earlab/EAR_VAE2

εar-VAE2

Fourier is Frontier: Frequency-Aware Autoencoding for High-Fidelity Music Reconstruction

Kangdi Wang¹ · Yusheng Dai² · Jin Xu^1†

¹ Qwen Team, Alibaba    ² Monash University    ^† Corresponding author

[Demo Page] - [Paper] - [Codebase]

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Overview

A spectral-domain music autoencoder compressing 48 kHz stereo audio into a 128-dimensional continuous latent sequence at 25 Hz — a 1920× temporal downsampling — through two frequency-aware components: Spec-SnakeBeta (per-bin periodic activation with log-frequency initialization) and a Duplex-Aware Refiner (band-specific magnitude/phase correction motivated by psychoacoustic masking).

✨ Highlights

• 🎵 Complex spectral domain — operates on STFT real/imag channels, not raw waveform
• 🧬 Spec-SnakeBeta — per-(channel, frequency-bin) periodic activation with log-frequency initialization; each bin learns its own oscillatory bias
• 🎛️ Duplex-Aware Refiner — band-specific mag/phase correction following psychoacoustic dominance (phase-only < 1.5 kHz, joint mid-band, mag-only > 4 kHz)
• 📊 1920× compression — 48 kHz stereo → 128-d × 25 Hz continuous latent
• 🏆 SOTA reconstruction on Song Describer Dataset across spectral metrics

Main Results

Reconstruction quality on Song Describer Dataset (546 full tracks, 48 kHz stereo):

System	SI-SDR ↑	STFT Dist ↓	Mel Dist ↓	CCPC ↑
εar-VAE	12.4	0.880	0.509	0.973
SA-Open	6.7	1.016	0.612	0.933
Levo 2	8.1	0.971	0.599	0.947
SAME-L	12.5	0.986	0.539	0.970
εar-VAE2 (base)	10.9	0.916	0.572	0.966
εar-VAE2 (full)	11.3	0.870	0.461	0.973

εar-VAE2 (full) achieves the best spectral fidelity (STFT Dist, Mel Dist) among all systems while matching the phase coherence (CCPC) of the εar-VAE baseline.

Spec-SnakeBeta

Per-(channel, frequency-bin) periodic activation with log-scale parameterization. Low-frequency bins stay near-identity; high-frequency bins become progressively oscillatory — providing a physically motivated inductive bias for spectral processing.

Input Representation

Complex STFT preserves organized high-frequency harmonic structure (panel A) where the same-backbone waveform-patch paradigm degrades (panel B). The spectral domain provides a physical frequency-axis inductive bias unavailable to waveform methods.

Installation

# Clone the repository
git clone https://github.com/Eps-Acoustic-Revolution-Lab/EAR_VAE2.git
cd EAR_VAE2

# Install dependencies
pip install -r requirements.txt

# Download pretrained weights (coming soon)
# huggingface-cli download eps-acoustic-revolution-lab/ear-vae2-small --local-dir checkpoints/

Usage

Python API

import torch
from ear_vae2 import EarVAE2

# Load model (full model, with refiner — see configs/ear_vae2.json)
config = {
    "C0": 64, "D": 128, "use_vae": True,
    "refiner": {"type": "banded", "dim": 256, "intermediate_dim": 1024,
                "num_layers": 12, "layer_norm_eps": 1e-5},
}
model = EarVAE2(config)
ckpt = torch.load("ear_vae2.pt", map_location="cpu")
model.load_state_dict(ckpt["gen"] if "gen" in ckpt else ckpt)
model.eval().cuda()

# Encode & decode
audio = torch.randn(1, 2, 48000 * 10).cuda()  # 10s stereo @ 48kHz
audio_padded, orig_len = model.preprocess_audio(audio)
latents = model.encode_audio(audio_padded, chunked=True, chunk_size=512, overlap=16, deterministic=True)
reconstructed = model.decode_audio(latents, chunked=True, chunk_size=512, overlap=16)
reconstructed = reconstructed[:, :, :orig_len]

Command Line

python inference.py --checkpoint ear_vae2.pt --config configs/ear_vae2.json --input input.wav --output output.wav

Model Details

Config	Params (M)	Latent dim	Rate (Hz)	Compression
Small (C0=64)	~42.6	128	25	1920×

• Sample rate: 48 kHz stereo
• STFT: 3840-point FFT, 1920-sample hop → 25 Hz frame rate
• Latent: 128-d continuous (VAE with KL regularization)
• Refiner: 12-layer banded Transformer (256-d, 1024 intermediate)

⚠️ Note on open-source weights: Due to data licensing constraints, the open-source model weights are retrained on publicly available datasets (not the full internal training corpus). Performance may differ from the numbers reported in the paper, which were obtained with the full-scale proprietary training data.

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Citation

@misc{earvae2,
  title         = {Fourier is Frontier: Frequency-Aware Autoencoding for High-Fidelity Music Reconstruction},
  author        = {Kangdi Wang and Yusheng Dai and Jin Xu},
  year          = {2026},
  eprint        = {2608.19843},
  archivePrefix = {arXiv},
  primaryClass  = {cs.SD},
  url           = {https://arxiv.org/abs/2608.19843}
}

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Acknowledgements

We gratefully acknowledge the following projects that inspired components of εar-VAE2:

• BigVGAN — SnakeBeta periodic activation design
• Vocos — ConvNeXt block architecture for spectral modeling
• Stable Audio Tools — Training infrastructure and audio pipeline patterns

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License

This project is licensed under the Apache License 2.0.