mirror of
https://github.com/google/liblc3.git
synced 2026-04-18 13:44:49 +00:00
python: Add python library wrapper
This commit is contained in:
Antoine Soulier
96
python/tools/decoder.py
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96
python/tools/decoder.py
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#!/usr/bin/env python3
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#
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# Copyright 2024 Google LLC
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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#
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import argparse
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import lc3
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import struct
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import sys
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import wave
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parser = argparse.ArgumentParser(description='LC3 Decoder')
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parser.add_argument(
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'lc3_file', nargs='?',
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help='Input bitstream file, default is stdin',
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type=argparse.FileType('rb'), default=sys.stdin.buffer)
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parser.add_argument(
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'wav_file', nargs='?',
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help='Output wave file, default is stdout',
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type=argparse.FileType('wb'), default=sys.stdout.buffer)
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parser.add_argument(
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'--bitdepth',
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help='Output bitdepth, default is 16 bits',
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type=int, choices=[16, 24], default=16)
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parser.add_argument(
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'--libpath', help='LC3 Library path')
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args = parser.parse_args()
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# --- LC3 File input ---
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f_lc3 = args.lc3_file
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header = struct.unpack('=HHHHHHHI', f_lc3.read(18))
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if header[0] != 0xcc1c:
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raise ValueError('Invalid bitstream file')
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samplerate = header[2] * 100
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nchannels = header[4]
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frame_duration = header[5] / 100
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stream_length = header[7]
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# --- Setup output ---
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bitdepth = args.bitdepth
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pcm_size = nchannels * (bitdepth // 8)
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f_wav = args.wav_file
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wavfile = wave.open(f_wav)
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wavfile.setnchannels(nchannels)
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wavfile.setsampwidth(bitdepth // 8)
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wavfile.setframerate(samplerate)
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wavfile.setnframes(stream_length)
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# --- Setup decoder ---
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dec = lc3.Decoder(
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frame_duration, samplerate, nchannels, libpath=args.libpath)
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frame_length = dec.get_frame_samples()
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encoded_length = stream_length + dec.get_delay_samples()
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# --- Decoding loop ---
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for i in range(0, encoded_length, frame_length):
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lc3_frame_size = struct.unpack('=H', f_lc3.read(2))[0]
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pcm = dec.decode(f_lc3.read(lc3_frame_size), bitdepth=bitdepth)
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pcm = pcm[max(encoded_length - stream_length - i, 0) * pcm_size:
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min(encoded_length - i, frame_length) * pcm_size]
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wavfile.writeframesraw(pcm)
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# --- Cleanup ---
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wavfile.close()
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for f in (f_lc3, f_wav):
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if f is not sys.stdout.buffer:
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f.close()
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88
python/tools/encoder.py
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88
python/tools/encoder.py
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@@ -0,0 +1,88 @@
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#!/usr/bin/env python3
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#
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# Copyright 2024 Google LLC
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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#
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import argparse
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import lc3
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import struct
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import sys
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import wave
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parser = argparse.ArgumentParser(description='LC3 Encoder')
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parser.add_argument(
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'wav_file', nargs='?',
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help='Input wave file, default is stdin',
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type=argparse.FileType('rb'), default=sys.stdin.buffer)
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parser.add_argument(
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'lc3_file', nargs='?',
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help='Output bitstream file, default is stdout',
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type=argparse.FileType('wb'), default=sys.stdout.buffer)
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parser.add_argument(
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'--bitrate', help='Bitrate in bps', type=int, required=True)
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parser.add_argument(
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'--frame_duration', help='Frame duration in ms', type=float, default=10)
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parser.add_argument(
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'--libpath', help='LC3 Library path')
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args = parser.parse_args()
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# --- WAV File input ---
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f_wav = args.wav_file
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wavfile = wave.open(f_wav, 'rb')
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samplerate = wavfile.getframerate()
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nchannels = wavfile.getnchannels()
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bitdepth = wavfile.getsampwidth() * 8
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stream_length = wavfile.getnframes()
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# --- Setup encoder ---
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enc = lc3.Encoder(
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args.frame_duration, samplerate, nchannels, libpath=args.libpath)
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frame_size = enc.get_frame_bytes(args.bitrate)
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frame_length = enc.get_frame_samples()
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bitrate = enc.resolve_bitrate(frame_size)
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# --- Setup output ---
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f_lc3 = args.lc3_file
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f_lc3.write(struct.pack(
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'=HHHHHHHI', 0xcc1c, 18,
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samplerate // 100, bitrate // 100, nchannels,
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int(args.frame_duration * 100), 0, stream_length))
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# --- Encoding loop ---
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for i in range(0, stream_length, frame_length):
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f_lc3.write(struct.pack('=H', frame_size))
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pcm = wavfile.readframes(frame_length)
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f_lc3.write(enc.encode(pcm, frame_size, bitdepth=bitdepth))
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# --- Cleanup ---
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wavfile.close()
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for f in (f_wav, f_lc3):
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if f is not sys.stdout.buffer:
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f.close()
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92
python/tools/specgram.py
Executable file
92
python/tools/specgram.py
Executable file
@@ -0,0 +1,92 @@
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#!/usr/bin/env python3
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#
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# Copyright 2024 Google LLC
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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#
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import argparse
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import lc3
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import matplotlib
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import matplotlib.pyplot as plt
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import numpy as np
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import scipy.signal as signal
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matplotlib.use('QtAgg')
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parser = argparse.ArgumentParser(description='LC3 Encoder')
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parser.add_argument(
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'--frame_duration', help='Frame duration (ms)', type=float, default=10)
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parser.add_argument(
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'--sample_rate', help='Sampling frequency (Hz)', type=float, default=48000)
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parser.add_argument(
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'--hrmode', help='Enable high-resolution mode', action='store_true')
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parser.add_argument(
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'--bitrate', help='Bitrate (bps)', type=int, default=96000)
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parser.add_argument(
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'--libpath', help='LC3 Library path')
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args = parser.parse_args()
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# --- Setup encoder + decoder ---
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fs = args.sample_rate
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enc = lc3.Encoder(
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args.frame_duration, fs, hrmode=args.hrmode, libpath=args.libpath)
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dec = lc3.Decoder(
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args.frame_duration, fs, hrmode=args.hrmode, libpath=args.libpath)
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frame_len = enc.get_frame_samples()
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delay_len = enc.get_delay_samples()
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# --- Generate 10 seconds chirp ---
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n = 10 * int(fs)
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t = np.arange(n - (n % frame_len)) / fs
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s = signal.chirp(t, f0=10, f1=fs/2, t1=t[-1], phi=-90, method='linear')
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# --- Encoding / decoding loop ---
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frame_size = enc.get_frame_bytes(args.bitrate)
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bitrate = enc.resolve_bitrate(frame_size)
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y = np.empty(len(s) + frame_len)
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for i in range(0, len(s), frame_len):
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y[i:i+frame_len] = dec.decode(enc.encode(s[i:i+frame_len], frame_size))
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y[len(s):] = dec.decode(enc.encode(np.zeros(frame_len), frame_size))
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y = y[delay_len:len(s)+delay_len]
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# --- Plot spectrograms ---
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fig, (ax1, ax2) = plt.subplots(nrows=2, sharex=True)
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NFFT = 512
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for (ax, s) in [(ax1, s), (ax2, y)]:
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ax.specgram(s, Fs=fs, NFFT=NFFT, pad_to=4*NFFT, noverlap=NFFT//2,
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vmin=-160, vmax=0)
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ax1.set_title('Input signal')
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ax1.set_ylabel('Frequency (Hz)')
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ax2.set_title(('Processed signal (%.1f kbps)' % (bitrate/1000)))
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ax2.set_ylabel('Frequency (Hz)')
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plt.show()
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