Re: [linux-audio-dev] protux, stereo and interleaving

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Subject: Re: [linux-audio-dev] protux, stereo and interleaving
From: David Olofson (david_AT_gardena.net)
Date: Sat Feb 10 2001 - 10:24:02 EET


On Friday 09 February 2001 12:50, Steve Harris wrote:
> On Fri, Feb 09, 2001 at 12:19:49PM +0100, David Olofson wrote:
> > On Friday 09 February 2001 11:57, Iain Sandoe wrote:
> > > > - the time to [de]interleave data is a knats-p in a
> > > > millpond compared to doing 600+ FFTs in real-time...
> > >
> > > Agreed.... and one can apply this argument to many facets of
> > > the process... unfortunately you then end up with 10**N
> > > gnats... which is one hell of a lot of p.
> >
> > Yep, another good argument. That's another reason why I'm not
> > just throwing the pitch in.
> >
> > BTW, this pitch value is more easy to use than it may seem. From
> > the Host perspective, it's just a matter of telling a Plugin how
> > many physical channels a buffer has when connecting one of the
> > Plugin's Buffer Slots to it. (Pitch is effectively # of channels
> > * sample frame size in any normal buffer.) Use the channel number
> > to index the buffer pointer when calculating the pointer to pass
> > to the Plugin.
>
> Maybe I'm missing someting, but most complex plugins require
> filters which require deinterleaving the data anyway.

I don't think mixers, various other matrixes of connections (add,
mul, ...), IIR filters, multichannel synths etc don't benefit much
from deinterleaving first, even though you'd normally process one
channel at a time.

Anyway, looking at it from that perspective, interleaving just seems
pontless in the first place... I must be forgetting something again.
:-)

> Also, I think you are better off (if you can) running small loops
> over each channel in series, rather than a more complicated loop
> over serveral channels at once - less cache polution.

Yep. And less Register Lack Induced Panic Situations for x86. ;-)

//David

.- M A I A -------------------------------------------------.
| Multimedia Application Integration Architecture |
| A Free/Open Source Plugin API for Professional Multimedia |
`----------------------> http://www.linuxaudiodev.com/maia -'
.- David Olofson -------------------------------------------.
| Audio Hacker - Open Source Advocate - Singer - Songwriter |
`--------------------------------------> david_AT_linuxdj.com -'


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