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APIsInstant Voice Cloning

REST Stream

Beta
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Beta. Converts the input text into a streamed spoken audio response using a cloned voice.

Provide exactly one of:

  • voice_id — a saved cloned voice from POST /voices/create (or Content Studio), or
  • ref_audio — a reference audio clip uploaded with this request (optional ref_text transcript).

Sending both returns 400. The response is a binary audio stream (not JSON), so you can begin playback as soon as the first sentence is ready.

Accepts multipart/form-data.

Base URL: https://api.sarvam.ai. Auth: send your key in the api-subscription-key header (recommended); Authorization: Bearer <key> is also accepted.

Streaming codecs: mp3 (default), wav, linear16, mulaw, alaw. flac, aac, and opus are not supported on this endpoint because each sentence would be a complete container that cannot be concatenated.

Quality checks (QC/VAD) and duration bounds (min_audio_duration / max_audio_duration) are not accepted — the stream path optimizes for time-to-first-byte.

Billing: charged per character of text against the text_to_speech_voice_cloning API. See the pricing page.

Authentication

api-subscription-keystring
API Key authentication via header

Request

This endpoint expects a multipart form containing an optional file.
voice_idstringOptional

Saved cloned voice ID (svc-{uuid}) from POST /voices/create or Content Studio. Exactly one of ref_audio or voice_id must be provided — sending both returns 400. Prefer voice_id when you already saved the voice so you do not re-upload the clip.

ref_audiofileOptional

Reference audio clip used to clone the voice for this request. Supported formats: WAV, MP3, FLAC, OPUS, AAC, MULAW, ALAW, LINEAR16. WAV is recommended.

Limits: max file size 10 MB; max duration 15 seconds; single speaker. Exactly one of ref_audio or voice_id must be provided — sending both returns 400.

ref_textstring or nullOptional<=500 characters

Optional transcript of ref_audio (max 500 characters). Improves fidelity when provided. Omit or leave empty to let the API transcribe the clip. Ignored when voice_id is used.

textstringRequired1-1000 characters

Text to synthesize in the cloned voice. Native scripts and code-mixed text are supported. Maximum 1000 characters; longer text is rejected with a 400. Split longer input client-side and synthesize it in parts.

language_codeenumRequired

BCP-47 language code for the synthesized output. The cloned voice can speak any supported language, regardless of the reference clip’s language (cross-lingual cloning).

Available Options:

  • as-IN: Assamese
  • bn-IN: Bengali
  • en-IN: English (Indian)
  • gu-IN: Gujarati
  • hi-IN: Hindi
  • kn-IN: Kannada
  • ml-IN: Malayalam
  • mr-IN: Marathi
  • od-IN: Odia
  • pa-IN: Punjabi
  • ta-IN: Tamil
  • te-IN: Telugu
pacedouble or nullOptional0.5-2

Speech speed multiplier. 1.0 is natural speed; 0.5 to 2.0 is accepted. Speed is adjusted without changing pitch.

output_audio_codecenum or nullOptionalDefaults to mp3

Audio codec for the streamed output. Default is mp3.

  • mp3: Self-framing; clients can decode and play as chunks arrive. Recommended.
  • wav: One RIFF header (unknown length), then raw PCM chunks.
  • linear16: Raw 16-bit PCM (no header).
  • mulaw / alaw: 8-bit telephony codecs for IVR pipelines.
Allowed values:
output_audio_bitrateenum or nullOptionalDefaults to 128k

Bitrate for lossy codecs (mp3). Default is 128k. Options: 32k, 64k, 96k, 128k, 192k.

Allowed values:
speech_sample_rateenum or nullOptional
Output sample rate in Hz. Supported values are 8000, 16000, 22050, 24000, 32000, 44100, 48000. If omitted, the API returns 24000 Hz.
enable_text_normalizationboolean or nullOptional

Enable pre-TTS text normalization: numbers, currencies and dates are converted to their spoken form before synthesis (e.g. 9840950950 becomes the spoken digit sequence). Defaults to the server-side setting.

Response

Success. Returns a streamed audio response in the requested format (e.g., audio/mpeg for MP3, audio/wav for WAV).

Errors

400
Bad Request Error
402
Payment Required Error
403
Forbidden Error
422
Unprocessable Entity Error
429
Too Many Requests Error
500
Internal Server Error
502
Bad Gateway Error
503
Service Unavailable Error
504
Gateway Timeout Error