Text-to-Speech

Streaming Text To Speech

Generate speech from text using real-time streaming, allowing audio playback to begin before the entire synthesis is complete.

This endpoint streams audio data in chunks, enabling low-latency audio playback for applications requiring immediate feedback.

Streaming Format:

WAV format: First chunk contains WAV header (size=0xFFFFFFFF for streaming) followed by raw PCM data. Subsequent chunks contain only PCM data.
MP3 format: Each chunk contains post-processed MP3 data that can be decoded independently.

Use Cases:

Conversational AI, chatbots and real-time voice assistants
Interactive applications requiring immediate audio feedback
Long-form content where waiting for full synthesis is impractical

Request Parameters: Uses the same TTSRequest schema as the standard TTS endpoint. Set output.audio_format to "wav" or "mp3" to control the streaming format.

post/v1/text-to-speech/stream

Request

Base URL: https://api.typecast.ai
URL: https://api.typecast.ai/v1/text-to-speech/stream
Auth: API key in header X-API-KEY

Request body

textstring required

Text to convert to speech. Minimum 1 character, maximum 2000 characters. Credits consumed based on text length. Supports multiple languages including English, Korean, Japanese, and Chinese. Special characters and punctuation are handled automatically.

model'ssfm-v30' | 'ssfm-v21' required

TTS model version to use for speech synthesis. Different models offer varying capabilities and quality levels.

Available models:

ssfm-v30: Latest model with improved prosody and additional emotion presets (recommended)
ssfm-v21: Stable production model with proven reliability and consistent quality

languagestring

Language code following ISO 639-3 standard. Case-insensitive (both "ENG" and "eng" are accepted). If not provided, will be auto-detected based on text content.

<details> <summary><strong>ssfm-v30 Supported Languages (37)</strong></summary>

Code	Language	Code	Language	Code	Language
ARA	Arabic	IND	Indonesian	POR	Portuguese
BEN	Bengali	ITA	Italian	RON	Romanian
BUL	Bulgarian	JPN	Japanese	RUS	Russian
CES	Czech	KOR	Korean	SLK	Slovak
DAN	Danish	MSA	Malay	SPA	Spanish
DEU	German	NAN	Min Nan	SWE	Swedish
ELL	Greek	NLD	Dutch	TAM	Tamil
ENG	English	NOR	Norwegian	TGL	Tagalog
FIN	Finnish	PAN	Punjabi	THA	Thai
FRA	French	POL	Polish	TUR	Turkish
HIN	Hindi	UKR	Ukrainian	VIE	Vietnamese
HRV	Croatian	YUE	Cantonese	ZHO	Chinese
HUN	Hungarian

</details> <details> <summary><strong>ssfm-v21 Supported Languages (27)</strong></summary>

Code	Language	Code	Language	Code	Language
ARA	Arabic	IND	Indonesian	RON	Romanian
BUL	Bulgarian	ITA	Italian	RUS	Russian
CES	Czech	JPN	Japanese	SLK	Slovak
DAN	Danish	KOR	Korean	SPA	Spanish
DEU	German	MSA	Malay	SWE	Swedish
ELL	Greek	NLD	Dutch	TAM	Tamil
ENG	English	POL	Polish	TGL	Tagalog
FIN	Finnish	POR	Portuguese	UKR	Ukrainian
FRA	French	HRV	Croatian	ZHO	Chinese

</details>

voice_idstring required

Voice identifier. Two prefixes are supported:

tc_ — Built-in Typecast voices (e.g., tc_60e5426de8b95f1d3000d7b5). See Listing all voices for available IDs.
uc_ — Custom voices created via Instant cloning (e.g., uc_64a1b2c3d4e5f6a7b8c9d0e1). Only the owner of a cloned voice can use it.

Case-sensitive: must use lowercase prefix.

Example request

{
  "text": "Everything is so incredibly perfect that I feel like I'm dreaming.",
  "output": {
    "audio_tempo": 1,
    "target_lufs": -14,
    "audio_format": "wav",
    "remove_silence_ms": 100
  },
  "prompt": {
    "next_text": "I am literally bursting with happiness and I never want this feeling to end!",
    "emotion_type": "smart",
    "previous_text": "I feel like I'm walking on air and I just want to scream with joy!"
  },
  "language": "eng",
  "voice_id": "tc_60e5426de8b95f1d3000d7b5"
}

Response

Success - Returns streaming audio data in chunks

Changes

No recorded changes to this operation across all 1 revision of this API.