Re: DMA Address Plug-In for HAL
Re: DMA Address Plug-In for HAL
- Subject: Re: DMA Address Plug-In for HAL
- From: Jeff Moore <email@hidden>
- Date: Mon, 29 Jul 2002 11:44:40 -0700
On Friday, July 26, 2002, at 03:56 AM, Brian Souder wrote:
I have been looking at way to setup a sound card to do accelerated
audio. At the moment it seems like there are two possibilities.
1) Make a HAL Plug-In which utlizes DMA Addresses to redirect the
audio streams to the card directly. We weren't sure if the data would
still pass through the G3/G4 processor before being passed to the card
though. The goal would be to remove all or almost all of the CPU load
from the the system.
HAL plug-ins allow for the implementation of custom device/stream
properties via the HAL's API. They have no access to the IO paths in
the HAL.
2) Change the Apple Audio Engine code to be for the Sound Card only,
thus redirecting the output directly to the card. Again hopefully
removing the audio load from the system.
If you have a better idea how this might be implemented, please feel
free to contact me. The documentation on the audio system in a lot of
these areas is very light to say the least. If there is not already a
system in place, now might be the time to work this out.
I don't see how redirecting the output to a card _after_ all the CPU
consuming DSP has already happened - well before the driver even gets a
chance to see the data - will lower the overall CPU load of processing
audio.
Perhaps you ought to take a step back and describe in detail the
hardware you have and _exactly_ what you want to do with it. Then we
will be in a better position to advise you on how to proceed.
--
Jeff Moore
Core Audio
Apple
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