Fast Byte Latent Transformer

Hugging Face Daily Papers Papers

Summary

This paper introduces BLT Diffusion and speculative decoding techniques for byte-level language models to significantly reduce generation latency and memory bandwidth costs while maintaining quality.

Recent byte-level language models (LMs) match the performance of token-level models without relying on subword vocabularies, yet their utility is limited by slow, byte-by-byte autoregressive generation. We address this bottleneck in the Byte Latent Transformer (BLT) through new training and generation techniques. First, we introduce BLT Diffusion (BLT-D), a new model and our fastest BLT variant, trained with an auxiliary block-wise diffusion objective alongside the standard next-byte prediction loss. This enables an inference procedure that generates multiple bytes in parallel per decoding step, substantially reducing the number of forward passes required to generate a sequence. Second, we propose two extensions inspired by speculative decoding that trade some of this speed for higher generation quality: BLT Self-speculation (BLT-S), in which BLT's local decoder continues generating past its normal patch boundaries to draft bytes, which are then verified with a single full-model forward pass; and BLT Diffusion+Verification (BLT-DV), which augments BLT-D with an autoregressive verification step after diffusion-based generation. All methods may achieve an estimated memory-bandwidth cost over 50% lower than BLT on generation tasks. Each approach offers its own unique advantages, together removing key barriers to the practical use of byte-level LMs.
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Cached at: 05/11/26, 02:42 AM

Paper page - Fast Byte Latent Transformer

Source: https://huggingface.co/papers/2605.08044

Abstract

Byte-level language models overcome slow autoregressive generation through diffusion-based parallel processing and speculative decoding techniques that improve both speed and quality.

Recentbyte-level language models(LMs) match the performance oftoken-level modelswithout relying onsubword vocabularies, yet their utility is limited by slow, byte-by-byteautoregressive generation. We address this bottleneck in theByte Latent Transformer(BLT) through new training and generation techniques. First, we introduceBLT Diffusion(BLT-D), a new model and our fastest BLT variant, trained with an auxiliaryblock-wise diffusion objectivealongside the standardnext-byte prediction loss. This enables an inference procedure that generates multiple bytes in parallel per decoding step, substantially reducing the number of forward passes required to generate a sequence. Second, we propose two extensions inspired byspeculative decodingthat trade some of this speed for higher generation quality:BLT Self-speculation(BLT-S), in which BLT’s local decoder continues generating past its normal patch boundaries to draft bytes, which are then verified with a single full-model forward pass; andBLT Diffusion+Verification(BLT-DV), which augments BLT-D with an autoregressive verification step after diffusion-based generation. All methods may achieve an estimatedmemory-bandwidth costover 50% lower than BLT on generation tasks. Each approach offers its own unique advantages, together removing key barriers to the practical use of byte-level LMs.

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