6.5.1.4 AFD
As part of the ANC Data, Active Format Description codes can also be transmitted.
These codes provide information to video devices about where in the coded picture
the active video is. The codes are defined by ETSI TS 101 154 V1.7.1 Annex B,
ATSC A/53 Part 4 and SMPTE 2016-1-2007.
Active Format Descriptor (AFD) uses three bits of video index to define the video
format. This information is encoded into user data and can then be used by a
Decoder for wide-screen switching.
6.5.1.5 Generic ANC
Up to 2 Mbps of generic data can be extracted from ANC of the incoming video and
encapsulated in accordance with SMPTE 2038 (Carriage of Ancillary Data Packets
in an MPEG-2 Transport Stream).
6.5.2 VBI Data
The extraction of VBI types can be enabled or disabled individually. The video line
from which the VBI is extracted can also be configured. The default is set according
to the relevant standard for the VBI type.
6.5.2.1 VBI Lines
Up to 8 VBI lines per field can be extracted. Unless otherwise stated, all VBI data
are formed into one VBI Transport Stream packet that conforms to ETSI EN 301 775
or SCTE 127.
6.5.2.2 VBI Data
Data can be extracted from the vertical blanking interval of the incoming video
stream, processed, and then included in the output Transport Stream. The following
table summarizes the VBI data types supported by the VCM module.
Table 6.6 VBI Data Types
Component Comments
Video Index It is possible to extract video index and another VBI type from the same line.
Closed Captions Via line 21 & 284 (CEA-608C).
Monochrome Samples Up to 3 lines can be extracted per frame.
Teletext Up to 18 lines can be extracted per field.
Aspect Ratio Signaling WSS/WSS-AFD
6.5.2.3 VBI Data on a Separate PID
The VBI data is packetized into MPEG-2 PES packets according to
ETSI ETS 300-472 for teletext and ETSI EN 301 775 or SCTE 127 for all other VBI
data types. Closed caption data and aspect ratio signaling can also be inserted into
the compressed video elementary stream.
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