Information Technology Reference
In-Depth Information
MPEG
encoder
engine
Eliminator
System
packet
inserter
HDSDI
input (1)
External queue
Mux
TS output (1)
Internal queue
Host
processor
Cascade switch (1)
Encoder #1
MPEG
encoder
engine
Eliminator
System
packet
inserter
HDSDI
input (2)
External queue
Mux
TS output (2)
Internal queue
Host
processor
Cascade switch (2)
Encoder #2
MPEG
encoder
engine
Eliminator
System
packet
inserter
HDSDI
input (3)
External queue
Mux
TS output (3)
Internal queue
Host
processor
Cascade switch (3)
Encoder #3
MPEG
encoder
engine
Eliminator
System
packet
inserter
HDSDI
input (4)
External queue
Mux
TS output (4)
Internal queue
Host
processor
Cascade switch (4)
Encoder #4
Serial cable
100 Base-TX
Fig. 6
Switchable cascade multiplexing in multiplexing mode
generated in the i-th encoder itself and the external one stores the packets transferred
from the (i-1)th encoder through a high-speed serial cable. The packets in these two
queues are mixed at the multiplexing circuit and the system packet inserter adds
various system layer packets such as the Program Association Table(PAT), Program
Map Table(PMT), Program Clock Reference(PCR), and NULL. The eliminator,
which is located at the front of the external queue rejects unnecessary system-layer
packets and outputs only video and audio packets to the external queue. Packets
from the i-th and (i-1)th encoder's packets are the output of the i-th encoder. The
cascade multiplexing function of each encoder is switchable to adapt to many types
of SHR images, as shown in Fig. 1. Output of the i-th encoder is the packets from
i-th and (i-1)th encoder's packets. Table 1. The left of this table shows the relation-
ship between all encoder inputs and the sub-image of the SHR video to be encoded.
The center indicates the cascade multiplexing switch settings of all encoders and
the right lists the SHR streams of all encoder outputs. We can see that the 6Kx1K
stream is output to encoder #3 and the HD stream is output to encoder #4 when all
multiplexing switches except the 3rd encoder's are turned on. The 4Kx2K stream is
output to encoder #4 when the multiplexing switches of all encoders turn on. This
means many SHR video sizes and many combinations of SHR video programs can
be handled using this switchable cascade multiplexing. Also, every stream can be
recorded and easily played back using a conventional PC with a DVB-ASI interface
card because the stream of each encoder's output is a single TS consisting of several
ESs.
There is a block diagram of SHR live transmission for two different sites and
local playback using the switchable cascade multiplexing function in Fig. 7. By
