User guide

ProMPEG FEC Support for IP Streaming
G.1 Introduction
The ProMPEG Forward Error Correction (FEC) scheme is designed to recover lost
or corrupted packets caused when transferring MPEG-2 transport streams, or newer
MPEG standards encapsulated as an MPEG-2 transport streams, over an IP
network.
The MX8400 supports ProMPEG FEC to the ProMPEG Code of Practice #3 release
2 standard on both input and output ports of the ProMPEG FEC option card.
FEC packets are generated for every column and optionally for every row. To
generate the FEC packets, RTP frames based on their sequence numbers are
arranged in a rectangle of dimensions D * L. The payload of the FEC packet
generated is the exclusive-OR of all RTP frames in the row/column it protects.
Figure G.1 shows the arrangement of the RTP frames and the FEC packets that
protect them.
1 165432
7 712111098
13 131817161514
19 192423222120
25 253029282726
1 65432
CoLumns (L)
Rows (D)
Figure G.1 Columns and Rows
G.2 Configuration of ProMPEG FEC Inputs
If a transport stream is protected using ProMPEG FEC, and arrives at the input of
the MX8400 ProMPEG FEC card, then the FEC streams and their parameters are
automatically detected. Hence configuration of ProMPEG FEC inputs is not
required.
2/1553-FGC 101 1014 Uen B
G-3