avi', fourcc, float(FPS), (width, height))
  
  for _ in range(FPS*length):
  
      frame = np.random.randint(0, 256,
  
                                (height, width, 3),
  
                                dtype=np.uint8)
  
      video.write(frame)
  
  
  
  video.release()