voice_audio_multi/docs/models/chatterbox_turbo.md

Chatterbox Turbo (community model)

Chatterbox Turbo is Resemble AI's distilled 350M-parameter sibling of Chatterbox (see the Chatterbox section in docs/tts.md): a GPT2-style T3 backbone (vs. the base model's 0.5B Llama-style backbone), a GPT2 BPE tokenizer with 19 built-in emotion/style tags ([laugh], [sigh], ...), and a 2-step meanflow-distilled S3Gen decoder (vs. the base model's 10-step CFG decoder) for substantially faster built-in-voice TTS. English-only.

Status: testing. The T3 backbone and the built-in default voice both load and generate audio end to end. Custom voice cloning is not supported. This family lives under community_models rather than the core model tree because it does not yet have the CUDA/Vulkan/Metal runtime test coverage core models carry.

--request-option max_tokens=<int> caps generated speech tokens (default 1000). Legacy max_new_tokens remains accepted with the same meaning.

Packaging: audio.cpp-native, self-contained GGUF

Resemble AI has not published Chatterbox Turbo weights in a format audio.cpp can convert directly. The only available conversion is a third-party GGUF, cstr/chatterbox-turbo-GGUF, published by cstr for their own CrispASR project (MIT-relicensed) — not published by ResembleAI or audio.cpp. It ships as two loose GGUF files (T3 and S3Gen) with a flat dot-separated tensor namespace and abbreviated S3Gen tensor names that don't match this codebase's own naming.

Rather than teach the runtime a compatibility layer for that third-party layout, tools/community_models/chatterbox_turbo/repack_chatterbox_turbo_gguf.py repacks it offline into one self-contained, audio.cpp-native GGUF:

• T3 and built-in-conditional tensors are moved from the upstream flat t3./conds. dot namespace into this project's own /-delimited packed-GGUF namespace convention.
• S3Gen tensors are renamed back to the exact names the shared S3Gen flow/HiFT-vocoder loader (src/framework/codecs/s3gen_runtime.cpp, src/framework/modules/vocoders/hift_vocoder.cpp) already expects, so that loader runs completely unmodified for Turbo — no tensor-name translation code exists in this family at runtime.
• The GPT2 BPE tokenizer (vocab, merges, and the trailing emotion/style special tokens) is extracted into plain vocab.json/merges.txt/special_tokens.json sidecar files instead of being read from raw GGUF metadata at load time.
• The result is fed through this project's own audiocpp_gguf converter, which quantizes, embeds the package spec (model_specs/chatterbox_turbo.json), and embeds the sidecar files — producing one file that loads with nothing else needed, like every other GGUF family here.

The ve.* (LSTM speaker-verification voice encoder) and s3.se.*/s3.tok.* (ResNet speaker encoder / S3 speech tokenizer) sections of the upstream checkpoint are not repacked: nothing in this codebase reads them yet (see Current limitations above).

Repacking it yourself

# 1. Build the converter
cmake --build build/debug --parallel --target audiocpp_gguf

# 2. Get the upstream third-party GGUF pair (~1 GB for Q8_0)
hf download cstr/chatterbox-turbo-GGUF \
    chatterbox-turbo-t3-q8_0.gguf chatterbox-turbo-s3gen-q8_0.gguf \
    --local-dir /tmp/chatterbox-turbo-src

# 3. Repack
pip install gguf numpy safetensors
python3 tools/community_models/chatterbox_turbo/repack_chatterbox_turbo_gguf.py \
    --t3-source /tmp/chatterbox-turbo-src/chatterbox-turbo-t3-q8_0.gguf \
    --s3gen-source /tmp/chatterbox-turbo-src/chatterbox-turbo-s3gen-q8_0.gguf \
    --output models/Chatterbox-Turbo-GGUF/chatterbox-turbo-q8_0.gguf \
    --type q8_0 --overwrite

Verify with build/debug/bin/audiocpp_gguf --inspect models/Chatterbox-Turbo-GGUF/chatterbox-turbo-q8_0.gguf (expect embedded_sidecars=true, embedded_model_spec=true, and t3/conds/s3gen namespaces).

Usage

audiocpp_cli --task tts --family chatterbox_turbo \
    --model models/Chatterbox-Turbo-GGUF/chatterbox-turbo-q8_0.gguf \
    --backend cuda --text "Hello from Chatterbox Turbo." --out out.wav

See the Chatterbox Turbo section in docs/tts.md for the full option table.

Checkpoints

Model	Source	License
Chatterbox Turbo (T3 + S3Gen)	cstr/chatterbox-turbo-GGUF (third-party repack of ResembleAI/chatterbox-turbo)	MIT