SNC: A Stem-Native Codec for Efficient Lossless Audio Storage with Adaptive Playback Capabilities

TL;DR

This work introduces the Stem-Native Codec (SNC), a novel lossless-capable audio format that stores music as independently encoded stems plus a lightweight mastering residual. By exploiting the lower information entropy of separated stems, SNC achieves a substantial file-size reduction (38.2% versus FLAC) while preserving perceptual quality (STOI = 0.996) and maintaining a low residual energy ($\mathrm{RMS}(R) = -29.97$ dB). Implemented over a Matroska container with Opus VBR for stems and residual, SNC supports adaptive playback, spatial rendering, and user remixing without extra storage overhead. The results, along with open-source encoders/decoders, indicate a practical pathway toward next-generation, stem-enabled audio distribution, including considerations of genre scalability and real-world deployment.

Abstract

Current audio formats present a fundamental trade-off between file size and functionality: lossless formats like FLAC preserve quality but lack adaptability, while lossy formats reduce size at the cost of fidelity and offer no stem-level access.We introduce the Stem-Native Codec (SNC), a novel audio container format that stores music as independently encoded stems plus a low-energy mastering residual. By exploiting the lower information entropy of separated stems compared to mixed audio, SNC achieves a 38.2% file size reduction versus FLAC (7.76 MB vs. 12.55 MB for a 2:18 test track) while maintaining perceptual transparency (STOI = 0.996). Unlike existing formats, SNC enables context-aware adaptive playback, spatial audio rendering, and user-controlled remixing without requiring additional storage. Our experimental validation demonstrates that the stems-plus residual architecture successfully decouples the conflicting requirements of compression efficiency and feature richness, offering a practical path toward next-generation audio distribution systems.