Audio
Generate Runway speech from text
Convert text into speech with a preset voice or reference audio using the Runway API.
POST
/
runwayml
/
v1
/
text_to_speech
curl https://api.cometapi.com/runwayml/v1/text_to_speech \
--request POST \
--header "Authorization: Bearer $COMETAPI_KEY" \
--header "Content-Type: application/json" \
--data '{
"model": "eleven_multilingual_v2",
"promptText": "Welcome to our audio guide. Let us begin the tour.",
"voice": {
"type": "runway-preset",
"presetId": "Maya"
}
}'{
"id": "123e4567-e89b-42d3-a456-426614174000"
}{
"code": "<string>",
"message": "<string>",
"data": "<unknown>"
}{
"error": {
"message": "<string>",
"type": "<string>",
"code": "<string>"
}
}Use
For preset voices, select a
For
POST /runwayml/v1/text_to_speech to create a speech task from text.
Send your CometAPI API key with Bearer authentication and a JSON request body.
Choose a model and voice
Every request requiresmodel and promptText. The voice field is required
for eleven_multilingual_v2, eleven_v3, and eleven_v4, and optional for seed_audio.
| Model ID | Text limit | Voice configuration |
|---|---|---|
eleven_multilingual_v2 | 1000 UTF-16 code units | type: runway-preset and a presetId, such as Maya |
eleven_v3 | 5000 characters | type: runway-preset and a presetId, such as Maya |
eleven_v4 | Non-empty text | type: runway-preset and a presetId, such as Maya |
seed_audio | 2048 characters | Omit voice for a default voice, or use type: reference-audio and an audioUri |
presetId from the request schema. For seed_audio,
replace the example audioUri with an accessible HTTPS URL of your voice reference.
Adjust speech expression
Witheleven_v3, promptText can include expressive tags such as [whispers]
or [laughs]. The model also accepts these controls:
| Field | Values | Meaning |
|---|---|---|
stability | Number from 0 to 1 | Lower nonzero values allow more expression; higher values are steadier. |
similarityBoost | Number from 0 to 1 | Higher values follow the selected voice more closely. |
style | Number from 0 to 1 | Higher values emphasize the voice style. |
speed | Number from 0.7 to 1.2 | 1 uses normal speed. |
useSpeakerBoost | true | Request greater similarity to the selected voice. |
languageCode | ISO 639-1 language code | Guide pronunciation and text normalization. |
applyTextNormalization | auto, on, off | Control how text such as numbers becomes spoken words. |
seed | Integer from 1 to 4294967295 | Set the sampling seed. |
stability, similarityBoost, and style, a value of 0 uses the model
default, as does omitting the field. useSpeakerBoost: false also uses the model
default. To set a sampling seed, use a positive integer; seed: 0 chooses a seed
automatically.
Adjust Eleven v4 speech
Witheleven_v4, promptText supports expressive tags such as [laughs],
[whispers], and [pause]. Use these optional controls:
| Field | Values | Meaning |
|---|---|---|
stability | Number from 0 to 1 | Lower values allow broader emotional range; higher values are steadier. |
similarityBoost | Number from 0 to 1 | Set how closely the output tracks the selected voice. |
style | Number from 0 to 1 | Higher values amplify the speaker style. |
speed | Number from 0.7 to 1.2 | Values below 1 slow speech; values above 1 speed it up. |
useSpeakerBoost | true or false | Boost similarity to the selected voice when true. |
languageCode | 2–16 characters | Enforce pronunciation, such as en or pt-BR. |
previousText | String | Continue speech from text generated before this request. |
nextText | String | Lead speech into text generated after this request. |
seed | Integer from 0 to 4294967295 | Choose a seed for more consistent output. |
eleven_v4 does not use applyTextNormalization. The previousText and
nextText fields are useful when you generate adjacent segments and want the
model to keep the transition coherent.
Adjust speech speed and format
Withseed_audio, use speechRate and loudnessRate from -50 to 100, or
pitchRate from -12 to 12 semitones. These controls accept integers; omission
or 0 keeps the normal value.
Set sampleRate to 8000, 16000, 24000, 32000, 44100, or 48000 Hz.
Set outputFormat to wav, mp3, or ogg_opus. Do not include duration,
referenceAudios, or Eleven v3 controls with seed_audio on this endpoint.
Retrieve the result
Save the returnedid, then use Get a Runway task
to retrieve task status. When status is SUCCEEDED, read the audio URLs in
output. If the task fails, inspect failure and failureCode.Authorizations
Use your CometAPI API key.
Body
application/json
- eleven_multilingual_v2
- eleven_v3
- eleven_v4
- seed_audio
Request settings for eleven_multilingual_v2.
Model ID for this request.
Available options:
eleven_multilingual_v2 Allowed value:
"eleven_multilingual_v2"Text to speak, from 1 to 1000 UTF-16 code units.
Required string length:
1 - 1000The voice to use for the generated speech.
Show child attributes
Show child attributes
Response
Task created. Save the returned id to retrieve task status.
Task ID for GET /runwayml/v1/tasks/{id}.
Task state, when returned.
Task submission timestamp, when returned.
Result URLs, when returned.
Failure explanation, when returned.
Machine-readable failure code, when returned.
Task estimate metadata, when returned.
Show child attributes
Show child attributes
Task cost metadata, when returned.
Show child attributes
Show child attributes
Last modified on October 11, 2026
⌘I
curl https://api.cometapi.com/runwayml/v1/text_to_speech \
--request POST \
--header "Authorization: Bearer $COMETAPI_KEY" \
--header "Content-Type: application/json" \
--data '{
"model": "eleven_multilingual_v2",
"promptText": "Welcome to our audio guide. Let us begin the tour.",
"voice": {
"type": "runway-preset",
"presetId": "Maya"
}
}'{
"id": "123e4567-e89b-42d3-a456-426614174000"
}{
"code": "<string>",
"message": "<string>",
"data": "<unknown>"
}{
"error": {
"message": "<string>",
"type": "<string>",
"code": "<string>"
}
}