cstr/chatterbox-GGUF

Chatterbox TTS — GGUF (ggml-quantised)

GGUF / ggml conversion of ResembleAI/chatterbox for use with CrispStrobe/CrispASR.

Chatterbox is a full TTS pipeline: character tokenizer → T3 (30-layer Llama AR, 520M) → speech tokens → S3Gen (Conformer encoder + UNet1D CFM denoiser, 10 Euler steps) → HiFTGenerator vocoder (conv chains + Snake activations + iSTFT) → 24 kHz WAV. Distributed under MIT license.

Two GGUF files are needed: the T3 model (text → speech tokens) and the S3Gen model (speech tokens → audio).

Files

File	Quant	Size	Notes
chatterbox-t3-f16.gguf	F16	1.1 GB	T3 AR model — reference quality
chatterbox-t3-q8_0.gguf	Q8_0	542 MB	T3 AR model — recommended
chatterbox-t3-q4_k.gguf	Q4_K	287 MB	T3 AR model — smallest
chatterbox-s3gen-f16.gguf	F16	548 MB	S3Gen + vocoder — reference quality
chatterbox-s3gen-q8_0.gguf	Q8_0	342 MB	S3Gen + vocoder — recommended
chatterbox-s3gen-q4_k.gguf	Q4_K	237 MB	S3Gen + vocoder — smallest

Note: vocoder weights (conv_pre, resblocks, conv_post, source fusion) are kept at F32 in all quant levels for audio quality. Quantization applies to the Conformer encoder, UNet decoder, and T3 Llama layers.

Quick start

# 1. Build CrispASR
git clone https://github.com/CrispStrobe/CrispASR
cd CrispASR
cmake -B build -DCMAKE_BUILD_TYPE=Release -DBUILD_SHARED_LIBS=OFF
cmake --build build -j --target chatterbox

# 2. Pull both model files
huggingface-cli download cstr/chatterbox-GGUF chatterbox-t3-q8_0.gguf --local-dir .
huggingface-cli download cstr/chatterbox-GGUF chatterbox-s3gen-q8_0.gguf --local-dir .

# 3. Synthesise (C API / test binary — CLI adapter in progress)
# See tests/test_voc_wav.cpp for vocoder-only usage

Architecture

Text → Character tokenizer (704 tokens)
     → T3 Llama AR (30 layers, 1024D, 16 heads, RoPE, SwiGLU, CFG)
     → 25 Hz speech tokens (6561 codebook)
     → Conformer encoder (6 pre + 4 post upsample, 512D, 8 heads)
     → 80-channel mel spectrogram
     → UNet1D CFM denoiser (1 down + 12 mid + 1 up, 256 ch, 10 Euler steps)
     → HiFTGenerator vocoder (3× ConvTranspose1d + 9 ResBlocks + Snake + iSTFT)
     → 24 kHz mono WAV

Quality verification

ASR roundtrip on Python reference mel (no source fusion, deterministic):

Metric	Value
ASR output (moonshine-base)	"Hello world" (correct)
Per-stage cosine vs Python ref	1.000 (conv_pre through rb_2)
Waveform cosine vs torch.istft	0.93
STFT range	[-0.82, 2.0] (ref [-1.1, 1.7])

All quantization levels (F16/Q8_0/Q4_K) produce ASR-identical output on the reference mel.

Conversion

python models/convert-chatterbox-to-gguf.py \
    --input ResembleAI/chatterbox \
    --output-dir .

Requires pip install gguf safetensors torch huggingface_hub.

Related models

• cstr/lahgtna-chatterbox-v1-GGUF — Arabic T3 variant (MIT, shares S3Gen)
• cstr/orpheus-3b-base-GGUF — Llama-3.2 + SNAC TTS
• cstr/qwen3-tts-0.6b-customvoice-GGUF — Qwen3-TTS with fixed speakers

License

MIT — same as the upstream ResembleAI/chatterbox.