Step TTS 2 | EmpirioLabs AI Docs

StepFun · Audio Generation

POST /v1/audio/speech

StepFun text-to-speech model with official voices, custom cloned voices, and voice tag controls.

At a glance

Field	Value
Model id	`step-tts-2`
Model release date	-
Input modalities	Text
Output modalities	Audio
Context window	-
Weight precision	-
Region	International
Features	text_to_speech, voice_tags, multilingual
Native inference	No
New	Yes
Supported endpoints	`POST /v1/audio/speech`

Pricing

Charge	Spec	Rate
Synthesis	per 10,000 characters	$0.40

Example request

$ curl https://api.empiriolabs.ai/v1/audio/speech \
>   -H 'Authorization: Bearer $EMPIRIOLABS_API_KEY' \
>   -H 'Content-Type: application/json' \
>   -d '{"model": "step-tts-2", "input": "Hello from EmpirioLabs."}'

Parameters

Parameter	Type	Required	Default	Description
`input`	string	yes	-	Text to synthesize. Maximum 1,000 characters. · Max: 1000
`voice`	string	no	`"lively-girl"`	Official voice ID or custom cloned voice ID.
`response_format`	enum	no	`"mp3"`	Output audio format. · Allowed: `mp3`, `wav`, `flac`, `opus`, `pcm`
`speed`	number	no	`1.0`	Speech speed. · Range: 0.5 – 2
`volume`	number	no	`1.0`	Output volume. · Range: 0.1 – 2
`sample_rate`	enum	no	`24000`	Output sample rate in Hz. · Allowed: `8000`, `16000`, `22050`, `24000`, `48000`
`voice_label`	object	no	-	Emotion and speaking-style tags for step-tts-2.
`pronunciation_map`	object	no	-	Optional pronunciation mapping.
`markdown_filter`	boolean	no	false	Filter markdown syntax before synthesis.

Notes

Maximum input is 1,000 characters. Supports official voice IDs, custom cloned voices, voice_label emotion tags, and voice_label style tags. The instruction parameter is only for stepaudio-2.5-tts.

Machine-readable schema: GET https://api.empiriolabs.ai/v1/models/step-tts-2.