bt848kpf ETC-unknow, bt848kpf Datasheet - Page 26

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

F
UltraLock
16
UNCTIONAL
D
ESCRIPTION
decoded for square pixel NTSC output. The first line is shorter than the nominal
NTSC line time interval of 63.5 s. On this first line, a line time of 63.2 s sampled
at 4*Fsc (14.32 MHz) generates only 905 pixels. The second line matches the
nominal line time of 63.5 s and provides the expected 910 pixels. Finally, the
third line is too long at 63.8 s within which 913 pixels are generated. In all three
cases, UltraLock outputs only 780 pixels.
Figure 4. UltraLock Behavior for NTSC Square Pixel Output
original video stream as long as the sum of the nominal pixel line length (910 for
NTSC and 1,135 for PAL/SECAM) and the worst case line length variation from
nominal in the active region is greater than or equal to the required number of out-
put pixels per line, i.e.,
where:
the falling edges of HRESET only to within one pixel. UltraLock does, however,
guarantee the number of active pixels in a line as long as the above relationship
holds.
Waveform
UltraLock
The example illustrated in Figure 4 shows three successive lines of video being
the FIFO
UltraLock can be used to extract any programmable number of pixels from the
It should be noted that, for stable inputs, UltraLock guarantees the time between
Per Line
Sent to
Analog
Length
Pixels
Pixels
Line
by
P
P
P
Nom
Var
Desired
905 pixels
780 pixels
63.2 s
L848A_A
= Nominal number of pixels per line at 4*Fsc sample rate
= Variation of pixel count from nominal at 4*Fsc (can be a
= Desired number of output pixels per line
(910 for NTSC, 1,135 for PAL/SECAM)
positive or negative number)
P
Nom
+
P
Var
910 pixels
780 pixels
63.5 s
P
Desired
Single-Chip Video Capture for PCI
Bt848/848A/849A
913 pixels
780 pixels
63.8 s
Brooktree
®