PSCodec: A Series of High-Fidelity Low-bitrate Neural Speech Codecs Leveraging Prompt Encoders

Kavli Affiliate: Xiang Zhang

| First 5 Authors: Yu Pan, Xiang Zhang, Yuguang Yang, Jixun Yao, Yanni Hu

| Summary:

Neural speech codecs have recently emerged as a focal point in the fields of
speech compression and generation. Despite this progress, achieving
high-quality speech reconstruction under low-bitrate scenarios remains a
significant challenge. In this paper, we propose PSCodec, a series of neural
speech codecs based on prompt encoders, comprising PSCodec-Base,
PSCodec-DRL-ICT, and PSCodec-CasAN, which are capable of delivering
high-performance speech reconstruction with low bandwidths. Specifically, we
first introduce PSCodec-Base, which leverages a pretrained speaker verification
model-based prompt encoder (VPP-Enc) and a learnable Mel-spectrogram-based
prompt encoder (MelP-Enc) to effectively disentangle and integrate voiceprint
and Mel-related features in utterances. To further enhance feature utilization
efficiency, we propose PSCodec-DRL-ICT, incorporating a structural similarity
(SSIM) based disentangled representation loss (DRL) and an incremental
continuous training (ICT) strategy. While PSCodec-DRL-ICT demonstrates
impressive performance, its reliance on extensive hyperparameter tuning and
multi-stage training makes it somewhat labor-intensive. To circumvent these
limitations, we propose PSCodec-CasAN, utilizing an advanced cascaded attention
network (CasAN) to enhance representational capacity of the entire system.
Extensive experiments show that our proposed PSCodec-Base, PSCodec-DRL-ICT, and
PSCodec-CasAN all significantly outperform several state-of-the-art neural
codecs, exhibiting substantial improvements in both speech reconstruction
quality and speaker similarity under low-bitrate conditions.

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