Re: fIsMixable
Re: fIsMixable
- Subject: Re: fIsMixable
- From: BlazeAudio Developer <email@hidden>
- Date: Tue, 17 Jun 2003 15:44:26 -0700
Jeff,
Can you tell me what parts of the CoreAudio driver quality determine the
latency?
From what I understand, these are the main factors (for a PCI based audio
device):
a. The size of the stream/dma buffers.
b. Accuracy of position reported by getCurrentSampleFrame().
c. The "latency" between receiving an interrupt (interruptFilter()) and
calling takeTimeStamp().
Is there a general "guideline" for the stream buffer size? How should one
determine what size to use?
What are other drivers using?
Thanks.
Devendra.
At 03:22 PM 6/17/2003, Jeff Moore wrote:
The latencies for CoreAudio/IOAudio are pretty much the same or
better than ASIO for the same piece of hardware. That said, the
quality of the driver is just as important, if not more important, on
Mac OS X as it is on ASIO for determining the latency.
On Tuesday, June 17, 2003, at 2:42 PM, BlazeAudio Developer wrote:
Everybody, thank you for your input!!
I think I will stay away from the Hog mode.
However, I have related questions (perhaps I should start another
thread).
How does CoreAudio compare against ASIO (OS9) in terms of
workable
latencies, say on a 500 MHz Dual G4, given everything else sort
of equal!
Thanks.
Devendra.
At 02:08 PM 6/17/2003, Markus Fritze wrote:
On Dienstag, Juni 17, 2003, at 01:12 Uhr, James Chandler Jr
wrote:
If just playing or recording a file, it might be desirable to
avoid float-int conversions.
But in this case performance is not an issue anyhow :-)
Logic does all it's internal processing in float (or even
double, if
necessary). I would expect that every even half-professional
audio
application does so, too. You don't have to deal with clipping
and
you can do real math without converting (converting float->int
is
extremely costly on a PowerPC!). How much effort is even a
volume
control with clipping in integer math? It is one cycle in
float...
BTW: On of CoreAudios real advantages _IS_ multi-client support
and
the customers love it. Only because they _had_ to use ASIO
under Mac
OS 9, doesn't mean that they prefer the old solution.
Ok, users don't like system beeps on their audio hardware, but
they
can change that in the system preferences, so this is no longer
a
problem.
I really would recommend not to deal with hog mode (BTW: we
never
tested Logic with hog mode, because AFAIK no audio hardware
supports
it :-), your tech support will be flooded (why is iTunes not
working,
etc.)
MMM
--
Markus Fritze
Apple Computer, Inc. <
http://www.apple.com>
Senior Engineer - Audio/Music Applications
_______________________________________________
coreaudio-api mailing list | email@hidden
Help/Unsubscribe/Archives:
http://www.lists.apple.com/mailman/listinfo/coreaudio-api
Do not post admin requests to the list. They will be ignored.
_______________________________________________
coreaudio-api mailing list | email@hidden
Help/Unsubscribe/Archives:
http://www.lists.apple.com/mailman/listinfo/coreaudio-api
Do not post admin requests to the list. They will be ignored.
--
Jeff Moore
Core Audio
Apple
_______________________________________________
coreaudio-api mailing list | email@hidden
Help/Unsubscribe/Archives:
http://www.lists.apple.com/mailman/listinfo/coreaudio-api
Do not post admin requests to the list. They will be ignored.
_______________________________________________
coreaudio-api mailing list | email@hidden
Help/Unsubscribe/Archives:
http://www.lists.apple.com/mailman/listinfo/coreaudio-api
Do not post admin requests to the list. They will be ignored.