bt865a Conexant Systems, Inc., bt865a Datasheet - Page 28

• Manufacturer Part Number: bt865a
• Description: Ycrcb To Ntsc/pal Digital Video Encoder
• Manufacturer: Conexant Systems, Inc.

Circuit Description
1.5.5
1.5.6
1.5.7
1.5.8
1.5.9
1-18
FIELD Output
Pixel Blanking
Digital Processing
Chrominance Disable
Burst Blanking
The FIELD output indicates whether FIELD 1 (logical zero) or FIELD 2 (logical one)
is being generated. This corresponds directly to the “bottom/top” convention of some
MPEG decoders. Field transitions after the rising edge of CLK, two clock periods
after the falling edge of VSYNC* if SYNCDLY = 0, or three clock periods after the
falling edge of VSYNC* if SYNCDLY = 1.
To invert the sense of the FIELD output, set the FIELDI bit to a logical one.
BLANK* is registered on the rising edge of CLK. For video outputs, BLANK* is
pipelined to match the luminance and chrominance paths and is applied to the digital
video before analog conversion. The automatic horizontal blanking sequence
described in
For interlaced NTSC, color burst information is automatically disabled on scan lines
1–9 and 264–272, inclusive. (SMPTE line numbering convention.)
For interlaced PAL-M color burst information is automatically disabled on scan lines
1–11 and 263–273 and 525 of FIELD 1 and FIELD 2 and scan lines 1–10 and 262–
272 of FIELDs 3 and 4.
For interlaced PAL–B, D, G, H, I, N, Nc, color burst information is automatically
disabled on scan lines 1–6, 310–318, and 623–625, inclusive, for FIELDs 1, 2, 5, and
6. During FIELDs 3, 4, 7, and 8, color burst information is disabled on scan lines 1–5,
311–319, and 622–625, inclusive.
For noninterlaced NTSC, color burst information is automatically disabled on scan
lines 1–6 and 260–262, inclusive.
For noninterlaced PAL-M, color burst information is automatically disabled on scan
lines 1–10 and 260–262.
For noninterlaced PAL–B, D, G, H, I, N, Nc, color burst information is automatically
disabled on scan lines 1–6 and 310–312, inclusive. See
The input is scaled to YUV format. For the CVBS, Y, and C outputs, the UV
components are low-pass filtered with a filter response shown in
(linearly scalable by clock frequency). The Y and filtered UV components are
upsampled to CLK frequency by a digital filter whose response is shown in
Figure 1-15
and output.
The chrominance subcarrier may be turned off by setting the DCHROMA bit to a logical
one. This kills burst as well, providing luminance only signals on the CVBS outputs and a
static blank level on the C/R output (RGBOUT = 0).
and 1-16. For the RGB outputs, the scaled YUV is color space converted
Table 1-3
takes precedence over the BLANK* input.
Conexant
Figure 1-4
Figure 1-13
Bt864A/Bt865A Data Sheet
through .
and
100138C
02/17/03
1-14