[opendtv] Re: Closer

  • From: Craig Birkmaier <craig@xxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Tue, 4 Jan 2005 11:54:20 -0500

At 10:35 AM -0500 1/4/05, John Shutt wrote:
>Which brings me to the nut of my question:  Have there been any studies on
>the relative quality of transcoder chips in various consumer devices such as
>Cable STBs, OTA STBs, and Consumer displays?  Is Sony's chip better than
>Panasonic's, or do they both purchase off the shelf solutions from a third
>party?  We know there are performance differences among ATSC demod chips,
>are there similar performance differences with transcoding chips?

I have not seen any studies, and for that matter I am not certain who 
the major chip foundries are, other than ATI.

Part of the problem is that there are different functions that may be 
integrated into a single chip, or spread out among several chips. 
These functions may include:

Video scaling (inter-format conversion)
De-interlacing
Generation of on screen graphics (OSG)
Composituion of multiple sources (OSG, main video, and PIP)
And in some cases support for a portion of the MPEG decoding functionality.

The scaling functions are fairly straight forward; it is now fairly 
inexpensive to provide high quality scaling with plenty of taps to 
get good results, even when the scaling factors are small.

It is the de-interlacing functions that seem to vary the most. The 
trend seems to be in the direction of fairly sophisticated chips that 
use block based processing for motion compensated predictions. 
Earlier designs generally relied on multi-field averaging 
(spatio/temporal filtering).

Last night I discovered something interesting about my new Samsung 
RPTV. As i noted in an earlier post, the set uses some form of block 
based motion compensated prediction for deinterlacing. I don't have 
the tools to make precise measurements, but it appears that this 
processing is introducing a delay of at least 3 frames, and possibly 
even more; the good news is that the set appears to have a built in 
audio delay to keep sound and picture in sync.

Last night we were watching the Sugar Bowl on the big screen; 
unfortunately we had to watch in SD as the local ABC station WCJB-DT 
is still not operational. Meanwhile my  wife was surfing the web in 
the bedroom; the 27" analog TV was tuned to the Sugar Bowl as well. 
When i walked into the bedroom I heard a distinct echo. The sound 
from the big screen was obviously delayed relative to the analog set 
that had no delay.

So there appears to be no direct answer to your question. The results 
you see on the screen will be impacted by the performance of the 
de-interlacer (assumes 480i/1080i source) and the video scaling 
engine.

>
>How long before a high end video manufacturer comes out with a stand alone
>transcoder for true videophiles? (To be connected to the display with
>outrageously over-gauged Monster Cable so the video signal can 'breathe.')
>
>Just staying curious,

An interesting question.

I believe that such devices already exist. First stop Faroudja, which 
is now a subsidiary of Genesis Microchip, one of the largest 
foundries of video scaling/deinterlacing chips in the world.

Here is a link for a .pdf file describing the Genesis FLI2300 Digital 
Video Format Converter chip that is used in many TVs and graphics 
cards for computers. The stuff about pixel by pixel motion 
compensated prediction is intersting.


Then check this link:

http://www.faroudja.com/prod_dvp-1000.phtml

Here's the spiel:

DVP-1000 Digital Cinema Source Processor

The DVP-1000 is offered as an option for installations that require 
adjustable output resolutions. Up to eight "Profiles" can be stored 
and easily recalled from the On-Screen Menu or via RS232 for easy 
operation and system integration. Each profile includes all setup and 
image parameters. HDTV Cross conversion is also added so HDTV sources 
can be optimized at the display's native resolution.

Digital projectors and plasmas offer the highest image quality when 
the DVI input is used. Faroudja's DVP-1000 digital video processor 
takes standard analog video and converts it to high-resolution 
digital video. The digital information is sent to the display as a 
pure digital DVI signal at the display's native resolution. The 
result is an extremely clear image with sharper depth and detail, 
free of motion and video processing artifacts. Patented technology 
such as 3:2 Pull-Down with bad edit detection, DCDi, Cross-color 
suppression and TrueLife non-linear enhancement combine to create 
superb results from any display technology: plasma DLP, LCD DILA and 
CRT.

     * Selectable output rates
     * HDTV cross-conversion
     * Analog sources converted to digital DVI
     * Digital DVI and analog RGBHV/YPrPb outputs
     * HDTV transcoding from YPrPb to RGBHV
     * Auto-detection of HDTV or 480P on the Component inputs
     * Aspect ratio control and image shift adjustments
     * Internal test pattern generator
     * HDTV/computer pass-through
     * Compact Single rack space size
     * Infrared and RS232 control

The list price appears to be $5,995; street prices seem to be in the 
range of $3300 - $3500. Quite a bargain, given that Faroudja line 
doubling products selling for upwards of $16,000 in the early '90s 
were a staple of upscale home theater installations. A <$20 Genesis 
chip now outperforms those early Faroudja products.

Regards
Craig
 
 
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