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ZR36057PQC

ENHANCED PCI BUS MULTIMEDIA CONTROLLER

Zoran Corporation 

Enhanced PCI Bus Multimedia Controller

7.0 VIDEO OUTPUT CONTROL

The ZR36057 outputs the video pixels over the PCI bus, using

DMA bursts, initiated and controlled by the ZR36057’s Video

DMA Controller. In order to enable the DMA Controller, the

Master Enable bit of the PCI configuration space must be set to

‘1’, and the VidEn bit in the Video Display Configuration Register

must also be set to ‘1’. Once VidEn==’1’, the software is not

allowed to change registered parameters that are involved in the

video processing. The register description (See “Application-

Specific Registers (ASRs)” on page 25) specifies the conditions

under which each parameter is allowed to be modified.

The ZR36057 transfers the video to a rectangle in the display (or

system) memory, defined by a base address for each field

(MaskTopBase, MaskBotBase), an inter-line stride (DispStride),

and the rectangle height (VidWinHt) and width (VidWinWid).

Obviously, these parameters must be provided by the host prior

to enabling the Video DMA Controller.

7.1 Display Modes

The ZR36057 can either display both fields, emulating the inter-

laced input, or only the top field. The latter option has the

advantage of reducing the motion artifacts that might be exhibit-

ed when interlaced video is diplayed on a non-interlaced

monitor. The parameter that controls the display mode is

DispMod.

By a proper configuration of the display base addresses it is also

possible to display two fields (from either one or two separate

video sources) on two separate rectangles (video windows).

7.2 Frame Grabbing

The ZR36057 has a special mode for capturing video frames (or

fields) and storing them in system memory. This mode is invoked

by setting the SnapShot parameter to ‘1’. When in this mode,

every time the host switches the FrameGrab bit from ‘0’ to ‘1’, the

ZR36057 downloads a frame (or a field, if DispMod==0), to

memory.

Following is an example of a flow of actions intended to grab one

frame. The example assumes that the vertical sync is used as an

interrupt source (by externally tying VSYNC to GIRQ0 or

GIRQ1), and that prior to grabbing the frame, the ZR36057

operates in the “normal” continuous scheme of live video

display.

• Through a push-button click in the application GUI the user

triggers a frame grabbing request.

• The host sets SnapShot=1. The ZR36057’s Video DMA

Controller waits for the next VSYNC and then freezes the

live display. Since now SnapShot=1 and FramGrab=0, video

parameters can be changed (even without VidEn=0; refer to

section 12.0 “Application-Specific Registers (ASRs)”).

• The host sets new addresses in VidTopBase and VidBot-

Base. These addresses point to main memory. DispStride is

also given a new value. If needed, other video parameters

can be changed now, e.g., pixel format, etc.

• The host sets FrameGrab=1. The ZR36057 waits until the

next VSYNC and then transmits two consecutive fields to

main memory.

• After the second of the two fields is completed, FrameGrab

is cleared by the ZR36057.

• When the host senses (after constant polling or polling in-

side VSYNC-triggered interrupts) that FrameGrab=0 again,

it sets the old addresses back to VidTopBase and VidBot-

Base. DispStride is given back its old value. The remainder

of the previous video parameters can be restored now.

• The host sets SnapShot=0, putting the ZR36057 back into

the continuous video display mode.

• With the next VSYNC the ZR36057’s Video DMA Controller

resumes “normal” live display operation.

7.3 Output Pixel Organization

The output pixel format is determined by the following parame-

ters: YUV2RGB, Pack24 (applicable only to RGB 8,8,8 format),

and LittleEndian (applicable to all formats, excluding the 24-bit

packed). Following are the bit organizations of the different pixel

formats when a video doubleword is transferred over the PCI

bus:

Table 4: YUV 4:2:2 Pixel Format

Endian-ness

Little Endian

Gib Endian

31...24

Y17...0

V07...0

Bits

23...16

15...8

V07...0 Y07...0

Y17...0 U07...0

7...0

U07...0

Y07...0

Table 5: RGB 5,5,5 Pixel Format

Endian-ness

Little Endian

Gib Endian

31...24

0,R14...0,

G14...3

G12...0,

B14...0

Bits

23...16

15...8

G12...0,

B14...0

0,R04...0,

G04...3

0,R14...0, G02...0,

G14...3 B04...0

7...0

G02...0,

B04...0

0,R04...0,

G04...3

Table 6: RGB 5,6,5 Pixel Format

Endian-ness

Little Endian

Gib Endian

31...24

R14...0,

G15...3

G12...0,

B14...0

Bits

23...16

15...8

G12...0,

B14...0

R04...0,

G05...3

R14...0,

G15...3

G02...0,

B04...0

7...0

G02...0,

B04...0

R04...0,

G05...3

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