function matchTempoAndPlay() {
// Get the tempo of the first audio file
const tempo1 = getTempo(audioFile1);
// Resample the second audio file to match the tempo of the first audio file
const resampledAudioFile2 = resample(audioFile2, audioContext.sampleRate * tempo1 / getTempo(audioFile2));
// Concatenate the two audio files with a 4-measure overlap
const overlap = audioContext.sampleRate * 4 * 60 / tempo1; // 4 measures in samples
const audioBuffer = audioContext.createBuffer(audioFile1.numberOfChannels, audioFile1.length + resampledAudioFile2.length - overlap, audioContext.sampleRate);
for (let i = 0; i < audioFile1.numberOfChannels; i++) {
const channel1 = audioFile1.getChannelData(i);
const channel2 = resampledAudioFile2.getChannelData(i);
const mergedChannel = audioBuffer.getChannelData(i);
for (let j = 0; j < audioFile1.length - overlap; j++) {
mergedChannel[j] = channel1[j] * (1 - j / (audioFile1.length - overlap)) + channel2[j + overlap] * (j / (audioFile1.length - overlap));
}
for (let j = audioFile1.length - overlap; j < audioBuffer.length; j++) {
mergedChannel[j] = channel2[j - audioFile1.length + overlap];
}
}
// Play the concatenated audio files
const audioPlayer = document.createElement('audio');
audioPlayer.controls = true;
audioPlayer.src = URL.createObjectURL(new Blob([audioBuffer.getChannelData(0)]));
document.body.appendChild(audioPlayer);
// Fade out the first audio file and fade in the second audio file over the last 4 measures
const fadeInStart = audioFile1.length - overlap;
const fadeInEnd = audioFile1.length;
const fadeOutStart = audioFile1.length - overlap;
const fadeOutEnd = audioFile1.length * 2 - overlap;
const gain1 = audioContext.createGain();
gain1.gain.setValueAtTime(1, audioContext.currentTime);
gain1.gain.linearRampToValueAtTime(0, audioContext.currentTime + (fadeOutEnd - fadeOutStart) / audioContext.sampleRate);
const source1 = audioContext.createBufferSource();
source1.buffer = audioFile1;
source1.connect(gain1);
source1.connect(audioContext.destination);
source1.start(0);
const gain2 = audioContext.createGain();
gain2.gain.setValueAtTime(0, audioContext.currentTime);
gain2.gain.linearRampToValueAtTime(1, audioContext.currentTime + (fadeInEnd - fadeInStart) / audioContext.sampleRate);
const source2 = audioContext.createBufferSource();
source2.buffer = resampledAudioFile2;
source2.connect(gain2);
source2.connect(audioContext.destination);
source2.start(0, fadeInStart / audioContext.sampleRate);
// Update the audio player's volume during the fade in/out
audioPlayer.volume = 1;
audioPlayer.addEventListener('timeupdate', function() {
const currentTime = audioPlayer.currentTime;
if (currentTime < fadeOutStart / audioContext.sampleRate)