Forced alignment

curl https://api.snapgen.org/v1/audio/alignment \
  -H "Authorization: Bearer $SNAPGEN_API_KEY" \
  -F model=eleven-forced-alignment \
  -F file=@narration.mp3 \
  -F text="The quick brown fox jumps over the lazy dog."

curl https://api.snapgen.org/v1/audio/alignment \
  -H "Authorization: Bearer $SNAPGEN_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "eleven-forced-alignment",
    "audio_url": "https://example.com/narration.mp3",
    "text": "The quick brown fox jumps over the lazy dog."
  }'

import os

import requests

with open("narration.mp3", "rb") as audio:
    response = requests.post(
        "https://api.snapgen.org/v1/audio/alignment",
        headers={"Authorization": f"Bearer {os.environ['SNAPGEN_API_KEY']}"},
        data={
            "model": "eleven-forced-alignment",
            "text": "The quick brown fox jumps over the lazy dog.",
        },
        files={"file": ("narration.mp3", audio, "audio/mpeg")},
        timeout=600,
    )
response.raise_for_status()
for word in response.json()["words"]:
    print(word["start"], word["end"], word["text"])

import { openAsBlob } from "node:fs";

const form = new FormData();
form.append("model", "eleven-forced-alignment");
form.append("file", await openAsBlob("narration.mp3"), "narration.mp3");
form.append("text", "The quick brown fox jumps over the lazy dog.");

const response = await fetch("https://api.snapgen.org/v1/audio/alignment", {
  method: "POST",
  headers: { Authorization: `Bearer ${process.env.SNAPGEN_API_KEY}` },
  body: form,
});
if (!response.ok) throw new Error(await response.text());
const { words } = await response.json();
for (const word of words) console.log(word.start, word.end, word.text);

{
  "words": [
    { "text": "The", "start": 0.08, "end": 0.21, "loss": 0.12 },
    { "text": "quick", "start": 0.21, "end": 0.48, "loss": 0.09 },
    { "text": "brown", "start": 0.48, "end": 0.77, "loss": 0.11 }
  ],
  "loss": 0.1
}

{
  "error": {
    "message": "The audio must be at most 3600 seconds long",
    "type": "invalid_request_error",
    "param": null,
    "code": "audio_too_long"
  }
}

POST

audio

alignment

curl https://api.snapgen.org/v1/audio/alignment \
  -H "Authorization: Bearer $SNAPGEN_API_KEY" \
  -F model=eleven-forced-alignment \
  -F file=@narration.mp3 \
  -F text="The quick brown fox jumps over the lazy dog."

curl https://api.snapgen.org/v1/audio/alignment \
  -H "Authorization: Bearer $SNAPGEN_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "eleven-forced-alignment",
    "audio_url": "https://example.com/narration.mp3",
    "text": "The quick brown fox jumps over the lazy dog."
  }'

import os

import requests

with open("narration.mp3", "rb") as audio:
    response = requests.post(
        "https://api.snapgen.org/v1/audio/alignment",
        headers={"Authorization": f"Bearer {os.environ['SNAPGEN_API_KEY']}"},
        data={
            "model": "eleven-forced-alignment",
            "text": "The quick brown fox jumps over the lazy dog.",
        },
        files={"file": ("narration.mp3", audio, "audio/mpeg")},
        timeout=600,
    )
response.raise_for_status()
for word in response.json()["words"]:
    print(word["start"], word["end"], word["text"])

import { openAsBlob } from "node:fs";

const form = new FormData();
form.append("model", "eleven-forced-alignment");
form.append("file", await openAsBlob("narration.mp3"), "narration.mp3");
form.append("text", "The quick brown fox jumps over the lazy dog.");

const response = await fetch("https://api.snapgen.org/v1/audio/alignment", {
  method: "POST",
  headers: { Authorization: `Bearer ${process.env.SNAPGEN_API_KEY}` },
  body: form,
});
if (!response.ok) throw new Error(await response.text());
const { words } = await response.json();
for (const word of words) console.log(word.start, word.end, word.text);

{
  "words": [
    { "text": "The", "start": 0.08, "end": 0.21, "loss": 0.12 },
    { "text": "quick", "start": 0.21, "end": 0.48, "loss": 0.09 },
    { "text": "brown", "start": 0.48, "end": 0.77, "loss": 0.11 }
  ],
  "loss": 0.1
}

{
  "error": {
    "message": "The audio must be at most 3600 seconds long",
    "type": "invalid_request_error",
    "param": null,
    "code": "audio_too_long"
  }
}

POST /v1/audio/alignment matches a known transcript to its audio and returns the start and end time of each word. Use it to time captions, karaoke lyrics, or highlighted read-along text when you already have the exact words. To transcribe audio you don’t have text for, use Speech to text.

Model	Input	Price
`eleven-forced-alignment`	Up to 3,600 seconds (1 hour) and 50 MB	$0.000092 per second ($0.3312 per hour)

string

required

Set to eleven-forced-alignment.

file

The audio file, in a multipart field named file, up to 50 MB. Send file or audio_url, not both.

string

Public http or https URL of the audio. The gateway downloads it, up to 50 MB. Send audio_url or file, not both.

string

required

The transcript to align, up to 100,000 characters. The text isn’t billed.

Send the audio as a multipart upload (one model field, one file in file, and text as a form field) or as JSON with audio_url. The gateway accepts WAV, AIFF, MP3, AAC, MP4, M4A, MOV, FLAC, Ogg, and WebM files whose length can be read.

Response

object[]

One entry per word, in order.

Show word

string

The word.

number | null

Start time in seconds.

number | null

End time in seconds.

number | null

The provider’s alignment loss for the word.

number | null

The provider’s alignment loss for the whole text.

When the charge has settled, the response carries it in micro-USD in the x-gateway-charge-microusd header.

Billing

The gateway bills the measured length of the audio at $0.000092 per second, rounded up to whole seconds after a 0.1-second allowance, with a minimum of 1 second. A 10-minute recording costs $0.0552. Failed requests aren’t charged. This endpoint rejects Idempotency-Key; if a request times out, check your Console request logs before you retry.

Errors

Status	`error.code`	Cause
400	`audio_input_required`	Neither `file` nor `audio_url` was sent.
400	`invalid_request`	`text` is missing, blank, or too long, a field is unknown, or both `file` and `audio_url` were sent.
400	`invalid_multipart`	The form has no `model` field, more than one file, a repeated field, or the file isn’t in the `file` field.
400	`unsupported_audio_format`	The format isn’t supported, or its length can’t be read.
400	`audio_too_long`	The audio is longer than 3,600 seconds.
400	`audio_download_failed`	The gateway couldn’t download `audio_url`.
400	`provider_rejected_request`	The provider refused the audio or text.
402	`insufficient_funds`	Your balance can’t cover the request.
413	`audio_too_large`, `request_too_large`	The downloaded file or the upload is larger than 50 MB.

See Errors for rate limits and provider failures.

curl https://api.snapgen.org/v1/audio/alignment \
  -H "Authorization: Bearer $SNAPGEN_API_KEY" \
  -F model=eleven-forced-alignment \
  -F file=@narration.mp3 \
  -F text="The quick brown fox jumps over the lazy dog."

curl https://api.snapgen.org/v1/audio/alignment \
  -H "Authorization: Bearer $SNAPGEN_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "eleven-forced-alignment",
    "audio_url": "https://example.com/narration.mp3",
    "text": "The quick brown fox jumps over the lazy dog."
  }'

import os

import requests

with open("narration.mp3", "rb") as audio:
    response = requests.post(
        "https://api.snapgen.org/v1/audio/alignment",
        headers={"Authorization": f"Bearer {os.environ['SNAPGEN_API_KEY']}"},
        data={
            "model": "eleven-forced-alignment",
            "text": "The quick brown fox jumps over the lazy dog.",
        },
        files={"file": ("narration.mp3", audio, "audio/mpeg")},
        timeout=600,
    )
response.raise_for_status()
for word in response.json()["words"]:
    print(word["start"], word["end"], word["text"])

import { openAsBlob } from "node:fs";

const form = new FormData();
form.append("model", "eleven-forced-alignment");
form.append("file", await openAsBlob("narration.mp3"), "narration.mp3");
form.append("text", "The quick brown fox jumps over the lazy dog.");

const response = await fetch("https://api.snapgen.org/v1/audio/alignment", {
  method: "POST",
  headers: { Authorization: `Bearer ${process.env.SNAPGEN_API_KEY}` },
  body: form,
});
if (!response.ok) throw new Error(await response.text());
const { words } = await response.json();
for (const word of words) console.log(word.start, word.end, word.text);

{
  "words": [
    { "text": "The", "start": 0.08, "end": 0.21, "loss": 0.12 },
    { "text": "quick", "start": 0.21, "end": 0.48, "loss": 0.09 },
    { "text": "brown", "start": 0.48, "end": 0.77, "loss": 0.11 }
  ],
  "loss": 0.1
}

{
  "error": {
    "message": "The audio must be at most 3600 seconds long",
    "type": "invalid_request_error",
    "param": null,
    "code": "audio_too_long"
  }
}

Overview

Text Series

Image Series

Video Series

Audio Series

Endpoint Reference

Task Management

Forced alignment

Response

Billing

Errors

​Response

​Billing

​Errors

Response

Billing

Errors