DVI
– a Practical Guide
Draft Version 0.83. July 16, 2003
This guide is my
attempt to capture the collective information on DVI in AVS Forum. Hopefully it
will stem the wasted tide of consumer dollars going into non-DVI devices, and
help forum members in their adoption of DVI.
This guide is
currently in draft form, and I need your help to get it to a level of
completeness and accuracy.
I am in no way affiliated with anyone in consumer entertainment business. The views in this guide are purely my own as a consumer.
Arun Gupta
Contents
DVI brings a
Quantum Jump in Picture Quality
Set Top Boxes
– HDTV Satellite/Cable Receivers and PVRs
PC Graphics
Cards with DVI Output
Links
to Related AVS Forum Threads and Guides
DVI - A Practical Guide: Thread Latest Version of this Document
My unofficial guide to Samsung HLN series: Thread Document
Introduction to DVI
As we change from
analog to digital for everything in consumer electronics, it is inevitable that
connections between our devices also become digital. For audio, this is already fully
underway. For video, DVI (Digital Video
Interface) represents this
inevitable change.
The most important lesson I've learned in 6 months of owning a Samsung DLP TV and few weeks of Bravo D1 player is that analog Component connections are history and digital DVI connections are the only way forward. There is a night and day difference in Picture Quality when we switch from Component to DVI connections. As we move towards all things digital:
Digital PQ Nirvana
= Digital Signal -> Digital DVI Connection -> Digital Display
Digital signals
include SD (Standard Def.) programs, HD (High Def.) programs, DVD playback, or
PC input. A digital display is any fixed
pixel display (LCD, DLP, LCoS, Plasma), as well as HDTV CRT displays.
Let me also
emphasize that DVI is video only. It
does not carry any audio. HDMI will have
both.
For more in-depth
info on DVI, see DVI Overview and this DataPro page.
DVI, however, comes with a big restriction - called HDCP
(High-bandwidth Digital Content Protection).
It is
Within the next
year or so, DVI will evolve into HDMI (High Definition Multimedia Interface), its second generation successor. HDMI
includes audio, has a smaller connector plug, and a bigger distance range. Fortunately, HDMI will be backward compatible
with DVI. See the in-depth section on HDMI – The Evolution of DVI.
DVI brings a Quantum Jump in Picture Quality
It was a surprise to me, and it is a surprise to most people when they first experience a DVD played back through a DVI connection. "Jaw dropping" is the phrase often used, and it describes my reaction. Except in my case I had no prior clue - so it contained shock and confusion as well. My wife kept insisting that the DVD we were playing was high definition. There are hundreds of reactions like mine in this forum, and now there are reviews in many publications attesting to the phenomenal quality difference. See DVI Quotes.
Why is that? DVI is not magically adding quality to your signal, it is Component that has been degrading the signal – we just didn’t how badly.
Component: When you use a component connection, your original digital signal is converted to analog, then it is sent over to the TV and becomes susceptible to noise, then it is converted back to digital by the TV. This dual conversion introduces conversion artifacts, plus the transmission can pick up noise.
DVI: In a DVI connection, the original digital signal is passed to the TV digitally in its original pristine condition.
In the past, when you had poor quality input signal and a poor fidelity TV, you could get by with component connections. Now you have high quality inputs (HD, PC or DVD) and high fidelity digital TVs (even CRT HDTV’s are digital in this context), so the component connection makes no sense. DVI is the only sensible option.
Indeed it is my opinion that HDTV without DVI is an oxymoron. Why go through all the trouble of creating an expensive digital setup, generating a high quality digital signal into a high fidelity digital display, if you are going to throw the analog Component monkey wrench into it.
And until you've switched to DVI, don't look for other culprits for video artifacts - clay faces, dithering, motion artifacts, etc. Find out first how many are actually introduced by your component connection.
Let's move on with DVI.
The State of DVI
Most consumers are not knowledgeable about DVI. Until a few months, I wasn't aware of the impact it could have. This AVS forum represents the most knowledgeable A/V consumers. I'd venture to say that most of us have also been in the dark until recently.
It is much more surprising, however, that most manufacturers are also in the dark. In a recent research in replying to a question on this forum, I was shocked to find out how many $10,000+ recently introduced displays are without DVI support. Satellite and Cable providers, as well set-top receiver and PVR manufacturers also have a mixed scorecard. DVD player vendors have also been a deep state of slumber and are just beginning to wake up.
In fairness to all of us, HDCP and the changeover to HDMI do bring a certain amount of confusion and uncertainty to DVI.
DVI - What We Need to Do
Suggestion General 1: If you are making a new
consumer electronics video item purchase, I strongly urge you to make sure it
has DVI support. Devices with DVI
inputs, such as televisions, should also have analog inputs so that you can
decide at what pace you want to move to DVI.
Suggestion General 2: All new equipment with DVI
inputs must also have HDCP support.
Suggestion General 3: For equipment with DVI outputs,
I think it is OK for consumers to buy ones without HDCP support, although
Suggestion General 4: If you have equipment with
DVI input ports that don’t support HDCP, look for equipment that has a DVI
output but doesn’t enforce HDCP – e.g. Bravo D1 DVD player. Buy them quickly before such devices become
non-existent.
Suggestion General 5: If you have an existing
item with DVI/HDCP support, test this capability as soon as possible. If it doesn’t work as advertised, demand
resolution.
Suggestion General 6: If you have a current A/V
setup that you are happy with, weigh the pros and cons of when you should
switch to DVI for each of your equipment.
Television is of course the first item to switch.
Televisions with DVI Inputs
State of
Note on CRT TVs: Since even a CRT HDTV is first converting the signal to digital for processing, CRT sets also benefit from the switch to DVI - although it may not be to the same extent as fully digital televisions.
Suggestion TV 1: Do not buy a new TV/monitor (over $1000) without
DVI/HDCP input.
Suggestion TV 2: I strongly recommend against buying a fixed pixel
TV (non-CRT) that has a non-standard native resolution. It will make 1x1 pixel mapping impossible,
and you will never achieve the best PQ.
I know this is a tough one, because non-standard resolutions seem to
have proliferated in front projectors, plasmas and some RPTV’s.
Suggestion TV 3: When you are buying a new expensive TV, it is more
than likely that a retail store is displaying the picture through a component
connection – which doesn’t help you much.
My advice is take a DVI equipped DVD player with some good reference
(Superbit?) DVD’s with you to test out the TV.
That way you can also compare television PQ in multiple stores.
Suggestion TV 4: Ideally, televisions should have 3 DVI inputs just
like they generally have 3 component inputs today. No televisions with 3 inputs are currently available,
and very few with 2 inputs. Look for
them starting in 2004. Meanwhile, we
have to use external DVI switches, and they are not quite there yet.
Suggestion TV 5: When you
connect your devices to fixed pixel televisions (LCD, DLP, LCoS, Plasma), it is
very important that you try to get one to one pixel mapping for best PQ.
One to One Pixel Mapping: If you have a fixed pixel television, then you will gain significantly in picture quality if you can get one to one pixel mapping to the NATIVE resolution of your TV. Of course, this is only possible if the original signal is the same as the native resolution. For example, if you have a 1290x720 pixel TV, you should make sure that an ABC 720p broadcast ends up in your TV without any scaling and 1x1 pixel mapped. Same is true for PC inputs. If your signal is going to be scaled, you want to make sure that it is scaled ONLY in one place, the place that has the best scaler.
DVI Compatibility Table for Televisions:
Notes: (This is work in progress.)
· This is not an exhaustive list, only those reported to work by forum members.
· Your help is needed here in checking its accuracy, completing the sets listed, and in listing more sets.
· Test successful column: The TV worked with one or both DVI equipped players and it produced a satisfactory picture in at least one resolution. There may be many caveats attached to this functioning.
· 1x1 pixel mapping column: At least 1 player output resolution could be matched one to one with the fixed pixel TV native resolution. Doesn't apply to CRT televisions.
Televisions with DVI
Support
|
Manufacturer and Set |
AVS Links Esp. on DVI support |
TYPE |
DVI Inputs |
HDCP |
Test Successful? |
1x1 Pixel Mapping |
|
Samsung TXN3098WHF |
CRT |
Yes |
|
Yes - Br D1 |
N. A. |
|
|
Sony 34XBR800 |
|
CRT |
Yes |
Yes |
Yes - Br D1 Yes - S 931 |
N. A. |
|
|
|
|
|
|
|
|
|
|
FP – DLP1 |
Yes |
|
?? |
No |
|
|
FP – DLP1 |
Yes |
Yes |
Yes - Br D1 Yes - 931 |
No |
||
|
|
FP – DLP1 |
Yes |
|
Yes - Br D1 |
No |
|
|
|
FP – DLP1 |
Yes |
|
No - Br D1 |
No |
|
|
|
FP – DLP1 |
Yes |
|
No - Br D1 |
No |
|
|
|
|
|
|
|
|
|
|
|
FP – DLP2 |
Yes - 2 |
|
Yes - Br D1 |
Yes |
|
|
|
FP – DLP2 |
Yes |
Yes |
Yes - Br D1 No - S 931 |
Yes |
|
|
|
FP – DLP2 |
Yes |
|
Yes - Br D1 |
Yes |
|
|
|
FP – DLP2 |
Yes |
|
Yes - Br D1 |
Yes |
|
|
Toshiba Mt8 |
|
FP – DLP2 |
Yes |
Yes |
?? - Br D1 Yes - S 931 |
Yes |
|
|
|
|
|
|
|
|
|
|
|
FP - LCD |
Yes |
No |
Yes - Br D1 |
|
|
Panasonic
PT-L300U |
|
FP - LCD |
Yes |
|
No - Br D1 |
|
|
|
FP - LCD |
Yes |
No |
Yes - Br D1 |
No |
|
|
Sony HS10 |
|
FP - LCD |
Yes |
Yes |
Yes - Br D1 Yes - S 931 |
Yes |
|
|
FP - LCD |
Yes |
No |
Yes - Br D1 |
No |
|
|
|
FP - LCD |
Yes |
|
Yes - Br D1 |
Yes |
|
|
|
|
|
|
|
|
|
|
Sony 30 inch LCD |
|
LCD |
Yes |
Yes |
?? - Br D1 Yes - S 931 |
|
|
|
|
|
|
|
|
|
|
Fujitsu P50XHA10US |
Plasma |
Yes |
|
Yes - Br D1 |
|
|
|
Fujitsu
PDS-5001 |
|
Plasma |
Yes |
|
No - Br D1 |
|
|
Pioneer
503CMX plasma (w/5002 input card). |
|
Plasma |
Yes |
|
?? |
|
|
Pioneer 433CMX (w/A303
DVI Input card) |
Plasma |
Yes |
Yes |
Yes - Br D1 Yes – S 931 |
|
|
|
Pioneer 503CMX (w/A303
DVI Input card) |
|
Plasma |
Yes |
Yes |
Yes - Br D1 Yes – S 931 |
|
|
Sony KE32TS2 |
|
Plasma |
Yes |
|
Yes - Br D1 |
No |
|
Sony KE-50XBR900 |
|
Plasma |
Yes |
Yes |
Yes - S 931 |
|
|
|
|
|
|
|
|
|
|
|
|
RP - CRT |
Yes |
Yes |
?? - Br D1 Yes - S 931 |
N. A. |
|
JVC 56" i'Art WP30 |
|
RP - CRT |
Yes |
|
Yes - Br D1 |
N. A. |
|
Pioneer Elite Pro730HD |
|
RP - CRT |
Yes |
Yes |
Yes - S 931 |
N. A. |
|
RCA
HD65W140, HD61W140, HD52W140 |
|
RP - CRT |
Yes |
Yes |
|
N. A. |
|
Sony KP46wt500 |
|
RP - CRT |
Yes |
|
Yes - Br D1 |
N. A. |
|
Toshiba 57HDX82 |
|
RP - CRT |
Yes |
|
Yes - S 931 |
N. A. |
|
|
|
|
|
|
|
|
|
Samsung HLN - all sizes |
RP – DLP2 |
Yes |
Yes |
Yes - Br D1 Yes - S 931 |
Yes, 720p TV-Wide |
|
|
Sony Grand Wega
60XBR800 |
|
RP - LCD |
Yes |
|
Yes - Br D1 |
No |
|
Toshiba 57HLX82 |
|
RP - LCoS |
Yes |
|
Yes - Br D1 No - S 931 |
Yes |
DVD Players with DVI Outputs
When I bought my Samsung DLP TV, I thought that the main PQ
pleasure will come from watching HDTV.
The most unexpected and pleasant surprise of owning this TV has been
discovering the hidden PQ gem inside the regular old DVD’s available
today. By using a DVI equipped player
with my TV, most of these DVD’s now appear near high definition to me. I am now discovering Superbit DVD’s, which
are raising picture quality even further.
I can honestly say that I am in no hurry for HD-DVD. I want to enjoy the plethora of DVD’s
available today in near high definition.
And the only extra investment needed was a ~$200 DVD player.
Suggestion DVD 1: If you have already invested
thousands of dollars in a TV with DVI input, don’t skimp on the DVD
player. Hurry and buy a DVI equipped
player. If you don’t like the current
crop, you shouldn’t have to wait too long.
By fall ’03 many more DVI players should become available. An alternative is to use your HTPC as a DVD
player.
Suggestion DVD 2:
If you are about to buy an expensive new DVD player anyway, I recommend against
buying one without DVI output, even if
your current TV doesn’t have DVI input.
Suggestion DVD 3: If your television has DVI
input but it doesn't support HDCP or you are not sure, hurry and buy Bravo D1
before they start enforcing HDCP. You
should of course continue to respect the copyrights of DVD makers.
DVI Equipped DVD Players
|
Manufacturer and Player |
Links |
Street Price |
DVI Output |
HDCP Enforced? |
|
Bravo D1 by V Inc. |
See below |
$199 |
Yes |
No |
|
Store, See
below |
$249 |
Yes |
Yes |
|
|
$220 |
Yes |
No ?? |
||
|
$1450 |
Yes |
|
||
|
|
|
Yes |
|
|
|
Tag
Mclaren DVD32R/DVD32FLR with the PSM192 module |
|
Yes |
|
Links to DVI Equipped Players:
Bravo
D1 vs. Samsung 931 shoot-out
Buy
Bravo D1 or wait for Samsung 931?
Bravo D1
You can
buy it from: www.vinc.us
Bravo
D1 DVI Compatibilty List
Bravo
D1 Review vs. Denon 3800 DVD
Bravo
D1 Review on HomeTheaterHiFi.COM:
Samsung HD 931
You can buy it many retailers.
Samsung
HD931 Review in USA Today: (
HD931 problem thread (note this really talks about DHCP compatibility issues)
Set Top Boxes – HDTV Satellite/Cable Receivers and PVRs
Unfortunately, many HDTV receivers today don’t support DVI. For DirecTV, there is a good choice of boxes that support DVI. For Dish network, the currently shipping Dish 6000U doesn’t support but the soon to be released boxes do -- Dish 811 receiver and 921 PVR. Most cable companies are at the very early stage of introducing boxes with DVI output. The surprise is that the Zenith 230 OTA HDTV PVR – just released – doesn’t support DVI.
Suggestion STB 1: DVI output should be an
important factor in deciding your service provider. Fortunately, all of them are now changing to
DVI.
Suggestion STB 2: If you have a choice of boxes,
definitely get the one with DVI output.
If your cable/satellite provider is just introducing DVI equipped boxes,
become the first in line to get one.
Set Top Boxes and
PVR’s for Satellite, Cable and OTA Reception
Note this is not an exhaustive list. This is very much a work in progress.
Go to this STB
Synopsis Thread for latest on Set top boxes. Other STB Threads: HDTV
FAQ, STB
Thread, Dish,
DirecTV
.
|
Manufacturer
and Box |
Status |
For |
DVI Output |
HDCP Enforced? |
AVS Threads |
|
Motorola 5100 |
|
Cable |
? |
|
|
|
Pace ?? – coming soon |
|
Cable |
Option ? |
|
|
|
Pioneer Voyager 3510HD
|
coming soon |
Cable |
Option ? |
? |
|
|
Scientific |
|
Cable |
No |
|
|
|
Scientific |
coming soon |
Cable |
Option ? |
|
|
|
|
|
|
|
|
|
|
Hughes HIRD-E86 |
|
DirecTV, OTA |
No |
|
|
|
LG LSS-3200A |
coming soon |
DirecTV, OTA |
Yes |
|
|
|
Mitsubishi SRHD-5, SR-HD400,
SR-HD500 |
Discontinued |
DirecTV, OTA |
No |
|
|
|
Panasonic TU-HDS20 |
Discontinued |
DirecTV, OTA |
No |
|
|
|
Samsung SIR-TS160 |
|
DirecTV, OTA |
Yes |
Yes |
|
|
Sony SAT-HD200 |
|
DirecTV, OTA |
Yes |
Yes |
|
|
Sony SAT-HD300 |
coming soon |
DirecTV, OTA |
|
|
|
|
Toshiba DST 3100 |
|
DirecTV, OTA |
Yes |
Yes |
|
|
Zenith HD-SAT520 |
|
DirecTV, OTA |
Yes |
Yes |
|
|
|
|
|
|
|
|
|
Dish 6000U
HDTV Receiver |
|
Dish, OTA |
No |
- |
|
|
Dish 811
HDTV Receiver |
coming soon |
Dish, OTA |
Yes |
Yes |
|
|
Dish 921
HDTV PVR |
coming soon |
Dish, OTA |
Yes |
Yes |
|
|
JVC TU-PVR9000 PVR |
coming soon |
Dish, OTA |
Yes |
Yes |
|
|
|
|
|
|
|
|
|
LG LST-3100A |
June 2003 |
OTA |
Yes |
Yes |
|
|
LG LST-3410A PVR |
Oct 2003 |
OTA |
Yes |
Yes |
|
|
LG LST-3510A DVD+Rcvr |
|
OTA |
Yes |
Yes |
|
|
Panasonic TU-DST50 |
|
OTA |
No |
|
|
|
Panasonic TU-DST52 |
|
OTA |
No |
|
|
|
Pioneer SH-D505 |
|
OTA |
No |
|
|
|
Samsung SIR-T150 |
|
OTA |
No |
|
|
|
Samsung SIR-T151 |
|
OTA |
No |
|
|
|
Samsung SIR-T165 |
|
OTA |
Yes |
Yes |
|
|
Samsung SIR-T351 |
Summer 2003 |
OTA |
Yes |
Yes |
|
|
Sony SAT-HD100 |
Discontinued |
OTA |
No |
|
|
|
Toshiba DST3000 |
Discontinued |
OTA |
No |
|
|
|
Zenith DTV1080 |
Discontinued |
OTA |
No |
|
|
|
Zenith HDV420 |
|
OTA |
No |
|
|
|
Zenith HDR
230 HDTV PVR |
|
OTA |
No |
|
|
PC Graphics Cards with DVI Output
I use my 61 inch TV more as a large monitor than as a TV. It is used for couch computing, web browsing, PC gaming, photo slide shows, mp3 music playback. It also serves as a backup DVD/ stored media player. Using a VGA connection, I achieve a surprising good PQ. DVI, however, provides another quantum jump.
Suggestion PC 1: Buy HTPC graphics cards only
with both VGA and DVI outputs. I
personally have very good experience with ATI cards and they are favored in
this forum.
Suggestion PC 2: When you connect your HTPC to a
fixed pixel TV using DVI, make sure that you set the graphics card resolution
to the native resolution of the TV. To
do that, you may have to use Powerstrip.
Most ATI and nVidia cards today support both VGA and DVI. How well they comply with DVI is another story -- see this developing story in ExtremeTech.
DVI Cables
Suggestion Cable 1: The cables you need to make your digital connections are DVI-D, Male to male – and they should cost $20-$30.
You can buy single link or dual link cables. Single link is fine for most connections, dual link is necessary for higher resolutions only.
Note that DVI-D is what you need for your purely digital connections (DVI-A is for analog, and DVI-I supports both digital and analog.)
Since DVI-D is a digital connection, there is no degradation of the signal due to noise. So you don’t need to buy expensive cable to assure quality of signal transmission. But the cable quality could limit the range of connection, see DVI Overview section.
Cables up to 5 meters (16 feet) are commonplace. Cables up to 30 feet can be obtained, but somewhere over 5 meters is the range of ordinary DVI connections. Some members have reported no problems with 30 feet runs using a 9 meter BetterCables DVI cable. If you get a picture with sparklies or no picture at all, you have exceeded the length limit. For much longer connections, up to about 500 feet, you can get DVI over optical fiber. It is significantly more expensive, costing up to $3000.
Some on-line sources
for DVI cables
http://www.pacificcable.com/dvi.htm
http://www.bettercables.com/dvicables.html
http://www.cablestogo.com/resources/dvi.asp
http://www.cable4pc.com/dfp.htm#connector
http://www.datapro.net/dvi.html#Page05
Some forum members have also reported buying DVI cables at e-bay.
DVI Switching
So you have a television that takes in DVI, and you have 3
devices that output DVI. How do you
connect them? Traditionally, either your
TV had enough inputs or you used an A/V receiver to do this task. Well, televisions with multiple DVI inputs
or A/V receivers with DVI switching are some years out. So meanwhile you need a DVI switch.
There are some DVI switches available today, but nothing satisfactory yet. There is hope that we shall have a DVI switch soon. Meanwhile, we have to live with switching cables.
DVI Switches
The ideal DVI switch should have:
-
Switch
- Passive switching so that HDCP compliance is not an issue
- No degradation of the signal whatsoever
- Cost < $250 street.
- As a plus point, it should be controllable from universal remote controls
This is one of the unsolved problems in using DVI connections today, but hopefully not for very long.
DVI switches today cost about $500 (Gefen, Lindy, Adderview). In this forum, only Gefen switch seems to have been tried with success – and there are questions regarding its HDCP compliance. Belkin has also announced DVI switches -- OmniView SOHO Series 2 and 4-Port KVM Switches -- and they look promising.
Suggestion Switch 1: If you are in a hurry to get a
switch and can afford it, get the Gefen switch.
Otherwise wait until a reasonable switch is available, and use manual
switching.
DVI Switch?
http://www.avsforum.com/avs-vb/show...threadid=269991
Calling
All DVI Switcher Boxes !!
http://www.avsforum.com/avs-vb/showthread.php?s=&threadid=278521
Switching Cables
Manually
Until a satisfactory DVI switch is available, manually switching between multiple DVI devices is becoming quite a hassle. So I am devising just an easier way of switching DVI cables while we all wait for a DVI switch that works and is reasonably priced.
Suggestion Switch 2: Connect a 2 meter DVI extender
cable (DVI-D, male to female, single link) to the back of the TV. Place its
free female connector to an easily accessible location near the TV. For each
input source, say a Bravo D1 DVD player, connect a DVI cable (DVI-D, male to
male, single link) and place its free male connector near the free female
connector so that it can be easily connected and disconnected. Label each
connector. Switch cables as needed.
When you get a DVI switch, you can use the same cables – just replace manual switching with the switch device.
Technology Overviews
DVI Technology Overview
A DVI (Digital Video Interface) connection sends video signal digitally in an uncompressed format from a transmitter (e.g. a DVD player) to a receiver (e.g. a TV).
DVI specification is created by the Digital Display Working Group (DDWG).
The specification is available here.
Types of DVI
A Cable may be DVI-D or DVI-I, single or dual link. Most connections need DVI-D, single link, Male to Male.
DVI-D vs. DVI-I: To make things really confusing for us, there are three different types of DVI connections:
- DVI-D for digital signals. Of course, our interest here is in DVI-D.
- DVI-A for analog signals (equivalent to and easily converted to RGB/VGA)
- DVI-I for both.
A DVI-D cable can carry only a digital connection. DVI-I cables are more versatile, and carry both types of signals.
Single vs. Dual Link: The DVI-D (as well as DVI-I) format is available in either Single or Dual link connectors. These cables send information using a format called TMDS (transition minimized differential signaling). Single link cables use one TMDS 165Mhz transmitter, while dual links use two. Single link can support up to 1280 x 1024 whereas dual link can go up to 1920 x 1080 resolution.
Cable Length: Up to 5 meter cables are commonly available for $30 or under. Longer cable runs up to 30 feet are harder to find. Much longer runs use optical fibers and are very expensive.
Quote from amillians:
Depending upon your equipment, a 25' DVI cable can be all
but guaranteed to introduce artifacts (AKA sparklies) into the picture...just
because the signal is digital in nature doesn't mean that DVI either
"works" or it "doesn't work."
Although there are no hard and fast rules with regards to
DVI-D cable lengths, at the max single link pixel clock, the generally accepted
cable length is 5m best case...the lower the pixel rate (e.g., 1080i/60,
800x600/60, 480p/60), the longer the DVI cable can be, ceretus paribus.
From a total system perspective, the maximum "safe" DVI cable length
is a function of DVI cable construction (copper, silver clad, etc.), DVI TX/RX
chipset performance and pixel clock (in order of impact).
That said, assuming no egregious construction/build
quality issues, a $20 6' DVI cable should work just as well as a $200 6' DVI
cable; however, there could be observable differences in 20'+ cables, depending
upon the setup...a 20' cable that works fine for someone using STB X at 720p/60
may show artifacts using STB Y at 1366x768p/60. Just make sure that whatever
you buy, you can return if it doesn't perform--lots of places are hawking 30'
DVI cables that are "guaranteed" to work, albeit only at 640x480p/60
(the lowest DVI pixel clock speed) if you press them for details.
DVI Links
http://www.datapro.net/dvi.html#Page05
http://www.matrox.com/mga/products/...ackgrounder.cfm
http://www.intechlabs.com/ourfaqs/tv/dvi.htm
What
does DVI stand for and what does it do?
http://www.avsforum.com/avs-vb/showthread.php?s=&threadid=277923
Why Use
DVI vs. Component- My Rant:
http://www.avsforum.com/avs-vb/show...838#post2391838
But DVI
comes with HDCP, which may be a problem:
http://www.avsforum.com/avs-vb/show...767#post2403767
DVI vs. Firewire
Firewire is another type of digital connection.
- DVI is a point-to-point interface for UNCOMPRESSED video between a source device (PC, STB, DVD-player) and a display device. It requires less logic in the display, and is therefore more suited to connecting display devices.
- Firewire is a networkable interface suitable for COMPRESSED multimedia streams between many devices, including PCs, displays, STBs, D-VHS recorders, and DVD players. It requires less logic in a recording device and therefore it is more suited for recording devices.
Firewire's origin are from the computer industry, specifically Apple. Its competitor from the PC side is USB. Firewire was offered in early digital consumer electronic devices that needed to connect to computers.
DVI standard originated with Intel and has been widely accepted as the digital connection in the consumer electronics industry. DVI standard is also enabled (or burdened depending on your perspective) with HDCP for content protection.
As consumers, some of us may prefer Firewire because it does not come with HDCP. This is, however, just wishful thinking. There is no indication that Firewire will be adapted for display devices. Its role is primarily in recording devices, and even there its not clear whether electronics industry will embrace it because of copy protection issues.
Firewire has its own version of content protection, known as
DTCP or "5C".
HDCP Overview
HDCP enforces copyrights of content that flows through DVI connections. HDCP is essentially a way to get the device makers follow the wishes of content providers. Device makers must get licenses that will equip their devices with licensed keys. These keys will enable them to receive and display encrypted content. To get the license, they agree to honor flags in the content that will generally limit the storage and re-transmission of content.
HDCP was originally developed by Intel Corporation. It is now published and maintained by Digital
Content Protection, LLC (http://www.digital-cp.com/)
As we go forward with HDCP, two major issues become of concern to us consumers.
Device compatibility issue: we are already seeing an
incompatibility between HDCP enforcing transmitters and receivers that are not
HDCP enabled. Now as the standard evolves, each generation will continue to see
the same compatibility problem.
Fair use issue: Following are the encoding rules proposed
to FCC in their original language:
“- Subscribers may make at least one copy for their private and personal use of any digital program sold by monthly subscription.
- Programs sold by the one (PPV, VOD and SVOD) may be marked as copy never, but cable subscribers may pause or store them (on PVR’s) for 90 minutes (or longer, if agreed to by the program provider).
- These devices may not permit content to flow only through a particular type of output. (This prohibition on “selectable output controls” will be effective when the FCC makes the restriction applicable to all MVPDs.)
- Free over-the-air broadcast signals may be copied freely, and may not be reduced in resolution (“down-res’d”) when output from unprotected high-definition analog ports.
- The proposed rules are neutral on down-resolution of all other content, leaving it to the FCC to decide how to address the “analog hole” through which high-quality high-value programming passes in unprotected format.”
We don’t know whether these rules will be passed as proposed, and we don’t know how exactly they will be implemented if passed.
There is also some concern whether HDCP will actually be effective, or
will it have to be replaced by something even stronger. If HDCP continues to cloud the issues, will
it potentially hamper the adoption of DVI?
HDCP Links
Digital Content Protection, LLC
HDCP Specification
http://www.digital-cp.com/data/HDCP...ationRev1_1.pdf
HDCP Upstream protocol on personal computers
http://www.digital-cp.com/data/hdcp...ecification.pdf
HDCP: what it is and how to use it - Jim Lyle, Silicon Image Inc -- EDN,
http://www.e-insite.net/ednmag/cont...ages/209091.pdf
HDMI - The Evolution of DVI
In a year or so, DVI will change over to HDMI. HDMI extends the DVI standard and adds audio to it. Functionally it is DVI for Video + HDCP for protection + Audio. It also uses a smaller more convenient connector and has a bigger range. It can also carry more types of video signals. It is expected to be available in devices starting in 2004.
It is supposed to be backward compatible with DVI as well as existing audio standards. For example, you will be able to take separate DVI video + audio outputs from devices, combine them, and feed it into a HDMI port on a TV. Or you can take HDMI output from a device, split it and feed the DVI part to a TV and the audio part to a receiver.
HDMI definition
from Whatis.com:
"HDMI (High Definition Multimedia Interface) is a specification that combines video and audio into a single digital interface for use with digital versatile disc (DVD) players, digital television (DTV) players, set-top boxes, and other audiovisual devices. The basis for HDMI is High Bandwidth Digital Content Protection (HDCP) and the core technology of Digital Visual Interface (DVI). HDCP is an Intel specification used to protect digital content transmitted and received by DVI-compliant displays.
HDMI supports standard, enhanced, or high-definition video
plus standard to multi-channel surround-sound audio. HDMI benefits include
uncompressed digital video, a bandwidth of up to 5 gigabytes per second, one
connector instead of several cables and connectors, and communication between
the video source and the DTV. HDMI development is overseen by the HDMI Working
Group that includes Sony,
HDMI Links
Here is the main link to HDMI, go to FAQ section:
An article by Silicon Image in Widescreen review:
http://www.siliconimage.com/documen...HDMI70lores.pdf
A column in Digital Cinema Report:
http://www.digitalcinemareport.com/hdmicolumn.html
Sigma designs, covers DVI and HDMI
http://www.sigmadesigns.com/support/DVI_HDMI.htm