Datasheet

Table Of Contents
ADV7188
Rev. A | Page 44 of 112
Refer to the
BL_C_VBI, Blank Chroma During VBI,
Address 0x04 [2]
section for information on the chroma path.
In a 16-/20-bit output interface where Y and Cr/Cb are delivered
via separate data buses, the AV code is over the whole 16/20 bits.
The SD_DUP_AV bit allows the user to replicate the AV codes
on both buses; therefore, the full AV sequence can be found on
the Y data bus and on the Cr/Cb data bus (see
Figure 25).
0 (default)—All video lines are filtered and scaled.
1—Only the active video region is filtered and scaled.
0 (default)—The AV codes are in single fashion (to suit 8-/10-bit
interleaved data output).
BL_C_VBI, Blank Chroma During VBI, Address 0x04 [2]
Setting BL_C_VBI high, blanks the Cr and Cb values of all
VBI lines. This is done to prevent data that arrives during VBI
from being decoded as color and output through Cr and Cb. As
a result, it is possible to send VBI lines into the decoder, and
then output them undistorted through an encoder. Without this
blanking, any incorrectly decoded color would be encoded by
the video encoder and therefore the VBI lines would be distorted.
1—The AV codes are duplicated (for 16-/20-bit interfaces).
VBI_EN, Vertical Blanking Interval Data Enable,
Address 0x03 [7]
The VBI enable bit allows data such as intercast and closed
caption data to be passed through the luma channel of the
decoder with a minimal amount of filtering. All data for Line 1
to Line 21 is passed through and available at the output port.
0—Decodes and outputs color during VBI.
1 (default)—Blanks Cr and Cb values during VBI.
The ADV7188 does not blank the luma data, but automatically
switches all filters along the luma data path into their widest
bandwidth. For active video, the filter settings for YSH and YPK
are restored.
05478-025
Y DATA BUS 00 AV YFF 00 00 AV Y
FF
C
r/Cb DATA BUS 00 00 AV Cb FF 00 Cb
AV CODE SECTION AV CODE SECTION
FF 00 00 AV Cb
AV CODE SECTION
Cb/Y/Cr/Y
INTERLEAVED
8-/10-BIT INTERFACE16-/20-BIT INTERFACE16-/20-BIT INTERFACE
SD_DUP_
V
= 1 SD_DUP_
V
= 0
Figure 25. AV Code Duplication Control