Re: How long do render callbacks have to execute?
Re: How long do render callbacks have to execute?
- Subject: Re: How long do render callbacks have to execute?
- From: Jonathan <email@hidden>
- Date: Fri, 12 Aug 2011 15:39:18 -0700
Okay, that makes sense, but are the callbacks called in parallel? In other words, is only one callback firing at a time? In the example with two inputs into the mixer, does it fire one right after another even though from a graph perspective they are peers?
I've been digging for that notification for a while now.. if you happen to think of it, please let me know ;)
On Fri, Aug 12, 2011 at 2:13 PM, Brian Willoughby
<email@hidden> wrote:
On Aug 12, 2011, at 13:36, Jonathan wrote:
I have two callbacks that each feed into a mixer, and then I have a render notify callback on the output of the mixer which feeds into the remote IO unit.
How much time do I have in each of those call backs? I'm assuming it's related to the IO Buffer duration.. so let's say I have it set to .005 seconds. Does that mean that each of the callbacks have .005 seconds to return, or is the duration divided by the number of callbacks? For example, if there are three callbacks in succession that each take .004 seconds to fill buffers, is that going to meet the requirement or no?
In your example with 3 callbacks, you probably only have about 0.001 seconds in each callback, with the remainder going to non-audio code.
Related to that, is there a way to reliably detect when the boat is missed, so to speak, so I can detect if the user is experiencing skips?
There are two ways. First of all, there should be a CoreAudio notification when you skip. You won't get this unless you register for the notification callback, specifically, so look it up in the documentation. I'm not sure whether iOS supports this notification, but I assume it would have to just like OSX. Second of all, the remote I/O unit should give you a time stamp on every callback, and if these are not contiguous then you have suffered a skip.
Brian Willoughby
Sound Consulting
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