[PD] packOSC TimeTag realtime vs. logicaltime

Wolfgang Jäger wolfgang.jaeger at gmx.at
Thu Oct 8 11:53:44 CEST 2009


Hello,

I'm using a combination of [pack~] [packOSC] -> transmission(UDP) ->
[unpackOSC] and a modified version of [unpack~] to send Audio over OSC.
The OSC packages are sent as Bundles so a TimeTag is generated at the
sender's side. I extended the [unpackOSC] object with another outlet
where I'm getting the particular TimeTag of each Bundle.
In the modified version of [unpack~] I evaluate these TimeTags with
regards to dropouts in the transmission.
My problem is that the TimeTags are not accurate, what I ascribe to the
fact, that the TimeTag in [packOSC] is generated as "real time" instead
of "logical time". Using "real time" the TimeTag-"Output" is a function
of the audiobuffersize (depending on the cpu load), so in my case, as
the CPU-load is quite big, the values of the TimeTags are not useable
for sequencing the datastream (as there are jumps in the TimeTag I
always assume some packages got lost).
As a workaround I established a sequence number, which is additionally
transmitted in each Bundle. This is an appropiate solution, but it
wouldn't be necessary if the TimeTag would be generated properly.
Are my considerations conclusive?

Wolfgang




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