Increase expected size of output sample buffer, to correctly handle input termination. - #22

#!/usr/bin/env python3

import numpy as np
import samplerate

# Synthesize data
fs = 1000.
t = np.arange(fs * 2) / fs
input_data = np.sin(2 * np.pi * 5 * t)

# Simple API
ratio = 1.5
converter = 'sinc_best'  # or 'sinc_fastest', ...
output_data_simple = samplerate.resample(input_data, ratio, converter)

# Full API
resampler = samplerate.Resampler(converter, channels=1)
output_data_full = resampler.process(input_data, ratio, end_of_input=True)

# The result is the same for both APIs.
assert np.allclose(output_data_simple, output_data_full)

# Full API, chunked
resampler.reset()
output_data_chunked = np.array([], dtype=np.float32)
chunk_size = 100
for i in range(0, len(input_data), chunk_size):
    chunk = input_data[i : i+chunk_size]
    resampled = resampler.process(chunk, ratio, end_of_input=False)
    print(f"{len(chunk)} input samples --> {len(resampled)} output samples")
    output_data_chunked = np.concatenate((output_data_chunked, resampled))
print(f"{len(output_data_chunked)} output samples before input is terminated")

# Terminate with an empty final chunk.
resampled = resampler.process([], ratio, end_of_input=True)
print(f"input terminated --> {len(resampled)} output samples")
output_data_chunked = np.concatenate((output_data_chunked, resampled))
print(f"{len(output_data_chunked)} output samples after input is terminated")

# The result is the same for all APIs.
assert np.allclose(output_data_chunked, output_data_simple)

# See `samplerate.CallbackResampler` for the Callback API, or
# `examples/play_modulation.py` for an example.