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| /** | |
| * Audio graph utilities for Web Audio API. | |
| * | |
| * This module provides helper functions for creating and managing | |
| * the audio processing graph used in the stem mixer. | |
| */ | |
| /** | |
| * Create a gain node with initial value. | |
| */ | |
| export function createGain(context, value = 1) { | |
| const gain = context.createGain() | |
| gain.gain.setValueAtTime(value, context.currentTime) | |
| return gain | |
| } | |
| /** | |
| * Create an analyser node for visualization. | |
| */ | |
| export function createAnalyser(context, fftSize = 128) { | |
| const analyser = context.createAnalyser() | |
| analyser.fftSize = fftSize | |
| analyser.smoothingTimeConstant = 0.8 | |
| return analyser | |
| } | |
| /** | |
| * Create a simple audio graph for a single stem. | |
| * | |
| * source -> gainNode -> masterGain | |
| */ | |
| export function createStemGraph(context, buffer, gainNode, masterGain) { | |
| const source = context.createBufferSource() | |
| source.buffer = buffer | |
| source.connect(gainNode) | |
| gainNode.connect(masterGain) | |
| return source | |
| } | |
| /** | |
| * Smoothly transition a gain value. | |
| */ | |
| export function fadeGain(gainNode, targetValue, duration = 0.05) { | |
| const now = gainNode.context.currentTime | |
| gainNode.gain.linearRampToValueAtTime(targetValue, now + duration) | |
| } | |
| /** | |
| * Get frequency data from analyser as normalized values (0-1). | |
| */ | |
| export function getFrequencyData(analyser) { | |
| const data = new Uint8Array(analyser.frequencyBinCount) | |
| analyser.getByteFrequencyData(data) | |
| return Array.from(data).map(v => v / 255) | |
| } | |
| /** | |
| * Calculate RMS level from audio data. | |
| */ | |
| export function calculateRMS(audioData) { | |
| let sum = 0 | |
| for (let i = 0; i < audioData.length; i++) { | |
| sum += audioData[i] * audioData[i] | |
| } | |
| return Math.sqrt(sum / audioData.length) | |
| } | |
| /** | |
| * Convert decibels to linear gain. | |
| */ | |
| export function dbToGain(db) { | |
| return Math.pow(10, db / 20) | |
| } | |
| /** | |
| * Convert linear gain to decibels. | |
| */ | |
| export function gainToDb(gain) { | |
| return 20 * Math.log10(gain) | |
| } | |