[PD] multiple OSC messages in one udp packet?

matteo sisti sette matteosistisette at gmail.com
Thu May 12 16:33:59 CEST 2011

2011/5/10 matteo sisti sette <matteosistisette at gmail.com>:
> Hi,
> Does the OSC standard (or to be more precise, the standard for OSC
> over UDP) allow to pack multiple OSC messages into a single UDP
> packet?
> If so, is there any chance that [packosc] and/or [udpsend] do so
> "behind the scene" (i.e. without explicitly asking them to do so) when
> you send them many messages in 0 or little logical time?

Ok that is definitely _not_ happening (whether it is possible or not).
Nor is packOSC unexpectedly bundling messages into bundles: it only
does it if you explicitely ask it, as expected.

> I ask this because I am sending OSC messages from Pd to TouchOSC (on
> an iPad) and when I send it multiple messages in 0 logical time (even
> just 3 or 4 messages at a time, not dozens), TouchOSC almost
> systematically loses many of them.

That's simply and plainly what is happening: either TouchOSC or the
iPad itself are dropping UDP packets if they are received too close to
one another.

On 10/05/11 10:38, matteo sisti sette wrote:
> Have you tried explicitly packing them into OSC bundles?
> it might fix the issue as a side effect.

Thanks a lot for the suggestion. It does fix the issue!!!!! :):):)

I hadn't tried at first because I thought that even if it worked it
was not an option, as I cannot know in advance how many messages are
to be sent. But then I realised I could buffer the messages and send a
bundle every XX milliseconds.

With this trick I have drastically reduced (almost eliminated) the
occurrence of packet losses. To remove the issue completely I have
created a memory of all the target osc addresses and I periodically
re-send (always in big bundles) the last values that have been sent -
which is feasible in my case because the messages I'm sending out
represent states and not events.

Does anybody of you perhaps know a (free) generic UDP monitoring
application for the iPad, so that I could figure out whether the
packets are being dropped by TouchOSC or by the iPad?


More information about the Pd-list mailing list