[PD] bi-directional OSC over TCP from liblo

Martin Peach martin.peach at sympatico.ca
Sat Nov 10 18:10:00 CET 2012

On 2012-11-10 05:24, Roman Haefeli wrote:
> On Fre, 2012-11-09 at 17:19 +0100, IOhannes m zmölnig wrote:
>> On 11/09/2012 02:51 PM, Jamie Bullock wrote:
>>> So, it seems like [packOSCstream] and [unpackOSCstream] are (un)packing message in a format that can't be used with external clients/servers. Is that correct?
>> from your experience with liblo, you seem to conclude that:
>> a) all "external clients/servers" are build on top of liblo.
>> b) liblo handles OSC over TCP/IP correctly
>> c) [(un)packOSCstream] handles it wrongly.
>> anyhow:
>> originally OSC did not define how to transmit OSC-packets over a
>> stream-based protocol like TCP/IP (that has no notion of ending packets).
>> implementations that wanted to transmit OSC over stream-based protocols
>> had to find solutions for themselves.
>> a few years ago, the OSC specs have been extended, to explicitely
>> mention "SLIP" encoding as the means to packetize streams of OSC-data.
> This was added to OSC 1.1, iirc.
> OSC 1.0 proposed to prepend to each OSC packet a 4 byte header that
> contains the byte count of following OSC packet. Old versions of
> [packOSCstream]/[unpackOSCstream] implemented this proposal.

The latest version of liblo does exactly this. See liblo-0.26/src/send.c 
at line 411. It actually sends a packet containing only the length of 
the OSC message that is sent next.


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