// Teaching function: measures Float32 channel payload, not total browser RAM.
async function inspectTeachingDecodedBuffer(encoded, requestedRate) {
  if (!(encoded instanceof ArrayBuffer) || !encoded.byteLength || encoded.byteLength > 1000000) {
    throw new RangeError('Exercise accepts one complete nonempty file up to 1000000 bytes');
  }
  if (![24000, 48000].includes(requestedRate)) throw new RangeError('Choose 24000 or 48000 for this exercise');
  const encodedBytes = encoded.byteLength;
  const context = new AudioContext({sampleRate: requestedRate});
  try {
    const decoded = await context.decodeAudioData(encoded.slice(0));
    const channels = [];
    for (let c = 0; c < decoded.numberOfChannels; c++) {
      const data = decoded.getChannelData(c);
      channels.push({index: c, samples: data.length, bytes: data.byteLength, float32: data instanceof Float32Array});
    }
    const payloadBytes = channels.reduce((n, c) => n + c.bytes, 0);
    const formulaBytes = decoded.length * decoded.numberOfChannels * Float32Array.BYTES_PER_ELEMENT;
    if (payloadBytes !== formulaBytes) throw new Error('Unexpected channel payload size');
    return {encodedBytes, requestedRate, contextRate: context.sampleRate, decodedRate: decoded.sampleRate,
      channels, frames: decoded.length, duration: decoded.duration, payloadBytes, formulaBytes,
      originalInputBytesAfterDecode: encoded.byteLength, totalBrowserRamMeasured: false};
  } finally {
    await context.close();
  }
}