STV2310 datasheet(24/112 Pages) STMICROELECTRONICS

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Functional Description

STV2310

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4.8.2

Programming

Fast Blanking mode is selected by the FBLANKMODE[2:0] bits in the DDECCONT5 register.

Note:

The FBLANKMODE value is only applied when the STV2310 is not in Analog YCrCb mode

The soft mixing slope or the Alpha Blending value, depending on the Fast Blanking mode, is set in

the MIX_SLOPE[7:0] bits in the DDECCONT6 register. When the blanking mode is in Forced RGB

or Forced CVBS mode, this value is ignored.

When one of the Alpha Blending modes is used for mixing, the alpha value is set in the

MIX_SLOPE[7:0] bits.

When the STV2310 is in normal RGB and CVBS mixing mode, the MIX_SLOPE[3:0] bits indicate

the mixing slope (duration of mixing). The MIX_SLOPE[7:4] bits must be set to 0000. The

MIX_SLOPE[3:0] bits code the soft mixing slope from 0000 to 1111, with 0000 corresponding to a

slope of 1 clock cycle (virtual 4 x fSC clock domain) and 1111 corresponding to a transition from one

signal to the other spanned on 16 clock cycles.

4.9

Output Scaler and Format Converter

4.9.1

General Description

An Output Sample Rate Converter (OSRC) is used to transpose the subcarrier locked virtual clock

domain to the output sample rate domain. This converter is used to provide a fixed number of pixels

per active line (i.e. 720 for ITU-R BT.601 format) independently of the input video standard and line

length.

● Upsampling is required for zoom-in functions.

● Downsampling is required for zoom-out functions.

The Output Sample Rate Converter compensates for line length variations. At this level, a skew

correction is applied on each pixel in order to compensate for the shift of the asynchronous

acquisition with respect to the current line horizontal sync pulse. New sample rate and skew

correction factors are computed at every line, taking into account the line length variation.

The Output Sample Rate Converter is also used to perform an horizontal format conversion to

support zoom in/out functions. For linear scaling, the scaling factor can be programmed in linear

steps from 0.25 to 4. Non-linear scaling is also available for Panorama mode. Region borders are

fully programmable as well as the associated scaling factors (in the 0.25 to 4 range).

Table 9: Fast Blanking Modes

Bit Value

Mixing Mode

Description

00x

Normal Mixing mode

FB active during active line. Soft Mixing between 0 and 1. (Default mode)

01x

Dynamic Mixer mode

FB active and Soft Mixing from 0 to MIXSLOPE[7:0]

100

Static Mixer or Alpha

Blending 1 mode

FB inactive. YOUT = alpha x YCVBS + (1-alpha) x YRGB

with alpha = MIXSLOPE[7:0] (same for Cr and Cb signals)

101

Static Mixer or Alpha

Blending 2 mode

FB inactive. YOUT = alpha x YRGB + (1- alpha) x YCVBS

with alpha = MIXSLOPE[7:0] (same for Cr and Cb signals)

110

Forced CVBS mode

FB inactive. YOUT = YCVBS (same for Cr and Cb signals)

111

Forced RGB mode

FB inactive. YOUT = YRGB (same for Cr and Cb signals)

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