Albretch Mueller writes:

> Hi,
> ~
> I need to stream/convert bytes of data from a file or connection
> oriented TC Protocol to connectionless UDP using Linux
> ~
> I would like to be able to do something like going:
> ~
> cat filename > /dev/udpdrvr
> ~
> I was wondering if there exist such a utility in Linux?

Yes. I think netcat (nc) can do this, and I have used ttcp as well.

But do you realize that because UDP is unreliable, the OS may not even
TRANSMIT outgoing packets?

Also - the jitter may be unpredictable.

Albretch Mueller wrote:
> I need to stream/convert bytes of data from a file or connection
> oriented TC Protocol to connectionless UDP using Linux

Try netcat (nc)

> I would like to be able to do something like going:
> cat filename > /dev/udpdrvr

That wouldn't make sense as it doesn't specify the destination host
or port.

Chris

Chris Davies wrote:
>> I would like to be able to do something like going:
>> cat filename > /dev/udpdrvr
>
> That wouldn't make sense as it doesn't specify the destination host
> or port.
~
the destination host and port would be defined in a configuration file
~
lbrtchx

Maxwell Lol wrote:
> But do you realize that because UDP is unreliable, the OS may not even
> TRANSMIT outgoing packets?
~
I just need the packets within the network segment
~
> Also - the jitter may be unpredictable.
~
Is there a way to avoid it?
~
lbrtchx

Albretch Mueller writes:

> Maxwell Lol wrote:
>> But do you realize that because UDP is unreliable, the OS may not even
>> TRANSMIT outgoing packets?
> ~
> I just need the packets within the network segment

Not all will be transmitted. ONe thing that helps is to allocate extra
buffer memory for the UDP socket.

>> Also - the jitter may be unpredictable.
> ~
> Is there a way to avoid it?

There are two things that can help.

1) Use real time mode. Lock the process into memory and give it
highest priority. Don't let another process swap it out.

2) For video, the program would need to try to generate data in
a consistent manner. Having a set delay between packets would
help, but it's not a trivial programming issue. Everry time you
transmit, the delta between the derised delay and the actual
delay changes. So I have to correct the skew after
each packet.

I wrote a program that tested the quality of a MPEG decoder years ago.
I'm not sure what your application needs. I'm just trying to point out
some pitfalls I hit.

Albretch Mueller writes:

>>> I would like to be able to do something like going:
>>> cat filename > /dev/udpdrvr
>>
>> That wouldn't make sense as it doesn't specify the destination host
>> or port.
> ~
> the destination host and port would be defined in a configuration file

That's what netcat can do

NC(1) NC(1)

NAME
nc - TCP/IP swiss army knife

SYNOPSIS
nc [-options] hostname port[s] [ports] ...
nc -l -p port [-options] [hostname] [port]

-u is UDP mode. so the sender would send to port 12345 using:

nc -u remotehost 12345