Panasonic aj-mk2700 Operation Manual

AJ-MK2700 Technical Guide

The AJ-MK2700 is an optional kit for the AJ-HD2700 to enable it to record and playback
META DATA. META DATA is user defined additional data like characters or binary data
and is most commonly used for closed captioning.

The AJ-MK2700 consists of replacement L2 and L3 boards and one ROM. The New L2
and L3 boards each contain META SUB boards. The L2 board (Encoder board) is used to
compress the HD video signal and the L3 board (Decoder board) is used to expand the
compressed video data.

The AJ-HD2700 compresses the HD video signal to 1/4. This video compression method
is not compatible with META DATA and will cause loss of information. In order to avoid
this problem the META DATA bypasses the compression circuit and is processed by the
META Sub circuit. The META Sub circuit is included on both the New L2 and the New L3
board. (Their software is different.)

The video signal is recorded in the active video area of SDI (Serial Digital Interface) and
META DATA is added in the non-active video area. There are two non-active areas; they
are VANC (Vertical Ancillary) and HANC (Horizontal Ancillary) area. The META DATA is
inserted in the VANC area. HANC area is used for embedded digital audio.

V BLANKING

VANC AREA

1123
8
9

20
21

HD signal in the SDI

H BLANKING

ACTIVE VIDEO AREA

(1st Field)

560

There are 12 VANC lines from the 9th line to 20th line. The total number of HD samples
including HANC is 2200 per line, however the effective number of video samples is 1920
per line in the 1080I format.
There are 23,040 words (1920 x 12 = 23,040) in one field, but META DATA can be
recorded up to 1920 bytes, and this is 1 line of effective HD information. During
transmission, data is sent as 10 bits, so it is called a word, not a byte. The byte is used
only for 8 bit data.
META DATA is not 1 line of continuous data, but it is a packet of data. The packet data
size is variable from 0 to 255 words. 6 words of header and 1 word check sum are added
to the User Data. The minimum size is 7 words when the User data is 0 words and the
maximum size is 262 words when the User data is 255 words.
The one packet can be added on one HD VANC line. When META DATA is added, it can
be added to any VANC line between lines 9 and 20. It must be within 1920 bytes length.
The META DATA position is automatically scanned up to 1920 bytes per line.

1

ADF

Max. 255 Word

LN DC LN DID

SDID

DC UDW CS

DATA PACKET

The packet format conforms to SMPTE 291M (Ancillary Data Packet and Space
Formatting) Type 2. Components are ADF (Ancillary Data Flag), DC (Data Count), LN
(Line Number), DID (Data Identification word), SDID (Secondary Data Identification word),
UDW (User Data Words) and CS (Checksum word). ADF is used to recognize the header
of the packet. DID and SDID give the packet meaning. DC records the number of User
Data Words, to identify the length of the packet. CS is used to confirm that the packet
contains no errors.

The maximum length of the META DATA packet is 1 line of information.
The number of Chroma HD line samples in HD-D5 (4:2:2) is 960, it is just half. Therefore 1
line of HD information becomes 2 lines in the C information.

The META DATA is recorded in the AUX data area of HD-D5 format. The format has 6
lines of AUX data area in 1 field. Two lines each are used for VITC and UB, so only 2 lines
are available for META DATA.

The detected META DATA from VANC must be added on the same line. This line number
must be recorded and played back exactly. AUX areas for META DATA for the HD-D5 are
fixed. Both the Y and C area are used for recording the META DATA. The following figure
shows the HD-D5 AUX usage. The 11th line is used for META DATA recording in the 1
field. The 272nd line can be used for META DATA recording in the second field.

2

st