Re: HAL vs. AU Output: Performance?
Re: HAL vs. AU Output: Performance?
- Subject: Re: HAL vs. AU Output: Performance?
- From: Jeff Moore <email@hidden>
- Date: Mon, 2 Jul 2007 11:44:37 -0700
On Jul 1, 2007, at 12:32 PM, Lubor Prikryl DS wrote:
I have used a direct access to the HAL for years, several months ago
we moved to AU input/output. The only thing which is much worse is
performance - the Output AU consumes a lot of CPU power. It seems to
perform some oversampling or format conversion, when checking in
Shark. But I don't need any sample rate change there, the input and
output sample rates are the same.
This is probably because you are letting it do this work.
Is there anything what could be changed to decrease the CPU load of
the output unit? I think the ComplexPlayThru has the same problem.
Absolutely. Just set the format of the data you are giving it to be
the format of the audio device. That will prevent AUHAL from doing the
format conversions. Note that this also requires that you pay
attention to the HAL's format change notifications and keep updating
things accordingly.
--
Jeff Moore
Core Audio
Apple
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