source: python/demos/demo_timestretch.py @ 3a004bbc

feature/autosinkfeature/cnnfeature/cnn_orgfeature/constantqfeature/crepefeature/crepe_orgfeature/pitchshiftfeature/pydocstringsfeature/timestretchfix/ffmpeg5sampleryinfft+
Last change on this file since 3a004bbc was 8489d7b, checked in by Paul Brossier <piem@piem.org>, 8 years ago

python/demos/demo_timestretch*: use to yield an integer (closes #71)

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1#! /usr/bin/env python
2
3# Implementation of the timescale algorithm according to Dan Ellis, *A Phase
4# Vocoder in Matlab*.  http://www.ee.columbia.edu/~dpwe/resources/matlab/pvoc/
5
6# This file follows the original implementation, with analysis in a first pass,
7# and synthesis in a second pass.
8
9import sys
10from aubio import source, sink, pvoc, cvec
11from aubio import unwrap2pi, float_type
12import numpy as np
13
14win_s = 1024
15hop_s = win_s // 8 # 87.5 % overlap
16
17warmup = win_s // hop_s - 1
18
19if len(sys.argv) < 3:
20    print("Usage: {:s} <source_filename> <output_filename> <rate> [samplerate]".format(sys.argv[0]))
21    print("""Examples:
22    # twice faster
23    {0} track_01.mp3 track_01_faster.wav 2.0
24    # twice slower
25    {0} track_02.flac track_02_slower.wav 0.5
26    # one and a half time faster, resampling first the input to 22050
27    {0} track_02.flac track_02_slower.wav 1.5 22050""".format(sys.argv[0]))
28    sys.exit(1)
29
30source_filename = sys.argv[1]
31output_filename = sys.argv[2]
32rate = float(sys.argv[3])
33
34samplerate = 0 if len(sys.argv) < 5 else int(sys.argv[4])
35source_in = source(source_filename, samplerate, hop_s)
36samplerate = source_in.samplerate
37p = pvoc(win_s, hop_s)
38
39# allocate memory to store norms and phases
40n_blocks = source_in.duration // hop_s + 1
41# adding an empty frame at end of spectrogram
42norms  = np.zeros((n_blocks + 1, win_s // 2 + 1), dtype = float_type)
43phases = np.zeros((n_blocks + 1, win_s // 2 + 1), dtype = float_type)
44
45block_read = 0
46while True:
47    # read from source
48    samples, read = source_in()
49    # compute fftgrain
50    spec = p(samples)
51    # store current grain
52    norms[block_read] = spec.norm
53    phases[block_read] = spec.phas
54    # until end of file
55    if read < hop_s: break
56    # increment block counter
57    block_read += 1
58
59# just to make sure
60#source_in.close()
61
62sink_out = sink(output_filename, samplerate)
63
64# interpolated time steps (j = alpha * i)
65steps = np.arange(0, n_blocks, rate, dtype = float_type)
66# initial phase
67phas_acc = phases[0]
68# excepted phase advance in each bin
69phi_advance = np.linspace(0, np.pi * hop_s, win_s / 2 + 1).astype (float_type)
70
71new_grain = cvec(win_s)
72
73for (t, step) in enumerate(steps):
74
75    frac = 1. - np.mod(step, 1.0)
76    # get pair of frames
77    t_norms = norms[int(step):int(step+2)]
78    t_phases = phases[int(step):int(step+2)]
79
80    # compute interpolated frame
81    new_grain.norm = frac * t_norms[0] + (1. - frac) * t_norms[1]
82    new_grain.phas = phas_acc
83    #print t, step, new_grain.norm
84    #print t, step, phas_acc
85
86    # psola
87    samples = p.rdo(new_grain)
88    if t > warmup: # skip the first few frames to warm up phase vocoder
89        # write to sink
90        sink_out(samples, hop_s)
91
92    # calculate phase advance
93    dphas = t_phases[1] - t_phases[0] - phi_advance
94    # unwrap angle to [-pi; pi]
95    dphas = unwrap2pi(dphas)
96    # cumulate phase, to be used for next frame
97    phas_acc += phi_advance + dphas
98
99for t in range(warmup + 1): # purge the last frames from the phase vocoder
100    new_grain.norm[:] = 0
101    new_grain.phas[:] = 0
102    samples = p.rdo(new_grain)
103    sink_out(samples, read if t == warmup else hop_s)
104
105# just to make sure
106#sink_out.close()
107
108format_out = "read {:d} blocks from {:s} at {:d}Hz and rate {:f}, wrote {:d} blocks to {:s}"
109print (format_out.format(block_read, source_filename, samplerate, rate,
110    len(steps), output_filename))
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