12 May
2007
12 May
'07
2:43 a.m.
On Fri, 2007-05-11 at 22:36 +0100, Steve Harris wrote:
On 11 May 2007, at 20:37, Fons Adriaensen wrote:
I'm not so sure I agree with that; you /could/ do multirate with LV2.
Yes, it's more complicated, but no more complicated than multirate audio
via any other API (other than the slight un-prettyness of having a
single hardcoded sample rate parameter).
Anyway, there's no doubt that the basic plugin API shouldn't be made
more complicated by this esoteric need, so agreed there. As with
everything else, that bridge can be crossed when someone gets there...
-DR-
On Fri, May 11, 2007 at 06:24:38PM +0100, Steve
Harris wrote:
I see. So that's the point that I missed. Here, I think the
difference of opinion is that I don't think LADSPA-style APIs are at
all appropriate for multirate audio - the LADSPA API was built very
much with input sample rate = output sample rate in mind. I think
that any move away from that will complicate the API, when a better
solution would be to use a different API altogether. On 11 May 2007, at 15:07, Fons Adriaensen wrote:
> Two 32-bit ints can represent (the
non-integer part of) most (not
> all)
> irrational values to better precision than a double. The algo to
> find
> them is a bit mysterious but very simple. Simple example: 355/113 is
> equal to pi with a relative error of less than 1e-7, not bad for two
> 3-digit numbers. It's not difficult to find two 32-bit ints that
> would
> be better than a double.
First, if you read the paragraph above in its context, it should be
clear that this is *not* the rationale for having sample rates as
a ratio of two integers. It's just a side note.
(Sigh) I have already written (some nights ago) that this has nothing
to do with _absolute_ precision. Most sound cards are way off their
nominal sample rate anyway, and very few people complain.
This is about _relative_ precision in multirate processing. It only
works if the ratios are exact. It does not work at all if they are
not. I can easily imagine processing networks where not all plugins
run at the same rate, but at rates related by simple integer ratios.
Maybe improbable for music production. But certainly possible for
audio DSP work in general.