Re: Using converter API for a multiple streams driver
Re: Using converter API for a multiple streams driver
- Subject: Re: Using converter API for a multiple streams driver
- From: Stéphane Letz <email@hidden>
- Date: Wed, 19 Jan 2005 09:56:17 +0100
Le 18 janv. 05, à 23:17, Doug Wyatt a écrit :
On Jan 18, 2005, at 13:41, Stéphane LETZ wrote:
On 18 janv. 05, at 19:35, Doug Wyatt wrote:
Stephane,
You'll need one converter per stream, since there's no way to
describe all of the 828's (or similar device's) streams with a
single AudioStreamBasicDescription. If all of the device's streams
are mono -- there are some devices like this -- you can special-case
that and just have one converter.
Or you could write your own set of interleaving/deinterleaving
routines (it's a bit of a pain to handle arbitrary numbers of
channels efficiently but it's certainly possible). If you do this it
would be wise to analyze the generated code for stalls.
Doug
Thanks.
I was thinking using Converter would always be more efficient
(because i guess they are Altivec optimized) than writing
interleaving/deinterleaving routines.
At the moment the interleave/deinterleave loops are not altiveced
(subject to change) though they are well scheduled.
BTW what does the AUHAL? can the AUHAL convert a set of stream (like
828) in a set of mono non inteleaved streams? does the HAL use also
several converter to do the convertion?
yes and yes.
Doug
Thanks. One last question. I need to actually implement a full-duplex
system like:
Audio device <==> converter <==> input set of n mono streams <==>
processing <==> output set of n mono streams <==> converter <==> Audio
device.
One of the reason to not use the AUHAL was that I did not find a way to
avoid buffer copies in the chain ( I want the maximum performances...)
It there a way to configure the AUHAL so that the "input set of n mono
streams" buffers can be used directly by the AUHAL and the same for
output : "ouput set of n mono streams " buffers directly used by the
AUHAL ?
Thanks
Stephane Letz
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