76 lines
2.3 KiB
JavaScript
76 lines
2.3 KiB
JavaScript
/**
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* Server-side Speech-to-Text Service
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*
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* Proxies audio to any OpenAI-compatible transcription endpoint
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* (e.g. faster-whisper, whisper.cpp) using the OpenAI Node SDK.
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*/
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import OpenAI, { toFile } from 'openai';
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import { normalizeCustomOpenAIBaseURL } from './base-url.js';
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/**
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* Transcribe an audio buffer via an OpenAI-compatible /v1/audio/transcriptions endpoint.
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*
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* @param {object} opts
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* @param {Buffer} opts.audioBuffer - Raw audio bytes
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* @param {string} opts.mimeType - MIME type of the audio (e.g. 'audio/webm')
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* @param {string} opts.model - Model name accepted by the remote server
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* @param {string} [opts.baseURL] - Base URL of the compatible server (including /v1)
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* @param {string} [opts.language] - Optional BCP-47 language hint (e.g. 'en')
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* @returns {Promise<string>} Transcribed text
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*/
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export async function transcribeAudio({ audioBuffer, mimeType, model, baseURL, language }) {
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const normalizedBaseURLResult = normalizeCustomOpenAIBaseURL(baseURL);
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if (normalizedBaseURLResult.error) {
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throw new Error(normalizedBaseURLResult.error);
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}
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const normalizedBaseURL = normalizedBaseURLResult.value;
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if (!normalizedBaseURL) {
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throw new Error('Custom server URL is required');
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}
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const clientOpts = {
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apiKey: process.env.OPENAI_API_KEY || 'not-required',
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};
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clientOpts.baseURL = normalizedBaseURL;
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const client = new OpenAI(clientOpts);
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// Derive a sensible filename extension from the MIME type so the server
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// can infer the codec when it isn't explicit in the stream header.
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const ext = mimeTypeToExt(mimeType);
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const filename = `audio.${ext}`;
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const file = await toFile(audioBuffer, filename, { type: mimeType });
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const result = await client.audio.transcriptions.create({
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file,
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model,
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response_format: 'json',
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...(language ? { language } : {}),
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});
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return result.text ?? '';
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}
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/**
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* Map a MIME type to a file extension understood by Whisper servers.
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* @param {string} mimeType
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* @returns {string}
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*/
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function mimeTypeToExt(mimeType) {
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const type = (mimeType || '').split(';')[0].trim().toLowerCase();
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const map = {
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'audio/webm': 'webm',
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'audio/ogg': 'ogg',
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'audio/wav': 'wav',
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'audio/wave': 'wav',
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'audio/mpeg': 'mp3',
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'audio/mp4': 'mp4',
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'audio/mp3': 'mp3',
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'audio/flac': 'flac',
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};
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return map[type] ?? 'webm';
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}
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