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#
# 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 lc3
import tables as T, appendix_c as C
BW_START = [
[ [], [ 24 ], [ 24, 35 ], [ 24, 33, 39 ], [ 22, 31, 37, 41 ] ],
[ [], [ 39 ], [ 35, 47 ], [ 34, 44, 50 ], [ 32, 42, 48, 52 ] ],
[ [], [ 51 ], [ 45, 58 ], [ 42, 53, 60 ], [ 40, 51, 57, 61 ] ],
[ [], [ 53 ], [ 47, 59 ], [ 44, 54, 60 ], [ 41, 51, 57, 61 ] ]
]
BW_STOP = [
[ [], [ 34 ], [ 32, 39 ], [ 31, 38, 42 ], [ 29, 35, 40, 43 ] ],
[ [], [ 49 ], [ 44, 51 ], [ 42, 49, 53 ], [ 40, 46, 51, 54 ] ],
[ [], [ 63 ], [ 55, 63 ], [ 51, 58, 63 ], [ 48, 55, 60, 63 ] ],
[ [], [ 63 ], [ 56, 63 ], [ 52, 59, 63 ], [ 49, 55, 60, 63 ] ]
]
TQ = [ 20, 10, 10, 10 ]
TC = [ 15, 23, 20, 20 ]
L = [ [ 4, 4, 3, 1 ], [ 4, 4, 3, 1 ],
[ 4, 4, 3, 2 ], [ 4, 4, 3, 1 ] ]
### ------------------------------------------------------------------------ ###
class BandwidthDetector:
def __init__(self, dt, sr):
self.dt = dt
self.sr = sr
def run(self, e):
dt = self.dt
sr = self.sr
### Stage 1, determine bw0 candidate
bw0 = 0
for bw in range(sr):
i0 = BW_START[dt][sr][bw]
i1 = BW_STOP[dt][sr][bw]
if np.mean(e[i0:i1+1]) >= TQ[bw]:
bw0 = bw + 1
### Stage 2, Cut-off random coefficients at each steps
bw = bw0
if bw0 < sr:
l = L[dt][bw0]
i0 = BW_START[dt][sr][bw0] - l
i1 = BW_START[dt][sr][bw0]
c = 10 * np.log10(1e-31 + e[i0-l+1:i1-l+2] / e[i0+1:i1+2])
if np.amax(c) <= TC[bw0]:
bw = sr
self.bw = bw
return self.bw
def get_nbits(self):
return 0 if self.sr == 0 else \
1 + np.log2(self.sr).astype(int)
def store(self, b):
b.write_uint(self.bw, self.get_nbits())
def get(self, b):
return b.read_uint(self.get_nbits())
### ------------------------------------------------------------------------ ###
def check_unit(rng, dt, sr):
ok = True
bwdet = BandwidthDetector(dt, sr)
for bw0 in range(sr+1):
for drop in range(10):
### Generate random 'high' energy and
### scale relevant bands to select 'bw0'
e = 20 + 100 * rng.random(64)
for i in range(sr):
if i+1 != bw0:
i0 = BW_START[dt][sr][i]
i1 = BW_STOP[dt][sr][i]
e[i0:i1+1] /= (np.mean(e[i0:i1+1]) / TQ[i] + 1e-3)
### Stage 2 Condition,
### cut-off random coefficients at each steps
if bw0 < sr:
l = L[dt][bw0]
i0 = BW_START[dt][sr][bw0] - l
i1 = BW_START[dt][sr][bw0]
e[i0-l+1:i1+2] /= np.power(10, np.arange(2*l+1) / (1 + drop))
### Check with implementation
bw_c = lc3.bwdet_run(dt, sr, e)
ok = ok and bw_c == bwdet.run(e)
return ok
def check_appendix_c(dt):
i0 = dt - T.DT_7M5
sr = T.SRATE_16K
ok = True
E_B = C.E_B[i0]
P_BW = C.P_BW[i0]
bw = lc3.bwdet_run(dt, sr, E_B[0])
ok = ok and bw == P_BW[0]
bw = lc3.bwdet_run(dt, sr, E_B[1])
ok = ok and bw == P_BW[1]
return ok
def check():
rng = np.random.default_rng(1234)
ok = True
for dt in range(T.NUM_DT):
for sr in range(T.SRATE_8K, T.SRATE_48K + 1):
ok = ok and check_unit(rng, dt, sr)
for dt in ( T.DT_7M5, T.DT_10M ):
ok = ok and check_appendix_c(dt)
return ok
### ------------------------------------------------------------------------ ###
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