S2ST-Omni: An Efficient and Scalable Multilingual Speech-to-Speech Translation Framework via Seamlessly Speech-Text Alignment and Streaming Speech Decoder
Multilingual speech-to-speech translation (S2ST) faces two major challenges: the trade-off between high translation quality and low end-to-end latency, and heavy reliance on scarce parallel speech data. To address these, we propose an end-to-end decoupled framework that jointly models speech-to-text (S2TT) and text-to-speech (TTS) components. It employs a lightweight speech adapter to align cross-modal representations, integrates Whisper’s audio encoder with Qwen-3.0’s strong textual understanding, and introduces a streaming autoregressive TTS decoder to ensure real-time inference. Our approach drastically reduces dependence on parallel speech corpora while achieving state-of-the-art BLEU and COMET scores on the CVSS benchmark—outperforming existing S2ST systems. Crucially, its end-to-end latency matches that of the best-performing baselines, demonstrating strong practical deployability for real-world multilingual translation applications.