[LAD] [ann] CAPS 0.4.5

Paul Giblock pgiblox at gmail.com
Wed Mar 30 13:15:43 UTC 2011

>From the docs for LV2_Descriptor::URI:

A globally unique, case-sensitive identifier for this plugin type.

All plugins with the same URI MUST be compatible in terms of 'port
signature', meaning they have the same number of ports, same port
shortnames, and roughly the same functionality. URIs should probably
contain a version number (or similar) for this reason.

Rationale: When serializing session/patch/etc files, hosts MUST refer
to a loaded plugin by the plugin URI only. In the future loading a
plugin with this URI MUST yield a plugin with the same ports (etc)
which is 100% compatible.


On Tue, Mar 29, 2011 at 1:17 PM, Olivier Guilyardi <list at samalyse.com> wrote:
> On 03/28/2011 11:27 PM, Philipp Überbacher wrote:
>> Excerpts from Stefano D'Angelo's message of 2011-03-28 22:59:46 +0200:
>>> 2011/3/28 Tim Goetze <tim at quitte.de>:
>>>>>> I'm planning to add a mode switch (low- or bandpass) to the AutoWah
>>>>>> instead of making a separate new plugin, or would that be a stupid
>>>>>> idea?
>>>>> For compatibility with LV2, it's better if you create a new plugin for that...
>>>> I don't see how compatibility with LV2 is a concern here?
>>> Heh... long story short: LV2 uses URIs, LADSPA uses UniqueIDs (not
>>> necessarily but...), two LV2 plugins with same URI are required to
>>> have the same "port signature" (i.e., ports) and I wrote a LADSPA to
>>> LV2 bridge where the URIs of the bridged plugins are in the form
>>> urn:ladspa:xxxx, where xxxx is the UniqueID.
>>> This means, if you change the port signature and maintain the same
>>> UniqueID, we would have incompatibilities in the LV2 world. If you
>>> create a new plugin or don't touch ports, instead, everything's fine.
>>> Stefano
>> I'd say you'd even have incompatibilities in LADSPA world. Even fixes in
>> LADSPA plugins would sometimes need a new ID (This was discussed a while
>> ago regarding a LADSPA that has an unintuitive port order).
> Sorry guys but I don't follow you here. Can't you add or remove ports to an
> existing plugin in a new release? Does LV2 considers that two plugins with the
> same URI but different ports are actually different plugins? As for two C++
> functions with the same name but different arguments?
> --
>  Olivier
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