GLM-TTS

GLM-TTS is a zero-shot Chinese and English speech-synthesis model. The native audio.cpp path executes its Llama speech-token generator, Whisper-VQ reference encoder, Flow/DiT mel generator, CAMPPlus speaker encoder, and HiFT vocoder. Both advertised routes are reference-conditioned: provide a clean WAV and the exact words spoken in it.

GLM-TTS is v1-native. model_specs/glm_tts.json is the single source of truth for metadata, packages, normalized options, and GGUF/safetensors resources. The runtime uses the generic spec-backed loader; the legacy request aliases listed below remain an internal compatibility layer for existing users.

Field	Value
Family	glm_tts
Model directory	models/GLM-TTS
Task	tts, clon
Modes	offline
Languages	Chinese, English
Voice input	Required reference WAV plus its exact transcript
Output	mono 24 kHz WAV

Install the default package:

python tools/model_manager_v2.py install glm_tts --models-root models

The default install is the standalone Q8 GGUF package.

The original safetensors preparation path remains available through the deprecated manager:

python tools/model_manager_deprecated.py install glm_tts --models-dir models

That installer downloads zai-org/GLM-TTS, converts the official Flow and HiFT PyTorch checkpoints to safetensors, prepares the ChatGLM tokenizer resources, and installs the matching CAMPPlus safetensors weights. The latter are sourced from mlx-community/index-tts2-mlx because the GLM-TTS repository publishes CAMPPlus as ONNX only; the native output was checked directly against that official ONNX graph.

Run the prepared safetensors package:

audiocpp_cli --task clon --family glm_tts \
  --model models/GLM-TTS --backend cuda \
  --voice-ref reference.wav \
  --reference-text "The exact words spoken in reference.wav." \
  --text "Hello from GLM-TTS." \
  --top-k 25 --top-p 0.8 --temperature 1.0 \
  --seed 0 --max-tokens 256 --out glm_tts.wav

The tts task accepts the same reference arguments. It is an alias for the same zero-shot synthesis path rather than an unconditioned preset voice.

Standalone GGUF

After installing the package, create a standalone mixed GGUF. The autoregressive Llama group remains F16 for speech-token quality; the speech tokenizer, Flow, HiFT, and CAMPPlus groups use Q8_0:

audiocpp_gguf \
  --input llama_weights=models/GLM-TTS/llm/model.safetensors.index.json \
  --input speech_tokenizer_weights=models/GLM-TTS/speech_tokenizer/model.safetensors \
  --input flow_weights=models/GLM-TTS/flow/model.safetensors \
  --input hift_weights=models/GLM-TTS/hift/model.safetensors \
  --input campplus_weights=models/GLM-TTS/frontend/campplus.safetensors \
  --root models/GLM-TTS \
  --family glm_tts \
  --model-spec model_specs/glm_tts.json \
  --type q8_0 \
  --keep-type "llama_weights/*=f16" \
  --overwrite \
  --output models/GLM-TTS-Q8/GLM-TTS_Q8.gguf

The resulting file embeds all five tensor groups, the package specification, configs, and tokenizer sidecars. It runs from a directory containing only the GGUF:

audiocpp_cli --task clon --family glm_tts \
  --model models/GLM-TTS-Q8/GLM-TTS_Q8.gguf --backend cuda \
  --voice-ref reference.wav \
  --reference-text "The exact words spoken in reference.wav." \
  --text "Hello from GLM-TTS." \
  --seed 0 --max-tokens 256 --out glm_tts_q8.wav

Controls

Option	Values	Default	Meaning
--reference-text	text	required	Exact transcript of --voice-ref.
--max-tokens	integer	automatic	Maximum generated speech-token count.
--temperature	float	1.0	Speech-token sampling temperature.
--top-k	integer	25	Speech-token top-k limit.
--top-p	float	0.8	Speech-token nucleus threshold.
--seed	integer	0	Seed used by token sampling, Flow noise, and HiFT.
--request-option num_inference_steps=<n>	integer	10	Flow Euler integration steps.
--request-option flow_guidance_scale=<float>	float	0.7	Flow classifier-free guidance rate.
--request-option flow_noise_path=<path>	raw F32 path	none	Optional exact initial Flow noise for parity tests.
--request-option hift_source_random_path=<path>	raw F32 path	none	Optional exact HiFT phase-uniform and Gaussian values for parity tests.
--request-option hift_prior_noise_count=<n>	integer	0	Torch RNG offset before normal HiFT source generation.

The legacy GLM-TTS request keys flow_steps, cfg_rate, flow_noise_file, hift_source_random_file, and hift_prior_noise_values remain accepted for backward compatibility. | --session-option glm_tts.weight_type=native|f32|f16|bf16|q8_0 | enum | native | Requested component weight storage type. | | --session-option glm_tts.mem_saver=true|false | bool | false | Release the reference-only Whisper-VQ and CAMPPlus runtimes after caching the voice, while keeping Llama, Flow, and HiFT warm. | | --session-option glm_tts.aggressive_mem_saver=true|false | bool | false | Also release Llama, Flow, and HiFT after each stage. This minimizes VRAM but reloads the generation path on every request. | | --session-option glm_tts.reference_cache_slots=<n> | integer | 1 | Prepared reference-audio cache slots. Reusing a reference skips Whisper-VQ, mel, fbank, and CAMPPlus preparation; 0 disables it. |

Balanced mem-saver is intended for a server repeatedly using a cached reference voice. On a reference-cache miss it first releases the warm generation path, prepares and caches the new voice, then reconstructs the generation path. This prevents the reference and generation weight groups from overlapping in VRAM. Set glm_tts.aggressive_mem_saver=true only when the lowest possible peak VRAM is more important than request latency; it implies balanced mem-saver even when glm_tts.mem_saver is omitted.

The reference transcript must match the audio. A mismatched transcript changes both semantic and speaker conditioning and can substantially reduce quality. Q8 generation can select a slightly different speech-token sequence from the native checkpoint, so waveform identity is not expected.

See GLM-TTS validation for exact component parity, path-test, timing, and output details.