pstruebi
2845458d3f
- Add .gitignore for Python, virtual environments, testing artifacts, IDE files, and LC3 test outputs including SQAM audio files - Add AGENTS.md with project context for LC3 implementation testing - Add LC3.TS.p5.pdf test specification document - Add LC3 conformance interoperability test software V1.0.8 with script readme and reference binary symlink
80 lines
2.6 KiB
Python
80 lines
2.6 KiB
Python
#!/usr/bin/env python3
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"""LC3 encoder wrapper for conformanceCheck.py.
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Called by conformanceCheck.py as:
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python lc3_encode.py -frame_ms <ms> [options] "<input.wav>" "<output.lc3>" <bitrate_bps>
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Bitstream format: 18-byte header (LC3 TS §3.2.8.2) + per-frame 2-byte size prefix + LC3 payload.
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"""
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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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def main():
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args = sys.argv[1:]
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frame_ms = 10.0
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positional = []
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i = 0
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while i < len(args):
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if args[i] == '-frame_ms' and i + 1 < len(args):
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try:
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frame_ms = float(args[i + 1])
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except ValueError:
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print(f'Usage: {sys.argv[0]} -frame_ms <ms> [opts] <input.wav> <output.lc3> <bitrate_bps>',
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file=sys.stderr)
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sys.exit(1)
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i += 2
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elif args[i].startswith('-'):
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i += 1 # skip unknown flags (e.g. -q)
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else:
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positional.append(args[i])
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i += 1
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if len(positional) < 3:
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print(f'Usage: {sys.argv[0]} -frame_ms <ms> [opts] <input.wav> <output.lc3> <bitrate_bps>',
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file=sys.stderr)
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sys.exit(1)
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wav_path = positional[0]
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lc3_path = positional[1]
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bitrate_bps = int(positional[2])
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frame_duration_us = int(frame_ms * 1000)
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with wave.open(wav_path, 'rb') as wavfile:
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samplerate = wavfile.getframerate()
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nchannels = wavfile.getnchannels()
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bit_depth = wavfile.getsampwidth() * 8
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stream_length = wavfile.getnframes()
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enc = lc3.Encoder(frame_duration_us, samplerate, nchannels)
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frame_size = enc.get_frame_bytes(bitrate_bps)
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frame_length = enc.get_frame_samples()
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resolved_bitrate = enc.resolve_bitrate(frame_size)
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with open(lc3_path, 'wb') as f_lc3:
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f_lc3.write(struct.pack(
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'=HHHHHHHI',
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0xcc1c, # signature
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18, # header size
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samplerate // 100, # sample rate / 100
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resolved_bitrate // 100, # bitrate / 100
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nchannels,
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int(frame_ms * 100), # frame duration * 100
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0, # reserved
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stream_length, # total PCM samples
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))
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for _ in range(0, stream_length, frame_length):
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pcm = wavfile.readframes(frame_length)
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encoded = enc.encode(pcm, frame_size, bit_depth=bit_depth)
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f_lc3.write(struct.pack('=H', frame_size))
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f_lc3.write(encoded)
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if __name__ == '__main__':
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main()
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