audio-ui/lib/audio/effects/gain.ts

/**
 * Gain/Volume adjustment effect
 */

import { getAudioContext } from '../context';

/**
 * Apply gain to an audio buffer
 * @param buffer - Source audio buffer
 * @param gainValue - Gain multiplier (1.0 = no change, 0.5 = -6dB, 2.0 = +6dB)
 * @returns New audio buffer with gain applied
 */
export function applyGain(buffer: AudioBuffer, gainValue: number): AudioBuffer {
  const audioContext = getAudioContext();
  const outputBuffer = audioContext.createBuffer(
    buffer.numberOfChannels,
    buffer.length,
    buffer.sampleRate
  );

  // Apply gain to each channel
  for (let channel = 0; channel < buffer.numberOfChannels; channel++) {
    const inputData = buffer.getChannelData(channel);
    const outputData = outputBuffer.getChannelData(channel);

    for (let i = 0; i < buffer.length; i++) {
      outputData[i] = inputData[i] * gainValue;
      // Clamp to prevent distortion
      outputData[i] = Math.max(-1, Math.min(1, outputData[i]));
    }
  }

  return outputBuffer;
}

/**
 * Convert dB to gain multiplier
 * @param db - Decibels
 * @returns Gain multiplier
 */
export function dbToGain(db: number): number {
  return Math.pow(10, db / 20);
}

/**
 * Convert gain multiplier to dB
 * @param gain - Gain multiplier
 * @returns Decibels
 */
export function gainToDb(gain: number): number {
  return 20 * Math.log10(gain);
}