ADV7180
•
AV Code Insertion.
At this point, the demodulated chroma (Cr and Cb) signal
is merged with the retrieved luma values. AV codes can be
inserted (as per ITU-R BT.656).
GENERAL SETUP
Video Standard Selection
The VID_SEL[3:0] register allows the user to force the digital
core into a specific video standard. Under normal circumstances,
this is not necessary. The VID_SEL[3:0] bits default to an auto-
detection mode that supports PAL, NTSC, SECAM, and variants
thereof. The following section provides more information on
the autodetection system.
SYNC PROCESSING
The ADV7180 extracts syncs embedded in the analog input
video signal. There is currently no support for external HS/VS
inputs. The sync extraction is optimized to support imperfect
video sources, such as videocassette recorders with head
switches. The actual algorithm used employs a coarse detection
based on a threshold crossing, followed by a more detailed
detection using an adaptive interpolation algorithm. The raw
sync information is sent to a line-length measurement and
prediction block. The output of this is then used to drive the
digital resampling section to ensure that the ADV7180 outputs
720 active pixels per line.
The sync processing on the ADV7180 also includes the
following specialized postprocessing blocks that filter and
condition the raw sync information retrieved from the digitized
analog video:
•
VSYNC Processor.
This block provides extra filtering of the detected VSYNCs
to improve vertical lock.
HSYNC Processor.
The HSYNC processor is designed to filter incoming
HSYNCs that have been corrupted by noise, providing
much improved performance for video signals with a
stable time base but poor SNR.
Autodetection of SD Modes
To guide the autodetect system of the ADV7180, individual
enable bits are provided for each of the supported video standards.
Setting the relevant bit to 0 inhibits the standard from being
detected automatically. Instead, the system picks the closest of
the remaining enabled standards. The results of the autodetection
block can be read back via the status registers. See the Global
VID_SEL[3:0], Address 0x00 [7:4]
Table 20. VID_SEL Function
VID_SEL[3:0]
0000 (default)
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
Description
Autodetect (PAL B/G/H/I/D) <–> NTSC J
(no pedestal), SECAM
Autodetect (PAL B/G/H/I/D) <–> NTSC M
(pedestal), SECAM
Autodetect (PAL N) (pedestal) <–> NTSC J
(no pedestal), SECAM
Autodetect (PAL N) (pedestal) <–> NTSC M
(pedestal), SECAM
NTSC J (1)
NTSC M (1)
PAL 60
NTSC 4.43 (1)
PAL B/G/H/I/D
PAL N = PAL B/G/H/I/D (with pedestal)
PAL M (without pedestal)
PAL M
PAL Combination N
PAL Combination N (with pedestal)
SECAM
SECAM (with pedestal)
•
VBI DATA RECOVERY
The ADV7180 can retrieve the following information from the
input video:
•
•
•
•
•
•
•
•
Wide-screen signaling (WSS)
Copy generation management system (CGMS)
Closed captioning (CCAP)
Macrovision protection presence
EDTV data
Gemstar-compatible data slicing
Teletext
VITC/VPS
AD_SEC525_EN, Enable Autodetection of SECAM 525
Line Video, Address 0x07 [7]
Setting AD_SEC525_EN to 0 (default) disables the
autodetection of a 525-line system with a SECAM-style, FM-
modulated color component.
Setting AD_SEC525_EN to 1 enables the detection of a
SECAM-style, FM-modulated color component.
The ADV7180 is also capable of automatically detecting the
incoming video standard with respect to
•
•
•
Color subcarrier frequency
Field rate
Line rate
The ADV7180 can configure itself to support PAL B/G/H/I/D,
PAL M/N, PAL Combination N, NTSC M, NTSC J, SECAM
50 Hz/60 Hz, NTSC 4.43, and PAL 60.
Rev. A | Page 23 of 112
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