mirror of
https://github.com/DJ2LS/FreeDATA
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100 lines
2.9 KiB
Python
100 lines
2.9 KiB
Python
#!/usr/bin/env python3
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# -*- coding: utf-8 -*-
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#
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# Unit test for FreeDV API resampler functions, from
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# codec2/unittest/t48_8_short.c - generate a sine wave at 8 KHz,
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# upsample to 48 kHz, add an interferer, then downsample back to 8 kHz
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#
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# You can listen to the output files with:
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#
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# aplay -f S16_LE in8.raw
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# aplay -r 48000 -f S16_LE out48.raw
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# aplay -f S16_LE out8.raw
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#
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# They should sound like clean sine waves
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import ctypes
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from ctypes import *
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import pathlib
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import argparse
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import sys
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sys.path.insert(0,'../..')
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from tnc import codec2
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import numpy as np
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# dig some constants out
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FDMDV_OS_48 = codec2.api.FDMDV_OS_48
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FDMDV_OS_TAPS_48K = codec2.api.FDMDV_OS_TAPS_48K
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FDMDV_OS_TAPS_48_8K = codec2.api.FDMDV_OS_TAPS_48_8K
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N8 = int(180) # processing buffer size at 8 kHz
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N48 = int(N8*FDMDV_OS_48) # processing buffer size at 48 kHz
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MEM8 = FDMDV_OS_TAPS_48_8K # 8kHz signal filter memory
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MEM48 = FDMDV_OS_TAPS_48K # 48kHz signal filter memory
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FRAMES = int(50) # number of frames to test
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FS8 = 8000
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FS48 = 48000
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AMP = 16000 # sine wave amplitude
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FTEST8 = 800 # input test frequency at FS=8kHz
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FINTER48 = 10000 # interferer frequency at FS=48kHz
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# Due to the design of these resamplers, the processing buffer (at 8kHz)
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# must be an integer multiple of oversampling ratio
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assert N8 % FDMDV_OS_48 == 0
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# time indexes, we advance every frame
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t = 0
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t1 = 0
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# output files to listen to/evaluate result
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fin8 = open("in8.raw", mode='wb')
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f48 = open("out48.raw", mode='wb')
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fout8 = open("out8.raw", mode='wb')
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resampler = codec2.resampler()
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for f in range(FRAMES):
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sine_in8k = (AMP*np.cos(2*np.pi*np.arange(t,t+N8)*FTEST8/FS8)).astype(np.int16)
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t += N8
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sine_in8k.tofile(fin8)
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sine_out48k = resampler.resample8_to_48(sine_in8k)
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sine_out48k.tofile(f48)
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# add interfering sine wave (down sampling filter should remove)
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sine_in48k = (sine_out48k + (AMP/2)*np.cos(2*np.pi*np.arange(t1,t1+N48)*FINTER48/FS48)).astype(np.int16)
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t1 += N48
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sine_out8k = resampler.resample48_to_8(sine_in48k)
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sine_out8k.tofile(fout8)
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fin8.close()
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f48.close()
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fout8.close()
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# Automated test evaluation --------------------------------------------
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# The input and output signals will not be time aligned due to the filter
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# delays, so compare the magnitude spectrum
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in8k = np.fromfile("in8.raw", dtype=np.int16)
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out8k = np.fromfile("out8.raw", dtype=np.int16)
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assert len(in8k) == len(out8k)
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n = len(in8k)
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h = np.hanning(len(in8k))
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S1 = np.abs(np.fft.fft(in8k * h))
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S2 = np.abs(np.fft.fft(out8k * h))
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error = S1-S2
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error_energy = np.dot(error,error)
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ratio = error_energy/np.dot(S1,S1)
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ratio_dB = 10*np.log10(ratio);
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print("ratio_dB: %4.2f" % (ratio_dB));
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threshdB = -40
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if ratio_dB < threshdB:
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print("PASS")
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else:
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print("FAIL")
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