> ## 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. # Language Detection Batch > Identify the spoken language of an audio file. Returns an ISO 639-1 language code, human-readable display name, and confidence score in a single synchronous response. ## OpenAPI ````yaml api/velma_2_language_detection_batch.yaml POST /api/velma-2-language-detection-batch openapi: 3.1.0 info: title: Velma 2 Language Detection Batch API version: 0.0.0 description: > Identify the spoken language of an audio file via HTTP POST. Submit a clip, get back the detected language - both an ISO code and a human-readable name - with a confidence score, in a single synchronous JSON response. Pure language detection only: no transcription, diarization, emotion, accent, or PII tagging. servers: - url: https://platform.modulate.ai description: Modulate Language Detection Batch Server security: - ApiKeyAuth: [] paths: /api/velma-2-language-detection-batch: post: summary: Identify the spoken language of an audio file description: | Accepts a single audio file and returns the detected language as a synchronous JSON response. operationId: detectLanguageBatch requestBody: required: true content: multipart/form-data: schema: type: object required: - upload_file properties: upload_file: type: string format: binary description: | Audio file to analyze. Must be non-empty. Supported formats: `.3g2`, `.3ga`, `.3gp`, `.3gpp`, `.8svx`, `.aa3`, `.aac`, `.ac3`, `.act`, `.adts`, `.aif`, `.aifc`, `.aiff`, `.alac`, `.amb`, `.amr`, `.ape`, `.asf`, `.at3`, `.au`, `.avi`, `.avr`, `.awb`, `.bwf`, `.c2`, `.caf`, `.dss`, `.dts`, `.dtshd`, `.eac3`, `.ec3`, `.f4a`, `.f4b`, `.flac`, `.flv`, `.gsm`, `.iff`, `.m2a`, `.m2ts`, `.m4a`, `.m4b`, `.m4r`, `.m4v`, `.mka`, `.mkv`, `.mlp`, `.mmf`, `.mov`, `.mp+`, `.mp1`, `.mp2`, `.mp3`, `.mp4`, `.mpa`, `.mpc`, `.mpeg`, `.mpg`, `.mpga`, `.mpp`, `.mts`, `.mxf`, `.nist`, `.oga`, `.ogg`, `.ogx`, `.oma`, `.omg`, `.opus`, `.paf`, `.pvf`, `.qcp`, `.ra`, `.rf64`, `.rka`, `.rm`, `.rmvb`, `.sf`, `.shn`, `.snd`, `.sph`, `.svx`, `.tak`, `.thd`, `.ts`, `.tta`, `.vob`, `.voc`, `.vqf`, `.w64`, `.wav`, `.wave`, `.weba`, `.webm`, `.wma`, `.wmv`, `.wv`. Maximum file size: 100 MB. responses: '200': description: Language detection completed successfully. content: application/json: schema: $ref: '#/components/schemas/LanguageDetectionResponse' examples: english: summary: English clip with high confidence value: predicted_language: English predicted_language_code: en confidence: 0.9847 duration_ms: 14253 french: summary: French clip value: predicted_language: French predicted_language_code: fr confidence: 0.9612 duration_ms: 8421 lowConfidence: summary: Low-confidence result value: predicted_language: Spanish predicted_language_code: es confidence: 0.4123 duration_ms: 5230 '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: .3g2, .3ga, .3gp, .3gpp, .8svx, .aa3, .aac, .ac3, .act, .adts, .aif, .aifc, .aiff, .alac, .amb, .amr, .ape, .asf, .at3, .au, .avi, .avr, .awb, .bwf, .c2, .caf, .dss, .dts, .dtshd, .eac3, .ec3, .f4a, .f4b, .flac, .flv, .gsm, .iff, .m2a, .m2ts, .m4a, .m4b, .m4r, .m4v, .mka, .mkv, .mlp, .mmf, .mov, .mp+, .mp1, .mp2, .mp3, .mp4, .mpa, .mpc, .mpeg, .mpg, .mpga, .mpp, .mts, .mxf, .nist, .oga, .ogg, .ogx, .oma, .omg, .opus, .paf, .pvf, .qcp, .ra, .rf64, .rka, .rm, .rmvb, .sf, .shn, .snd, .sph, .svx, .tak, .thd, .ts, .tta, .vob, .voc, .vqf, .w64, .wav, .wave, .weba, .webm, .wma, .wmv, .wv. empty_file: summary: Empty file value: detail: The uploaded file is empty. 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_file: summary: Corrupted or truncated audio file value: detail: The audio file appears to be corrupted or truncated. 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. '401': description: Unauthorized - the API key is missing or invalid. 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, or the API key does not have access to this model. 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: Payload too large - the uploaded file exceeds the maximum file size. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: detail: The uploaded file is too large. '422': description: > Unprocessable entity - a required request parameter is missing or invalid (for example, the `upload_file` field). content: application/json: schema: $ref: '#/components/schemas/HTTPValidationError' '429': description: > Too many requests - the request was denied due to insufficient credits, a concurrent request limit, or a monthly 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 '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: LanguageDetectionResponse: type: object required: - predicted_language - predicted_language_code - confidence - duration_ms properties: predicted_language: type: string description: > Human-readable language name (e.g. `"English"`, `"French"`, `"Mandarin"`). Suitable for display to end users. example: English predicted_language_code: type: string description: > Lowercase ISO 639-1 language code (e.g. `"en"`, `"fr"`, `"zh"`). Suitable for routing, locale switching, or BCP-47 tags. example: en confidence: type: number format: double minimum: 0 maximum: 1 description: > Probability associated with the predicted language, in the range 0.0-1.0. Higher means more confident. example: 0.9847 duration_ms: type: integer minimum: 0 description: > Total duration of the decoded audio in milliseconds. Note: only the first 30 seconds are analyzed regardless of this value. 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. ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.