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Video Processor Module (Continued)

6.2.3.1

YUV to RGB CSC in Video Data Path

This CSC mustbeenabled if thevideo dataisinthe YUV

color space. The CSC_FOR_VIDEO bit, F4BAR0+Memory

Offset 4Ch[10], controls this CSC.

YUV video data is passed through this CSC to obtain 24-bit

RGB data using the following CCIR-601-1 recommended

formula:

• R = 1.1640625(Y – 16) + 1.59375(V – 128)

• G = 1.1640625(Y – 16) – 0.8125(V – 128) –

0.390625(U – 128)

• B = 1.1640625(Y – 16) + 2.015625(U – 128)

The CSC clamps inputs to prevent them from exceeding

acceptable limits.

6.2.3.2

Gamma Correction

Either the video or graphics data can be routed through an

integrated palette RAM for Gamma correction. There are

three 256-byte RAMs, one for each color component value.

Gamma correctionsupportedinthe YUVorRGB color

space for the video data and RGB color space for the

graphics data. Gamma correction is accomplished by treat-

ing each color component as an address into each RAM.

Theoutput of theRAM is thenew color. AsimpleRGB

Gamma correction example is to increase each color com-

ponent by one. The address 00h in the RAMs would con-

tain the data 01h. The address 01h would contain the data

02h and so on. This would have the effect of increasing

each original Red, Green, and Blue value by one.

• G_V_GAMMA, F4BAR0+Memory Offset 04h[21] selects

which data path (video or graphics) to send to the

Gamma correction block. GAMMA_EN,

F4BAR0+Memory Offset 28h[0] enables the Gamma

correction function. To load the Gamma correction

palette RAM, use F4BAR0+Memory Offset 1Ch and

20h.

6.2.3.3

Color/Chroma Key

A color/chroma key mechanism is used to support the

Mixer/Blender logic. There are two keys: key1 is for the cur-

sor and key2 is for graphics or video data. Key1, the cursor

key, is always a color key. The cursor color key registers

are located at, F4BAR0+Memory Offset 50h-5CF. How the

cursor key mechanism works with the Mixer/Blender is

explained in Section 6.2.3.4. COLOR_CHROMA_KEY

(F4BAR+Memory Offset 04h[20]) determines whether key2

is a color key or a chroma key. The Video Color Key Regis-

ter (F4BAR0+Memory Offset 14h) stores the key. Color

keying is used when video is overlaid on the graphics

(GFX_INS_VIDEO, F4BAR0+Memory Offset 4Ch[8] = 0).

Chroma keying is used when graphics is overlaid on the

video (GFX_INS_VIDEO = 1). How the color/chroma key

mechanism works with the Mixer/Blender is explained in

Section 6.2.3.4.

Table 6-1. Valid Mixing/Blending Configurations

Mixing/Blending1

(Bit)

Flicker

Filter2 (Bit)

Mode

Comment

001000

Input: YUV Progressive Video

Mixing: RGB

•

Produces highest quality RGB output (see Section

6.2.1.2 "Capture Video Mode", Weave subsection on

page 321).

100000

Input: RGB Progressive Video

Mixing: RGB

•

Produces highest quality RGB output (see Section

6.2.1.2 "Capture Video Mode", Weave subsection on

page 321).

010101

Input: YUV Interlaced Video

Mixing: YUV

•

Not supported.

010000

Input: YUV Progressive Video

Mixing: YUV

•

Not supported.

001000

Input: YUV Interlaced Video

upscaled by 2

Mixing: RGB

•

Typically Direct Video mode.

•

Must be vertically upscaled by a factor of 2 (see

Section 6.2.2.5 "2-Tap Vertical and Horizontal

Upscalers" on page 325).

F4BAR0+Memory Offset 4Ch[13, 11:9].

F4BAR0+Memory Offset 814h[30:29].

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