audio-ui/lib/audio/decoder.ts

/**
 * Audio file decoding utilities
 */

import { getAudioContext } from './context';

/**
 * Decode an audio file to AudioBuffer
 */
export async function decodeAudioFile(file: File): Promise<AudioBuffer> {
  const arrayBuffer = await file.arrayBuffer();
  const audioContext = getAudioContext();

  try {
    const audioBuffer = await audioContext.decodeAudioData(arrayBuffer);
    return audioBuffer;
  } catch (error) {
    throw new Error(`Failed to decode audio file: ${error}`);
  }
}

/**
 * Get audio file metadata without decoding the entire file
 */
export async function getAudioFileMetadata(file: File): Promise<{
  name: string;
  size: number;
  type: string;
}> {
  return {
    name: file.name,
    size: file.size,
    type: file.type,
  };
}

/**
 * Check if a file is a supported audio format
 */
export function isSupportedAudioFormat(file: File): boolean {
  const supportedFormats = [
    'audio/wav',
    'audio/wave',
    'audio/x-wav',
    'audio/mpeg',
    'audio/mp3',
    'audio/ogg',
    'audio/webm',
    'audio/flac',
    'audio/aac',
    'audio/m4a',
    'audio/x-m4a',
  ];

  return supportedFormats.includes(file.type) ||
         /\.(wav|mp3|ogg|webm|flac|aac|m4a)$/i.test(file.name);
}

/**
 * Format duration in seconds to MM:SS format
 */
export function formatDuration(seconds: number): string {
  const mins = Math.floor(seconds / 60);
  const secs = Math.floor(seconds % 60);
  return `${mins.toString().padStart(2, '0')}:${secs.toString().padStart(2, '0')}`;
}

/**
 * Format file size to human-readable format
 */
export function formatFileSize(bytes: number): string {
  if (bytes === 0) return '0 B';

  const k = 1024;
  const sizes = ['B', 'KB', 'MB', 'GB'];
  const i = Math.floor(Math.log(bytes) / Math.log(k));

  return `${parseFloat((bytes / Math.pow(k, i)).toFixed(2))} ${sizes[i]}`;
}