candle-whisper / whisperWorker.js
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add quantized models support (#4)
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//load the candle Whisper decoder wasm module
import init, { Decoder } from "./build/m.js";
async function fetchArrayBuffer(url) {
const cacheName = "whisper-candle-cache";
const cache = await caches.open(cacheName);
const cachedResponse = await cache.match(url);
if (cachedResponse) {
const data = await cachedResponse.arrayBuffer();
return new Uint8Array(data);
}
const res = await fetch(url, { cache: "force-cache" });
cache.put(url, res.clone());
return new Uint8Array(await res.arrayBuffer());
}
class Whisper {
static instance = {};
// Retrieve the Whisper model. When called for the first time,
// this will load the model and save it for future use.
static async getInstance(params) {
const {
weightsURL,
modelID,
tokenizerURL,
mel_filtersURL,
configURL,
quantized,
is_multilingual,
timestamps,
task,
language,
} = params;
// load individual modelID only once
if (!this.instance[modelID]) {
await init();
self.postMessage({ status: "loading", message: "Loading Model" });
const [
weightsArrayU8,
tokenizerArrayU8,
mel_filtersArrayU8,
configArrayU8,
] = await Promise.all([
fetchArrayBuffer(weightsURL),
fetchArrayBuffer(tokenizerURL),
fetchArrayBuffer(mel_filtersURL),
fetchArrayBuffer(configURL),
]);
this.instance[modelID] = new Decoder(
weightsArrayU8,
tokenizerArrayU8,
mel_filtersArrayU8,
configArrayU8,
quantized,
is_multilingual,
timestamps,
task,
language
);
} else {
self.postMessage({ status: "loading", message: "Model Already Loaded" });
}
return this.instance[modelID];
}
}
self.addEventListener("message", async (event) => {
const {
weightsURL,
modelID,
tokenizerURL,
configURL,
mel_filtersURL,
audioURL,
} = event.data;
try {
self.postMessage({ status: "decoding", message: "Starting Decoder" });
let quantized = false;
if (modelID.includes("quantized")) {
quantized = true;
}
let is_multilingual = false;
if (modelID.includes("multilingual")) {
is_multilingual = true;
}
let timestamps = true;
const decoder = await Whisper.getInstance({
weightsURL,
modelID,
tokenizerURL,
mel_filtersURL,
configURL,
quantized,
is_multilingual,
timestamps,
task: null,
language: null,
});
self.postMessage({ status: "decoding", message: "Loading Audio" });
const audioArrayU8 = await fetchArrayBuffer(audioURL);
self.postMessage({ status: "decoding", message: "Running Decoder..." });
const segments = decoder.decode(audioArrayU8);
// Send the segment back to the main thread as JSON
self.postMessage({
status: "complete",
message: "complete",
output: JSON.parse(segments),
});
} catch (e) {
self.postMessage({ error: e });
}
});