Ericsson SVP 2000, Справочное руководство, Страница: 18 / 196

Introduction
The amount of data that can be transferred across a network may change because
the bandwidth changes over time. However, because the Decoder is continuously
monitoring the amount of data it can receive through the network, the encoded bit
rate is managed (using profiles) such that there will be video delivered through the
network. The transport stream is rebuilt from the file segments created using the
appropriate video profiles.
1.3.3 SVP 2000 Video Processor Operating Modes
There are two modes of operation for the SVP 2000:

Dynamic Adaptive Streaming over HTTP (MPEG-DASH
1
)
This uses the MPEG-DASH format whereby the incoming video is encoded into
multiple bit rates files (profiles) of small playout times (generally two seconds).
Each of these files is then presented as available to the decoder. The decoder,
depending upon the available bandwidth, selects the appropriate size file that it
can extract from the encoder so that it can then be recreated into video without
any gaps. As the video bit rate is adapted for the available network, this
methodology is generally referred to as Adaptive Bit Rate (ABR). This is
probably the most common method that will be used for unmanaged networks.

Real-time Transfer Protocol (RTP) / User Datagram Protocol (UDP) unicast or
multicast.
Over an IP network, there are a number of protocols that can be run. The ABR
method uses the TCP protocol whereby an acknowledgement is provided for
every delivered packet. For the RTP/UDP method, a packet is transmitted and
assumed that it will be delivered i.e. there is no guarantee of delivery. Although
this may appear to be not a secure transmission method, it is the method that is
best suited for video delivery. As there is no acknowledgement for packet
receipt, there is the option of FEC (Forward Error Correction) to ensure that if
there is any corruption in the data packet then FEC can be used to recover the
video.
The availability of the RTP-TS mode is governed by the license on the unit.
Caution!
Both the Encoder and Decoder need to operate in the same mode.
1
Also known as DASH
EN/LZT 790 0046/1 R1A 1-10