[LAD] [ALPHA] ladspa.m.lv2 - Some questions :D

hermann meyer brummer- at web.de
Tue Apr 23 10:47:39 UTC 2013

Am 22.04.2013 07:33, schrieb Florian Paul Schmidt:
> Hi,
> These last few days I found some time to work on ladspa.m.lv2, an LV2 
> plugin to load ladspa.m.proto instrument definition files:
> https://github.com/fps/ladspa.m.lv2
> It is in a somewhat usable state, i.e. used in ardour3 it loads the 
> example instrument generated by this python script:
> https://github.com/fps/ladspa.m.proto/blob/master/example_instrument.py
> which is a very simple polyphonic sawtooth synth with exponential 
> envelopes and an echo with differing delay times per voice. There's 
> still some things to do (e.g. expose control ports, implement 
> All-Notes-Off midi messages, lots of optimizations - right now I care 
> more for correctness than for efficiency, etc.) and I also have some 
> questions:
> 1] This one is regarding waf. I'm not used to writing wscript files 
> and I adapted the whole thing from the example sampler from the 
> LV2-distribution. I wonder how I can make waf to use e.g. -fPIC and 
> other compiler flags needed for my 64-bit system. Right now I have put 
> a little makefile into the repository which passes the missing options 
> along as CXXFLAGS environment variable. This is a dirty hack. So if 
> anyone waf guru might want to take a look, I'd be so ever grateful.
> https://github.com/fps/ladspa.m.lv2/blob/master/makefile
> https://github.com/fps/ladspa.m.lv2/blob/master/wscript


I'm far from being a waf expert, but I will try to help you out here:
You can use






somewhere in the  def configure(conf): part to set the link flag

and you can use in the obj = bld

cflags     = '-Wall -O3 -march=native',


cxxflags     = '-Wall -O3 -march=native',

depending on your seated
  obj = bld(features     = 'c cshlib',


obj = bld(features     = 'cxx cxxshlib',

> 2] I'm a little bit puzzled by how the patch_set messages together 
> with the LV2 worker extension works. If you take a look at this run() 
> function
> https://github.com/fps/ladspa.m.lv2/blob/master/instrument.cc#L702
> you'll see that I have an extra LV2_ATOM_SEQUENCE_FOR_EACH at the 
> start of the function to process the patch_set messages. I tried to 
> integrate that into the loop later on (that iterates over the 
> sample_count frames and lets the midi events take effect at their 
> respective frame), but once I do that, patch loading stops to work. I 
> must be missing something fundamental. So if any LV2 guru might want 
> to take a look, I'd be very grateful, too
> Thanks and have fun,
> Flo

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