gmane.linux.audio.devel

[LAD] Plugin buffer size restrictions

David Robillard — 2012-05-26T02:43:36

Hello laddies,

I am making an LV2 extension for accessing and/or restricting the buffer
size.  This is straightforward, but I need to know just what
restrictions are actually needed by various sorts of DSP.

The sort of thing we're looking for here is "buffer size is always at
least 123 frames" or "buffer size is always a power of 2" or "buffer
size is always a multiple of 123".

I know "multiple of a power of two" is needed for convolution.  Not sure
what else...

-dr

[LAD] Should LV2 Activate() clear MIDI CC parameters?

Jeremy Salwen — 2012-05-25T07:21:41

Hi all,

The LV2 spec says that on a call to activate(), "the plugin instance MUST
reset all state information dependent on the history of the plugin instance
except for any data locations provided by connect_port()"

I am not certain whether MIDI CC parameters are included in this category
of "data locations provided by connect_port()".  The CC parameters are sent
through port buffers provided by connect_port(), but because they are *event
* buffers, all information passed through them is necessarily part of the *
history* of the plugin instance.

I could imagine cases where you would want to reset all internal state of
the plugin, but since CC values are very much like port values, they would
be kept.  On the other hand, I could also imagine cases where you would
want to reset all internal data including the CC parameters.

I'm assuming MIDI note on/off status certainly should be reset.

Thanks,
Jeremy Salwen
_______________________________________________
Linux-audio-dev mailing list
Linux-audio-dev-cunTk

Re: [LAD] simple FAUST OSC example

Kaspar Bumke — 2012-05-24T15:10:40

Cool! I will take a look at this just for reference. I guess I will have to
make my own way from there as graphical programming gives me the
heebie-jeebies.
_______________________________________________
Linux-audio-dev mailing list
Linux-audio-dev-cunTk1MwBs/CEJeg2xFRV2D2FQJk+8+b< at >public.gmane.org
http://lists.linuxaudio.org/listinfo/linux-audio-dev

Re: [LAD] simple FAUST OSC example

Albert Graef — 2012-05-24T15:06:23

Oops, I misread that, too. I remember writing a little helper object for
Pd which triggers control messages for nonzero sample values in its
audio input. Once you have that, you can easily map that to a MIDI
message in Pd, so you might be able to use that for your purposes. The
object is called bit~ and is contained in this tarball:
http://prdownloads.sourceforge.net/q-lang/kcs-example.tar.gz

Of course, you then still need to write a Faust program which computes
the trigger pulses from its input, so that you can pipe the output
signal from that unit into bit~.

Re: [LAD] simple FAUST OSC example

Albert Graef — 2012-05-24T14:47:33

That's not standalone, though, it needs an LV2 host and is coded as an
LV2 plugin. You could probably use the voice allocation algorithm and
the mapping of notes to Faust control variables, though.

I also have an example of a standalone Faust MIDI synthesizer, but it's
written in Pure, so probably not that much help if you want to do it in
C++. But I can send it if you want.

Albert

Re: [LAD] simple FAUST OSC example

Kaspar Bumke — 2012-05-24T14:27:43

Thanks a lot for your help.




Will do, would you recommend the faust or the new faust2 branch?

You can have a look at Albert Gräf faust-lv2 project

I did look at faust-lv2, the problem is it seems to be for MIDI to Audio
rather than Audio to MIDI which I am interested in as I would like to write
a drum triggger/replacer type application.
_______________________________________________
Linux-audio-dev mailing list
Linux-audio-dev-cunTk1MwBs/CEJeg2xFRV2D2FQJk+8+b< at >public.gmane.org
http://lists.linuxaudio.org/listinfo/linux-audio-dev

Re: [LAD] simple FAUST OSC example

Yann Orlarey — 2012-05-24T13:44:24

Le 24/05/2012 14:29, Kaspar Bumke a écrit :

This probably means that you are using a pre-osc version of Faust. Try to update to the 
git version.



You can have a look at Albert Gräf faust-lv2 project http://code.google.com/p/faust-lv2/, 
a Faust architecture for LV2 Audio and MIDI Plugins.

Cheers

Yann

Re: [LAD] simple FAUST OSC example

Kaspar Bumke — 2012-05-24T12:29:28


OK! Now we are getting somewhere.

When you start ./noise you should see several messages on the standard

Nothing of that sort on stdout. I do get that sort of message as OSC on
port 5511.

While I have you on the line here. Did you see my other question about
MIDI? I would be really interested to learn how easy it would be to do a
direct MIDI output using FAUST and a little example would go a long way I
think.
_______________________________________________
Linux-audio-dev mailing list
Linux-audio-dev-cunTk1MwBs/CEJeg2xFRV2D2FQJk+8+b< at >public.gmane.org
http://lists.linuxaudio.org/listinfo/linux-audio-dev

Re: [LAD] simple FAUST OSC example

Yann Orlarey — 2012-05-24T07:44:26

Le 24/05/2012 01:04, Kaspar Bumke a écrit :

The documentation can certainly be improved and questions are very helpful for that.


OSC support is an option available on some Faust architectures. To activate this option 
with faust2xxx scripts you need to use the flag -osc. Try for example :

    faust2jack -osc noise.dsp

When you start ./noise you should see several messages on the standard output, in particular :

    Faust OSC version 0.91 application 'noise' is running on UDP ports 5510, 5511, 5512

indicating that the OSC support is active and the UDP ports used.


Cheers

Yann

Re: [LAD] simple FAUST OSC example

Kaspar Bumke — 2012-05-23T23:04:06

Thanks for the help Yann. I think that could be made clearer in the docs,
the exact message you are supposed to send for idiots like me.

Anyway, I don't seem to be getting any response from it.

I compiled noise.dsp to a jackgtk application and I am using the oscsend
and oscdump utilities provided by liblo.
I tried all of these without success:

oscsend localhost 5510 "/*" s hello
oscsend localhost 5510 "/*" s get
oscsend localhost 5510 "/a" s get
oscsend 127.0.1.1 5510 / s hello
oscsend 127.0.1.1 5510 / s get
oscsend 127.0.0.1 5510 "/a" s get
oscsend 127.0.0.1 5510 "/*" s get
oscsend 127.0.1.1 5510 "/*" s get
oscsend `hostname` 5510 "/*" s get
.
.
.

Could it be because the wildcard expansion isn't supported by liblo? Am I
supposed to do something special at compile time?

Cheers,

Kaspar
_______________________________________________
Linux-audio-dev mailing list
Linux-audio-dev-cunTk1MwBs/CEJeg2xFRV2D2FQJk+8+b< at >public.gmane.org
http://lists.linuxaudio.org/listinfo/linux-audio-dev

Re: [LAD] simple FAUST OSC example

Yann Orlarey — 2012-05-23T22:15:28

Hi Kaspar,

For hello and get you should send :
      /* s "hello"
      /* s "get"

Assuming "noise.dsp" is running, you will receive
     /noise 192.168.1.105 5510 5511 5512
and
     /noise/Volume 0.5 0 1

Sending
     /noise/Volume f 0.8
will set the volume of noise.dsp to 0.8


Cheers

Yann


  Le 23/05/2012 20:48, Kaspar Bumke a écrit :

Re: [LAD] Proposals for JACK

Paul Davis — 2012-05-23T19:24:41


note that this has been a feature of jack since day zero, and is supported
by jack1, using the same command.
_______________________________________________
Linux-audio-dev mailing list
Linux-audio-dev-cunTk1MwBs/CEJeg2xFRV2D2FQJk+8+b< at >public.gmane.org
http://lists.linuxaudio.org/listinfo/linux-audio-dev

Re: [LAD] Faust MIDI?

kaspar bumke — 2012-05-23T18:58:18

Sorry to dig up this old thread but I too would be interested in seeing a
simple example of an "architecture
file providing MIDI communication". I would be interested in creating MIDI
output especially.

Re: [LAD] simple FAUST OSC example

Kaspar Bumke — 2012-05-23T18:49:52

Sorry i meant ports 5510, 5511 and 5512 , I did get this right when
actually doing it.
_______________________________________________
Linux-audio-dev mailing list
Linux-audio-dev-cunTk1MwBs/CEJeg2xFRV2D2FQJk+8+b< at >public.gmane.org
http://lists.linuxaudio.org/listinfo/linux-audio-dev

[LAD] simple FAUST OSC example

Kaspar Bumke — 2012-05-23T18:48:34

Hi all,

I am trying to wrap my head around the OSC interface to FAUST and am trying
to get the noise.dsp from the examples to respond to OSC messages. I have
tried sending it things like "/hello" and "/1/slider1 s 'hello'" and
"/hello f 1.0" on port 5010 while listening on 5011 and 5012 to no avail. I
must be completely missing something here but what exactly am I supposed to
send when it says "a hello message" in the docs? Could someone just go
through all the simple steps of an OSC "hello world" in FAUST?

Kind Regards,

Kaspar
_______________________________________________
Linux-audio-dev mailing list
Linux-audio-dev-cunTk1MwBs/CEJeg2xFRV2D2FQJk+8+b< at >public.gmane.org
http://lists.linuxaudio.org/listinfo/linux-audio-dev

Re: [LAD] Proposals for JACK

Robin Gareus — 2012-05-23T18:09:21

[..]

jack2 features In-Server Clients: a dynamically loadable shared object
that is run inside the server. see example-clients/inprocess.c that
comes with JACK2's source. They're added with the `jack_load` command.

Adding additional audio-devices as jack-clients can be done via
zita-a2j/zita-j2a or alsa_in/alsa_out. IIRC there was some work to wrap
those into an in-server client, but I did not follow up on that
endaevour. I think it's used in context with netjack (adding a local
soundcard) and the in-server client is called 'audioadapter'.

Exposing additional cards automatically is something that jack should
IMHO not do. There are too many variables to get this right. Also tying
this feature to jackd release-cycles is IMHO something to avoid.
zita-?2? runs perfectly fine as standalone client.

As for changing backend driver settings: you can already change most of
them on the fly using `jack_control` (with jack2+dbus). Some settings
(eg. changing the sample-rate) require an engine-restart, though.

AFAIK

Re: [LAD] Proposals for JACK

Robin Gareus — 2012-05-23T16:15:23

..or new ports are available. but even if the number of ports stays the
same, the actual pinout may be different.

Currently all connections to and from the backend are lost when
switching backends. JACKd (currently) has no clue and it's the only sane
thing to do.

Here's a bash script that can re-connect or re-map connections after
switching backends. It's a bit hacky but works for me.
  http://rg42.org/blog/jack2dbus
  http://rg42.org/wiki/jack2contol


+1

Cheers!
robin

Re: [LAD] Proposals for JACK

Paul Davis — 2012-05-23T16:05:54


which is another place where port metadata comes into play.
_______________________________________________
Linux-audio-dev mailing list
Linux-audio-dev-cunTk1MwBs/CEJeg2xFRV2D2FQJk+8+b< at >public.gmane.org
http://lists.linuxaudio.org/listinfo/linux-audio-dev

Re: [LAD] Proposals for JACK

Paul Davis — 2012-05-23T16:05:29


of course, "full" support for this requires some semantics to define what
to do if after the switch some ports are missing.
_______________________________________________
Linux-audio-dev mailing list
Linux-audio-dev-cunTk1MwBs/CEJeg2xFRV2D2FQJk+8+b< at >public.gmane.org
http://lists.linuxaudio.org/listinfo/linux-audio-dev

Re: [LAD] Proposals for JACK

Paul Davis — 2012-05-23T16:04:52


had a feeling that was true but didn't want to embarass myself again by
mis-remembering. good to know (again)
_______________________________________________
Linux-audio-dev mailing list
Linux-audio-dev-cunTk1MwBs/CEJeg2xFRV2D2FQJk+8+b< at >public.gmane.org
http://lists.linuxaudio.org/listinfo/linux-audio-dev

Re: [LAD] Proposals for JACK

Robin Gareus — 2012-05-23T15:58:20

It's working just fine in jack2, already since over two years. requires
dbus though.