Re: Sample-accurate parameter automation? Possibe at all with AUs?
Re: Sample-accurate parameter automation? Possibe at all with AUs?
- Subject: Re: Sample-accurate parameter automation? Possibe at all with AUs?
- From: Greg X <email@hidden>
- Date: Tue, 11 Mar 2008 13:28:09 -0700 (PDT)
Mr. Kemmish!
Thank you for your reply!
The base of my conception is a statement from Apple
which you can read here:
http://lists.apple.com/archives/coreaudio-api/2005/May/msg00104.html
Anyway, let's talk about your solution:
It works nice only if hosts doesn't allow
high-resolution parameter automation. For example it
would be a huge performance hit to process parameters
that change their value each sample. ..and I would
like to support parameter changes for each sample.
Your solution may be even bigger performance hit than
simply calling GetParameter for each sample in render.
So, I'm still wondering why isn't there an input
parameter buffer with series of floats for handling
high resolution (per sample) parameters with minimal
overhead.
I've never read about such thing in AUs. Do such
buffers exist?
Regards,
Greg1X
--- Ian Kemmish <email@hidden> wrote:
>
> On 11 Mar 2008, at 7:03 pm, Greg X
> <email@hidden> wrote:
>
> > What is your answer to my other questions?
> > For example:
> > Why are AU examples calling GetParameter only at
> the
> > beginning of the render process?
> > Why is it acceptable? ..why is it a widely used
> > approach?
>
>
> It's possible that your question is based on a
> misconception.
>
> GetParameter() and SetParameter() are methods in the
> AU which get
> called by the host. They don't get called by the
> AU. Or at least,
> they shouldn't get called by the AU:-).
>
>
> The normal sequence of events is that the host calls
> the AU's
> SetParameter() method for all parameter changes in
> the upcoming
> timeslice, just before calling the AU's Render()
> method. You will
> notice that one of the parameters to SetParameter()
> is the extremely
> handy inOffsetSampleFrame, which tells you at
> exactly which sample in
> that timesclie to change the value of the parameter
> to which your
> rendering code refers when it is calculating stuff.
>
> Your AU is entirely free to honour or ignore
> inOffsetSampleFrame as
> you see fit. If you want sample-accurate parameter
> changes, you'll
> honour it.
>
> - - - - - - - - - - - - - - - - - - - - - - - - - -
> - - - - - - - - -
> - - -
> Ian Kemmish 18 Durham Close,
> Biggleswade, Beds
> SG18 8HZ
> email@hidden Tel: +44 1767 601361
> Mob: +44 7952
> 854387
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>
>
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