DDPチェッカーの仕組み

// Timecode conversion (BCD → MM:SS:FF)
function parseBCDTimecode(minutes: number, seconds: number, frames: number): string {
  const m = ((minutes >> 4) * 10) + (minutes & 0x0F);
  const s = ((seconds >> 4) * 10) + (seconds & 0x0F);
  const f = ((frames >> 4) * 10) + (frames & 0x0F);
  return `${m.toString().padStart(2, '0')}:${s.toString().padStart(2, '0')}:${f.toString().padStart(2, '0')}`;
}

// Byte offset calculation
const sectorSize = 2352; // bytes per CD sector
const byteOffset = sectorNumber * sectorSize;

// Extract track audio from DDP file
function extractTrackAudio(
  buffer: ArrayBuffer,
  startSector: number,
  endSector: number
): ArrayBuffer {
  const sectorSize = 2352;
  const startByte = startSector * sectorSize;
  const endByte = endSector * sectorSize;
  return buffer.slice(startByte, endByte);
}

// Decode to playable format
async function decodeAudio(
  context: AudioContext,
  arrayBuffer: ArrayBuffer
): Promise<AudioBuffer> {
  return await context.decodeAudioData(arrayBuffer);
}