[OSC_dev] OSC Questions regarding Protocol

[Andy W. Schmeder]

On Jan 21, 2008, at 1:56 PM, Angelo Fraietta wrote:

>> This technique works of course but now we recommend slip encoding  
>> for stream oriented protocols. This arose from more experience as  
>> OSC was implemented on cheap microcontrollers and slower point to  
>> point transports such as USB. Since slip works just as well over a  
>> reliable TCP link why have two recommended encodings?
>>
> In the paper I have, the assumption was that the transport layer would
> delivered a whole packet.

We are using SLIP (RFC 1055) to delineate packet boundaries on a  
serial line.  Double-ENDed SLIP is also a good idea as it slightly  
more robust.

See also the Make Controller Kit by Making Things which uses this on  
its USB-serial connection.

Serial transport in conjunction with OSC bundles is advantageous for  
small-memory microcontrollers as the packet size can easily exceed  
the available memory.


>> I actually disagree on efficiency of OSC and I will be addressing  
>> it in
> the paper. As an end to end protocol, I do not believe that it will be
> able to cut it. However, I think that it makes an excellent API and  
> will
> be suggesting that also.

OSC avoids the end-to-end principle by design.

For efficiency discussions also note that OSC generally assumes a 32- 
bit architecture, thus the 4-byte alignment saves instruction cycles  
and costs no additional memory.  This isn't explained explicitly in  
the specification but is the reasoning behind that decision.


---

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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