SAA7134 Philips Semiconductors, SAA7134 Datasheet - Page 28

• Manufacturer Part Number: SAA7134
• Description: PCI audio and video broadcast decoder
• Manufacturer: Philips Semiconductors

Philips Semiconductors
7.6.6
The SAA7134HL incorporates a filter and processing unit
to downscale or upscale the video picture in the horizontal
and vertical dimension, and in frame rate
(see Figs 11 and 12). The phase accuracy of the
re-sampling process is
This is equivalent to a clock jitter of less than 1 ns. The
filter depth of the anti-alias filter adapts to the scaling ratio,
from 10 taps horizontally for scaling ratios close to 1 : 1, to
up to 74 taps for an icon sized video picture.
Most video capture applications will typically require for
downscaling. But some zooming is required for conversion
of ITU sampling to square pixel (SQP), or to convert the
240 lines of an NTSC field to 288 lines to comply with
CCITT video phone formats.
2002 Dec 17
handbook, full pagewidth
PCI audio and video broadcast decoder
The capture acquisition for scaling and DMA has separate programming
parameters for VBI and video region and associated DMA channels.
video first line
video last line
VBI first line
VBI last line
V
IDEO SCALING
1
video first pixel
VBI first sample
VBI region, raw samples
VBI region, raw samples
64
active video area
active video area
of the original sample distance.
video region
- cropped
- scaled
video region
- cropped
- scaled
Fig.11 Scaler processing with DMA interfacing.
2nd field (even, FID = 1)
1st field (odd, FID = 0)
scaling
scaling
video last pixel
sample rate
sample rate
VBI last sample
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The scaling acquisition definition also includes cropping,
frame rate reduction, and defines the amount of pixels and
lines to be transported through DMA over the PCI-bus.
Two programming pages are available to enable
re-programming of the scaler in the ‘shadow’ of the running
processing, without holding or disturbing the flow of the
video stream. Alternatively, the two programming pages
can be applied to support two video destinations or
applications with different scaler settings, e.g. firstly to
capture video to CPU for compression (storage, video
phone), and secondly to pre-view the picture on the
monitor screen. A separate scaling region is dedicated to
capture raw VBI samples, with a specific sampling rate,
and be written into its own DMA channel.
1st buffer (A)
2nd buffer (A)
1st buffer (upper field)
2nd buffer (lower field)
VBI DMA
video DMA (A)
e.g. interlaced
SAA7134HL
Product specification
MHB997