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]

⚠️ 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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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):

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 config + pretrained weights from the Hub
huggingface-cli download earlab/EAR_VAE2 --local-dir checkpoints/

Usage

Python API

import json
import torch
from huggingface_hub import hf_hub_download
from ear_vae2 import EarVAE2

REPO_ID = "earlab/EAR_VAE2"

# Resolve config and weights from the Hub (cached locally after the first call)
config_path = hf_hub_download(REPO_ID, "config.json")
ckpt_path = hf_hub_download(REPO_ID, "weights/ear_vae2.pt")

with open(config_path) as f:
    config = json.load(f)["model"]["gen"]["config"]

model = EarVAE2(config)
ckpt = torch.load(ckpt_path, 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

Using the checkpoints/ directory populated in the Installation step:

python inference.py \
  --checkpoint checkpoints/weights/ear_vae2.pt \
  --config checkpoints/config.json \
  --input input.wav --output output.wav

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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.