Vangelis doesn't honor LV2 ttl controller order

Software
1

When I added my plugin to Vangelis, each time I restart zynthian the parameters appear in a different random order. They’re nicely ordered in the MyPlugin.lv2/dsp.ttl:

plug:_1_Bypassed
        a lv2:Parameter ;
        rdfs:label "Bypassed" ;
        rdfs:range atom:Float ;
        lv2:default 0 ;
        lv2:minimum 0 ;
        lv2:maximum 1    ;
        lv2:portProperty lv2:enumeration , lv2:toggled ;
        lv2:scalePoint [
                rdfs:label "Off" ;
                rdf:value 0 ;
        ], [
                rdfs:label "On" ;
                rdf:value 1 ;
        ] .

plug:_2_InputGain
        a lv2:Parameter ;
        rdfs:label "Input Gain" ;
        rdfs:range atom:Float ;
        lv2:default 1.07288e-06 ;
        lv2:minimum -72 ;
        lv2:maximum 36 .

Do I have to write a separate ttl file for Zynthian? Is there a better way in the plugin code to provide ordering hints? (Or could Zynthian sort them?)

Note that I’m using JUCE with Projucer, so I’m not writing the dsp.ttl by hand, but the parameters are correctly ordered and the IDs are sortable.

2

I tried to write down some things here. Look out for the term displayPriority:

1 Like
3

Thanks. Just above, it says "If not edited further, LV2 parameters will be presented in a manner being sorted by their parameter ID "

Is this no longer true?

4

You must use DisplayPriority .

Regards

5

OK, I changed “in a manner being sorted by their parameter ID” to “in a random order.”

Really not possible to sort them? Won’t this affect existing plugins that don’t have z-specific ttl’s?

Hannesmenzel’s notes apply to groups. How do we order the parameters themselves, and assign them to groups?

6

Use this, please.
DisplayPriority is the way. All LV2 hosts, including zynthian, would honor DisplayPriority.

2 Likes
8

It applies to both. Groups are ordered first, then parameters with the same group. Assigning parameters to groups is described in the wiki, ch. 3.2.2 / 3.2.3

I can imagine it would be possible to sort by param ID, I would even like to say it used to default to that. DisplayPrioruty anyhow isn’t zynthian specific, its part of lv2 port properties:

1 Like
9

Right, I added the priorities. But some existing plugins might now get re-ordered randomly.

10

By the way, I think in your ttl your control parameters don’t even have an index. In fact, only your audio ports have the ID. So that might be the reason they’re not ordered. I’m pretty sure my own plugin compiled with the DPF framework automatically introduced the index and it ordered it accordingly. Could you please review this in order to review your wiki changes?

plug:_2_InputGain
	lv2:displayPriority 190 ;
	a lv2:Parameter ;
	rdfs:label "Input Gain" ;
	rdfs:range atom:Float ;
	lv2:default 1.07288e-06 ;
	lv2:minimum -72 ;
	lv2:maximum 36 .

a lv2:OutputPort , lv2:AudioPort ;
		lv2:index 2 ; // output port ID
		lv2:symbol "audio_out_1" ;
		lv2:name "Audio Out 1" ;
		pg:group plug:output_group_1 ;
		lv2:designation <http://lv2plug.in/ns/ext/port-groups#left> ;
1 Like
11

OK, I’ll look into it. My ttl file was created by JUCE, so I’d have to do a feature request to JUCE to add these indexes. But thanks for pointing them out. If it turns out as we both expect, I’d change the text to “sorted by index if present, or random order” or something like that.

(I’m currently postprocessing what Projucer creates to add the priorities.)

12

What does your lv2:Parameter entry look like?

13

You can have a look right here:

Or you can have a look as some best practice examples here: