runtime/omnivoice-python/omnivoice-source/docs/generation-parameters.md

Generation Parameters

Parameters can be passed as keyword arguments to model.generate(...) or via the OmniVoiceGenerationConfig dataclass. See below for the full list and which category each belongs to.

# 1) Direct keyword arguments
audio = model.generate(text="Hello world", num_step=32, guidance_scale=2.0)

# 2) Via OmniVoiceGenerationConfig dataclass
from omnivoice import OmniVoiceGenerationConfig

config = OmniVoiceGenerationConfig(num_step=32, guidance_scale=2.0)
audio = model.generate(text="Hello world", generation_config=config)

Decoding

Parameter	Type	Default	Description
num_step	int	32	Number of iterative unmasking steps. Higher values improve quality but slow down generation. Use 16 for faster inference.
denoise	bool	True	Prepend the `<
guidance_scale	float	2.0	Classifier-free guidance scale.
t_shift	float	0.1	Time-step shift for the noise schedule. Smaller values emphasise earlier steps in decoding.

Sampling

Parameter	Type	Default	Description
position_temperature	float	5.0	Temperature for mask-position selection. 0 = greedy (deterministic). Higher values increase randomness.
class_temperature	float	0.0	Temperature for token sampling at each step. 0 = greedy (deterministic). Higher values increase randomness.
layer_penalty_factor	float	5.0	Penalty applied to deeper codebook layers, encouraging earlier (lower) layers to unmask first.

Duration & Speed

These accept a single value applied to all items, or a per-item list (useful in batch mode):

# Fixed 10-second output
audio = model.generate(text="Hello, this is a test of duration control", duration=10.0)

# Faster speech (1.2x faster than estimated)
audio = model.generate(text="Hello, this is a test of duration control", speed=1.2)

Parameter	Type	Default	Description
duration	float or list[float | None]	None	Fixed output duration in seconds. Overrides speed when set.
speed	float or list[float | None]	None	Speed factor. Values > 1.0 produce shorter audio (faster); values < 1.0 produce longer audio (slower). Ignored when duration is set. Defaults to 1.0 when both are None.

Priority: duration > speed.

Note: When using duration, the default post-processing step may trim trailing silence, causing the actual output to be slightly shorter than the requested duration. If you need the output duration to exactly match the specified value, set postprocess_output=False to disable silence removal.

Pre/Post Processing

Parameter	Type	Default	Description
preprocess_prompt	bool	True	Whether to apply preprocessing to the voice-clone prompt audio (remove long silences in reference audio, add punctuation in the end of reference text).
postprocess_output	bool	True	Apply post-processing to generated audio (remove long silences).

Long-Form Generation

To support stable long-form speech generation with low VRAM consumption, the text is automatically split into smaller segments when the estimated duration of the generated speech exceeds audio_chunk_duration, with each segment producing approximately audio_chunk_duration seconds of audio. This approach allows the model to accept arbitrarily long text and generate arbitrarily long speech with near-constant VRAM consumption.

Parameter	Type	Default	Description
audio_chunk_duration	float	15.0	Target chunk duration (seconds) when splitting long text.
audio_chunk_threshold	float	30.0	Estimated audio duration (seconds) above which chunking is activated.