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• Reduce volume when the watermark playing using FFMPEG

  2 novembre 2020, par Mouaad Abdelghafour AITALI

  I'm using the createWaterMark method to create an audio watermark that play 3 times, the injectWaterMark inject the created watermark into the original audio file, everything works fine, but I would like to reduce the volume of the original audio file when the watermark start playing.

  


   public static String createWaterMark(String inputPath, String outputPath, int duration) {
        return "-y -i " + inputPath + " -af apad -t " + duration / 3 + " " + outputPath;
    }

    public static String injectWaterMark(String inputPath, String waterMarkPath, String outputPath) {
        return "-y -i " + inputPath + " -filter_complex amovie=" + waterMarkPath + ":loop=0,asetpts=N/SR/TB[beep];[0][beep]amix=duration=shortest,volume=2 " + outputPath;
    }


  


  Thank you

  


• How to read realtime microphone audio volume in python and ffmpeg or similar

  20 octobre 2016, par Ryan Martin

  I’m trying to read, in near-realtime, the volume coming from the audio of a USB microphone in Python.

  I have the pieces, but can’t figure out how to put it together.

  If I already have a .wav file, I can pretty simply read it using wavefile :

  from wavefile import WaveReader
  
  
  
  with WaveReader("/Users/rmartin/audio.wav") as r:
  
      for data in r.read_iter(size=512):
  
          left_channel = data[0]
  
          volume = np.linalg.norm(left_channel)
  
          print volume

  This works great, but I want to process the audio from the microphone in real-time, not from a file.

  So my thought was to use something like ffmpeg to PIPE the real-time output into WaveReader, but my Byte knowledge is somewhat lacking.

  import subprocess
  
  import numpy as np
  
  
  
  command = ["/usr/local/bin/ffmpeg",
  
              '-f', 'avfoundation',
  
              '-i', ':2',
  
              '-t', '5',
  
              '-ar', '11025',
  
              '-ac', '1',
  
              '-acodec','aac', '-']
  
  
  
  pipe = subprocess.Popen(command, stdout=subprocess.PIPE, bufsize=10**8)
  
  stdout_data = pipe.stdout.read()
  
  audio_array = np.fromstring(stdout_data, dtype="int16")
  
  
  
  print audio_array

  That looks pretty, but it doesn’t do much. It fails with a [NULL @ 0x7ff640016600] Unable to find a suitable output format for ’pipe :’ error.

  I assume this is a fairly simple thing to do given that I only need to check the audio for volume levels.

  Anyone know how to accomplish this simply ? FFMPEG isn’t a requirement, but it does need to work on OSX & Linux.

• How to increase de volume of an interval of an mp3 file with ffmpeg ?

  30 avril 2017, par user2128078

  I’d like to increase de volume of an interval of and mp3 file, i.e. from 20s to 30s increase in 15%. I’m using ffmpeg.

  Thank you so much for your help !

  Regards,

  Raul.