A Brief Introduction to DVD
(If you are experienced with DVD already, please
get straight to the details )
At SRT, Producing a DVD is simple.
We can handle everything for you - just supply
us with suitable video and audio sources and we'll take it from there. Or, if you prefer to be more involved, you can collaborate
with our designers and authoring team at every stage, or even handle
You Need To Know
DVDs are essentially CDs with much more space, so there's
enough room to fit high-quality video on as well. Even so, the video
has to be "compressed" in order to fit. This compression is in a format
called MPEG-2. There are two common sizes of DVD, called DVD-5
and DVD-9 . A DVD-5 can hold 90 minutes or so of high-quality
video, and a DVD-9 can hold 3 hours. If you're prepared to risk sacrificing
a little image quality, even more can be squeezed on.
SRT uses the Sonic SD-2000 MPEG-2 Hardware Encoder,
an "industry standard" system used on thousands of "Hollywood" feature
films every year, to give you the best possible video quality.
This is vitally important, because at the end of the day, the highest
quality video and audio are the most important elements of a professional
Useful DVD Terms:
Assets - the various "ingredients" to be put on the DVD. These
include video, audio, images, text and graphics. They may be supplied
in various different formats, eg. images may be on CD-ROM, or may need
to be scanned. SRT can accept video supplied on any format.
Chapter - DVD titles are divided up into chapters. These are
often sections of a film, or musical tracks in a concert, for example.
They are similar to tracks on a CD.
Menu - Menus are where you "navigate" through a DVD.
They can be based on still images, or video in which case they are referred
to as "motion menus". Still menus are quicker and cheaper
to create, and take up less space. There is an example of a menu on
Button - Part of a menu which you can select with the remote
control or mouse - buttons allow interactive behaviour, for example
to play a chapter, view images or go to another
menu. On the menu to the right for example, the arrows and thumbnail
images are buttons. On a DVD they can change brightness and/or colour
depending on which one is selected.
Authoring - combining all the assets
into a complete DVD. People often refer to "authoring" when they really
mean DVD Production , which correctly means the design
and creation of all the graphics, fonts, logos, menus etc. Authoring
is really only the process of linking all of these together via menus
& buttons to make the DVD work. Once complete, the DVD master is
supplied on a DLT master ( Digital linear tape ).
DVD-5 ( single-layer), DVD-9 ( dual-layer ) - The two most
common sizes of DVD. DVD-5s are simpler and cheaper, but hold less information.
If there is much more than 90 mins of video, it is best to go for a
DVD-9. DVD-9s cost more to author and manufacture.
Layer break - DVD-9s have 2 layers, which is how they hold
more information. When the player reaches the end of the first layer
( Layer 0 ) it will pause for a moment as the laser re-focuses on the
second layer ( Layer 1 ). This will cause a pause in playback, of between
half a second up to 1 or 2 seconds on older players.
MPEG-2 Data Rate - determines the quality of the MPEG-2
video files. Higher data rates mean better quality, but less available
space on the DVD. Rules of thumb: we recommend a data rate of 6 Mbps
( "mega-bits per second" ) to ensure good quality video. At
this rate, you can fit about 90 mins of video on a DVD-5.
-the process of choosing the best data rates & organisation of assests
on a DVD to fit the most time on at the best possible quality. For DVD-9s,
this becomes very complicated.
5.1 Surround-sound - One of DVD's best features is the ability
to offer high-quality multi-channel surround-sound. If you only have
access to stereo audio, SRT can create "pseudo surround" from
stereo masters, using the TC Electronics System 6000, using a process
called "un-wrap". Alternatively we can make a brand new
surround mix from multi-track tapes..
AC-3, Dolby Digital - audio can also be compressed on DVDs,
to save space. AC-3 is the standard format for this. Typical data rates
are 192 Kbps ( "kilo-bits per second" ) for stereo, and 448
Kbps for 5.1 surround-sound. Suround-sound audio must always be compressed.
There is another surround format, called DTS , but only some
players decode it.
Scripting - DVDs are capable of very complex interactive behaviour,
for example presenting the user with a quiz and keeping track of correct
answers. This is acomplished via scripting, which is essentially
computer programming. Complex scripting can be quite time-consuming
and requires detailed testing.
Copy Protection - DVDs include several ways to make it harder
for people to copy your material. These include Region Coding
so that your discs are only playable in certain countries, CSS
to prevent people copying your DVD in a computer, and Macrovision
to stop the video being copied to a DVD-Recorder or VHS.
Standards Conversion - Different countries have different types
of TV playback system. Most places including Europe and the UK use PAL,
whereas the USA and Japan use NTSC. You will need to decide
which standard to use for your disc. SRT can make a high-quality conversion
of your footage, if necessary.
Subtitling - DVDs are able to display subtitles in multiple
languages, if necessary. We can include subtitles on your DVD, including
auto-selection by language.
So, hopefully now you should be ready to look at
the details of the services SRT can offer you. Click HERE
for more info, or contact us now:
Tel. +44 (0) 1480 461880