ADV7181 AD [Analog Devices], ADV7181 Datasheet - Page 36

• Manufacturer Part Number: ADV7181
• Description: Multiformat SDTV Video Decoder
• Manufacturer: AD [Analog Devices]

ADV7181B
AV CODE INSERTION AND CONTROLS
This section describes the I
•
•
•
•
Note that some of the decoded VBI data is being inserted
during the horizontal blanking interval. See the Gemstar Data
Recovery section for more information.
BT656-4 ITU Standard BT-R.656-4 Enable, Address 0x04 [7]
The ITU has changed the position for toggling of the V bit
within the SAV EAV codes for NTSC between revisions 3 and 4.
The BT656-4 standard bit allows the user to select an output
mode that is compliant with either the previous or the new
standard. For further information, review the standard at
http://www.itu.int.
Note that the standard change affects NTSC only and has no
bearing on PAL.
When BT656-4 is 0 (default), the BT656-3 specification is used.
The V bit goes low at EAV of Lines 10 and 273.
When BT656-4 is 1, the BT656-4 specification is used. The V bit
goes low at EAV of Lines 20 and 283.
SD_DUP_AV Duplicate AV codes, Address 0x03 [0]
Depending on the output interface width, it may be necessary to
duplicate the AV codes from the luma path into the chroma path.
Cr/Cb DATA BUS
Y DATA BUS
Insertion of AV codes into the data stream.
Data blanking during the vertical blank interval (VBI).
The range of data values permitted in the output data
stream.
The relative delay of luma versus chroma signals.
FF
FF
16-BIT INTERFACE
AV CODE SECTION
SD_DUP_AV = 1
2
C based controls that affect
00
00
00
00
AV
AV
Figure 18. AV Code Duplication Control
Cb
Y
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AV CODE SECTION
FF
00
16-BIT INTERFACE
In an 8-bit-wide output interface (Cb/Y/Cr/Y interleaved data),
the AV codes are defined as FF/00/00/AV, with AV being the
transmitted word that contains information about H/V/F.
In this output interface mode, the following assignment takes
place: Cb = FF, Y = 00, Cr = 00, and Y = AV.
In a 16-bit output interface where Y and Cr/Cb are delivered via
separate data buses, the AV code is over the whole 16 bits. The
SD_DUP_AV bit allows the user to replicate the AV codes on
both busses, so the full AV sequence can be found on the Y bus
as well as on the Cr/Cb bus. See Figure 18.
When SD_DUP_AV is 0 (default), the AV codes are in single
fashion (to suit 8-bit interleaved data output).
When SD_DUP_AV is 1, the AV codes are duplicated (for
16-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 Lines 1
to 21 is passed through and available at the output port. The
ADV7181B does not blank the luma data, and 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.
Refer to the BL_C_VBI Blank Chroma during VBI section for
information on the chroma path.
When VBI_EN is 0 (default), all video lines are filtered/scaled.
When VBI_EN is 1, only the active video region is
filtered/scaled.
AV
00
Cb
Y
SD_DUP_AV = 0
INTERLEAVED
Cb/Y/Cr/Y
FF
AV CODE SECTION
8-BIT INTERFACE
00
00
AV
Cb