PNX1300 Philips, PNX1300 Datasheet - Page 117

• Manufacturer Part Number: PNX1300
• Description: Media Processors
• Manufacturer: Philips

Philips Semiconductors
7.9.2
The CCIR 656-compliant 525/60 and 625/50 timing
specifications define an overlap period where the field
number in the SAV and EAV codes from Field 1 persists
into the vertical blanking interval for Field 2, and the
codes for Field 2 persist into the vertical blanking interval
for Field 1. The F1_OLAP and F2_OLAP fields of the
VO_FIELD register define these overlap intervals.
F1_OLAP and F2_OLAP are small two’s complement
values in the range -8... +7. A positive value indicates
that the overlap extends into the current field, while a
negative value indicates that it extends backward into the
previous field. See
and positive values.
During the overlap interval, the vertical blanking for the
next field has begun; however, the field number flag in
the SAV and EAV codes still shows the field number for
the previous field. The field number is updated to the cor-
rect field value at the end of the overlap interval.
F1_OLAP defines the overlap from Field 1 to Field 2.
This overlap occurs during the beginning of vertical
blanking for Field 2. The SAV and EAV codes continue
to show Field 1 during this overlap interval, and they
change to Field 2 at the end of the interval.
F2_OLAP defines the overlap from Field 2 to Field 1.
This overlap occurs during the beginning of vertical
blanking for Field 1. The SAV and EAV codes continue
to show Field 2 during this overlap interval, and they
change to Field 1 at the end of the interval.
Figure 7-13. Active Video Area and Image Area in re-
lation to vertical and horizontal blanking intervals.
SAV and EAV Overlap Period
Start Pixel
Image Width
Vertical Blanking, Field 2
Vertical Blanking, Field 1
Figure 7-31
Image Area, Field 2
Image Area, Field 1
Frame
Active Video Area
Active Video Area
Image V Offset
Image V Offset
Overlay
Overlay
for the effect of negative
Start
Line
7.9.3
The frame and image counters have different start and
stop points. The frame counters begin in the vertical
blanking interval of the first field and the horizontal blank-
ing interval of the first line. They stop counting when they
reach the height and width values of the frame. When the
EVO generates frame timing, the frame counters are re-
set to their start values when they reach their stop val-
ues. When the EVO receives frame timing signals, the
frame counters continue counting until reset by the exter-
nal signals.
The image area is defined by VO_YTHR register fields
IMAGE_VOFF and IMAGE_HOFF. These values are
added to the F1_VIDEO_LINE or F2_VIDEO_LINE and
VIDEO_PIXEL_START values to define the starting line
and pixel, respectively, of the image area. The image
area is active when the contents of the Frame Line
Counter and Frame Pixel Counter equal or exceed these
values.
The Image Line Counter and Image Pixel Counter start
counting at the first active pixel in the image area and the
first active line in the image area, respectively. The im-
age counters start at zero and stop counting when they
reach their image height and width values. The image
counters are reset by frame counter values indicating the
start of the image pixel in a line and the start of the image
line in a field.
The image counters define the active image area of the
frame, the area of interest for image processing. This al-
lows the overlay start address to be defined relative to
the active image area, for example. When the EVO is not
sending out active pixels from the image area, it sends
out blanking codes. The blanking codes are 0x80, 0x10,
0x80, and 0x10 for each 2-pixel group in YUV 4:2:2 im-
age data format, as defined by CCIR 656 and shown in
Figure
7.9.4
The EVO can supply horizontal and frame timing signals
or receive a frame timing signal from an external source.
When VO_CTL. SYNC_MASTER = 1, the EVO gener-
ates horizontal and frame timing for the external video
device. When SYNC_MASTER = 0, the EVO operates in
Genlock mode and an external device, such as a DENC,
must provide frame sync. This section describes EVO
operation when it is sync master. See
description of Genlock mode.
If SYNC_MASTER = 1, the VO_IO1 signal generates a
horizontal timing signal, and the VO_IO2 signal gener-
ates a frame timing signal. When EVO_ENABLE = 1 and
FIELD_SYNC = 1, the VO_IO2 signal indicates the field
number (low = Field 1, high = Field 2), according to the
SAV/EAV field indication (bit[6]) as shown in
The VO_IO2 signal toggles just before the first byte of the
preamble that protects the EAV code and after the SAV
code. Non-interlaced output can be simulated by pro-
gramming the EVO to generate fields equivalent to the
desired frames. In this case, VO_IO2 indicates odd or
even frames.
PRELIMINARY SPECIFICATION
7-10.
Control of Frame and Image Counters
Horizontal and Frame Timing Signals
Enhanced Video Out
Section 7.10
Figure
7-14.
for a
7-7