TM1100 Preliminary Data Book
Philips Semiconductors
7-22
PRELIMINARY INFORMATION
File: evo.fm5, modified 7/24/99
The bit 4 of VO_STATUS (VO_STATUS[4]) allows to de-
termine if the EVO extra registers are present, or if it is a
classical
Video
Out
unit.
On
Video
Out
unit,
VO_STATUS[4] is a copy of the HBE flag. On EVO unit,
it is hard-wired to 1. Software can easily determine the
type of Video Out unit by clearing the HBE bit then read-
ing VO_STATUS[4].
The four MSB of the EVO_CTL MMIO register indicate
the EVO revision that is implemented. For the TM1100,
EVO_CTL[31:28] = 0x1. This 4-bit number will be in-
creased for each version of EVO that add new function-
alities.
7.20
CLIPPING FUNCTION
The CLIPPING MMIO register is used to store four 8-bit
values that are used to clip the output components. The
Y output component is clipped between the value stored
in LOWER_CLIPY and HIGHER_CLIPY registers. A val-
ue lower or equal to LOWER_CLIPY is forced to
LOWER_CLIPY and a value higher than or equal to
HIGHER_CLIPY is forced to HIGHER_CLIPY.
Same behavior for U and V with the values stored in
LOWER_CLIPUV and HIGHER_CLIPUV.
This mode allows to program the fully compliant 16 to
235 Y and 16 to 240 Cb, Cr clipping range. This are the
default values of the EVO_CLIP register after reset. If
CLIPPING_ENABLE bit is not set, the clipping is per-
formed for Y, U and V between 16 and 240, as it is imple-
mented in TM1000.
When LOWER_CLIP registers are set to 0 and
HIGHER_CLIP registers to 255, no clipping is per-
formed.
The clipping is performed in the last step of the video
pipeline, after chroma keying and blending. It is applied
only on the images areas (field 1 and field 2) defined by
IMAGE_WIDTH, IMAGE_HEIGHT, IMAGE_VOFF and
IMAGE_HOFF inside the Active Video Area. Blanking
values are not clipped.
Table 7-12. EVO Related MMIO Registers Fields
Register
Field
Description
EVO_MASK
MASK_Y
This 4-bit value is used to mask the four lower bits of the overlay Y compo-
nent during the chroma key process. Example: Setting MASK_Y to “1” will
eliminate the inuence of the LSB of KEY_Y in the keying process.
MASK_UV
This 4-bit value is used to mask the four lower bits of the overlay U and V
components during the chroma key process. Example: Setting MASK_UV
to “1” will eliminate the inuence of the LSB of KEY_U and KEY_V in the
keying process.
EVO_CLIP
LOWER_CLIPY
An Y value lower or equal to LOWER_CLIPY is forced to LOWER_CLIPY.
HIGHER_CLIPY
An Y value higher or equal to HIGHER_CLIPY is forced to
HIGHER_CLIPY.
LOWER_CLIPUV
An U or an Y value lower or equal to LOWER_CLIPUV is forced to
LOWER_CLIPUV.
HIGHER_CLIPUV
An U or and an V value higher or equal to HIGHER_CLIPUV is forced to
HIGHER_CLIPUV.
EVO_KEY
KEY_Y
Value compared to the Y component of the overlay for chroma keying.
KEY_U
Value compared to the U component of the overlay for chroma keying.
KEY_V
Value compared to the V component of the overlay for chroma keying.
EVO_SLVDLY
Number of VO_CLK cycles of internal delay for VO_IO2 in genlock mode.