AudioSource.SetScheduledEndTime

Parameters

Description

Changes the time at which a sound that has already been scheduled to play will end. Notice that depending on the timing not all rescheduling requests can be fulfilled.

Note that the time specified is still a time on the absolute time-line, meaning that the sound will stop when reaching that time, regardless of when it was started. So if you have a 5 second long sound and want it to play at time T and stop after 3 seconds (i.e. silencing the last 2 seconds of the sound), you need to specify the end time to be T+3. This function is useful in music systems to overcome the discontinuities in signals that frame-based lossy codecs cause.

using UnityEngine;
using System.Collections;

// While this may seem unnecessarily complicated to do this in the case of uncompressed sounds, you can now use
// the SavWav code from https://gist.github.com/2317063 to save the generated clips into new assets,
// run the program once with a specified sourceClip and the script will generate "cut1.wav" and "cut2.wav".
// These can now be imported into Unity as assets and changed to compressed sounds.
// Since psychoacoustic compression severely alters the waveforms and frequency content of sounds and
// furthermore operates in a block-based fashion, it would cause very noticeable pops and clicks if we didn't
// have the sound data after and before the cut point. By having it, even though we are not playing it, the decoder is "warmed up",
// i.e. it has matching frequency content before and after the transition, so at least the
// frequency spectrum will be more or less the same before and after the transition and so the click will be less audible
// than if we had just cut up the sound without the 0.2s overlap regions.
// This method may also be combined with cross-fading in order to further smoothen out any remaining artifacts.
[RequireComponent(typeof(AudioSource))]
public class ExampleClass : MonoBehaviour
{
    public AudioClip sourceClip;
    private AudioSource audio1;
    private AudioSource audio2;
    private AudioClip cutClip1;
    private AudioClip cutClip2;
    private float overlap = 0.2F;
    private int len1 = 0;
    private int len2 = 0;
    void Start()
    {
        GameObject child;
        child = new GameObject("Player1");
        child.transform.parent = gameObject.transform;
        audio1 = child.AddComponent<AudioSource>();
        child = new GameObject("Player2");
        child.transform.parent = gameObject.transform;
        audio2 = child.AddComponent<AudioSource>();
        int overlapSamples;
        if (sourceClip != null)
        {
            len1 = sourceClip.samples / 2;
            len2 = sourceClip.samples - len1;
            overlapSamples = (int)(overlap * sourceClip.frequency);
            cutClip1 = AudioClip.Create("cut1", len1 + overlapSamples, sourceClip.channels, sourceClip.frequency, false, false);
            cutClip2 = AudioClip.Create("cut2", len2 + overlapSamples, sourceClip.channels, sourceClip.frequency, false, false);
            float[] smp1 = new float[(len1 + overlapSamples) * sourceClip.channels];
            float[] smp2 = new float[(len2 + overlapSamples) * sourceClip.channels];
            sourceClip.GetData(smp1, 0);
            sourceClip.GetData(smp2, len1 - overlapSamples);
            cutClip1.SetData(smp1, 0);
            cutClip2.SetData(smp2, 0);
        }
        else
        {
            overlapSamples = (int)overlap * cutClip1.frequency;
            len1 = cutClip1.samples - overlapSamples;
            len2 = cutClip2.samples - overlapSamples;
        }
    }

    void OnGUI()
    {
        if (GUI.Button(new Rect(10, 50, 230, 40), "Trigger source"))
            audio1.PlayOneShot(sourceClip);

        if (GUI.Button(new Rect(10, 100, 230, 40), "Trigger cut 1"))
            audio1.PlayOneShot(cutClip1);

        if (GUI.Button(new Rect(10, 150, 230, 40), "Trigger cut 2"))
            audio1.PlayOneShot(cutClip2);

        if (GUI.Button(new Rect(10, 200, 230, 40), "Play stitched"))
        {
            audio1.clip = cutClip1;
            audio2.clip = cutClip2;
            double t0 = AudioSettings.dspTime + 3.0F;
            double clipTime1 = len1;
            clipTime1 /= cutClip1.frequency;
            audio1.PlayScheduled(t0);
            audio1.SetScheduledEndTime(t0 + clipTime1);
            Debug.Log("t0 = " + t0 + ", clipTime1 = " + clipTime1 + ", cutClip1.frequency = " + cutClip1.frequency);
            Debug.Log("cutClip2.frequency = " + cutClip2.frequency + ", samplerate = " + AudioSettings.outputSampleRate);
            audio2.PlayScheduled(t0 + clipTime1);
            audio2.time = overlap;
        }
    }
}

Note: If possible create clips that overlap, and use the scheduled end time for the first, and AudioSource.time for the second to trim out the overlapped part, as the example above shows.