Subject: Re: [linux-audio-dev] XAP: a polemic
From: David Olofson (david_AT_olofson.net)
Date: Wed Dec 18 2002 - 23:43:07 EET
On Wednesday 18 December 2002 19.19, Tim Hockin wrote:
> > Two standard float controls would work fine. Better, in fact, as
> > you can handle defaults and presets without any special-casing at
> > all.
>
> That could work, too. I want to be careful how much we expect the
> plugin coder to do, though.
Yes... Well, first of all, this is all totally optional. It's only
needed by tempo and beat sync plugins. (Through that doesn't mean it
needs a hairy API. ;-)
[...]
> > BTW, how about making integer controls 64 bit? (*41* extra bits!
> > :-)
>
> Is there a justification?
I can't think of any example. It's just more bits, basically.
Frankly, that's the only strong motivation I see for ints at all,
since if you just need an integer *value*, float should do. (Just
disable rounding.)
It might be nice to know that you'll never get 1.5 on a port
hinted/typed as integer, but I'm not sure that's a good motivation.
If you really need an integer, you'll round or truncate first thing
anyway, so such illegal values never get into the machinery.
> 32 bit CPUs are bad at 64 bit math.
> Maybe a hint that says INT64, otherwise assume int32 ?
Yes... Might be interesting if you want compact protocols for sending
events over networks or something.
> Do we
> assume signed or unsigned? having it be 64 bits means we need to
> deal with sign extension.
Well, fp is signed, and AFAIK, there are a bunch of programming
languages that don't have unsigned ints at all, so I would suggest
assuming they're signed. (Unless they're strictly meant for flags or
something, but that seems like a nasty thing to do...)
> > It's no big deal in any way, because they can't be ramped (no
> > event
>
> They can be, it's just not so accurate. If you want to swing
> between 0 and 1000 in one block, set a ramp event.
Well, yeah... You'd have to implement ramping for integers in
plugins, and that's not quite as trivial as ramping floats. (I do it
all the time in Audiality - but that's 16:16 fixed point, so no one
relies on much accuracy in the lowest bits.)
//David Olofson - Programmer, Composer, Open Source Advocate
.- The Return of Audiality! --------------------------------.
| Free/Open Source Audio Engine for use in Games or Studio. |
| RT and off-line synth. Scripting. Sample accurate timing. |
`---------------------------> http://olofson.net/audiality -'
--- http://olofson.net --- http://www.reologica.se ---
This archive was generated by hypermail 2b28 : Wed Dec 18 2002 - 23:48:15 EET