Re: Computing latency
Re: Computing latency
- Subject: Re: Computing latency
- From: Jeff Moore <email@hidden>
- Date: Mon, 23 Feb 2004 15:58:18 -0800
On Feb 23, 2004, at 3:04 PM, Josh Anon wrote:
Hi,
This is slightly related to what Philippe just posted (Changing the
latency from within the render callback), but I'm wondering about
computing latency.
Are device and stream latencies constant, or might they change
periodically? Specifically, can I just compute it once in my
configure routine, or do I need to compute it and then register a
callback for if that param changes?
The latency of hardware tends to be fixed unless something changes like
the sample rate or what have you. You can receive a notification when
kAudioDevicePropertyLatency changes if you ask for it.
I also can't find any documentation on a stream latency property, but
people have mentioned using AudioStreamGetProperty to get it. Do you
pass in kAudioDevicePropertyLatency to AudioStreamGetProperty, or is
there some undocumented property that I should ask for?
You pass kAudioDevicePropertyLatency to AudioStream routines to find
out about individual stream latency. This figure is summed with the
device's latency to get the total hardware latency of data going to or
coming from that stream.
--
Jeff Moore
Core Audio
Apple
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