[LV2] Feature request: DSP write_function() ?

Hanspeter Portner dev at open-music-kontrollers.ch
Mon Dec 21 15:55:43 PST 2020


On 21.12.20 20:55, Filipe Coelho wrote:
> 
> On 21/12/20 19:44, Hanspeter Portner wrote:
>> On 21.12.20 19:43, Hermann Meyer wrote> Synthpod have it own issues as well,
>> so for example it create controls
>>> for patch:writable and patch:readable separately (Means it double
>>> controls and only sync the readable ones to the plugin GUi, while you
>>> could only change the writable ones, which are basically the same, but
>>> threaded different). This do as well not allow to sync the plugin GUI
>>> with host provided UI, and easily lead to a overflow in the atom ring
>>> buffer.
>>
>> Can you show your *.ttl, please?
>>
>> I think you've misinterpreted something there. An lv2:Parameter either
>> is patch:writable (read-write) OR patch:readable (read-only), but not
>> both, if I'm not totally mistaken, that is.
>>
>> If you list the same parameter both as patch:writable AND patch:readable,
>> then indeed synthpod may show two generic UI elements with only one being
>> active.
> 
> I think you are mistaken, the LV2 parameter example plugin includes such a case,
> see the spring parameter
> in https://github.com/lv2/lv2/blob/master/plugins/eg-params.lv2/params.ttl#L100

Interesting. I hope it's just a typo.

from https://lv2plug.in/ns/ext/patch#readable:

> A property that can be read with a patch:Get message.

from https://lv2plug.in/ns/ext/patch#writable:

> A property that can be set with a patch:Set or patch:Patch message.

If patch:writable indeed does *not* include patch:readable, e.g. is only
writable (not read-write), then the whole rest of the eg-params plugin is wrong,
 because all of its parameters listed as patch:writable *do* respond to
patch:Get messages and should thus be listed as patch:readable, too.

A write-only parameter makes no sense to me as there's no way to query its value.

... or I'm totally confused about it, indeed.


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