Technical Specifications
Closed Captioning
Makito
X User’s Guide, v2.2, Issue 02
404
Closed Captioning
The Makito
X
supports
capture,
multiplexing
and
transport
of
Closed
Captioning
(CC)
and
other Line 21 information over Composite (with no 7.5 IRE setup on Line 21), as well as
HD/SD SDI input interfaces.
Closed Captioning data, as defined by the EIA-608-B standard, includes the following
services over Line 21 Fields 1 and 2 of an NTSC analog video signal: CC1, CC2, CC3,
CC4, Text1, Text2, Text3, Text4, and XDS (see
below). The Makito
X
encoder
supports transport of all these services. [Note that Closed Captioning as specified by EIA-
608-B does not exist over PAL.]
Figure B-1
EIA-608-B Line 21 Services
Line 21 of each field can contain up to 2 bytes of information, which can be used by any of
the above services (not simultaneously but rather successively). With NTSC video at 30fps,
the maximum EIA-608-B mandated throughput represents:
2 bytes x 2 Fields x 30fps x 8 bit/byte = 960 bps
The block diagram below shows the workflow for video and CC data into the encoder.
Closed Caption 1
Text 1
Field 2
Field 1
Closed Caption 2
Text 2
Closed Caption 3
Text 3
Closed Caption 4
Text 4
XDS
Video+CC
Video
Encoder
Processor
Closed
Caption
Transport
Stream Mux
IP
Encapsulator
De-Embedder
MPEG TS
over IP