power-of-two buffer size. (was: Re: [LAD] [ANN] LV2 beta3)

Florian Schmidt mista.tapas at gmx.net
Fri May 11 14:42:50 UTC 2007


On Friday 11 May 2007, Pieter Palmers wrote:
> Florian Schmidt wrote:
> > On Wednesday 09 May 2007, Dave Robillard wrote:
> >> If you want to discuss fixed block sizes, etc, discuss the existing work
> >> done in that area by tapas (who has longed for that feature for ages
> >> now, and I assume from the lack of objections from him that things are
> >> fine on that front).  There is already a solution to this, if you have a
> >> problem with the solution, let it be known.
> >
> > Yep, no objections :) As these extensions (fixed-buffersize and
> > power-of-two-buffersize) are rather easy to implement, especially for
> > jack apps where the API guarantees a fixed power of two buffersize in
> > between buffer-size callbacks [aha - this should be an extension, too
> > ;)], i hope all LV2 hosts which are useful [for me] at all will support
> > it :) So i considered this problem solved.
>
> I don't think the power-of-two buffersize is guaranteed by the jack API.
> It is true that the ALSA backend wants the buffers to be a power of two.
>   But AFAIK it is not an API guarantee.
>
> If I'm wrong, I'll have to fix the freebob backend because it doesn't
> enforce this.

I remember i looked this up before. Right now i only found this:

http://jackaudio.org/files/docs/html/jack_8h.html#a14

"nframes   new buffer size. Must be a power of two"

This is the jack_set_buffer_size docs. I think i remember having read this in 
a different context, too. But it seems the docs have changed or i have 
dreamed..


Regards,
Flo

-- 
Palimm Palimm!
http://tapas.affenbande.org



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