> ## Documentation Index > Fetch the complete documentation index at: https://docs.modulate.ai/llms.txt > Use this file to discover all available pages before exploring further. # Multilingual Fast Transcription Batch > Fast multilingual batch transcription. Optionally declare the spoken language for the fastest path; otherwise the language is detected automatically. ## OpenAPI ````yaml api/velma_2_stt_batch_multilingual_vfast.yaml POST /api/velma-2-stt-batch-multilingual-vfast openapi: 3.1.0 info: title: Modulate Multilingual Speech-to-Text (Batch) version: 1.1.0 description: > Transcribe an audio file in any supported language. Optionally declare the spoken language for direct, fastest-path transcription; if omitted, the language is detected automatically. Returns one transcript, the language the transcript is in, and audio duration metadata. Pure transcription only - no diarization, emotion detection, accent detection, PII/PHI tagging, or per-utterance data. servers: - url: https://platform.modulate.ai security: - ApiKeyAuth: [] paths: /api/velma-2-stt-batch-multilingual-vfast: post: summary: Transcribe a multilingual audio file description: | Accepts a single audio file plus an optional `language` form field and returns its full transcript as a synchronous JSON response. operationId: transcribeMultilingual requestBody: required: true content: multipart/form-data: schema: type: object required: - upload_file properties: upload_file: type: string format: binary description: > Audio file to transcribe. Must be non-empty. Supported formats: `.aac`, `.aiff`, `.flac`, `.mov`, `.mp3`, `.mp4`, `.ogg`, `.opus`, `.wav`, `.webm`. Maximum file size: 100 MB. language: type: string description: | Optional. The spoken language as a short code (e.g. `en`, `es`, `fr`, `ja`). When provided, the audio is transcribed directly in that language and the same value is echoed back in the `language` response field. When omitted, the language is detected automatically and the detected code is returned in that field. example: es responses: '200': description: Transcription completed successfully. content: application/json: schema: $ref: '#/components/schemas/TranscriptionResponse' examples: declared_language: summary: Spanish audio with a declared language value: text: Hola a todos. Bienvenidos a la junta semanal. duration_ms: 4200 language: es detected_language: summary: Language detected automatically value: text: >- Welcome to today's meeting. We'll be discussing the quarterly results. duration_ms: 9000 language: en '400': description: > Bad request - the uploaded file is empty, its format is not supported, or the audio could not be decoded. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' examples: invalid_format: summary: Invalid file format value: detail: >- Unsupported file format. Supported formats: .aac, .aiff, .flac, .mov, .mp3, .mp4, .ogg, .opus, .wav, .webm. empty_file: summary: Empty file value: detail: The uploaded file is empty. unprocessable: summary: Audio could not be decoded value: detail: >- The audio could not be processed. It may be corrupted or in an unsupported format. no_audio_stream: summary: No decodable audio stream value: detail: No decodable audio stream was found in the file. unsupported_codec: summary: Unsupported audio codec value: detail: The audio codec is not supported. corrupt_audio: summary: Corrupted or truncated audio value: detail: The audio file appears to be corrupted or truncated. '401': description: Unauthorized - the API key is missing or not valid. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' examples: missing_api_key: summary: Missing API key value: detail: Missing API key. invalid_api_key: summary: Invalid API key value: detail: Invalid API key. '403': description: Forbidden - the request is not permitted. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' examples: not_permitted: summary: Request not permitted value: detail: This request is not permitted. model_access_denied: summary: No access to this model value: detail: This API key does not have access to this model. '413': description: >- Request entity too large - the file exceeds the maximum allowed size. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: detail: The uploaded file is too large. '422': description: > Unprocessable entity - a required request field is missing or malformed (for example, the `upload_file` form field). content: application/json: schema: $ref: '#/components/schemas/HTTPValidationError' '429': description: > Too many requests - the request was denied due to insufficient credits or a usage limit. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' examples: insufficient_credits: summary: Insufficient credits value: detail: Insufficient credits. concurrency_limit: summary: Concurrent request limit reached value: detail: >- Concurrent request limit reached. Please retry after your in-flight requests complete. monthly_limit: summary: Monthly usage limit reached value: detail: Monthly usage limit reached. '500': description: Internal server error during processing. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: detail: Internal server error '502': description: Bad gateway - the request could not be completed. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: detail: Unable to complete the request. Please try again. '504': description: Gateway timeout - processing timed out. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: detail: The request timed out. Please try again. security: - ApiKeyAuth: [] components: schemas: TranscriptionResponse: type: object required: - text - duration_ms - language properties: text: type: string description: | The complete transcribed text from the audio file. Text includes automatic capitalization and punctuation. May be an empty string if no speech was recognized. example: Hola a todos. Bienvenidos a la junta semanal. duration_ms: type: integer minimum: 0 description: The total duration of the processed audio in milliseconds. example: 4200 language: type: string description: | The language the transcript is in, as a short code (e.g. `en`, `es`, `fr`, `ja`). If the request declared a `language`, that value is echoed back unchanged. If it was omitted, this is the language detected automatically from the audio. For audio containing more than one language, this reports the predominant language detected. The transcript itself still reflects each part of the audio in the language spoken there. example: es ErrorResponse: type: object required: - detail properties: detail: type: string description: Human-readable error message. HTTPValidationError: type: object properties: detail: type: array items: $ref: '#/components/schemas/ValidationError' ValidationError: type: object required: - loc - msg - type properties: loc: type: array items: anyOf: - type: string - type: integer msg: type: string type: type: string securitySchemes: ApiKeyAuth: type: apiKey in: header name: X-API-Key description: API key used for authentication and usage tracking. ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.