What is "HD"?HD stands for High Definition. HD is really just a resolution standard for your TV... they list these resolutions by the vertical pixel count and whether or not the picture is interlaced or progressive scan.
Progressive Scan vs. Interlaced
Imagine the picture on your TV is drawn like your computer's printer, one line across at a time... a progressive scan picture draws these lines in order [1,2,3,4,5...] while and interlaced picture does the odds first then goes back and does all the evens [1,3,5,7,9.......then back to the top and 2,4,6,8........] It's generally considered that progressive scan image is superior in quality to a interlaced image of equal resolution.
"HD Ready" vs. "HD Built-In"
HD Ready simply means that the display is incapable of accecpting a cable TV or broadcast signal and extracting HD content from it. That is the ONLY thing it means. In other words it does not have built in tuner so you'll need a "cable box" or "HD Antenna" to watch TV shows from cable and over the air in HD. In most cases cable providers have a specialized box anyway meaning even if you had a display with an "HD Tuner Built In" it wouldn't be used anyway. This has NO effect on the TV's compatability with consoles, DVD players or anything other then Cable and Broadcast television signals.
The Aspect Ratio is basically the relationship in length between the width and the height of the video. There are two basic aspect ratios. Widescreen which has a ratio of 16:9 and FullScreen which has a ratio of 4:3. If you do some simple math it can be deduced that widescreen is 1/3 wider than a Fullscreen counterpart of the same height.
There are 3 formats of TV... SDTV, EDTV and HDTV
SDTV is Standard Definition TV which is 480i
So the image is interlaced with a 640x480 resolution (or 720x480 if it's widescreen)
EDTV is Enhanced Definition TV which is 480p
So it's similar to SDTV except the image is progressive scan instead of interlaced
again it's 640x480 for square screens and 720x480 for wide screens
HDTV is High Definition TV which can be either 720p or 1080i (and eventually 1080p)
1280x720 progressive scan and 1920 x 1080 interlaced respectively
Depending on who you talk to some will claim that 720p is better than 1080i and visa versa. Most TVs will only support one or the other. When 1080p becomes an official standard there will be no contest. However it is not yet an official standard as recognized by the Consumer Electronics Association. These formats are available in WIDESCREEN ONLY.
Composite - Often referred to as "RCA" cables; the lowest quality cable you can get, this is a single pin Yellow dongle cable typically found alongside the Red and White stereo audio connectors. The entire video signal is contained on a single wire within this cable. This cable only supports SDTV.
S-Video - S-Video is a significant improvement over Composite; Luminance (Contrast Information) and Chrominance (Color information) have been separated to improve clarity. This cable also sports a yellow dongle and is typically found along side the red and white audio connectors. This cable only supports SDTV.
Component - A dramatic improvement over S-Video and Composite this breaks down the signal even further for greater quality. This is a set of 3 cables with Red Green and Blue dongles that look similar to the composite connector. Despite the colors being Red Green and Blue in the NTSC standard they aren't actually broken down color wise like that. This cable supports SDTV, EDTV, and HDTV.
RGB - This is an old school format sometimes the connector looks like a VGA computer connector sometimes it it is split out over 3 cables colored Red Green and Blue with BNC type connectors (push on a twist lock). Unlike Component, these cables actually represent Red Green and Blue. This Cable supports SDTV, EDTV and various computer resolutions.
SCART -SCART stands for "Syndicat des Constructeurs d’Appareils Radio Recepteurs et Televisieurs" (again French). Scart Carries both Analog Audio (see audio section below) As well as Composite Video and can be configured to carry either RGB Video or S-Video (S-VHS) type signals all in the same cable. SCART cables support SDTV and sometimes (although rare) EDTV, and HDTV signals. SCART cables and connectors are available in Europe and other PAL countries as well as Japan.
VGA - I'm sure you're familiar with VGA, VGA is very similar to RGB except not only are the colors broken down separately but the vertical and horizontal syncs are broken down as well. This is only ever found an single cable with a 15 pin connector (usually Blue). This Cable supports various computer resolutions
DVI - DVI is the first True Digital Interface. All previously mentioned cables are analog video data while DVI supports digital video data. There are 2 versions of DVI cables DVI-I and DVI-D. DVI-I supports both analog and digital data while DVI-D support ONLY digital data. The analog data that can travel through a DVI-I connector is the same as VGA. This cable typically has a narrow wide White connector that looks like a squashed version of a VGA connector. If you have a True Digital video screen such as a DLP projector or LCD TV (or LCD computer monitor) DVI-D is the purest video connector for you, This Cable supports SDTV, EDTV, HDTV as well as computer resolutions.
HDMI - The king daddy of them all This cable is essentially a smaller version of the DVI-D connector with Digital Audio built in as well(see below). A single Hi-Definition cable for Audio and Video. This will most likely be the cable standard of choice for a while. This Cable also supports SDTV, EDTV, and HDTV
What's the Best Video Format to use?
In general the pecking order of the above format is as follows:
RF (Cable) < Composite < S-Video (SVHS SCART) < Component < RGB (RGB SCART) < VGA (DVI-A) < HDMI (DVI-D)
You may see listings like "5.1" or "7.1" but what does it actually mean? The number before the point refers to the number of "satellite" speakers, which are typically cover the mid to high sound range. The number after the point refers to the number of low frequency speakers, typically sub-woofers. It is generally accepted that if no sub-woofer is being used the satellite speakers are outputting the full range. So if you were to see:
2.0 -front-left and front-right
2.1 -front-left, front-right, and sub-woofer
3.0 -front-left, front-right, and front-center
3.1 -front-left, front-right, front-center, and sub-woofer
4.0 -front-left, front-right, front-center, and rear(two speakers with identical outputs)
4.1 -front-left, front-right, front-center, rear(two speakers with identical outputs), and sub-woofer
5.0 -front-left, front-right, front-center, rear-left, and rear-right
5.1 -front-left, front-right, front-center, rear-left, rear-right and sub-woofer
6.1 -front-left, front-right, front-center, rear-left, rear-right, rear-center, and sub-woofer
7.1 -front-left, front-right, front-center, rear-left, rear-right, rear-center(two speakers with identical outputs), and sub-woofer
Why only one sub woofer?
Low frequency noises are "non-directional" meaning that the human ear cannot typically determine the direction in which the sound is coming from. Under this theory it shouldn't matter where we place the sub woofer or how many sub woofers we have as the output would generally be the same. If you can easily tell the direction in which your subwoofer's sound is coming from your system either needs to be adjusted or upgraded.
Monaural (Mono or Phono) [1.0]
This is a 1 channel analog sound source. The full name is Monaural but it's often called Mono or Phono for short. Mono is obviously derived from Monaural but phono is derived from phonograph (a record player) which only has a single channel output.
Stereo [2.0 or 2.1]
This is a 2 channel analog sound source. It is probably the most frequently used today. The sub-woofer channel (if used) is "created" by the decoding device as there is no data in the source material to identify what sounds should be sent to the sub-woofer.
Dolby Pro Logic [3.0, 3.1, 4.0 or 4.1]
This is a 3 or 4 channel analog sound source. Dolby Pro Logic basically encodes the signals for front-center and rear within an analog stereo signal. A Pro Logic decoder then expands the stereo signal by looking at differences in the left and right speaker's signals to extrapolate what sounds should be coming out of the front-center and rear channels. If the receiving devices does not support Pro Logic decoding it will output only stereo sound. Despite the fact that it only has a single rear channel two speakers are typically used in the rear and their outputs are identical. Again, the sub-woofer channel (if used) is "created" by the decoding device as there is no data in the source material to identify what sounds should be sent to the sub-woofer.
Dolby Pro Logic II [5.0 or 5.1]
This is a 5 channel analog sound source. Dolby Pro Logic II uses the same idea as the encoding/decoding methods as the aforementioned Dolby Pro Logic with the exception that the rear channels are now independent.
Dolby Pro Logic IIx [7.0 or 7.1]
This is a 7 channel analog sound source. Dolby Pro Logic IIx uses the same idea as the encoding/decoding methods as the aforementioned Dolby Pro Logic with the exception that there is an extra set of independent rear channels bringing it to full 7.1
Dolby Digital 5.1 [5.1]
This is a 5 channel digital sound source. Unlike Dolby Pro Logic each of the 5 satellite channels as well as the sub-woofer channel are encoded independently and remain completely independent throughout the system.
DTS (Digital Theater System) [5.1]
This is a 5 channel digital sound source. Similar To Dolby Digital 5.1 each of the 5 satellite channels as well as the sub-woofer channel are encoded independently and remain completely independent throughout the system. DTS uses less compression than Dolby Digital 5.1 and because of this is often considered a superior format. It's important to note that DTS is not officially supported by the DVD format which is probably why not many DVDs use it.
Dolby Digital EX [6.1 or 7.1]
This is a 6 channel digital sound source. Similar to Dolby Digital This features the addition of a rear center channel. In some cases the rear-left and rear-right channels are moved forward to become center-left and center-right channels and the rear center is broken into two rear channels to make 7.1
DTS-ES [6.1 or 7.1]
This is a 6 channel digital sound source. Similar to Dolby Digital EX.
DTS:Neo6 [6.1 or 7.1]
This is a 6 channel analog sound source. Similar to DTS-ES and Dolby Digital EX in terms of speaker setup but similar in encoding/decoding to Dolby Pro Logic II.
Patch Cables (RCA)
Patch cables are the most common type of analog audio connection. One RCA patch cable is required for a mono signal. Two RCA patch cables are required for Stereo, Dolby Pro Logic, Dolby Pro Logic II, and DTS:Neo6. In some instances where no particular multi channel encoding format is used (like in SACD and DVD-A devices) a single RCA patch cable might be used for each individual channel.
SCART Carries both Analog Audio As well as various video signal (see video section above). SCART cables have 2 way analog audio, meaning it can send and accept audio signals at the same time. SCART supports the same audio formats as RCA patch cables. SCART cables and connectors are only available in Europe and other PAL countries and Japan.
Coaxial is the most common type of digital audio connection. It uses the S/PDIF (Sony/Phillips Digital Interface) standard to transfer the digital information. A Coaxial connection is essentially a single RCA patch cable that transfers all audio information digitally through a single cable. This format supports Mono, Stereo, Dolby Pro Logic, Dolby Pro Logic II, DTS:Neo6, Dolby Digital 5.1, DTS, Dolby Digital EX, and DTS-ES
Optical is very similar to Coaxial in that it also uses to the S/PDIF format to transfer digital audio data except rather than using an RCA patch cable it uses a fiber optic Toslink cable. This means that rather than the digital signal being transfered with electronic pulses through the cable. The signal is converted into pluses of light and then converted back into electronic pulses once it reaches it's destination. This format has the benefit of not being effected by outside interference between the source to the decoder. This format supports Mono, Stereo, Dolby Pro Logic, Dolby Pro Logic II, DTS:Neo6, Dolby Digital 5.1, DTS, Dolby Digital EX, and DTS-ES
HDMI is a single digital cable for Audio and Video (see video section above). This will most likely be the cable standard of choice for a while. For the audio portion of this cable it uses the same S/PDIF format as Optical and Coaxial. This format supports Mono, Stereo, Dolby Pro Logic, Dolby Pro Logic II, DTS:Neo6, Dolby Digital 5.1, DTS, Dolby Digital EX, and DTS-ES
I'm not the foremost authority on this stuff, I've only been into the A/V scene for short while now so I could be wrong on some accounts. If I stated something incorrect please let me know.
Edited by twistedsymphony, 21 April 2006 - 10:00 PM.