Re: [LAD] LV2 mono instruments recommended?

[Rui Nuno Capela]

On 09/10/2016 03:21 PM, Stefan Westerfeld wrote:
 >
 > If you as host author say that this is the way Qtractor users should 
go for
 > mono instruments, I'll keep my plugin as it is, the other way would 
have been
 > kind-of a workaround. Still from the user experience I prefer what 
Ardour does,
 > as it automatically gets the intended result without the user needing 
to do
 > anything.
 >

well, if you really want to keep the mono audio chain all the way, you 
should make it to a mono audio output bus that you create on purpose, 
instead of relying on the default Master stereo out.

byee
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Re: [LAD] LV2 mono instruments recommended?

[Stefan Westerfeld]

   Hi!

On Fri, Sep 09, 2016 at 09:55:59PM +, Rui Nuno Capela wrote:
> On 09/09/2016 06:33 PM, Stefan Westerfeld wrote:
> >
> > I have tested with Ardour and Qtractor. Ardour does what I'd expect: it 
> > plays
> > my instrument output on both channels. Qtractor however just plays my mono 
> > data
> > on one channel, the other is silent. Which is not what I want.
> >
> until the last release, qtractor used to replicate mono plugins as much 
> as audio output channels is for where it's inserted, so that you would 
> have exactly as many instances of a mono plugin as there are audio 
> output channels.
> 
> unfortunately this "cleverness" didn't work well for all cases, 
> specially regarding instrument plugins vs. its own GUI state and 
> communication--quite often, only one plugin instance reflects some 
> changes done via the GUI, being one notable example about selection of 
> presets (only one instance would get it loaded one time). you would need 
> to save and reload the whole session to get everything in sync again.

Right. This particular "cleverness" would be wrong for the SpectMorph plugin as
well. Computing the audio data is quite CPU intensive, so if you would
instantiate it twice, you'd be wasting precious resources (for computing the
same data twice). Plugin UI problems would also occur.

> > So I am considering making my LV2 instrument always stereo, and just copy 
> > the
> > output buffer from left to right - this is cheap, and probably not much more
> > expensive than what the host would need to do anyway.
> >
> 
> you don't really need to make it stereo all the way. at least on 
> qtractor, you can make use of balance.lv2 [1], inserted right after the 
> mono instrument and then set channel assignemnt = 1 (L->L, L->R) ...

Ok, I tried that, and this produces the intended result.

If you as host author say that this is the way Qtractor users should go for
mono instruments, I'll keep my plugin as it is, the other way would have been
kind-of a workaround. Still from the user experience I prefer what Ardour does,
as it automatically gets the intended result without the user needing to do
anything.

   Cu... Stefan
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Re: [LAD] LV2 mono instruments recommended?

[Rui Nuno Capela]

On 09/09/2016 06:33 PM, Stefan Westerfeld wrote:
>
> I have tested with Ardour and Qtractor. Ardour does what I'd expect: it plays
> my instrument output on both channels. Qtractor however just plays my mono 
> data
> on one channel, the other is silent. Which is not what I want.
>
until the last release, qtractor used to replicate mono plugins as much 
as audio output channels is for where it's inserted, so that you would 
have exactly as many instances of a mono plugin as there are audio 
output channels.

unfortunately this "cleverness" didn't work well for all cases, 
specially regarding instrument plugins vs. its own GUI state and 
communication--quite often, only one plugin instance reflects some 
changes done via the GUI, being one notable example about selection of 
presets (only one instance would get it loaded one time). you would need 
to save and reload the whole session to get everything in sync again.


> So I am considering making my LV2 instrument always stereo, and just copy the
> output buffer from left to right - this is cheap, and probably not much more
> expensive than what the host would need to do anyway.
>

you don't really need to make it stereo all the way. at least on 
qtractor, you can make use of balance.lv2 [1], inserted right after the 
mono instrument and then set channel assignemnt = 1 (L->L, L->R) ...

[1] http://gareus.org/oss/lv2/balance

hth.
cheers
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Re: [LAD] LV2 mono instruments recommended?

[Spencer Jackson]

Hi Stefan:

Cool to see spectmorph come as a plugin!

IMO I'd let the host deal with it how they see fit. There's probably a
panner in Qtractor to put it in the center. To have a "stereo" output
with no actual stereo data seems wasteful and misleading to me. My lv2
CA synth is mono and I haven't had complaints (though I don't have
high usership either).

_Spencer
p.s. there's also an lv2_dev mailing list if you have other lv2 questions.

On Fri, Sep 9, 2016 at 11:33 AM, Stefan Westerfeld  wrote:
>Hi!
>
> I'm currently implementing a LV2 plugin for SpectMorph, and so far I only
> defined one audio port in the ttl file/source, as the output of the morphing
> algorithm is just mono.
>
> I have tested with Ardour and Qtractor. Ardour does what I'd expect: it plays
> my instrument output on both channels. Qtractor however just plays my mono 
> data
> on one channel, the other is silent. Which is not what I want.
>
> So I am considering making my LV2 instrument always stereo, and just copy the
> output buffer from left to right - this is cheap, and probably not much more
> expensive than what the host would need to do anyway.
>
> Does this sound like the reasonable way to go?
>
>Cu... Stefan
> --
> Stefan Westerfeld, http://space.twc.de/~stefan
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[LAD] LV2 mono instruments recommended?

[Stefan Westerfeld]

   Hi!

I'm currently implementing a LV2 plugin for SpectMorph, and so far I only
defined one audio port in the ttl file/source, as the output of the morphing
algorithm is just mono.

I have tested with Ardour and Qtractor. Ardour does what I'd expect: it plays
my instrument output on both channels. Qtractor however just plays my mono data
on one channel, the other is silent. Which is not what I want.

So I am considering making my LV2 instrument always stereo, and just copy the
output buffer from left to right - this is cheap, and probably not much more
expensive than what the host would need to do anyway.

Does this sound like the reasonable way to go?

   Cu... Stefan
-- 
Stefan Westerfeld, http://space.twc.de/~stefan
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