> ## Documentation Index > Fetch the complete documentation index at: https://docs.slng.ai/llms.txt > Use this file to discover all available pages before exploring further. # Cognigy STT > Transcribe audio via Cognigy Voice Gateway protocol bridge. ## OpenAPI ````yaml POST /v1/bridges/cognigy/stt/{model_variant} openapi: 3.0.3 info: title: SLNG Gateway API - Cognigy Bridges version: 0.1.0 description: Unified API for speech-to-text and text-to-speech services. contact: name: SLNG Support email: support@slng.ai servers: - url: https://api.slng.ai description: Production - url: https://stageapi.slng.ai description: Staging security: - BearerAuth: [] tags: - name: Cognigy STT Bridge description: Cognigy Voice Gateway STT protocol bridge. - name: Cognigy TTS Bridge description: Cognigy Voice Gateway TTS protocol bridge. paths: /v1/bridges/cognigy/stt/{model_variant}: parameters: - $ref: '#/components/parameters/SttModelVariantPath' - $ref: '#/components/parameters/RegionQuery' - $ref: '#/components/parameters/WorldPartQuery' post: tags: - Cognigy STT Bridge summary: Cognigy STT Bridge description: Transcribe audio via Cognigy Voice Gateway protocol bridge. operationId: cognigy-stt-http requestBody: required: true content: multipart/form-data: schema: $ref: '#/components/schemas/CognigySTTRequest' examples: binary: summary: Binary audio upload value: audio: language: en application/json: schema: $ref: '#/components/schemas/CognigySTTRequest' examples: url: summary: URL-based transcription value: url: https://docs.slng.ai/audio/hello.wav language: en responses: '200': $ref: '#/components/responses/CognigyTranscriptionSuccess' '400': $ref: '#/components/responses/ProviderBadRequest' '403': $ref: '#/components/responses/ForbiddenBearerToken' '500': $ref: '#/components/responses/ProviderInternalServerError' components: parameters: SttModelVariantPath: name: model_variant in: path required: true description: >- Target STT model. Must support WebSocket streaming with final_transcript. schema: type: string enum: - deepgram/nova:2 - deepgram/nova:3 - deepgram/nova:3-medical - gradium/stt:default - reson8/reson8stt:v1 - sarvam/saaras:v3 - slng/deepgram/nova:3-en - slng/deepgram/nova:3-es - slng/deepgram/nova:3-hi - slng/deepgram/nova:3-in - slng/deepgram/nova:3-kn - slng/deepgram/nova:3-mr - slng/deepgram/nova:3-multi - slng/deepgram/nova:3-te - slng/openai/whisper:large-v3 - soniox/speech-ai:rt-v4 examples: deepgramNova3: summary: Deepgram Nova 3 value: deepgram/nova:3 slngWhisper: summary: SLNG-hosted Whisper Large v3 value: slng/openai/whisper:large-v3 RegionQuery: name: region in: query required: false description: >- Target region override. Auto-selected if not provided. Equivalent to the `X-Region-Override` header; the header takes precedence when both are set. schema: type: string enum: - ap-southeast-2 - eu-north-1 - us-east-1 WorldPartQuery: name: world-part in: query required: false description: >- Target world part override. Auto-selected if not provided. Equivalent to the `X-World-Part-Override` header; the header takes precedence when both are set. schema: type: string enum: - ap - eu - na schemas: CognigySTTRequest: type: object description: >- Cognigy STT request. Provide either `audio` (multipart upload) or `url` (publicly accessible HTTPS URL). properties: audio: type: string format: binary description: Audio file (multipart) or base64-encoded audio (JSON). url: type: string description: Publicly accessible audio URL. example: https://docs.slng.ai/audio/hello.wav language: type: string description: Language code. CognigySTTTranscriptionResponse: type: object description: Cognigy STT transcription response. properties: type: type: string description: Response type. enum: - transcription is_final: type: boolean description: Whether this is a final transcription. alternatives: type: array description: Transcription alternatives. items: $ref: '#/components/schemas/CognigyTranscriptionAlternative' channel: type: integer description: Audio channel number. language: type: string description: Detected language code. required: - type - is_final - alternatives ProviderErrorResponse: type: object description: > Provider error response. Contains error information from the upstream provider. Common errors include invalid speakers, unsupported languages, or malformed requests. properties: error: type: string description: >- Error type or category (e.g., "TTS service error", "Validation error"). example: TTS service error status: type: number description: >- Original HTTP status code from the provider (may differ from gateway response code). example: 400 details: type: string description: > Detailed error message from the provider. For TTS errors, this typically includes the specific validation failure (e.g., invalid speaker ID for the selected model/language). example: >- Rime TTS API error: 400 Bad Request - Invalid argument: Invalid speaker: aurelie required: - error ErrorResponse: type: object description: Standard error response. properties: error: type: string description: Error type or code. message: type: string description: Human-readable error message. statusCode: type: integer description: HTTP status code. required: - error CognigyTranscriptionAlternative: type: object description: Transcription alternative. properties: confidence: type: number description: Confidence score. transcript: type: string description: Transcribed text. responses: CognigyTranscriptionSuccess: description: Transcription successful. content: application/json: schema: $ref: '#/components/schemas/CognigySTTTranscriptionResponse' ProviderBadRequest: description: Bad request - invalid parameters provided. content: application/json: schema: $ref: '#/components/schemas/ProviderErrorResponse' examples: validation-error: summary: Validation error value: error: Validation error details: 'Missing required field: text' ForbiddenBearerToken: description: Missing or invalid Bearer token. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' ProviderInternalServerError: description: Internal server error from the provider. content: application/json: schema: $ref: '#/components/schemas/ProviderErrorResponse' examples: processing-error: summary: Processing error value: error: Service error details: Internal processing error securitySchemes: BearerAuth: type: http scheme: bearer description: | API key issued by SLNG. Pass as `Authorization: Bearer `. ````