Technical Specifications
Closed Captioning
Makito
X User’s Guide, v2.2, Issue 02
405
NOTE
The extracted CC information from Line 21 is embedded in the MPEG stream as
per ATSC A/72 Part 1:2008 (ATSC A/53 Part 4:2007).
Unicast and Multicast streams all carry the same CC data.
The Makito
X
encoder
supports
the
capture
of
EIA-608
and
EIA-708
closed
captions
from
the video input at the HD/SD SDI interface and encodes it in the Makito
X
Transport
Stream using the encapsulation format specified in ATSC A/72.
The Makito
X encoder supports the capture of EIA-608 and EIA-708 captions encapsulated
in a Caption Description Packet (CDP), as described in SMPTE-334-2, within the VANC
as mentioned in SMPTE 334-1. The Caption information is multiplex and transported as
per ATSC A/72 in a CC SEI NAL. The caption services stored in the Caption Service
Descriptor (CSD) are announced in the Program Map table (PMT) of the MPEG-2 TS as
per ATSC A/65.
NOTE
The Makito
X only supports a maximum of three (3) Caption active services at a
time plus CC1-4 Text1-4 and XDS.
SMPTE 334-2 defines a Caption Distribution Packet (CDP) consisting of a sequence of
bytes that can hold: the CEA-708 DTV caption data, CEA-608 caption data, caption
service information, and SMPTE 12M-1 time code. CDP also includes the Caption Service
Descriptor (CSD). As defined in ATSC A/65.
With the support of EIA-708, ATSC A/72 mandates a dedicated link bitrate of 9600
bits/sec. (1200 bytes/sec or 20 bytes per frame for a p60 SDI signal). Of the 9600 bits/sec,
960 bits/sec are reserved for EIA-608 captions. 8640 bits/s are dedicated to 708-CC. This
is a dedicated channel, so it has to be filled with filler data if no captioning information is
present.
Supported resolutions include 1080p, 720p, 1080i, 480i, and 576i.
