Power Core User ManualVersion: 6.6.0/386/539
9. Audio IO
9.3.8 Make-Before-Break
This feature minimizes the audio interruption when a stream changeover occurs on a receiver. If make-before-
break is enabled, the receipt of the new stream is prepared before the original stream is disabled. Thus, the
audio interruption at the receiver is minimized.
The Rx Make-before-Break Enable option can be turned on or off in the "System -> Definition -> Parameter =
Stream Settings" (described later). A prerequisite is that there must be free receivers available (i.e. there must
be fewer than 128 stream receivers in use).
Once the configuration has been transferred to the system, you can use the Web UI RAVENNA -> Outputs page
to check the scheduled stream name before the changeover occurs.
9.3.9 Configuring Redundant Streaming
Power Core supports two redundancy mechanisms: Hitless Merge (SMTPE ST2022-7) and LACP (Link
Aggregation Control Protocol).
Hitless Merge / Seamless Protection Switching (SMPTE ST2022-7)
Hitless Merge or Seamless Protection Switching (SPS) is a method of redundancy which employs two different
networks (i.e. routes) to transport data. If one "route" fails, then the other can be used to recover the missing
data.
The standard is defined by SMPTE ST2022-7.
SPS has been implemented into the Power Core configuration and the goal has been to make this as simple as
possible. SPS adds stream redundancy on the physical level in that two streams carrying the same data are
transmitted independently on the two RAVENNA NIC’s. The degree of redundancy can be up to the level of two
physically independent networks with their own PTP down to simply two ethernet cables plugging into the same
switch. Each stream is given its own multicast address and even though transmitted via different paths this
information is captured in the SDP that accompanies both streams. The receiver or subscriber thus knows of the
existence of the other stream and internally rebuilds any missing data.
To create a Hitless Merge enabled stream, set the Devices field to ra0+ra1 in the RAVENNA Output branch of
the 'Tree Definition':
These are referenced in several of the Web UI pages relating to RAVENNA and are typically called Device ID’s.
The Statistics pages refers to the devices as Primary and Secondary.
LACP (Link Aggregation Control Protocol)
LACP is a networking protocol supported by some network switches and routers.
It can provide redundancy by "bonding" or “teaming” physical ports together to form a single logical channel.
Enabling LACP not only provides redundancy but can also increase throughput, although the usage here is the
former. A single IP address is configured and LACP enabled via the Web UI System -> Network Devices page.
Note that the connecting network infrastructure needs to support LACP for this to function properly.
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