S5D2650 Samsung Semiconductor, Inc., S5D2650 Datasheet - Page 31

• Manufacturer Part Number: S5D2650
• Description: Multistandard Video Decoder/scaler
• Manufacturer: Samsung Semiconductor, Inc.

S5D2650 Data Sheet
MULTIMEDIA VIDEO
1.6.2. Luma Vertical Scaler
Vertical luma scaling uses either a 3-tap or 5-tap 8-phase interpolation filter depending on the horizontal scaling
ratio.
Vertical scaling ratio is programmed via the 14-bit register VSCL. A valid scaled line is indicated by the timing
signal EVAV being active. The EVAV can be programmed to be internally gated by the VAV signal so it can only be
valid within the vertically cropped region.
Luma horizontal scaling can use either a 3-tap or a 5-tap interpolation filter depending on the horizontal scaling
ration. If the scaled horizontal line has less than or equal to 384 pixels, the 5-tap luma interpolation filter can be
turned on by programming the VRT2X bit to a “1”. Otherwise, the VRT2X bit should be set to “0” and the 3-tap filter
be used.
The VYBW bit provides additional vertical bandwidth control for vertical scaling. Typically, when the vertical scaling
ratio is less than 1/2, this bit should be set to “1” to eliminate any aliasing effect.
Luma vertical scaler interpolation filter frequency response is shown in Figure 28.
Figure 28.
Luma Vertical Scaler Interpolation Filter Frequency Response
In vertical scaling, the start of signal VAV controls the phase of the vertical scaler interpolation filter. If VAVB, VAVE,
VAVOD0, VAVEV0, and VSCL are programmed such that the vertical interpolation filter has the same phase and
scaling ratio as that of a memory controller (most memory controller has simple line dropping vertical scaling), it is
possible to interface the S5D2650 to the memory controller without using EVAV.
1.6.3. Chroma Vertical Scaling
Chroma vertical scaling uses different algorithms depending on video input standard and horizontal scaling ratio. If
horizontal scaling results in line with less than or equal to 384 pixels, and the VRT2X is set to a “1”, a 5-tap
interpolation filter will be used for all video inputs. Otherwise, for NTSC, a 3-tap interpolation filter will be used for
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7/18/03
ELECTRONICS