bt848kpf ETC-unknow, bt848kpf Datasheet - Page 45

• Manufacturer Part Number: bt848kpf
• Description: Single-chip Video Capture For Pci
• Manufacturer: ETC-unknow

Bt848/848A/849A
Single-Chip Video Capture for PCI
Brooktree
®
VBI Data Output Interface
A frame of video is composed of 525 lines for NSTC and 625 for PAL/SECAM.
Figure 18 illustrates an NTSC video frame, in which there are a number of distinct
regions. The video image or picture data is contained in the odd and even fields
within lines 21 to 263 and lines 283 to 525 respectively. Each field of video also
contains a region for vertical synchronization (lines 1 through 9 and 263 through
272) as well as a region which can contain non-video ancillary data (lines 10
through 20 and 272 through 283). We will refer to these regions which are between
the vertical synchronization region and the video picture region as the Vertical
Blanking Interval or VBI portion of the video signal.
Figure 18. Regions of the Video Frame
The Bt848 is able to capture VBI data and store it in the host memory for later pro-
cessing by the Bt848 VBI decoder software. Two modes of VBI capture exist: VBI
line output mode and VBI frame output mode. Both types of data may be captured
during the same field.
terval. The start of VBI data capture is set by the VBI_HDELAY bit in the VBI
Packet Size/Delay register, and is in reference to the trailing edge of the HRESET
signal. The number of DWORDs of VBI data is selected by the user. Each
DWORD contains 4 VBI bytes, and each VBI pixel consists of two VBI samples.
For example, for a given 800 pixel line in the VBI region, there exist 1600 VBI
samples, which is equivalent to 400 DWORDs of VBI data. The VBI_PKT_HI and
VBI_PKT_LO register bits are concatenated to create the 9-bit value for the num-
ber of DWORDs to be captured.
In the VBI line output mode, VBI capture occurs during the vertical blanking in-
Lines 263–272
Lines 272–283
Lines 283–525
Lines 21–263
Lines 10–20
Lines 1–9
L848A_A
Vertical Synchronization Region
Vertical Synchronization Region
Vertical Blanking Interval
Vertical Blanking Interval
Video Image Region
Video Image Region
F
UNCTIONAL
VBI Data Output Interface
D
ESCRIPTION
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