Progressive scan

Video outputs

Digital audio

DTS, Dolby Digital decoding

External 5.1/7.1 output DVD-Audio

Video/Audio DAC resolution

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

- Background on the Technology back to menu

A DVD, Digital versatile disc, is very similar to a CD, but has a much larger data capacity. A standard DVD holds about seven times more data than a CD does. This huge capacity means that a DVD has enough room to store a full-length movie, as well as a lot of other information such as subtitles and multi language soundtracks

DVD can also be used to store almost eight hours of CD-quality music per side. DVD players are compatible with audio CDs. Some DVD movies have both the format which fits wide-screen TVs, and the standard TV size format, so you can choose which way you want to watch the movie.

Even though its storage capacity is huge, the video data of a full-length movie would never fit on a DVD. In order to fit a movie on a DVD, you need video compression. A group called the Moving Picture Experts Group (MPEG) establishes the standards for compressing moving pictures. For more details click here.

When movies are put onto DVDs, they are encoded in MPEG-2 format and then stored on the disc. This compression format is a widely accepted international standard. Your DVD player contains an MPEG-2 decoder, which can uncompress this data as quickly as you can watch it.

A movie is usually filmed at a rate of 24 frames per second. This means that every second, there are 24 complete images displayed on the movie screen. American and Japanese television use a format called NTSC, which displays a total of 30 frames per second; but it does this in a sequence of 60 fields, each of which contains alternating lines of the picture. Other countries use PAL format, which displays at 50 fields per second, but at a higher resolution. Because of the differences in frame rate and resolution, an MPEG movie needs to be formatted for either the NTSC or the PAL system.

The DVD manufacturers made agreements with film makers to encode individual DVD’s and DVD players with a region code. Therefore if you purchase a film from a different region it will not play on your machine at home. This enables movie-makers to stagger the release of films worldwide and maximize their profits.

There are six main regions, region 1 the North American region rarely notices a problem as 99% of English language movies are available there first (Crouching Tiger Hidden Dragon, a Chinese production is a notable exception.) Region 4, Australia and region 2, western Europe fall foul of the coding system. Not only do these regions have to wait for up to 12 months longer than the USA and Canada they also pay more for the privilege.

Multi region machines, which have become increasingly difficult to find, are designed to play discs from all regions. Thus over the internet you can buy discs at U.S prices and anything up to 12 months early. Strictly speaking this is not a legal practice. Mainly because films from different regions have not been classified by the native board of film censors.

 

- Progressive scan back to menu

This technology effectively doubles the amount of information being sent to your display devices. Displays capable of handling this higher frequency will show significant sharpness and crispness improvements.

Objects moving quickly across the screen were previously comb like along their edges showing the interlaced nature of the signal. Progressive scan displays both fields each scan.

Progressive scan is only usable on component or better video standards on a compatible display device.

 

- Video outputs back to menu

These days a DVD player without component video output isn't much more than a games console as far as image quality goes.

You should expect to see a composite video (normally yellow), an S Video (small DIN plug) and a component output (Red Green and Blue) you may also find a SCART (which carries Composite, S Video and RGB to any SCART equipped display device)

Composite is the lowest picture quality, followed by S Video then Component being the best of the analog consumer standards.

Depending on the model and brand, you may also find DVI or HDMI video output multipin sockets. These are generally at least as good as component video, and with a good digital HDMI equipped display potentially vastly better.

 

- Digital audio back to menu

In the case of DVD movies there is no question digital audio is the way to go! This is the only way of transferring digital data to the receiver for decoding to each of the speakers. You cannot send Dolby Digital or DTS via analog.

The question of which is better for music - analog or digital outputs is not an entirely simple one to answer. A lot depends upon the quality of the circuits and components inside the player itself. If your amplifier supports a digital input you should probably consider using it in addition to the analog connections.

The difference lies in the number of times a signal is processed and converted. Let's follow the signal from a CD disc to the speaker through each possible connection.

CD and DVD Digital Audio are recorded in digital format. The player reads the digital information as carefully as it's jitter prevention will allow. This is then up sampled by better players offering 2x,4x or even 8x "over-sampling". This means that for every 16bit "word" of data actually read from the disc there is added another 1,3 or 7 16bit "words" of data copied from the original sample. This has the subtle though useful effect in better CD players of shifting the harsh edge noise away from the actual information we want to hear. This in turn allows for more subtle filters to now be employed for waveform smoothing.

It is at this point, immediately prior to the D/A conversion process, that the digital output is tapped off and exits the chassis via Coax or Optical cable.

The analog output goes through the D/A conversion process in the DAC surprisingly enough! And then exits the chassis through the analog outputs.

Now that should be the end of the story, obviously the digital should be better right? wrong!

The amplifier or receiver that will be lending it's current to this signal has to handle the incoming signal. This step can easily bring a fine CD player to it's knees. The whole process has to end in an analog signal for the power amplification circuits to supply to the speakers. To make matters worse, along the way the signal must be in a digital format for the receiver to process into the sort of curve it's transformers need to produce the right sounds. Hmmm. Looks as though the answer to this question is not a straightforward one.

 

- DTS, Dolby Digital decoding back to menu

It's worth a little look back at the origins of the surround sound phenomena in order to understand what these modes are and what they attempt to do.

Throughout the 60’s and 70’s Dolby Laboratories, sound recording pioneers, were developing Dolby Stereo: An exhilarating 4 channel surround sound designed to be used in cinemas. In 1977 Close Encounters and Star Wars made a huge impact on the movie going public by embracing this new technology. Previous to 1977 movie theatres were still using mono technology developed in the 1930’s.

Dolby Stereo became Dolby Surround and was produced for the home video market in the early ‘80s. Dolby Pro Logic (1987) became the first home system to use a center channel and consequently for the first time the public had an affordable surround sound system to compete with the one Star Wars used so well in the 70’s.

Dolby AC-3 was born in 1992, an improved surround sound system developed for use with digital cinema devices. By the late ‘90s every home had its own Digital cinema device in the form of a DVD (Digital Versatile Disc) player. Dolby AC-3, which became known simply as Dolby Digital, was the obvious format to replace and improve upon Dolby Pro Logic.

Meanwhile in 1990, with backing from Universal studios, The DTS, or Digital Theatre System company was born. They created a rival digital cinema sound system. With the release of Jurassic Park, and an incredible 876 DTS systems installed within 6 months in U.S. cinemas, DTS was established as the leading cinema audio system.

Any respectable DVD player or home theatre receiver will happily decode either Dolby Digital or DTS soundtracks and both systems are 5.1. This is simply 5 channels or speakers and 1 subwoofer to add bass depth to them. Since this isn't a full channel of information - in fact it's normally only the bottom few hundred hertz that is available, this is known as .1 of a channel. Logically then 6.1 would use 6 speakers and 1 subwoofer, 7.1 would use 7 speakers and so on.

Next time you catch a movie, watch the opening credits to see which system is in use.

If the next opening credits you see at the cinema, use the famous THX logo, you are in for an audio visual treat. This is not however, another type of surround sound. THX, named after the title of George Lucas’ first film THX 1138, is actually a standard set by Lucasfilm.

In the early ‘80s George Lucas set out to ensure a movie looked and sounded the same no matter which cinema screened it. Extremely rigorous tests of room acoustics, projector quality and audio performance must be met for a cinema to receive a THX rating. Return of the Jedi in 1983 was the first film to be shown in a THX certified auditorium. To date there are around 2000 THX cinemas worldwide.

Increasingly home cinema products are meeting the Lucasfilm requirements for performance and display the THX logo accordingly. Many VHS and DVD titles have gone through the demanding THX digital mastering program for high post-production quality of sound and video compression as well as overall replication. For the full THX effect in the home however it is necessary to apply the same THX standards to the room the movies are going to be played in. For technical specifications on THX standards

In 1997 DTS Entertainment, a subsidiary record label of the DTS company, began creating DTS products for the home market such as DVD’s, video games and DVD audio.

DVD audio is probably the most interesting audio innovation since the compact disc. This is not necessarily because of its improved CD sound quality, but rather its use of 5.1 speaker systems. Artists such as Eric Clapton, Neil Young and Underworld, understanding that millions of us have DVD systems in place in our homes, have begun creating music with 5.1 in mind.

Not only is this a far more involving listening experience, it also gives artists “on screen” credits, sleeve notes, lyric guides and artwork opportunities that were lost after the demise of vinyl albums.

 

- External 5.1/7.1 output DVD-Audio back to menu

Many better DVD players these days are offering a pre-out output for 5.1 or 7.1 audio channels. These are connected to the matching pre-in inputs on the receiver to enable DVD-Audio and SACD where the DVD player is so equipped with decoders of those formats.

Signals sent to the amp along these cables will have significantly less processing performed on them, as well as far fewer conversions from digital to analog or vice versa.

Setting the amplifier to receive signal from this External 7.1 or 5.1 input will allow you to hear a whole new world of open and airy clarity from your recordings.

 

- Video/Audio DAC resolution back to menu

A DAC/ADC are Digital to Analog converters. They are critical to the quality of the DVD player in both Audio and Video reproduction. These devices are approximaters that fit data to a curve or curves to data. Resolution in this case is a measure of the length of tiny increments of time.Resolution refers to the actual number of samples the DAC or ADC can handle per second.

All things being equal (jitter management etc) the higher the sampling resolution - the more musical or the sharper more colourful the image. Back to that phrase "all things being equal", in the real world they're not equal. Chassis rigidity, power filtering and isolation, internal interconnect quality, component choices and pickup and transport differences ensure that the resolution is not the holy grail - though it's a mighty fine chalice to chase in general.

In order to convert an analog waveform into a digital bitstream it is necessary to slice the wave up into very very small instants of time and record the snapshot of sound or colour intensity  in the case of digitising video. Play these digital snapshots back at the same speed they were captured and you can reconstruct an approximate to the original waveform - thus sound or image.