# Autoplay next item in AudioTable

**URL:** <https://qa.fmod.com/t/autoplay-next-item-in-audiotable/16300>\
**Category:** Unity\
**Tags:** unity, csharp\
**Created:** [October 15, 2020, 2:10pm UTC](https://qa.fmod.com/t/autoplay-next-item-in-audiotable/16300 "2020-10-15T14:10:02Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![NikMikk](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/nikmikk/32/5599_2.png) [@NikMikk](https://qa.fmod.com/u/NikMikk)\
**Post date:** [October 15, 2020, 2:10pm UTC](https://qa.fmod.com/t/autoplay-next-item-in-audiotable/16300/1 "2020-10-15T14:10:02Z")

</div>

Hi everyone!

So I have a WALKMAN in my game that’s using an AudioTable together with Programmer Instrument to play music tracks. The tracks play and everything works except one crucial part, autoplay.

I know which key is the next one I want to play, I just simply can’t get it to work without freezing the game.

After a track has been played I want it to play the next one from an audio table. I can provide the next key no problem but everything seems to crash. This is my programmer instrument callback, everything is matching FMOD’s example except `case EVENT_CALLBACK_TYPE.DESTROYED:` where I try to play the next in my list.

Doing this freezes the game completely, anyone got a clue on how I can implement this?

Here’s my programmer music callback

```
[AOT.MonoPInvokeCallback(typeof(EVENT_CALLBACK))]
static RESULT MusicEventCallback(EVENT_CALLBACK_TYPE type, EventInstance instance, IntPtr parameterPtr)
{
	// Retrieve the user data
	instance.getUserData(out var stringPtr);

	// Get the string object
	GCHandle stringHandle = GCHandle.FromIntPtr(stringPtr);
	string key = stringHandle.Target as string;

	switch (type)
	{
		case EVENT_CALLBACK_TYPE.CREATE_PROGRAMMER_SOUND:
		{
			const MODE soundMode = MODE.LOOP_NORMAL | MODE.CREATECOMPRESSEDSAMPLE | MODE.NONBLOCKING;
			var parameter = (PROGRAMMER_SOUND_PROPERTIES) Marshal.PtrToStructure(parameterPtr, typeof(PROGRAMMER_SOUND_PROPERTIES));

			var keyResult = RuntimeManager.StudioSystem.getSoundInfo(key, out var dialogueSoundInfo);
			if (keyResult != RESULT.OK)
			{
				break;
			}
		
			var soundResult = RuntimeManager.CoreSystem.createSound(dialogueSoundInfo.name_or_data, soundMode | dialogueSoundInfo.mode, ref dialogueSoundInfo.exinfo, out var dialogueSound);
			if (soundResult == RESULT.OK)
			{
				parameter.sound = dialogueSound.handle;
				parameter.subsoundIndex = dialogueSoundInfo.subsoundindex;
				Marshal.StructureToPtr(parameter, parameterPtr, false);
			}

			break;
		}
		case EVENT_CALLBACK_TYPE.DESTROY_PROGRAMMER_SOUND:
		{
			var parameter = (PROGRAMMER_SOUND_PROPERTIES) Marshal.PtrToStructure(parameterPtr, typeof(PROGRAMMER_SOUND_PROPERTIES));
			var sound = new Sound {handle = parameter.sound};
			sound.release();
			
			CassettePlayer.instance.PlayNext(); // Play next song
			break;
		}
		case EVENT_CALLBACK_TYPE.DESTROYED:
		{
			// Now the event has been destroyed, unpin the string memory so it can be garbage collected
			stringHandle.Free();
			break;
		}
	}

	return RESULT.OK;
}
```

---

<div class="post-metadata">

**Author:** ![cameron-fmod](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/cameron-fmod/32/261_2.png) [@cameron-fmod](https://qa.fmod.com/u/cameron-fmod)\
**Post date:** [October 25, 2020, 11:07pm UTC](https://qa.fmod.com/t/autoplay-next-item-in-audiotable/16300/2 "2020-10-25T23:07:32Z")

</div>

One way to do this would be to use a looping multi-instrument in the event that contains a programmer instrument, then in the `CREATE_PROGRAMMER_SOUND` you could get the key before playing it. You could also use a parameter or sustain point to control when the event finishes.

---

<div class="post-metadata">

**Author:** ![NikMikk](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/nikmikk/32/5599_2.png) [@NikMikk](https://qa.fmod.com/u/NikMikk)\
**Post date:** [October 26, 2020, 8:10am UTC](https://qa.fmod.com/t/autoplay-next-item-in-audiotable/16300/3 "2020-10-26T08:10:07Z")

</div>

Hi Cameron, thanks for the reply.

What do you mean getting the key before playing it, how do you intend on using that information? What I essentially needs is a way to know when the programmer instrument is done playing, I tried adding a method call to `DESTROYED` and `DESTROY_PROGRAMMER_SOUND` callback event without luck as that freezes Unity.

---

<div class="post-metadata">

**Author:** ![cameron-fmod](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/cameron-fmod/32/261_2.png) [@cameron-fmod](https://qa.fmod.com/u/cameron-fmod)\
**Post date:** [October 28, 2020, 1:57am UTC](https://qa.fmod.com/t/autoplay-next-item-in-audiotable/16300/4 "2020-10-28T01:57:57Z")

</div>

I’m not sure entirely of the cause of the freeze, depending on how the event is setup it sounds like it could be due to the event naturally ending/stopping as the instrument finishes while you try to update the audio table key.

By doing it the way I said, with a looping multi-instrument, you can avoid trying to update the event from a destroy callback.

 ![image](https://canada1.discourse-cdn.com/flex036/uploads/fmod/original/2X/d/d756e817f48a900fa040cdb1a6426cecab0a7ca9.png)

```auto
switch (type)
{
    case EVENT_CALLBACK_TYPE.CREATE_PROGRAMMER_SOUND:
    {
        ...
        string key = GetNextKey();
        ...

```

---

<div class="post-metadata">

**Author:** ![NikMikk](https://yyz2.discourse-cdn.com/flex036/user_avatar/qa.fmod.com/nikmikk/32/5599_2.png) [@NikMikk](https://qa.fmod.com/u/NikMikk)\
**Post date:** [November 2, 2020, 12:29pm UTC](https://qa.fmod.com/t/autoplay-next-item-in-audiotable/16300/5 "2020-11-02T12:29:26Z")

</div>

I just realized what made the editor freeze, the callback where I’m trying to play the next track is also accessing a GameObject which will cause unity to freeze if it doesn’t happen on the main thread…

Will see if everything is fixed if I work around that! 🙂