Visual Productions Kiosc Manual page 14

2.2.2 UDP
User Datagram Protocol (UDP) is a simple protocol for sending messages across
the network. It is supported by various media devices like video projectors and
Show Controllers. It does not incorporate error checking, making it an easy and
fast protocol.
2.2.3 TCP
Transmission Control Protocol (TCP) is a secured protocol for sending messages
across the network. It is supported by various media devices like video projectors
and Show Controllers. It creates a secured connection link between the sender
and the receiver of the message and incorporates error checking. This makes it
slower than UDP.
2.2.4 OSC vs UDP
There are many similarities between OSC and UDP. In fact, OSC uses UDP
packets under the hood.
There is one difference between these protocols that is significant when choosing
the right protocol for the job. OSC has a fixed syntax and UDP does not. Al-
though UDP's technical characteristics are specified in the protocol, the syntax
is not. This means that two UDP capable equipment from two different vendors
will be able to send each other technically correct UDP messages. What they
write into the messages is left to the discretion of the developers. As it turns
out, different developers come up with different syntaxes. Even though the two
devices say 'UDP' on the box, they might not be able to speak to each other.
This problem can be illustrated by an example. Let's assume a device from
vendor X wants to send a message to a device from vendor Y. The message
should set a parameter inside device Y to 50%. Device X could send something
like:
• parameter=50% assuming a range from 0% to 100%
• parameter=0.5 assuming a range from 0.0 to 1.0
• parameter=128 assuming a range from 0 to 255
• parameter=0x80 assuming a single hexadecimal byte
There are even more variations possible. The point being that whatever syntax
vendor X has chosen, the chance that vendor Y choose the same is not that
great.
OSC solves this problem by incorporating rules on syntax in its protocol spec-
ification. Each OSC compatible device uses exactly the same syntax. This is
a strong reason to prefer OSC over UDP when possible. Of course, there are
many devices out there that do not support OSC, leaving UDP an important
asset inside your protocol toolbox.
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