[Unity] AudioSourceの無音を削除してループ再生するサンプル

AudioRemoveZeroVolume.cs

using UnityEngine;
using System.Collections;

/// <summary>
/// AudioSourceの無音を削除してループ再生するサンプル
/// </summary>
[RequireComponent(typeof(AudioSource))]
public class AudioRemoveZeroVolume : MonoBehaviour {

	AudioSource audioSource;
	float startTime;
	float endTime;

	// Use this for initialization
	void Start () {
		audioSource = GetComponent<AudioSource>();

		// クリップの全サンプルデータ取得
		AudioClip clip = audioSource.clip;
		if (null == clip) {
			Debug.Log("clip null");
			this.enabled = false;
			return;
		}

		int sampleLength = clip.samples * clip.channels;
		Debug.Log("clip length : " + sampleLength);
		float[] allSamples = new float[ sampleLength ];
		clip.GetData(allSamples, 0);

		int start, end;
		start = 0;
		end = sampleLength;

		// 音の開始位置を取得
		for (int i=0; i<sampleLength; i+=clip.channels) {
			if (allSamples[i] < 0.03f) continue;
			start = i;
			break;
		}
		// 音の終了位置を取得
		for (int i=sampleLength-1; i>=0; i-=clip.channels) {
			if (allSamples[i] < 0.03f) continue;
			end = i;
			break;
		}

		startTime	= clip.length * (float)start	/ sampleLength;
		endTime		= clip.length * (float)end		/ sampleLength;

		Debug.Log("音の長さ : " + clip.length);
		Debug.Log("音の開始位置 : " + startTime + "\n音の終了位置 : " + endTime);
	}
	
	// Update is called once per frame
	void Update () {
		if (Input.GetKeyDown(KeyCode.Z))
		{
			// 通常ループ再生
			audioSource.loop = true;
			audioSource.Play();
		}
		if (Input.GetKeyDown(KeyCode.A))
		{
			// 無音除去してループ再生
			StartCoroutine(audio_loop());
		}
		if (Input.GetKeyDown(KeyCode.S))
		{
			// 停止
			stop = true;
			audioSource.Stop();
		}
	}

	bool stop;
	IEnumerator audio_loop()
	{
		stop = false;
		audioSource.loop = false;
		while (!stop)
		{
//			audioSource.Play((ulong)startTime * 1000);
			audioSource.PlayDelayed(startTime);

			float waitTime = Mathf.Abs(endTime - startTime);
			yield return new WaitForSeconds( waitTime );
		}
	}
}