SAA7115 View Datasheet(PDF) - Philips Electronics

Part Name

Description

View to exact match

SAA7115

PAL/NTSC/SECAM Video Decoder with Adaptive PAL/NTSC Comb Filter, High Performance Scaler, I2C Sliced Data Readback and SQ Pixel Output

Philips Electronics 

Philips Semiconductors

CS-PD Hamburg

CVIP2

Datasheet

SAA7115

Date:

Version:

10/23/01

0.67

8.3 Scaler

The high performance video scaler in the SAA7115 has the following major blocks:

• Acquisition control (horizontal and vertical timer) and task handling (the region/field/frame based processing)

• Prescaler, for horizontal down-scaling by an integer factor, combined with appropriate band limiting filters, especially

anti-aliasing for CIF format

• Brightness, saturation, contrast control to adjust scale dependent amplification

• Line buffer, with asynchronous read and write, to support vertical up-scaling (e.g. for videophone application,

converting 240 into 288 lines, Y-CB-CR 4 : 2 : 2)

• Vertical scaling, with phase accurate Linear Phase Interpolation (LPI) for zoom and downscale, or phase accurate

Accumulation Mode (ACM) for large downscaling ratios and better alias suppression

• Variable Phase Delay (VPD), operates as horizontal phase accurate interpolation for arbitrary non-integer scaling

ratios, supporting conversion between square and rectangular pixel sampling

• Output formatter for scaled Y-CB-CR 4 : 2 : 2, Y-CB-CR 4 : 1 : 1 and Y only (format also for raw data)

• FIFO, 32-bit wide, with 64 pixel capacity in Y-CB-CR formats

• Output interface, 8 or 16-bit (only if extended by H-port) data pins wide, synchronous or asynchronous operation, with

stream events on discrete pins, or coded in the data stream.

The overall H and V zooming (HV_zoom) is restricted by the input/output data rate relationships. With a safety margin of

2% for running in and running out,

the maximum HV_zoom is equal to: 0.98 × i--n---_----p---i-x---e----l--×-----i--n-T--_-_--l--ii-nn---pe----us---t-×-_---f-o-i-e-u--l--td-_----–c---y-T--c--_-l-e-v--_-_---pb---e-l-a-r--_n----pk---ii-n-x---g-×-----T----_---o---u----t-_---c---l--k-

For example:

1. Input from decoder: 50 Hz, 720 pixel, 288 lines, 16-bit data at 13.5 MHz data rate, 1 cycle per pixel; output: 8-bit data

at 27 MHz, 2 cycles per pixel;

the maximum HV_zoom is about: 0.98 × -7--2-2---00-----m×-----s2---8-–---8--2--×-4----2-×----×-6---4-3---7--µ---n-s---s- = 1.18

2. Input from X-port: 60 Hz, 720 pixel, 240 lines, 8-bit data at 27 MHz data rate (ITU 656), 2 cycles per pixel; output via

I + H-port: 16-bit data at 27 MHz clock, 1 cycle per pixel;

the maximum HV_zoom is about: 0.98 × -1--7-6---2.--6-0--6---×-6----2-m--4---s0----–-×----2-1--2---×--×---3--6-7--4---n---µ-s--s-- = 2.34

The data flow in the scaler is controlled by internal data valid and data request flags (internal handshake signalling)

between the sub-blocks, as the scaling process itself is discontinuous and dynamical. Therefore the entire scaler acts as

a pipeline buffer. Depending on the actually programmed scaling parameters the effective buffer can exceed to an entire

line. This allows vertical upscaling, more flexible video stream timing at the image port, discontinuous transfers and

handshake. The access/bandwidth requirements to the VGA frame buffer are reduced significantly.

The video scaler receives its input signal from the video decoder or from the expansion port (X-port). It gets 16-bit

Y-CB-CR 4 : 2 : 2 input data at a continuous rate of 13.5 MHz from the decoder. Discontinuous data stream can be

accepted from the expansion port (X-port), normally 8-bit wide ITU 656 like Y-CB-CR data, accompanied by a pixel

qualifier on XDQ.

The input data stream is sorted into two data paths, one for luminance (or raw samples) and one for time multiplexed

chrominance CB and CR samples. An Y-CB-CR 4 : 1 : 1 input format from the X-port is converted to 4 : 2 : 2 for the

horizontal prescaling and vertical filter scaling operation.

The scaler operation is defined by two programming pages A and B, representing two different tasks, that can be applied

field alternating or to define two regions in a field (e.g. with different scaling range, factors and signal source during odd

and even fields).

Each programming page contains control:

Confidential - NDA required

Filename: SAA7115_Datasheet.fm

page 49

Last edited by H. Lambers

Share Link: