Modify and save audio files with afplay [closed]

I discovered the command line program afplay and it can turn a audio file up / down very quickly and I want this file to be saved afterwards.

I don't know of any program like this that can change details so quickly.

I've tried this, but it doesn't work. Any ideas?

afplay audio.mp3 -v 2 > new_audio.mp3

Solution 1:

afplay options are for playback of the audio file and redirecting as you have in the command afplay audio.mp3 -v 2 > new_audio.mp3 just creates a zero length file because the output afplay goes to the sound system, not stdout for redirection.

The Audio File Play in the help output kind of says it all.

If you want to modify/create audio files, then you'll need to use program designed for that as afplay is designed for playback.

% afplay -h

    Audio File Play
    Version: 2.0
    Copyright 2003-2013, Apple Inc. All Rights Reserved.
    Specify -h (-help) for command options

Usage:
afplay [option...] audio_file

Options: (may appear before or after arguments)
  {-v | --volume} VOLUME
    set the volume for playback of the file
  {-h | --help}
    print help
  { --leaks}
    run leaks analysis
  {-t | --time} TIME
    play for TIME seconds
  {-r | --rate} RATE
    play at playback rate
  {-q | --rQuality} QUALITY
    set the quality used for rate-scaled playback (default is 0 - low quality, 1 - high quality)
  {-d | --debug}
    debug print output
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