The Audio API from LLM Gateway — 2 operation(s) for audio.
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openapi: 3.2.0
info:
version: 1.0.0
title: LLM Gateway Audio API
description: 'OpenAI-compatible LLM gateway: chat completions, embeddings, images, audio, video, moderation, OCR, rerank, web search and typed decisions across providers with one API key.'
servers:
- url: https://api.llmgateway.io
- url: http://localhost:4001
tags:
- name: Audio
paths:
/v1/audio/speech:
post:
operationId: v1_audio_speech
summary: Create speech
description: Generates audio from input text (text-to-speech). Returns the audio file as binary data.
security:
- bearerAuth: []
requestBody:
content:
application/json:
schema:
type: object
properties:
model:
type: string
description: ID of the speech generation (text-to-speech) model to use.
example: gemini-2.5-flash-preview-tts
input:
type: string
minLength: 1
description: The text to synthesize into speech.
example: Hello, welcome to LLM Gateway!
voice:
type: string
description: The prebuilt voice to use. Defaults to the model's default voice when omitted.
example: Kore
response_format:
type: string
enum:
- wav
- pcm
- mp3
- opus
- aac
- flac
description: The audio format of the returned audio. OpenAI models support mp3 (default), opus, aac, flac, wav and pcm. Gemini models emit PCM, so only wav (default) and pcm are supported.
example: wav
speed:
type: number
minimum: 0.25
maximum: 4
description: Playback speed hint. Forwarded to OpenAI models; not applied by Gemini speech models.
example: 1
instructions:
type: string
description: Optional style/delivery instructions prepended to the input as a natural-language directive (e.g. 'Say cheerfully').
example: Say in a warm, friendly tone
required:
- model
- input
responses:
'200':
description: Generated audio.
headers:
RateLimit-Policy:
schema:
type: string
description: Quota policy as an HTTP Structured Fields list, e.g. "requests";q=60;w=60.
RateLimit:
schema:
type: string
description: Available quota and reset delay, e.g. "requests";r=59;t=60.
RateLimit-Limit:
schema:
type: string
description: Request limit for the current window.
RateLimit-Remaining:
schema:
type: string
description: Requests remaining in the current window.
RateLimit-Reset:
schema:
type: string
description: Seconds until the current window resets.
content:
audio/wav:
schema: {}
audio/mpeg:
schema: {}
application/octet-stream:
schema: {}
'400':
description: Invalid request body or parameters.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'401':
description: Missing or invalid API key.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'402':
description: Insufficient credits or plan limits reached.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'403':
description: Forbidden request or upstream response.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'404':
description: Unknown model or upstream not-found response.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'408':
description: Request timeout.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'410':
description: Archived or unavailable project.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'413':
description: Request too large.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'415':
description: Unsupported media type.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'429':
description: Rate limited. Response headers describe only LLMGateway-enforced limits; upstream provider headers are not forwarded. Honor Retry-After when present.
headers:
RateLimit-Policy:
schema:
type: string
description: Quota policy as an HTTP Structured Fields list, e.g. "requests";q=60;w=60.
RateLimit:
schema:
type: string
description: Available quota and reset delay, e.g. "requests";r=59;t=60.
RateLimit-Limit:
schema:
type: string
description: Request limit for the current window.
RateLimit-Remaining:
schema:
type: string
description: Requests remaining in the current window.
RateLimit-Reset:
schema:
type: string
description: Seconds until the current window resets.
Retry-After:
schema:
type: string
description: Seconds to wait before retrying.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'500':
description: Internal server error.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'502':
description: Failed to connect to the upstream provider.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'503':
description: Service unavailable upstream response.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'504':
description: Upstream provider timeout.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'529':
description: Gateway overloaded.
headers:
Retry-After:
schema:
type: string
description: Seconds to wait before retrying.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
tags:
- Audio
/v1/audio/transcriptions:
post:
operationId: v1_audio_transcriptions
summary: Create transcription
description: Transcribes audio into text (speech-to-text) with word-level timestamps. The request body is multipart/form-data carrying the audio file (or a URL to it).
security:
- bearerAuth: []
requestBody:
content:
multipart/form-data:
schema:
type: object
properties:
model:
type: string
description: ID of the transcription (speech-to-text) model to use.
example: grok-stt-1-0
file:
type: string
description: The audio file to transcribe. Required unless `url` is provided.
format: binary
url:
type: string
description: URL of an audio file to download and transcribe upstream. Required unless `file` is provided.
language:
type: string
description: Language code (e.g. 'en'). When set, enables inverse text normalization so numbers and currencies are formatted in their written form.
example: en
diarize:
type: string
description: When 'true', enables speaker diarization; each word in the response includes a `speaker` field.
filler_words:
type: string
description: When 'true', filler words (e.g. 'uh', 'um') are kept in the transcript instead of being removed.
keyterm:
type: string
description: A key term to bias transcription toward (e.g. product names). Repeat the field for multiple terms.
required:
- model
description: Multipart form fields for the transcription request.
responses:
'200':
description: Transcription response.
headers:
RateLimit-Policy:
schema:
type: string
description: Quota policy as an HTTP Structured Fields list, e.g. "requests";q=60;w=60.
RateLimit:
schema:
type: string
description: Available quota and reset delay, e.g. "requests";r=59;t=60.
RateLimit-Limit:
schema:
type: string
description: Request limit for the current window.
RateLimit-Remaining:
schema:
type: string
description: Requests remaining in the current window.
RateLimit-Reset:
schema:
type: string
description: Seconds until the current window resets.
content:
application/json:
schema:
type: object
properties:
text:
type: string
language:
type: string
duration:
type: number
words:
type: array
items:
type: object
properties:
text:
type: string
start:
type: number
end:
type: number
speaker:
type: number
channels:
type: array
items:
type: object
additionalProperties: {}
description: 'Transcription payload: full transcript text, detected language, audio duration in seconds and word-level timestamps.'
'400':
description: Invalid request body or parameters.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'401':
description: Missing or invalid API key.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'402':
description: Insufficient credits or plan limits reached.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'403':
description: Forbidden request or upstream response.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'404':
description: Unknown model or upstream not-found response.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'408':
description: Request timeout.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'410':
description: Archived or unavailable project.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'413':
description: Request too large.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'415':
description: Unsupported media type.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'429':
description: Rate limited. Response headers describe only LLMGateway-enforced limits; upstream provider headers are not forwarded. Honor Retry-After when present.
headers:
RateLimit-Policy:
schema:
type: string
description: Quota policy as an HTTP Structured Fields list, e.g. "requests";q=60;w=60.
RateLimit:
schema:
type: string
description: Available quota and reset delay, e.g. "requests";r=59;t=60.
RateLimit-Limit:
schema:
type: string
description: Request limit for the current window.
RateLimit-Remaining:
schema:
type: string
description: Requests remaining in the current window.
RateLimit-Reset:
schema:
type: string
description: Seconds until the current window resets.
Retry-After:
schema:
type: string
description: Seconds to wait before retrying.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'500':
description: Internal server error.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'502':
description: Failed to connect to the upstream provider.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'503':
description: Service unavailable upstream response.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'504':
description: Upstream provider timeout.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
'529':
description: Gateway overloaded.
headers:
Retry-After:
schema:
type: string
description: Seconds to wait before retrying.
content:
application/json:
schema:
$ref: '#/components/schemas/OpenAIError'
tags:
- Audio
components:
schemas:
OpenAIError:
type: object
properties:
error:
type: object
properties:
message:
type: string
type:
type: string
param:
type:
- string
- 'null'
code:
type:
- string
- 'null'
required:
- message
- type
- param
- code
required:
- error
description: OpenAI-compatible error object.
securitySchemes:
bearerAuth:
type: http
scheme: bearer
description: Bearer token authentication using API keys
externalDocs:
url: https://docs.llmgateway.io
description: LLMGateway Documentation