peterf@2: #!/usr/bin/env python
peterf@2: '''CREATED:2013-12-08 14:28:34 by Brian McFee <brm2132@columbia.edu>
peterf@2: 
peterf@2: Demonstration of phase vocoder time stretching.
peterf@2: '''
peterf@2: from __future__ import print_function
peterf@2: 
peterf@2: import argparse
peterf@2: import sys
peterf@2: import librosa
peterf@2: 
peterf@2: 
peterf@2: def stretch_demo(input_file, output_file, speed):
peterf@2:     '''Phase-vocoder time stretch demo function.
peterf@2: 
peterf@2:     :parameters:
peterf@2:       - input_file : str
peterf@2:           path to input audio
peterf@2:       - output_file : str
peterf@2:           path to save output (wav)
peterf@2:       - speed : float > 0
peterf@2:           speed up by this factor
peterf@2:     '''
peterf@2: 
peterf@2:     # 1. Load the wav file, resample
peterf@2:     print('Loading ', input_file)
peterf@2: 
peterf@2:     y, sr = librosa.load(input_file)
peterf@2: 
peterf@2:     # 2. Time-stretch through effects module
peterf@2:     print('Playing back at {:3.0f}% speed'.format(speed * 100))
peterf@2: 
peterf@2:     y_stretch = librosa.effects.time_stretch(y, speed)
peterf@2: 
peterf@2:     print('Saving stretched audio to: ', output_file)
peterf@2:     librosa.output.write_wav(output_file, y_stretch, sr)
peterf@2: 
peterf@2: 
peterf@2: def process_arguments(args):
peterf@2:     '''Argparse function to get the program parameters'''
peterf@2: 
peterf@2:     parser = argparse.ArgumentParser(description='Time stretching example')
peterf@2: 
peterf@2:     parser.add_argument('input_file',
peterf@2:                         action='store',
peterf@2:                         help='path to the input file (wav, mp3, etc)')
peterf@2: 
peterf@2:     parser.add_argument('output_file',
peterf@2:                         action='store',
peterf@2:                         help='path to the stretched output (wav)')
peterf@2: 
peterf@2:     parser.add_argument('-s', '--speed',
peterf@2:                         action='store',
peterf@2:                         type=float,
peterf@2:                         default=2.0,
peterf@2:                         required=False,
peterf@2:                         help='speed')
peterf@2: 
peterf@2:     return vars(parser.parse_args(args))
peterf@2: 
peterf@2: 
peterf@2: if __name__ == '__main__':
peterf@2:     # get the parameters
peterf@2:     parameters = process_arguments(sys.argv[1:])
peterf@2: 
peterf@2:     # Run the HPSS code
peterf@2:     stretch_demo(parameters['input_file'],
peterf@2:                  parameters['output_file'],
peterf@2:                  parameters['speed'])