Omnia .9 Installation & User Manual page 185

SYSTEM MENU CHAPTER 23 |
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If there are audible glitches, the workaround is to disable the Allow Livestream button, which will cause Omnia.9 MKII to send
1ms AES67 Low Latency packets in response. This solves one problem, but creates another: While AXIA gear uses just 0.75ms
(three quarters of a millisecond) buffer when receiving a livestream, the default receive buffer for all other types of streams
(standard streams, AES67 low latency streams) is 100 milliseconds. This will of course add far too much delay for the feed to
be useful, so we must reduce the buffer size in the receiving unit down to 3 milliseconds. Not all AXIA gear will not let you do
this per channel (understandable since they all pre-date Omnia.9 MKII), but the xNode will, through LWRP.
Example
telnet to port 93 of your xNode
LOGIN <password>
DST 1 BUFF:3
This sets the playback latency (receive buffer) on destination 1 to 3 milliseconds. The setting is persistent.
This should result in a total Microphone to Headphone delay of about 10 milliseconds, which is well within acceptability for
most talent.
Some General Notes
MPX Outputs, and MPX Inputs may be turned around and transmitted as Livewire channels, but note that they would need to
be received by some other MPX receiver, for example another Omnia 9, or a Livewire MPX compliant transmitter, of which
none yet exist at the time of this writing. It's a chicken-and-egg problem – one of them has to come first, and in this case we
were.
You will note the existence of the Download AES67 SDP buttons (on the outputs) and Upload AES67 SDP (on the inputs).
SDP stands for session description protocol and gives you a "portable" file that can be used for configuration. For example, you
might have an AES67 audio stream to receive in to your Omnia.9. The AES67 compliant unit generating that source stream will
have a way to download an SDP file, which you can then upload to your Omnia.9, and it would describe that stream to the O9 in
sufficient detail that it could receive the stream.
An SDP file is a carefully formatted plain text file and looks for example like this for a normal audio stream:
v=0
o=- 0 1 IN IP4 192.168.2.49
s=Omnia9FM @ OMNIA9-1759
i=FM Pre-final L/R
c=IN IP4 239.192.19.37/127
t=0 0
a=type:multicast
m=audio 5004 RTP/AVP 96
a=rtpmap:96 L24/48000/2
a=ptime:1
a=mediaclk:direct=0
a=sync-time:0