Page 91 - DCAP303_MULTIMEDIA_SYSTEMS

Unit 5: Video

The chart below compares standard audio CDs with several versions of DVDs: notes
recording technique audio CD DvD
Single-sided, single-layer 0.74 GB 4.7 GB

Single-sided, double-layer — 8.5 GB
Double-sided, single-layer — 9.4 GB
Double-sided, double-layer — 17 GB
HD-DVD, single-layer (obsolete) — 15 GB

HD-DVD, double-layer (obsolete) — 20 GB
HD single layer, Blu-ray — 25 GB
HD double layer, Blu-ray — 50 GB
Recording technology has been demonstrated that raises the Blu-ray data capacity to 200 GB for a
double-sided platter. In 2008, several decisions were made by the industry that meant HD-DVD
format would be replaced by Blu-ray.

Data compression is used in almost all audio and video digital formats. Data compression is a
little like freeze-dried instant coffee; elements are removed that can be later restored without
appreciably affecting the final result.
In the same way that instant coffee is almost as good as the real thing, compressed video is almost
as good as the original video signal.

Even though an engineer with a sharp eye (or ear) can tell the difference (just as coffee connoisseurs
can tell the difference between instant and freshly brewed coffee), by “dehydrating” video and
audio signals they take up much less digital space.
Since the spiral tracks on the DVD disk surface are microscopic in size, it means that DVD
equipment requires a high level of mechanical precision.

The move from videotape to DVDs was also accelerated when DVDs became cheaper to
manufacture than VHS tapes.
The DVDs also allow for random-access, while VHS tapes were totally linear in nature. This
means that with a DVD you can almost instantly jump to any point in a recording. No lengthy
fast-forward or rewind process is involved.

The high data capacity of DVDs also means that a production can include a number of “extras.”
Depending on the length of the original production, these extra options may include out-takes,
audio in multiple languages, and commentary from the stars or production personnel.
The narration from the director can be of particular value to people in production because it can
add significant insight into music selection, production problems, acting issues and why particular
scenes were deleted.
5.6.3 High-definition DVDs

In 2006 we began to see “home theatres” cantered around 5.1 sound from HDTV videodisks (and
even 7.1 sound, with an option for two more speakers).

With images that rival or exceed those in theatres, many people—at least those who can afford
home theatres—now find little reason leave their homes to see a movie.
At the end of 2007, there were two major competing and incompatible standards for DVDs in the
high-definition. There was the HD-DVD format led by Toshiba consortium and Blu-ray backed
by a Sony-led consortium.

LoveLy professionaL University 85