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ZR36057PQC

ENHANCED PCI BUS MULTIMEDIA CONTROLLER

Zoran Corporation 

Enhanced PCI Bus Multimedia Controller

input or output. When configured as an output, the host is able

to force the level of a pin through its corresponding register bit.

5.8 Interrupt Requests

The ZR36057’s interrupt manager connects to the various con-

ditions that may generate an interrupt request, enables or

disables them as specified in the Interrupt Control Register, and

drives the INTA output. It stores the corresponding status bits in

the Interrupt Status Register, and clears the status bits per host

instructions.

The ZR36057 can associate any one of the following events with

an interrupt request:

• A positive edge on the GIRQ1 input pin.

• A positive edge on the GIRQ0 input pin.

• MPEG mode - the code memory buffer pointer passing one

of its report points.

• JPEG modes - successful completion of a JPEG field or

frame process (in compression or decompression).

Each one of these events can be separately enabled or disabled

through the corresponding bit in the Interrupt Control Register.

An additional global enable bit enables or disables all interrupts.

When an interrupt-associated event occurs, two things happen:

• The corresponding bit in the Interrupt Status Register is set.

• If the interrupt is enabled, and the interrupts are enabled glo-

bally, then the INTA open-drain output pin is asserted to its

active-low level.

Both the status bit(s) and INTA remain active, until the host

clears those status bits that are currently set. This is done by

writing a ‘1’ to those bits. When the host does that, the INTA

output signal returns to its passive, tri-state level.

If the host attempts to clear any of the Interrupt Status Register

bits at the same time that the interrupt logic attempts to set it

(because of an interrupt event), the set operation has priority

over the clear operation.

6.0 VIDEO INPUT PROCESSOR

6.1 Horizontal Filter

Prior to a significant horizontal down scaling of the input image,

it is advisable to apply one of the possible horizontal filters. The

filter type is selected through the HFilter parameter.

HFilter = 0 Filter 1: No luminance filter, 3-tap pre-interpolation filter

of chrominance.

HFilter = 1 Filter 2: 3-tap luminance filter, 3-tap pre-interpolation

chrominance filter.

HFilter = 2 Filter 3: 4-tap luminance filter, 4-tap chrominance filter.

HFilter = 3 Filter 4: 5-tap luminance filter, 4-tap chrominance filter.

HFilter = 4 Filter 5: 4-tap luminance filter, 4-tap chrominance filter.

6.2 Horizontal/Vertical Downscaler

The horizontal and vertical down scalers are independent of

each other. The horizontal scaling ratio is configured through the

HorDcm parameter. HorDcm indicates the number of pixels to

drop out of every 64 consecutive pixels. HorDcm ranges from 0

to 63, where 0 represents the no scaling configuration (1:1 input

to output ratio).

The vertical scaling ratio is configured through the VerDcm

parameter. VerDcm indicates the number of lines to drop out of

every 64 consecutive lines. VerDcm ranges from 0 to 63, where

0 represents the no scaling configuration (1:1 input to output

ratio).

The vertical downscaler can operate in two ways. If DupFld=0 it

treats the top and bottom fields the same way. If DupFld=1 it

uses different line dropping topologies for the top and the bottom

fields, such that if the fields are equal (one field is actually dupli-

cated, like the output of most MPEG-1 decoders), then the total

loss of information is minimized. For example, when the video

source is a video digitizer, it is recommended to apply DupFld=0,

and when the video source is the ZR36110, and the CCIR size

is down scaled by half or more, it is recommended to apply

DupFld=1.

6.3 Color Space Converter

The color space converter converts the YUV input to RGB

format. The YUV2RGB parameter determines the type of

conversion:

YUV2RGB = 00b

YUV2RGB = 01b

YUV2RGB = 10b

YUV2RGB = 11b

no conversion, output format is YUV 422.

conversion to RGB 8,8,8 (24-bit output)

conversion to RGB 5,6,5 (16-bit)

conversion to RGB 5,5,5 (15-bit)

When the 15- or 16-bit RGB format is selected, it is advisable to

apply the error diffusion option, in order to eliminate false

contours from the output image. This option is selected by the

ErrDif parameter (1 turns the error diffusion option on, while 0

turns it off).

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