Predict duration

Predict text-to-speech duration

curl --request POST \
  --url https://supertoneapi.com/v1/predict-duration/{voice_id} \
  --header 'Content-Type: application/json' \
  --header 'x-sup-api-key: <api-key>' \
  --data '
{
  "text": "<string>",
  "style": "<string>",
  "model": "sona_speech_1",
  "output_format": "wav",
  "voice_settings": {
    "pitch_shift": 0,
    "pitch_variance": 1,
    "speed": 1,
    "duration": 0,
    "similarity": 3,
    "text_guidance": 1,
    "subharmonic_amplitude_control": 1
  }
}
'

import requests

url = "https://supertoneapi.com/v1/predict-duration/{voice_id}"

payload = {
    "text": "<string>",
    "style": "<string>",
    "model": "sona_speech_1",
    "output_format": "wav",
    "voice_settings": {
        "pitch_shift": 0,
        "pitch_variance": 1,
        "speed": 1,
        "duration": 0,
        "similarity": 3,
        "text_guidance": 1,
        "subharmonic_amplitude_control": 1
    }
}
headers = {
    "x-sup-api-key": "<api-key>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {'x-sup-api-key': '<api-key>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    text: '<string>',
    style: '<string>',
    model: 'sona_speech_1',
    output_format: 'wav',
    voice_settings: {
      pitch_shift: 0,
      pitch_variance: 1,
      speed: 1,
      duration: 0,
      similarity: 3,
      text_guidance: 1,
      subharmonic_amplitude_control: 1
    }
  })
};

fetch('https://supertoneapi.com/v1/predict-duration/{voice_id}', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://supertoneapi.com/v1/predict-duration/{voice_id}"

	payload := strings.NewReader("{\n  \"text\": \"<string>\",\n  \"style\": \"<string>\",\n  \"model\": \"sona_speech_1\",\n  \"output_format\": \"wav\",\n  \"voice_settings\": {\n    \"pitch_shift\": 0,\n    \"pitch_variance\": 1,\n    \"speed\": 1,\n    \"duration\": 0,\n    \"similarity\": 3,\n    \"text_guidance\": 1,\n    \"subharmonic_amplitude_control\": 1\n  }\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("x-sup-api-key", "<api-key>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://supertoneapi.com/v1/predict-duration/{voice_id}",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'text' => '<string>',
    'style' => '<string>',
    'model' => 'sona_speech_1',
    'output_format' => 'wav',
    'voice_settings' => [
        'pitch_shift' => 0,
        'pitch_variance' => 1,
        'speed' => 1,
        'duration' => 0,
        'similarity' => 3,
        'text_guidance' => 1,
        'subharmonic_amplitude_control' => 1
    ]
  ]),
  CURLOPT_HTTPHEADER => [
    "Content-Type: application/json",
    "x-sup-api-key: <api-key>"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

HttpResponse<String> response = Unirest.post("https://supertoneapi.com/v1/predict-duration/{voice_id}")
  .header("x-sup-api-key", "<api-key>")
  .header("Content-Type", "application/json")
  .body("{\n  \"text\": \"<string>\",\n  \"style\": \"<string>\",\n  \"model\": \"sona_speech_1\",\n  \"output_format\": \"wav\",\n  \"voice_settings\": {\n    \"pitch_shift\": 0,\n    \"pitch_variance\": 1,\n    \"speed\": 1,\n    \"duration\": 0,\n    \"similarity\": 3,\n    \"text_guidance\": 1,\n    \"subharmonic_amplitude_control\": 1\n  }\n}")
  .asString();

{
  "duration": 123
}

{
  "status": "error",
  "message": "Invalid request data"
}

{
  "status": "error",
  "message": {
    "message": "Invalid API Key",
    "error": "Unauthorized"
  }
}

{
  "status": "error",
  "message": {
    "message": "Not enough credits",
    "error": "Payment Required"
  }
}

{
  "status": "error",
  "message": {
    "message": "Permission denied",
    "error": "Forbidden"
  }
}

{
  "status": "error",
  "message": {
    "message": "Voice not found",
    "error": "Not Found"
  }
}

{
  "status": "error",
  "message": {
    "message": "Request timed out",
    "error": "Request Timeout"
  }
}

{
  "status": "error",
  "message": {
    "message": "rate limit exceeded",
    "error": "Too Many Requests"
  }
}

{
  "status": "error",
  "message": {
    "message": "Failed to convert text to speech",
    "error": "Internal Server Error"
  }
}

POST

predict-duration

{voice_id}

Predict text-to-speech duration

curl --request POST \
  --url https://supertoneapi.com/v1/predict-duration/{voice_id} \
  --header 'Content-Type: application/json' \
  --header 'x-sup-api-key: <api-key>' \
  --data '
{
  "text": "<string>",
  "style": "<string>",
  "model": "sona_speech_1",
  "output_format": "wav",
  "voice_settings": {
    "pitch_shift": 0,
    "pitch_variance": 1,
    "speed": 1,
    "duration": 0,
    "similarity": 3,
    "text_guidance": 1,
    "subharmonic_amplitude_control": 1
  }
}
'

import requests

url = "https://supertoneapi.com/v1/predict-duration/{voice_id}"

payload = {
    "text": "<string>",
    "style": "<string>",
    "model": "sona_speech_1",
    "output_format": "wav",
    "voice_settings": {
        "pitch_shift": 0,
        "pitch_variance": 1,
        "speed": 1,
        "duration": 0,
        "similarity": 3,
        "text_guidance": 1,
        "subharmonic_amplitude_control": 1
    }
}
headers = {
    "x-sup-api-key": "<api-key>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {'x-sup-api-key': '<api-key>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    text: '<string>',
    style: '<string>',
    model: 'sona_speech_1',
    output_format: 'wav',
    voice_settings: {
      pitch_shift: 0,
      pitch_variance: 1,
      speed: 1,
      duration: 0,
      similarity: 3,
      text_guidance: 1,
      subharmonic_amplitude_control: 1
    }
  })
};

fetch('https://supertoneapi.com/v1/predict-duration/{voice_id}', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://supertoneapi.com/v1/predict-duration/{voice_id}"

	payload := strings.NewReader("{\n  \"text\": \"<string>\",\n  \"style\": \"<string>\",\n  \"model\": \"sona_speech_1\",\n  \"output_format\": \"wav\",\n  \"voice_settings\": {\n    \"pitch_shift\": 0,\n    \"pitch_variance\": 1,\n    \"speed\": 1,\n    \"duration\": 0,\n    \"similarity\": 3,\n    \"text_guidance\": 1,\n    \"subharmonic_amplitude_control\": 1\n  }\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("x-sup-api-key", "<api-key>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://supertoneapi.com/v1/predict-duration/{voice_id}",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'text' => '<string>',
    'style' => '<string>',
    'model' => 'sona_speech_1',
    'output_format' => 'wav',
    'voice_settings' => [
        'pitch_shift' => 0,
        'pitch_variance' => 1,
        'speed' => 1,
        'duration' => 0,
        'similarity' => 3,
        'text_guidance' => 1,
        'subharmonic_amplitude_control' => 1
    ]
  ]),
  CURLOPT_HTTPHEADER => [
    "Content-Type: application/json",
    "x-sup-api-key: <api-key>"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

HttpResponse<String> response = Unirest.post("https://supertoneapi.com/v1/predict-duration/{voice_id}")
  .header("x-sup-api-key", "<api-key>")
  .header("Content-Type", "application/json")
  .body("{\n  \"text\": \"<string>\",\n  \"style\": \"<string>\",\n  \"model\": \"sona_speech_1\",\n  \"output_format\": \"wav\",\n  \"voice_settings\": {\n    \"pitch_shift\": 0,\n    \"pitch_variance\": 1,\n    \"speed\": 1,\n    \"duration\": 0,\n    \"similarity\": 3,\n    \"text_guidance\": 1,\n    \"subharmonic_amplitude_control\": 1\n  }\n}")
  .asString();

{
  "duration": 123
}

{
  "status": "error",
  "message": "Invalid request data"
}

{
  "status": "error",
  "message": {
    "message": "Invalid API Key",
    "error": "Unauthorized"
  }
}

{
  "status": "error",
  "message": {
    "message": "Not enough credits",
    "error": "Payment Required"
  }
}

{
  "status": "error",
  "message": {
    "message": "Permission denied",
    "error": "Forbidden"
  }
}

{
  "status": "error",
  "message": {
    "message": "Voice not found",
    "error": "Not Found"
  }
}

{
  "status": "error",
  "message": {
    "message": "Request timed out",
    "error": "Request Timeout"
  }
}

{
  "status": "error",
  "message": {
    "message": "rate limit exceeded",
    "error": "Too Many Requests"
  }
}

{
  "status": "error",
  "message": {
    "message": "Failed to convert text to speech",
    "error": "Internal Server Error"
  }
}

Returns the expected length (in seconds) of speech generated from the given input. Useful for cost forecasting, UI hints, and pre-flighting batch jobs.

This endpoint does not consume credits. The same 300-character text limit applies — it is not auto-chunked.

Endpoint

POST https://supertoneapi.com/v1/predict-duration/{voice_id}

Path parameters

Name	Required	Description
`voice_id`	✅	The ID of the target voice.

Request body

Same shape as Create speech — text, language, style, model, voice_settings — minus output_format, include_phonemes, and normalized_text (none of which affect duration).

Name	Required	Description
`text`	✅	Text to analyze. Max 300 characters.
`language`	✅	Language code. Must be supported by the voice and the model.
`style`	—	Emotional style. Defaults to the voice’s first style.
`model`	—	TTS model. Defaults to `sona_speech_1`.
`voice_settings`	—	Affects duration through `speed` and `duration`. See Create speech for the full table.

Request example

POST /v1/predict-duration/20160a4c5ba38967330c84
x-sup-api-key: $SUPERTONE_API_KEY
Content-Type: application/json

{
  "text": "This is a long-form sentence for duration prediction.",
  "language": "en",
  "style": "neutral"
}

Response

{
  "duration": 3.57
}

Duration is returned in seconds as a float.

Notes

Use the same model and speed in your prediction as in your eventual create_speech call — both affect the result. Predicting at one speed and generating at another produces mismatched durations.
No credits are deducted. Safe to use as a UI hint or budget pre-flight.

Docs: Cost and usage

How to use predict_duration for forecasting and budgeting.

Create speech

Actually generate the audio once you’ve validated the estimate.

Authorizations

x-sup-api-key

string

header

required

Path Parameters

voice_id

string

required

Body

application/json

text

string

required

The text to convert to speech. Max length is 300 characters.

Maximum string length: 300

language

enum<string>

required

Language code of the voice

Available options:

en,

ko,

ja,

bg,

cs,

da,

el,

es,

et,

fi,

hu,

it,

nl,

pl,

pt,

ro,

ar,

de,

fr,

hi,

id,

ru,

vi,

hr,

lt,

lv,

sk,

sl,

sv,

tr,

uk

style

string

The style of character to use for the text-to-speech conversion

model

enum<string>

default:sona_speech_1

The model type to use for the text-to-speech conversion

Available options:

sona_speech_1,

sona_speech_2,

sona_speech_2_flash,

supertonic_api_1,

supertonic_api_3

output_format

enum<string>

default:wav

The desired output format of the audio file (wav, mp3). Default is wav.

Available options:

wav,

mp3

voice_settings

object

Show child attributes

Response

Returns predicted duration of the audio in seconds

duration

number

Stream speech

Get usage

⌘I

Supertone API

Voices

Custom voices

Text to speech

Usage

Endpoint

Path parameters

Request body

Request example

Response

Notes

See also

Docs: Cost and usage

Create speech

Authorizations

Path Parameters

Body

Response

​Endpoint

​Path parameters

​Request body

​Request example

​Response

​Notes

​See also

Docs: Cost and usage

Create speech

Authorizations

Path Parameters

Body

Response

Endpoint

Path parameters

Request body

Request example

Response

Notes

See also