OSC Query Systems & Binary Protocol

[Christopher Graham]

I'm developing a family of modular electronic wind instruments that will use
OSC as their external interface to other applications.  You can see more
details at www.multiwind.com.

The plan is that the instruments are mainly rich sources of control data.
Higher level interpretation of the control gestures into music control
signals (in OSC or MIDI) is done on a host computer.  The hardware is
modular and highly configurable and it is desirable that the host computer
software be able to query what modules are present, i.e. what the overall
namespace of the instrument currenly is.  It will also be desirable for host
computer sofware to be able to configure the instrument using OSC commands
regarding what sensors to sample, sampling rate, prescaling, hysteresis to
apply, etc., and where to send the data.

Therefore I need a query interface, and preferably I would use one that is
compatible with what others are doing.

The closest proposal I have seen to what I need is the one by Martin Habets
which is available at http://liboscqs.sourceforge.net/ . This describes a
way to inquire of an OSC client the details of its namespace, and to ask it
to send specific data items to specific data consumers.  I would add to the
the ability to set the sampling rate for a given sensor, transformations to
apply, etc.

I see from the list archives that there was some controversy about whether
this, or any dynamic patching systems was desirable, but I definitely need
something like this and I expect that others do also.

Martin, if you see this post, could you explain more details about the
"category" field is in your patching system?  It's not clear to me how this,
an integer, specifies what item in the namespace is supposed to be sent to
the requested destination.

More generally, what is the current state of the art in query systems and
patching?  I saw in another post that the Lemur group was developing a query
system.  What is this?  Any others?

I'm also developing a compact binary version semantically equivalent to the
essential elements of OSC, but suitable for lower bandwidth connections.
For example the expansion bus in my instruments uses the SPI protocol with a
maximum shared rate of about 1Mbps.  Also, my devices use USB with a USB 1.1
equivalent data rate to link to the host, and I want to be efficient of
bandwidth on that link.  My binary protocol which will arrive at the host on
USB HID (for tighter timing than USB bulk) will be translated into normal
OSC by my USB driver, so it will not necessarily be seen to the outside
world, but my lower level solutions may be of interest to others.  I will
open source the host software for this project so others can use it.

I will be at NIME next week, so if anyone is interested in discussing these
things, please let me know.

- Chris Graham

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