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#!/usr/bin/env python3
#
# Copyright 2022 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
import numpy as np
import scipy.signal as signal
import scipy.io.wavfile as wavfile
import struct
import argparse
import build.lc3 as lc3
import tables as T, appendix_c as C
import mdct, energy, bwdet, sns, tns, spec, ltpf
import bitstream
### ------------------------------------------------------------------------ ###
class Decoder:
def __init__(self, dt_ms, sr_hz):
dt = { 7.5: T.DT_7M5, 10: T.DT_10M }[dt_ms]
sr = { 8000: T.SRATE_8K , 16000: T.SRATE_16K, 24000: T.SRATE_24K,
32000: T.SRATE_32K, 48000: T.SRATE_48K }[sr_hz]
self.sr = sr
self.ne = T.NE[dt][sr]
self.ns = T.NS[dt][sr]
self.mdct = mdct.MdctInverse(dt, sr)
self.bwdet = bwdet.BandwidthDetector(dt, sr)
self.spec = spec.SpectrumSynthesis(dt, sr)
self.tns = tns.TnsSynthesis(dt)
self.sns = sns.SnsSynthesis(dt, sr)
self.ltpf = ltpf.LtpfSynthesis(dt, sr)
def decode(self, data):
b = bitstream.BitstreamReader(data)
bw = self.bwdet.get_bw(b)
if bw > self.sr:
raise ValueError('Invalid bandwidth indication')
self.spec.load(b)
self.tns.load(b, bw, len(data))
pitch = b.read_bit()
self.sns.load(b)
if pitch:
self.ltpf.load(b)
else:
self.ltpf.disable()
x = self.spec.decode(b, bw, len(data))
return (x, bw, pitch)
def synthesize(self, x, bw, pitch, nbytes):
x = self.tns.run(x, bw)
x = self.sns.run(x)
x = np.append(x, np.zeros(self.ns - self.ne))
x = self.mdct.run(x)
x = self.ltpf.run(x, len(data))
return x
def run(self, data):
(x, bw, pitch) = self.decode(data)
x = self.synthesize(x, bw, pitch, len(data))
return x
### ------------------------------------------------------------------------ ###
def check_appendix_c(dt):
ok = True
dec_c = lc3.setup_decoder(int(T.DT_MS[dt] * 1000), 16000)
for i in range(len(C.BYTES_AC[dt])):
pcm = lc3.decode(dec_c, bytes(C.BYTES_AC[dt][i]))
ok = ok and np.max(np.abs(pcm - C.X_HAT_CLIP[dt][i])) < 1
return ok
def check():
ok = True
for dt in range(T.NUM_DT):
ok = ok and check_appendix_c(dt)
return ok
### ------------------------------------------------------------------------ ###
if __name__ == "__main__":
parser = argparse.ArgumentParser(description='LC3 Decoder Test Framework')
parser.add_argument('lc3_file',
help='Input bitstream file', type=argparse.FileType('r'))
parser.add_argument('--pyout',
help='Python output file', type=argparse.FileType('w'))
parser.add_argument('--cout',
help='C output file', type=argparse.FileType('w'))
args = parser.parse_args()
### File Header ###
f_lc3 = open(args.lc3_file.name, 'rb')
header = struct.unpack('=HHHHHHHI', f_lc3.read(18))
if header[0] != 0xcc1c:
raise ValueError('Invalid bitstream file')
if header[4] != 1:
raise ValueError('Unsupported number of channels')
sr_hz = header[2] * 100
bitrate = header[3] * 100
nchannels = header[4]
dt_ms = header[5] / 100
f_lc3.seek(header[1])
### Setup ###
dec = Decoder(dt_ms, sr_hz)
dec_c = lc3.setup_decoder(int(dt_ms * 1000), sr_hz)
pcm_c = np.empty(0).astype(np.int16)
pcm_py = np.empty(0).astype(np.int16)
### Decoding loop ###
nframes = 0
while True:
data = f_lc3.read(2)
if len(data) != 2:
break
if nframes >= 1000:
break
(frame_nbytes,) = struct.unpack('=H', data)
print('Decoding frame %d' % nframes, end='\r')
data = f_lc3.read(frame_nbytes)
x = dec.run(data)
pcm_py = np.append(pcm_py,
np.clip(np.round(x), -32768, 32767).astype(np.int16))
x_c = lc3.decode(dec_c, data)
pcm_c = np.append(pcm_c, x_c)
nframes += 1
print('done ! %16s' % '')
### Terminate ###
if args.pyout:
wavfile.write(args.pyout.name, sr_hz, pcm_py)
if args.cout:
wavfile.write(args.cout.name, sr_hz, pcm_c)
### ------------------------------------------------------------------------ ###
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