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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 | + | |
| 9 | +import sys | |
| 10 | +from aubio import source, sink, pvoc, mfcc, cvec | |
| 11 | +from aubio import unwrap2pi, float_type | |
| 12 | +import numpy as np | |
| 13 | + | |
| 14 | +win_s = 1024 | |
| 15 | +hop_s = win_s / 8 # 87.5 % overlap | |
| 16 | + | |
| 17 | +warmup = win_s // hop_s - 1 | |
| 18 | + | |
| 19 | +if 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 | + | |
| 30 | +source_filename = sys.argv[1] | |
| 31 | +output_filename = sys.argv[2] | |
| 32 | +rate = float(sys.argv[3]) | |
| 33 | + | |
| 34 | +samplerate = 0 if len(sys.argv) < 5 else int(sys.argv[4]) | |
| 35 | +source_in = source(source_filename, samplerate, hop_s) | |
| 36 | +samplerate = source_in.samplerate | |
| 37 | +p = pvoc(win_s, hop_s) | |
| 38 | + | |
| 39 | +# allocate memory to store norms and phases | |
| 40 | +n_blocks = source_in.duration // hop_s + 1 | |
| 41 | +# adding an empty frame at end of spectrogram | |
| 42 | +norms = np.zeros((n_blocks + 1, win_s // 2 + 1), dtype = float_type) | |
| 43 | +phases = np.zeros((n_blocks + 1, win_s // 2 + 1), dtype = float_type) | |
| 44 | + | |
| 45 | +block_read = 0 | |
| 46 | +while 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 | + | |
| 62 | +sink_out = sink(output_filename, samplerate) | |
| 63 | + | |
| 64 | +# interpolated time steps (j = alpha * i) | |
| 65 | +steps = np.arange(0, n_blocks, rate, dtype = float_type) | |
| 66 | +# initial phase | |
| 67 | +phas_acc = phases[0] | |
| 68 | +# excepted phase advance in each bin | |
| 69 | +phi_advance = np.linspace(0, np.pi * hop_s, win_s / 2 + 1).astype (float_type) | |
| 70 | + | |
| 71 | +new_grain = cvec(win_s) | |
| 72 | + | |
| 73 | +for (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 | + | |
| 99 | +for 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 | + | |
| 108 | +format_out = "read {:d} blocks from {:s} at {:d}Hz and rate {:f}, wrote {:d} blocks to {:s}" | |
| 109 | +print (format_out.format(block_read, source_filename, samplerate, rate, | |
| 110 | + len(steps), output_filename)) | |