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906c43a | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 | export const TARGET_SAMPLE_RATE = 16000;
export async function decodeAudioBlob(blob) {
if (!(blob instanceof Blob)) throw new TypeError('Expected an audio Blob.');
const AudioContextClass = window.AudioContext || window.webkitAudioContext;
if (!AudioContextClass) throw new Error('Web Audio API is not supported in this browser.');
const context = new AudioContextClass();
try {
const buffer = await context.decodeAudioData(await blob.arrayBuffer());
const mono = mixToMono(buffer);
const samples = resampleLinear(mono, buffer.sampleRate, TARGET_SAMPLE_RATE);
return { samples, samplingRate: TARGET_SAMPLE_RATE, duration: samples.length / TARGET_SAMPLE_RATE, originalSamplingRate: buffer.sampleRate, channels: buffer.numberOfChannels };
} catch (error) {
throw new Error(`The browser could not decode this audio file: ${error.message}`);
} finally {
await context.close();
}
}
export function mixToMono(audioBuffer) {
const output = new Float32Array(audioBuffer.length);
for (let channel = 0; channel < audioBuffer.numberOfChannels; channel += 1) {
const data = audioBuffer.getChannelData(channel);
for (let i = 0; i < data.length; i += 1) output[i] += data[i] / audioBuffer.numberOfChannels;
}
return output;
}
export function resampleLinear(samples, sourceRate, targetRate = TARGET_SAMPLE_RATE) {
if (sourceRate === targetRate) return new Float32Array(samples);
if (sourceRate <= 0 || targetRate <= 0) throw new Error('Sampling rates must be positive.');
const ratio = sourceRate / targetRate;
const length = Math.max(1, Math.round(samples.length / ratio));
const output = new Float32Array(length);
for (let i = 0; i < length; i += 1) {
const position = i * ratio;
const left = Math.floor(position);
const right = Math.min(left + 1, samples.length - 1);
const weight = position - left;
output[i] = samples[left] * (1 - weight) + samples[right] * weight;
}
return output;
}
export function formatDuration(seconds) {
const safe = Math.max(0, Number(seconds) || 0);
const minutes = Math.floor(safe / 60);
const remainder = Math.floor(safe % 60);
return `${String(minutes).padStart(2, '0')}:${String(remainder).padStart(2, '0')}`;
}
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