HDTVs are built to display HD material, but SD television signals were designed for [older] CRT television
sets. While most HDTVs have on-board signal processing for viewing normal television, it's often a compromise of
quality and cost.
Dscaler is free software that
turns a normal PC into a very high end video scaler. NTSC and PAL video are both delivered in interlaced format -- in a
nutshell, half of each video frame is drawn at a time, NTSC drawing the screen 60 times each second, but delivering 30
frames per second. We'll use Dscaler to grab the incoming television signal, de-interlace it and scale it for our
display. (In our case, a projector with a 103 inch wide screen.) While this How-To covers using windows
software, die-hard linux fans should check out tvtime at http://tvtime.sourceforge.net
Update: ffdshow http://ffdshow.sourceforge.net. can make use of the dscaler dlls, but still
runs on windows. [Thanks Larry]
For this project you will need:
Before hunting down the hardware for this project, it's a good idea to take a look at your existing setup and determine
We'll be getting our video signal
from either the TiVo or the laserdisc player. (Don't laugh too hard, certain movies can only be found in their original
form on LD.) Both have S-video outputs, so we wanted a capture card with s-video input. Our ATI TV-Wonder PCI card has a
single s-video input, so we use our surround receiver to switch between the TiVo and Laserdisc. Since the receiver
handles all the sound switching, we don't use any of the sound features of the capture card.
Don't mistake the capture cards that work with Dscaler for the more expensive hardware encoding type. The
type of card you need is usually available for under $50. There's a large number of manufacturers that make cards with
right chip set. The basic Hauppauge WinTV or ATI TV-Wonder cards both work great. If you already have a card, you might
want to check the supported cards
Dscaler doesn't need much CPU, but it does want a decent video card. The HTPC for the projector is a 2GHz Pentium 4
with a lowly GeForce4 mx AGP video card, and 1GB of ram running Windows XP.
Install your capture card
and the latest drivers. Download Dscaler 4
(not 5). The
installer is standard fare. When Dscaler is started for the first time, the General Hardware Setup screen will
Select the appropriate options for your
setup. If you're using fairly recent hardware, these probably won't make a big difference in performance.
normal use, Dscaler will be running fullscreen. When it is, the usual File menus won't be visable. All of these menu
items may be accessed by right clicking anywhere on the Dscaler window, fullscreen or not. Right click and select View,
then Full Screen. Now Dscaler will run fullscreen every time it's started up.
To get set up Dscaler needs to know which capture card it's supposed to be using. Right click or use the file
menu to select sources, and choose your card.
You may need to adjust the
settings for the card you're using. Right click and choose "Bt Card" then "Setup Card / Tuner". If
you're going to use the card to tune in cable or over the air signals, you may need to select the tuner chip that's on
your card to get it working properly. For our setup, the default "No Tuner/Unknown" option worked fine.
Now the input for the video needs to be
selected. Right click and choose Bt Card, then your input choice.
The aspect ratio
of your video source needs to be set. Normal television is 1.33 or 4:3 format. Right click, choose AspectRatio, then 4:3
Finally, the the aspect ratio of
your display needs to be set. If you have a recent HDTV, it's probably 16:9 or 1.78. Those with projectors are
dependent on their screen. Our screen is a 2.35:1 "Scope" size. If your video appears too wide or narrow, you
may have your display aspect ratio set incorrectly.
Now it's time to enjoy the
new higher quality video. The results on our setup were impressive. Be sure to try out the various de-interlace
algorithms under the Deinterlace menu. Our favorite is Video (Greedy, High Motion).
How well does it
This pair of screen shots is from the deinterlace website. They are taken from a VHS copy of Titanic
by by Mark Rejhon.
Left is without Dscaler, right shows
the impressive results of using Dscaler.
If you're interested in a dedicated hardware solution, DVDO
hardware seems to have a good reputation. Check them out at http://www.dvdo.com/