STV2310 datasheet(27/112 Pages) STMICROELECTRONICS

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STV2310

Functional Description

The position where the zoom-in operation starts is programmed in the ZOOMIN_OFFSET[9:0] bits

in the DDECCONTA and DDECCONTB registers. If the value is 0, the zoom-in starts at the

beginning of the TV scan line (first left pixel). The number of pixels per line is based on the vertical

frequency and the pixel mode. For more information, refer to Table 10. The default value is 0; i.e. the

first left pixel of the active line is the first pixel of zoom.

4.9.2.3 Zoom-Out Mode

To enable Zoom-Out mode, the ZOOMOUT_EN bit in the DDECCONTB register must be set.

The zoom-out value must be between 256 and 1023. A value of 512 will zoom-out the picture by a

factor of 0.5; i.e. pixels are twice as small. The zoom-out factor is programmed in the

ZOOMOUT_FACT[9:0] bits in the DDECCONT9 and DDECCONTB registers.

4.9.2.4 Panorama Mode

Panorama mode is enabled when both the ZOOMIN_EN bit in the DDECCONTB register and the

ZOOMOUT_EN bit in the DDECCONTB register are set to 1.

In Panorama mode, the ZOOMIN_FACT, the ZOOMOUT_FACT and the ZOOMIN_OFFSET values

are used (see Figure 16).

● The ZOOMIN_FACT bits determine the zoom-in factor at the left and right edges of the picture

● The ZOOMOUT_FACT bits determine the zoom-out factor at the center of the picture

● The ZOOMIN_OFFSET bits determine the border width where the zoom factor increases from

the zoom-in factor to the zoom-out factor, starting from the left edge (resp. the border width

finishing on the right edge where the zoom factor decreases from the zoom-out factor to the

zoom-in factor)

For correct programming the following formula must be checked:

Zt x (Zout - Zin) = N x (Zout -1)

where Zin = ZOOMIN_FACT ; Zout = ZOOMOUT_FACT ; Zt = ZOOMIN_OFFSET ; N number of Y

pixels per line (720 in Normal Pixel mode, 640 or 768 in Square Pixel mode).

4.10

RGB Insertion

4.10.1 General Description

The RGB signals are captured by three 8-bit A/D converters and should be synchronous to the

selected CVBS or Y/C sources. The RGB signals are also adjusted in the analog domain by clamp

circuits used for sourcing and sinking charges on the front end capacitor.

A digital adjustable gain can be applied to the RGB data flow, in order to adapt to the CVBS

dynamic range.

The RGB signals are YCrCb formatted and mixed with the YCrCb signals from the main picture.

Soft mixing is driven by the FB signal. The rising and falling edges of the FB signal are measured

with subpixel accuracy to perform correct insertion. (For more information, refer to Section 4.8: Soft

Mixer on page 23).

The RGB insertion block also provides a Cr Cb overload mechanism. This mechanism is used to

avoid clipping YCrCb signals (i.e when the input RGB signals are too large). The Cr Cb overload

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