evertz 570EMR-AG-HUB, User Manual

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570EMR-AG-HUB
User Manual
Revision 0.1
Page - 23
6. APPENDIX
Real-Time Transport Protocol (RTP): The use of RTP is recommended as it provides services such
as time stamping, sequence numbering and delivery monitoring which can be beneficial for real-time
delivery systems.
Time To Live (TTL): TTL is a mechanism that limits the life span of data in a network. Using the
Multicast IP protocol, the TTL value indicates the scope or range in which a packet may be forwarded.
By convention:
0 is restricted to the same host
1 is restricted to the same subnet
32 is restricted to the same site
64 is restricted to the same region
128 is restricted to the same continent
255 is unrestricted
Type of Service (ToS): The ToS field could specify a datagram's priority and request a route for low-
delay, high-throughput, or highly-reliable service. Based on these ToS values, a packet would be
placed in a prioritized outgoing queue or take a route with appropriate latency, throughput, or reliability.
If the network doesn’t support ToS, use zero as default.
Program Clock Reference (PCR):
Synchronization of the Receiver System Time Clock (STC) with the
Transmitter STC depends on transmitting PCRs through a constant-delay portion of the system. Thus, PCRs are
inserted following the encoder buffer and extracted before the receiver buffer. PCRs are inserted with a maximum
interval of 100ms.
Packet Time (AES67):
Packet time is the real-time duration of the media data contained in a media packet.
Given the sampling rate and packet time, the number of samples per packet can be calculated. Short packet
times allow for lower latency but introduce overhead and high packet rates that may overtax some devices or
networks. Long packet times imply higher latency and require additional buffering which may not be available on
memory-constrained devices.
Packet time is determined by the sender and negotiated through connection management. Senders shall not
change packet time for the duration of a session. Receivers may assume that packet time does not change for the
duration of a session. To enable interoperation with standard RTP implementations, receivers should not rely on
the presence or accuracy of any packet time description. Receivers should be able to determine packet time
based on the timestamps in received packets.