Block Aligned linearisation is dealt with in Annex B of the Pro-MPEG Code of Practice. In Block Aligned column FEC packets are sent
every D’th frame and the L Column FEC packets are played out every D slots. They are therefore evenly spread over the D*L matrix
period.
Non Block Aligned linearisation is dealt with in Annex A of the Pro-MPEG Code of Practice. In Non Block Aligned the matrix is
‘skewed’ for the column calculation. The L column FEC packets are played out at the end of every column plus a constant. For
‘square’ matrices (diamonds) where L=D then these column packets will emerge at regular intervals. For ‘rectangular’ diamonds
they will not. In the case of a 4 column by 20 row matrix the 4 FEC packets will emerge within 16 slots, followed by a gap of 64
slots before the next 4. It therefore produces a less linear spread of packets.
Receivers which do not have FEC capability can simply ignore the FEC packets and just make use of the media packets.
Transport Stream
Gives information relating to the components of the transport stream.
Services
This topic gives an overview of how the Service Information is formed and the Service Information Tables (MPEG-2 SI) available
from the VCMs. General information about repetition rates for SI packets is also given.
Coded Elementary Stream
Supported Profiles and the Output Bit Rate are given. Describes the use of PCR Placeholders.
Audio Output
Gives information on Encoding and associated delay and lip sync.
Describes the use of PCR Placeholders in audio packets.
Transport Packets
General information on packetised elementary stream (PES) Packets. Also some specific information relating to video Streams. Talks
about PIDs used in Transport Packet Headers.
VBI Data on a Separate PID
States the conditions for VBI on a separate PID.
PID Assignment
Describes the assignment of PID values.
Services
Overview
The system is capable of forming up to six services divided between the output transport streams.
Each service can contain a maximum of 16 elementary streams. The elementary streams that make up a service can be selected
from the elementary streams available from the option cards. The only restriction is that the elementary streams in a service must
all reference the same
27 MHz clock
.
An elementary stream can be included in up to eight services, but the
PID
of the elementary stream must be the same in all
services. Only one video elementary stream can be assigned to a service, and the audio delay of audio services should be matched
© Ericsson AB 2011. All rights reserved
© Ericsson AB 2011. All rights reserved
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