V1.1-OCTOBER 2019
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OMNIA MPX NODE MANUAL
Because packet loss typically occurs in bursts, the Error Correction Overhead value is
far more important for successfully recovering lost packets than Error Correction Size/
Delay.
With the same Overhead setting, you can change the Size setting to trade-off between
higher streaming bitrate overheads or higher decoder latencies. Using Size=64,
Overhead=8 gives you the same amount of overhead as Size=32, Overhead=4, but will
handle bursts of up to 8 dropped packets instead of 4. This comes at the cost of a higher
required latency. Size=32, Overhead=8 gives you a similar recovery but the overhead is
twice as big because the blocks are sent twice as often. Latency requirements are lower
for a smaller block size.
Rate Limiter (On/O)
Enables or disables rate limiting for the error correction packets. This setting can assist
with bandwidth management when utilizing error correction. While it will not prevent
you from exceeding available bandwidth, (μMPX has no way of knowing what your
connection can provide) it will allow you to “fine tune” the amount of bandwidth used
for error correction.
Turning the Rate Limiter off completely can actually cause dropouts if recovery packets
are flooding the network, especially when Error Correction Overhead is set to a high
value. The network may then decide to just throw away some of the packets. If you turn
error correction rate/overhead on, it is recommended you leave this control enabled.
Limit Rate Below
This control manages the bandwidth use (including error correction) limiting below
the specified value. This value will change dynamically depending on the error correc-
tion span and overhead settings, so use this setting to predict approximately how much
bandwidth your μMPX stream will ultimately consume when applying error correction.
Recovery packets are generated in burst after a block (Size) is finished. The rate limiter
offers all the packets to the network in a controlled fashion, to avoid overloading it. If
this value is set higher than what the network allows, the network can get overloaded
and may then start to randomly drop packets. In extreme cases, the rate limiter throws
away recovery packets to make sure that at least all the normal packets can get through.
The network itself cannot distinguish between normal packets and error correction
packets; in extreme cases it could throw away so many packets that it could actually
cause dropouts.
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