146 lines
4.2 KiB
Python
146 lines
4.2 KiB
Python
# ------------------------------------------------------------
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# AAC Coder/Decoder - Level 1 Wrappers + Demo
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#
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# Multimedia course at Aristotle University of
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# Thessaloniki (AUTh)
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#
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# Author:
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# Christos Choutouridis (ΑΕΜ 8997)
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# cchoutou@ece.auth.gr
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#
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# Description:
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# Level 1 wrapper module.
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#
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# This file provides:
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# - Thin wrappers for Level 1 API functions (encode/decode) that delegate
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# to the corresponding core implementations.
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# - A demo function that runs end-to-end and computes SNR.
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# - A small CLI entrypoint for convenience.
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# ------------------------------------------------------------
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from __future__ import annotations
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from pathlib import Path
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from tabnanny import verbose
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from typing import Union
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import soundfile as sf
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from core.aac_types import AACSeq1, StereoSignal
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from core.aac_coder import aac_coder_1 as core_aac_coder_1
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from core.aac_coder import aac_read_wav_stereo_48k
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from core.aac_decoder import aac_decoder_1 as core_aac_decoder_1
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from core.aac_utils import snr_db
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# -----------------------------------------------------------------------------
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# Public Level 1 API (wrappers)
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# -----------------------------------------------------------------------------
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def aac_coder_1(filename_in: Union[str, Path]) -> AACSeq1:
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"""
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Level-1 AAC encoder (wrapper).
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Delegates to core implementation.
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Parameters
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----------
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filename_in : Union[str, Path]
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Input WAV filename.
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Assumption: stereo audio, sampling rate 48 kHz.
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Returns
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-------
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AACSeq1
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List of encoded frames (Level 1 schema).
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"""
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return core_aac_coder_1(filename_in, verbose=True)
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def aac_decoder_1(aac_seq_1: AACSeq1, filename_out: Union[str, Path]) -> StereoSignal:
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"""
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Level-1 AAC decoder (wrapper).
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Delegates to core implementation.
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Parameters
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----------
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aac_seq_1 : AACSeq1
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Encoded sequence as produced by aac_coder_1().
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filename_out : Union[str, Path]
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Output WAV filename. Assumption: 48 kHz, stereo.
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Returns
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-------
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StereoSignal
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Decoded audio samples (time-domain), stereo, shape (N, 2), dtype float64.
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"""
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return core_aac_decoder_1(aac_seq_1, filename_out, verbose=True)
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# -----------------------------------------------------------------------------
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# Demo (Level 1)
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# -----------------------------------------------------------------------------
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def demo_aac_1(filename_in: Union[str, Path], filename_out: Union[str, Path]) -> float:
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"""
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Demonstration for the Level-1 codec.
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Runs:
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- aac_coder_1(filename_in)
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- aac_decoder_1(aac_seq_1, filename_out)
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and computes total SNR between original and decoded audio.
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Parameters
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----------
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filename_in : Union[str, Path]
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Input WAV filename (stereo, 48 kHz).
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filename_out : Union[str, Path]
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Output WAV filename (stereo, 48 kHz).
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Returns
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-------
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float
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Overall SNR in dB.
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"""
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filename_in = Path(filename_in)
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filename_out = Path(filename_out)
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# Read original audio (reference) with the same validation as the codec.
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x_ref, fs_ref = aac_read_wav_stereo_48k(filename_in)
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if int(fs_ref) != 48000:
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raise ValueError("Input sampling rate must be 48 kHz.")
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# Encode / decode
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aac_seq_1 = aac_coder_1(filename_in)
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x_hat = aac_decoder_1(aac_seq_1, filename_out)
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# Optional sanity: ensure output file exists and is readable
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_, fs_hat = sf.read(str(filename_out), always_2d=True)
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if int(fs_hat) != 48000:
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raise ValueError("Decoded output sampling rate must be 48 kHz.")
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return snr_db(x_ref, x_hat)
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# -----------------------------------------------------------------------------
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# CLI
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# -----------------------------------------------------------------------------
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if __name__ == "__main__":
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# Example:
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# cd level_1
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# python -m level_1 input.wav output.wav
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# or
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# python -m level_1 material/LicorDeCalandraca.wav LicorDeCalandraca_out.wav
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import sys
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if len(sys.argv) != 3:
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raise SystemExit("Usage: python -m level_1 <input.wav> <output.wav>")
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in_wav = Path(sys.argv[1])
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out_wav = Path(sys.argv[2])
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print(f"Encoding/Decoding {in_wav} to {out_wav}")
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snr = demo_aac_1(in_wav, out_wav)
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print(f"SNR = {snr:.3f} dB")
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