Playing sounds takes a loooong time?

Unity Engine
,
1

Playing sounds seems to be very slow on the iPhone - anyone else confirm this?

What I’m seeing is a 220ms average time to kick off a sound using code such as:

   audioSource.clip = clip;
   audioSource.Play();

or even:

audioSource.PlayOneShot( clip, volume );

The 220ms is just time taken to start the clip, i.e. complete the Play call. This is true on the first and subsequent calls for that clip (its not just a one-time thing). The clip is sampled at 44.1kHz for 1.7s duration, about 70kB on disk.

So, its very disruptive to frame rate, especially in the worst case when I have 3-4 sounds playing per second. That’s CPU time spent almost entirely playing sounds!

Is there a way around the slow playback, or a way to improve the slowness? Halp!

2

I assume thats a WAV right, because mp3 / aac can’t be used or better shouldn’t be used for that due to the 1 track at a time restriction and the time required to startup them on the dedicated decompressor chip

3

Hmmm, actually its an MP4, do WAVs work better? I could try another format, haven’t done that yet.

4

they need to be uncompressed, otherwise they are handled by the dedicated decompressor and thats bound to a lag but reduces the cpu usage

5

That was it, thank you very much dreamora :slight_smile:

For anyone interested in the speedup, I’m seeing 5ms now per clip. Much improved!

6

HamulTech had a good suggestion on another thread - sometime before the game starts, play each of the sounds for a very short time and then stop them. They should now be cached, and subsequent plays will be faster.

As far as I can tell this is untested, and also relies on something you have no control over (i.e. memory cache, GC). But it might work :slight_smile:

7

Hmm… it would be nice to have audio clips compressed, even if only to save disk footprint.

I couldn’t find the thread but here’s what I tried so far (and no luck):

Add a GO to the scene, attach the AudioSource component, then get it to reference the clip, and make sure PlayOnAwake is checked. On startup, the clip is played.

But when I use it, I’m still seeing 220ms for play time. Am I doing it right?

Its odd though, if I import the file as a compressed file, it has its DecompressOnLoad checked, which I would think would decompress it and keep it around. That doesn’t seem to be the case, even when I have another reference sitting around in my GO.

scratches head

8

iPhone doesn’t work that way, it’s too slow…decompress on load has no effect.

–Eric

9

So you use uncompressed as well, Eric5h5?

10

Except for music, yes. That’s really the only option. You don’t think anything of playing compressed sounds on a modern computer, because they are really fast, but iPhones are not.

–Eric

11

I have a few short loops playing (1-2 seconds) of uncompressed Wavs at 22khz… I find the audio glitches quite often, clicking noticably. I am just about to update version to Unity 1.5 - is the audio handling better?

12

I should actually. We’ve improved some audio related code in 1.5, though those were mostly bugfixes