[Ardour-Users] ambix LV2 vs ardour?

Fernando Lopez-Lezcano nando at ccrma.Stanford.EDU
Sat Feb 23 23:17:37 PST 2019

On 2/23/19 6:39 PM, Fernando Lopez-Lezcano wrote:
> On 2/23/19 4:13 PM, Robin Gareus wrote:
>> On 2/21/19 12:52 AM, Fernando Lopez-Lezcano wrote:
>>> Hi all,
>>> Anyone out there successfully using the Ambix (0.2.8) LV2 plugins with
>>> Ardour5?
>>> [ERROR]: LV2: Failed to instantiate plugin
>>> file:///usr/lib64/lv2/ambix_converter_o1.lv2/ambix_converter_o1
>>> The directory looks like this:
>>> ls -l /usr/lib64/lv2/ambix_converter_o1.lv2/
>>> total 5068
>>> -rwxr-xr-x. 1 root root 5171056 Nov 29 20:43 ambix_converter_o1.so
>>> -rw-r--r--. 1 root root    5504 Nov 29 19:50 ambix_converter_o1.ttl
>>> -rw-r--r--. 1 root root     901 Nov 29 19:50 manifest.ttl
>>> -rw-r--r--. 1 root root     378 Nov 29 19:50 presets.ttl
>>> I built the plugins according to the build instructions, and nothing
>>> weird is shappening there that I can see (the build uses a recent
>>> lv2-devel package, etc). All the Ambix standalone applications that are
>>> also built work just fine with jack.
>> I just had a quick look. The plugin has an invalid URI, it just uses the
>> plugin-name as-is.
>> liblilv will prefix that with the absolute path, resulting in a
>> file://URI, 
> (darn, I had noticed that it was the only plugin to use file:// but 
> failed to mention it)
>> and when Ardour tries to instantiate the plugins this causes
>> a failure. The given URI does not match the URI in the plugin's so. It
>> also fails with jalv. I'm surprised that it works in qtractor, perhaps
>> you were using the VST, there?
> Nope, I was loading the lv2. But not very useful since qtractor is stereo.
>> Could you try patching ambix like http://paste.debian.net/1069875/ (That
>> patch also includes an update for zita-convolver3 new API and removes a
>> call to fftw's thread-safe planner which is for a plugin-host to make.)
> I'm building now, will take a while - will report back.

Well, much better!

Some plugins load fine after the patch (I dropped the third chunk as it 
was already taken care slightly differently in 0.2.8, I believe).

So, for example ambix_warp, ambix_widening, ambix_rotator_z, 
ambix_converter load fine. Others (like ambix_encoder) just segfault 
when inserted. I suspect the JUCE interface is having problems - it has 
always been a problem and I though that was disabled by default.

(ardour-5.12.0:3068): Gdk-CRITICAL **: 23:10:30.535: 
IA__gdk_window_get_origin: assertion 'GDK_IS_WINDOW (window)' failed
(ardour-5.12.0:3068): Gdk-CRITICAL **: 23:10:30.536: 
IA__gdk_window_get_origin: assertion 'GDK_IS_WINDOW (window)' failed
Segmentation fault (core dumped)

... later ...

If I set "open gui of plugin automatically" or words to that effect, 
then I get a segfault. If I unset it, the plugin is inserted just fine 
and then I can use the "generic interface" to edit parameters. Using the 
nice gui segfaults ardour.

This is a long standing problem that has never been tackled to my 
knowledge and has to do, if memory serves me, with JUCE running the GUI 
in the wrong thread.

Anyway, at least now there is a way to load plugins!
-- Fernando

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