> ## 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.

# Speech-to-Text Transcription Batch English VFast

> Fast English-only batch transcription. Trades enrichment features for the lowest possible turnaround.



## OpenAPI

````yaml api/velma_2_stt_batch_english_vfast.yaml POST /api/velma-2-stt-batch-english-vfast
openapi: 3.1.0
info:
  title: Velma 2 English STT Batch API
  version: 0.0.0
  description: |
    Fast, accurate English speech-to-text via HTTP POST. Pure transcription
    only - no diarization, emotion detection, accent detection, or PII/PHI
    tagging. Submit an audio file, get back a single JSON response with the
    full transcript (cased and punctuated) and the audio duration.
servers:
  - url: https://platform.modulate.ai
    description: Modulate English STT Batch Server
security:
  - ApiKeyAuth: []
paths:
  /api/velma-2-stt-batch-english-vfast:
    post:
      summary: Transcribe an English audio file
      description: |
        Accepts a single audio file and returns its full transcript as a
        synchronous JSON response.
      operationId: transcribeEnglishVfast2
      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.
      responses:
        '200':
          description: Transcription completed successfully.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/TranscriptionResponse'
              examples:
                short_audio:
                  summary: Short audio transcription
                  value:
                    text: Hello, how are you doing today?
                    duration_ms: 2000
                longer_audio:
                  summary: Longer audio with multiple sentences
                  value:
                    text: >-
                      Welcome to today's meeting. We'll be discussing the
                      quarterly results and planning for next quarter.
                    duration_ms: 14253
        '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.
                bad_value:
                  summary: Malformed request value
                  value:
                    detail: Invalid request.
        '403':
          description: Forbidden - the request is not permitted.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
              example:
                detail: This request is not permitted.
        '422':
          description: >
            Unprocessable entity - a required request parameter is missing or
            invalid (for example, the `X-API-Key` header or the `upload_file`
            field).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
        '429':
          description: >-
            Too many requests - the request could not be completed due to
            insufficient credits.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
              example:
                detail: Insufficient credits.
        '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 validated.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
              example:
                detail: Unable to validate request. Please try again.
        '503':
          description: Service unavailable - the service is temporarily unavailable.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
              example:
                detail: >-
                  The service is temporarily unavailable. Please try again
                  later.
        '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
      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: Hello, how are you doing today?
        duration_ms:
          type: integer
          minimum: 0
          description: |
            The total duration of the processed audio in milliseconds.
          example: 14253
    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.

````