[OSC_dev] OSC Query Systems & Binary Protocol

[Andy W. Schmeder]

USB interrupt transfer mode (e.g. HID) is given higher priority over  
bulk, but it isn't guaranteed bandwidth nor latency -- it also has a  
very small bandwidth allocation in USB 1.1 / Full-speed.  I would  
benchmark the latency of USB Bulk transport before discounting it as  
a possibility, since, as long as the bus isn't saturated, there  
shouldn't be any delay.

Ultimately, isochronous transfers are ideal and meet the requirements  
for transport outlined in the OSC spec.

...

OSC is already a binary format but assumes by design that the  
protocol is not significantly bandwidth-constrained.  I'm not certain  
that a version of "compact OSC" would have broad applicability.

For non-packetized transports (e.g. serial, TCP, etc) we recommend  
SLIP-encoding -- this is both microcontroller-friendly and already  
incorporated into commercial products (The Make Controller).

...

As for query systems, Matt Wright and I presented a paper on this at  
the OSC Conference 2004, which I have put online here: http:// 
a2hd.com/query-system-open-sound-control

The query system described above is also partially implemented in  
Open Sound World, http://osw.sourceforge.net

However, my current line of reasoning is that putting the query  
system into OSC is technically flawed for a number of reasons (e.g.  
violates the state-machine-free requirement and also needs assured  
delivery), and furthermore is a redundant effort because query  
systems have already been defined in more appropriate meta-languages  
and are already sufficiently expressive for our requirements (e.g.  
web services).  At some near-future point we are planning to publish  
general recommendation on how to leverage these protocols in  
conjuction with OSC.



Best
Andy.


---

Andy W. Schmeder
andy [at] cnmat.berkeley.edu
phone:	+1-510-643-9990 x.313

Programmer/Analyst II
Center for New Music and Audio Technologies
University of California at Berkeley
http://cnmat.berkeley.edu




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