AMD SC2200 manual Valid Mixing/Blending Configurations, YUV to RGB CSC in Video Data Path

Video Processor Module 32580B

Table 7-1. Valid Mixing/Blending Configurations

	Mixing/Blending1					Flicker
			(Bit)			Filter2 (Bit)
13		11		10	9	30	29	Mode	Comment
0		0		1	0	0	0	Input: YUV Progressive Video	• Produces highest quality RGB output (see Section
								Mixing: RGB		7.2.1.2 "Capture Video Mode", Weave subsection on
										page 325).
1		0		0	0	0	0	Input: RGB Progressive Video	• Produces highest quality RGB output (see Section
								Mixing: RGB		7.2.1.2 "Capture Video Mode", Weave subsection on
										page 325).
0		1		0	1	0	1	Input: YUV Interlaced Video	•	Not supported.
								Mixing: YUV
0		1		0	0	0	0	Input: YUV Progressive Video	•	Not supported.
								Mixing: YUV
0		0		1	0	0	0	Input: YUV Interlaced Video	• Typically Direct Video mode.
								upscaled by 2	• Must be vertically upscaled by a factor of 2 (see
								Mixing: RGB
										Section 7.2.2.5 "2-Tap Vertical and Horizontal
										Upscalers" on page 329).

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

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

7.2.3.1YUV to RGB CSC in Video Data Path

This CSC must be enabled if the video data is in the 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.

7.2.3.2Gamma 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 correction supported in the YUV or RGB 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. The output of the RAM is the new color. A simple RGB 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.

7.2.3.3Color/Chroma Key

A color/chroma key mechanism is used to support the Mixer/Blender logic. There are two keys: key1 is for the cursor and key2 is for graphics or video data. Key1, the cursor key, is always a color key. The cursor color key reg- isters are located at, F4BAR0+Memory Offset 50h-5CF. How the cursor key mechanism works with the Mixer/

Blender is explained in Section 7.2.3.4. COLOR_CHROMA_KEY (F4BAR0+Memory Offset 04h[20]) determines whether key2 is a color key or a chroma key. The Video Color Key Register (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 7.2.3.4.

AMD Geode™ SC2200 Processor Data Book 331