Specifications
11
A Digital Video Primer
MPEG-2 compression
MPEG stands for the Moving Pictures Expert Group, an organization of lm and video profes-
sionals involved in establishing industry standards. e 2 refers to compression standard version 2.
MPEG-2 can provide very high-quality video. Readily supporting data rates in excess of 8 Mbps
(equivalent to 1MB per second), MPEG-2 is ideal for DVD with its high-end data rate of 9.8
Mbps. It is also one of the compression schemes used in the upcoming high denition optical
disc formats, and is used in the new HDV format.
While MPEG-2 is an excellent compression choice for distribution, it was only recently that
computer speed and memory reached the point where MPEG-2 video could easily be edited. And
only recently has there been a need to edit MPEG-2 video. With the introduction of the HDV
format, the impetus to move toward MPEG-2 editing has increased. HDV enables producers on
a budget to produce video in high denition. Adobe Premiere Pro includes support for native
HDV editing, which means you can capture and edit high denition video with one of the new
relatively inexpensive HDV camcorders, a standard computer, and Adobe Premiere Pro.
It is important to note that not all MPEG-2 codecs are the same. MPEG-2 is not a patent; it is
a set of standards and specications that must be met for the codec to qualify as MPEG-2 and
for the encoding and decoding sides of the process to mesh. Codec developers have created and
continue to create a wide variety of applications based on MPEG standards, some more ecient
than others. is variance is most signicant when considering the encoding side of the process,
which can greatly impact the quality of the resulting decoded video. If the standard continues to
be MPEG-2, the decoder chip in playback devices will not need to change to yield better quality
for video that has been compressed with better encoding technology.
Getting video into your computer
Because a computer only understands digital (binary) information, video has to be converted to
a supported digital format before you can work with it.
• Analog. Traditional (analog) video camcorders record what they “see and hear” in an analog
format. So, if you are working with an analog video camera or other analog source material
(such as videotape), you will use a video capture device to digitize and then store the video
on your computer. Most capture devices are cards that you install in your computer. A wide
variety of analog video capture cards are available, with many dierent features and levels of
quality, including support for dierent types of video signals and formats, such as composite
and component. Make sure you understand what you are getting. An inexpensive capture card
may lack features, produce low-quality video, and be incompatible with your editing soware.
e digitization process may be controlled by soware such as Adobe Premiere Pro. Once the
video has been digitized, it can be manipulated in your computer with Adobe Premiere Pro
and Aer Eects, or other soware. Aer you have nished editing, you can then produce your
nal video for distribution by exporting a digital format, or by recording to an analog format
like VHS or Beta-SP.
• Digital. Digital video camcorders have become widely available and aordable for both consumers
and professionals. Digital camcorders translate what they record into digital format inside the
camera. Your computer can work with this digital information as it is fed straight from the
camera via a digital interface such as IEEE 1394 or SDI. Digital capture is far easier and less
expensive than analog capture, and produces much better results. A capturing program, such
as Adobe Premiere Pro, can also control playback of a device through the IEEE 1394 interface
or through RS-232C and RS-422 ports.
OTHER FORMS OF MPEG
MPEG-1, limited to a 352 x 240-pixel frame size, was
the rst MPEG standard established and is still used
for CD-ROMs, VideoCD (VCD), and some web video.
The specications for MPEG-3 were abandoned, as
the industry moved on to complete MPEG-4. Note
that MP3, which stands for MPEG-1, Layer 3, is an
audio-only compression format and should not be
confused with MPEG video formats.
MPEG-4 Part 10, better known as AVC and H.264, is
currently in use in the latest releases of the QuickTime
and Microsoft® Windows Media architectures. The
codec facilitates streaming video on the web and over
wireless networks, as well as providing mechanisms
for multimedia interactivity. MPEG-4, with its lower-
bit-rate approach, is one of three codecs adopted for
HD-DVD and Blu-ray DVD for high-denition video.
The names MPEG-5 and MPEG-6 will not be used; the
next release is expected to be MPEG-7, which will not
advance compression, but will focus on the incorpo-
ration of metadata, enabling sophisticated indexing
and retrieval of multimedia content.
MPEG-21, also in the planning stages, is expected to
create a complete structure for the management and
use of digital assets, incorporating e-commerce that
will make sharing creative products more commer-
cially viable.