[Devel] port-props extension (rescued "extended port information" extension)

[Stefano D'Angelo]

2011/11/2 Stefano D'Angelo <zanga.mail at gmail.com>:
> 2011/11/2 David Robillard <d at drobilla.net>:
>> On Wed, 2011-11-02 at 14:03 +0200, Stefano D'Angelo wrote:
>>> 2011/11/2 David Robillard <d at drobilla.net>:
>>> > Hi all,
>>> >
>>> > I rescued the "extended port information" extension from the old wiki
>>> > dump.  It was a quasi-turtle document (bad syntax) that seemed extremely
>>> > stale but useful, so I figured it'd be good to clean it up and keep it
>>> > maintained with the others.
>>> >
>>> > This does mean a different URI.  I am not sure who is currently using
>>> > this. ?
>>>
>>> NASPRO bridges for the logarithmic port property, and IIRC
>>> zynjacku/lv2rack too, and probably others too.
>>>
>>> However, feel free to define a new URI, the old property IIRC has an
>>> erroneous description, that is the bounds must have same sign (WTF?),
>>> and it takes me 2 seconds to just let the bridges produce a new
>>> statement together with the old one.
>>
>> IIRC the lack of a rigorous definition is why logarithmic was left out
>> of lv2core.
>>
>> This extension's logarithmic hint lacks one as well.  Can we make one?
>> Are there inherent reasons why one mapping might not apply to different
>> plugins?  Is there some kind of standard or existing practise for this
>> somewhere?
>
> I don't know if there's any standard, but I'd say that semilog
> plotting rules could apply well, so it could be something like:
>
> value = exp(scale * (upper - lower + 1)) + lower - 1

Whoops, I meant: value = exp(scale * log(upper - lower + 1)) + lower - 1

Stefano