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Unity Engine

AudioClip.PCMSetPositionCallback

Unity calls this delegate each time AudioClip changes read position.
Read time 2 minutesLast updated 4 days ago

Definition

  • Type: Delegate
  • Namespace: UnityEngine
  • Assembly: UnityEngine.AudioModule
public delegate void AudioClip.PCMSetPositionCallback(int position)

Remarks

Unity uses this delegate to signal when the audio clip changes its playback position, for example:
  • A user seeks through an audio clip.
  • The audio clip restarts.
When you use AudioClip.Create to create a clip, use this delegate as a parameter and define what happens whenever the audio clip changes position.
The position Unity passes to PCMSetPositionCallback are sample frames, not individual samples. For example, if you have a clip with a sampling rate of 44,100 Hz and you seek 1.0 s into the clip, Unity does the following:
  • Calls 
    PCMSetPositionCallback
    .
  • Sets the position parameter to 44,100 regardless of the audio channel count.
If the audio clip is stereo (2 channels), each frame has 2 samples- one per channel. The total number of samples at 1 s into the clip is 88200 (44100 frames x 2 channels), but 
position
is still 44100.
Additional Resources: AudioClip.Create

Examples

 // This script creates an audio clip, sets its data and creates a sinusoid graph when it reads the data and changes positions. using UnityEngine;using System.Collections;public class ExampleClass : MonoBehaviour{    public int position = 0;    public int samplerate = 44100;    public float frequency = 440;   void Start()    {        AudioClip myClip = AudioClip.Create("MySinusoid", samplerate * 2, 1, samplerate, true, OnAudioRead, OnAudioSetPosition);        AudioSource aud = GetComponent<AudioSource>();        aud.clip = myClip;        aud.Play();    } // When Unity calls PCMReaderCallback, create a graph from the audio clip’s data.     void OnAudioRead(float[] data)    {        int count = 0;        while (count < data.Length)        {            data[count] = Mathf.Sin(2 * Mathf.PI * frequency * position / samplerate);            position++;            count++;        }    } //When Unity calls PCMSetPositionCallback, update the position variable.    void OnAudioSetPosition(int newPosition)    {        position = newPosition;    }}