omdTranscriptionService

The omdTranscriptionService class provides an interface to an AI-powered transcription service for handwritten content. It sends image data to a server-side endpoint for processing, abstracting away the complexities of AI model interaction and API key management.

Class Definition

export class omdTranscriptionService

Constructor

new omdTranscriptionService([options])

Creates a new omdTranscriptionService instance.

• options (object, optional): Configuration options for the service:
  • endpoint (string): The server endpoint for the transcription service. Defaults to '/.netlify/functions/transcribe'.
  • defaultProvider (string): The default transcription provider to use. Defaults to 'gemini'.

Public Properties

• options (object): The configuration options for the service, including endpoint and defaultProvider.

Public Methods

async transcribe(imageBlob, [options])

Transcribes an image containing handwritten content by sending it to the configured server endpoint. The image is converted to base64 before transmission.

• imageBlob (Blob): The image blob to transcribe.
• options (object, optional): Transcription options:
  • prompt (string): A custom prompt for the transcription service. If not provided, a default mathematical transcription prompt is used.
• Returns: Promise<object> - A promise that resolves with the transcription result, containing the text, provider, and confidence.
• Throws: Error if the API call fails.

async transcribeWithFallback(imageBlob, [options])

Transcribes an image with a fallback mechanism. Currently, this method simply calls transcribe(), but it is designed to allow for future implementations of fallback transcription providers or strategies.

• imageBlob (Blob): The image blob to transcribe.
• options (object, optional): Transcription options.
• Returns: Promise<object> - A promise that resolves with the transcription result.

isAvailable()

Checks if the transcription service is available. In the current implementation, this always returns true as it relies on a serverless function endpoint.

• Returns: boolean - true if the service is available, false otherwise.

getAvailableProviders()

Gets the list of available transcription providers. In the current implementation, this always returns ['gemini'] as the server handles the actual provider selection.

• Returns: Array<string> - An array of available provider names.

isProviderAvailable(provider)

Checks if a specific transcription provider is available. In the current implementation, this only returns true for the 'gemini' provider.

• provider (string): The name of the provider to check.
• Returns: boolean - true if the provider is available, false otherwise.

Internal Methods

• _getDefaultEndpoint(): Returns the default server endpoint URL for the transcription service ('/.netlify/functions/transcribe').
• _blobToBase64(blob): Converts an imageBlob into a base64 encoded string, suitable for sending in a JSON payload.

Example Usage

import { omdTranscriptionService } from '@teachinglab/omd';

// Create a transcription service instance
const transcriptionService = new omdTranscriptionService();

// Assume getMyImageBlob() is a function that returns an image Blob
async function getMyImageBlob() {
    // Example: Create a dummy canvas and get its blob
    const canvas = document.createElement('canvas');
    canvas.width = 100; canvas.height = 50;
    const ctx = canvas.getContext('2d');
    ctx.fillText('2x + 3', 10, 30);
    return new Promise(resolve => canvas.toBlob(resolve, 'image/png'));
}

// Get an image blob from a canvas or file input
const imageBlob = await getMyImageBlob();

// Transcribe the image
const result = await transcriptionService.transcribe(imageBlob, {
    prompt: 'Transcribe the handwritten math equation. Return only the mathematical expression.'
});

console.log(result.text); // The transcribed text (e.g., "2x + 3")