[PD] Floats and negative numbers over OSC

IOhannes m zmoelnig zmoelnig at iem.at
Mon Feb 1 11:36:18 CET 2010

Georg Werner wrote:
> Hi,
> i tried your patch on winxp just with udpsend and had the same problems:
> error: udpsend_send: item 0 (-1.000000) is not between 0 and 255
> error: udpsend_send: item 0 (1.100000) is not an integer
> so maybe the problem is not OSC but UDP? as it seems to handle only
> single bytes.
> So my question how to send a -1.1 over UDP?
> g.

haven't looked at the patch, but there are two possible reasons for this:
- somebody (the patch?) is injecting non-byte-values into the data to
udpsend. udpsend takes a list of bytes, not a Pd message. this means:
you cannot just send the message "/test -1" to udpsend, you need an
object inbetween that translates the message "/test -1" into a binary
format. [packOSC] is one such object which will translate the given
message into a list of bytes "47 116 101 115 116 0 0 0 44 105 0 0 255
255 255 255" (all atoms are floats and the values are integer and
between [0, 255]).
 [udpsend] is NOT a drop-in replacement for [netsend 1]!

- very old(!) versions of [udpsend] (or was it [udpreceive]?) had a
problem with signed/unsignedness, resulting in "255" (binary 11111111 in
unsigned)  being interpreted as "-1" (binary 11111111 in signed). if
this is the case, you have to upgrade udpsend/receive (e.g. install a
newer stable release of Pd-extended)

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