murmuraba/dist/api/process-file-with-metrics.js

Real-time audio noise reduction with advanced chunked processing for web applications

import { getEngine } from '../api';
/**
 * Apply gain to WAV audio buffer
 */
function applyGainToBuffer(arrayBuffer, gain) {
    const view = new DataView(arrayBuffer);
    const newBuffer = new ArrayBuffer(arrayBuffer.byteLength);
    const newView = new DataView(newBuffer);
    // Copy WAV header (first 44 bytes)
    for (let i = 0; i < 44; i++) {
        newView.setUint8(i, view.getUint8(i));
    }
    // Apply gain to audio samples (16-bit PCM)
    for (let i = 44; i < arrayBuffer.byteLength - 1; i += 2) {
        const sample = view.getInt16(i, true);
        const amplified = Math.max(-32768, Math.min(32767, sample * gain));
        newView.setInt16(i, amplified, true);
    }
    return newBuffer;
}
/**
 * Process audio file and capture VAD metrics frame by frame
 */
export async function processFileWithMetrics(arrayBuffer, onFrameProcessed, outputGain = 2.5 // Apply 2.5x gain to processed audio for balanced louder output
) {
    const engine = getEngine();
    const metrics = [];
    let frameCount = 0;
    let totalVad = 0;
    // Hook into the engine's frame processing
    const originalProcessFrame = engine['processFrame'].bind(engine);
    engine['processFrame'] = function (frame) {
        const result = originalProcessFrame(frame);
        // Calculate RMS
        let sum = 0;
        for (let i = 0; i < frame.length; i++) {
            sum += frame[i] * frame[i];
        }
        const rms = Math.sqrt(sum / frame.length);
        const metric = {
            vad: result.vad,
            frame: frameCount++,
            timestamp: Date.now(),
            rms
        };
        metrics.push(metric);
        totalVad += result.vad;
        if (onFrameProcessed) {
            onFrameProcessed(metric);
        }
        return result;
    };
    try {
        // Process the file
        let processedBuffer = await engine.processFile(arrayBuffer);
        // Apply output gain to make audio louder
        if (outputGain !== 1.0) {
            processedBuffer = applyGainToBuffer(processedBuffer, outputGain);
        }
        // Restore original method
        engine['processFrame'] = originalProcessFrame;
        const averageVad = metrics.length > 0 ? totalVad / metrics.length : 0;
        return {
            processedBuffer,
            metrics,
            averageVad
        };
    }
    catch (error) {
        // Restore original method on error
        engine['processFrame'] = originalProcessFrame;
        throw error;
    }
}