The Florida SunFlash
Multimedia: Introduction (1 of 6)
SunFLASH Vol 40 #25 April 1992
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This set of 6 articles explains the tecnologies of Multimedia
technology. -johnj
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1. Introduction to Multimedia
2. Sun's Multimedia Direction
3. Key Multimedia Concepts
4. Audio
5. Video
6. ISDN
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1 Introduction to Multimedia
Multimedia technology will ultimately take the disparate technologies
of the computer, the telephone, the fax machine, the CD player, and the
video camera and combine them into one powerful communication
center. Technologies that were once analog - video, audio, telephony
- are now digital. The power of multimedia is the integration of these
digital technologies. At some point in the future, Sun Workstations"
will be connected via Integrated Services Digital Network (ISDN) phone
lines to workstations around the world. The implementation of ISDN will
make possible an international phone system that will serve as a global
network. If as the saying goes, the "network is the computer", then the
"computer" is about to become very large.
This will geometrically expand the number of ways that we can exchange
information. We'll exchange electronic mail with people on other
networks, in other companies, in other countries. We'll fax information
to them directly from our workstations. We'll be able to set up a
video-conference from our workstations with people on the other side of
the world who aren't even on the same network. They'll be able to see
us and hear us, and we'll be able to see and hear them at the same
time. We'll develop documents with audio and video components that we
can then send anywhere. There is even the future possibility that we'll
be able to speak into our computers and mail a translated audio message
electronically to a recipient in another country speaking another
language!
This booklet describes some key concepts for multimedia. It talks about
Sun's multimedia directions, and describes some of the more technical
aspects of audio, video, and ISDN technologies.
Before looking at multimedia in more detail, let's take a look at how
multimedia technology can benefit a company's business. The following
scenario will become more and more common in the months and years
ahead.
Let's say that you run a major credit card company that employs
thousands of people, and that you have recently succeeded in getting
your company to adopt multimedia technology. What kinds of changes
might you see that tell you that your efforts have paid off?
o Service time per customer reduced, and an additional increase
in customer satisfaction
When a customer calls in, a window displays on the service
representative's screen with complete information about the
customer: records of the last series of transactions, images of
credit card slips, and a variety of other pertinent
information. A service representative can raise a customer's
credit limit by creating a document on-line with the customer's
request and credit information, and forwarding it over the
network to a credit agent in another city. The agent can send
the customer a fax of the request. Based on the information in
the database, the service representative can propose other
services to the customer. For instance, for a customer that
travels often the agent can discuss new travel discounts.
o A decrease in travel time and expenses and an increase in the
level of communication
Now you as CEO can hold meetings with your executives by simply
setting up a videoconference on your workstation so you can all
see and hear each other. You can discuss current issues,
examine and mark up documents together, and even share a
whiteboard - all on your own workstations. Your company's
high-level executives also like the way that multimedia keeps
them in touch with each other when they do travel. Via phone
lines, they can check back with the main office to receive
voice or electronic mail messages. They can even pull important
information from their workstations and have it faxed to them
or read to them over the phone, using a text-to-speech
application.
o A decrease in the amount of time required to train new
employees, less money spent on training efforts, and an increase
in customer satisfaction
A series of modular multimedia presentations were developed
in-house incorporating text, still images, full-motion video,
graphics, and audio. New employees can now learn their jobs
interactively at their workstations by viewing presentations
specific to their work. Because the modules are developed
in-house, they can also be easily updated to accommodate the
latest information.
The above scenarios might seem like a slice of life from the next
century, but these scenarios are really a lot closer than that. To
learn more about multimedia and the plans Sun has for incorporating
multimedia into its products, read on!
The Florida SunFlash
Multimedia: Sun's Directions (2 of 6)
SunFLASH Vol 40 #26 April 1992
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2 Sun's Multimedia Direction
Sun's direction in multimedia centers around the concept of
collaborative multimedia - multimedia applied to corporate
communication enabling increased group productivity and creativity,
faster development of higher quality products, more efficient corporate
processes, better customer service. In short Sun intends to provide a
competitive advantage by empowering teams with powerful access to and
manipulation of information.
Collaborative Multimedia
Sun defines collaborative multimedia as the combination of multimedia
with desktop systems and networking to enable powerful communication
systems for groups of people working in teams.
Multimedia
Multimedia enables people to communicate using integrated media: audio,
video, text, graphics, fax, and telephony. The benefit is more powerful
communication. The combination of several media often provides richer,
more effective communication of information or ideas than a single
media such as traditional text-based communication can accomplish.
The Desktop
The desktop workstation is the new communication center - the
individual's connection to the enterprise. Through the desktop the
individual can connect with other individuals and with information
sources such as documents and databases.
The desktop is also the focus for the integration of critical office
automation resources such as fax, telephone, answering machine, address
file, and so on. It integrates these resources, both into the
workstation and with each other.
Finally, the multimedia desktop will provide built-in standard
multimedia capabilities such as audio, video, telephony and fax.
Multimedia functionality will be built-in, both in hardware and in
software development platforms as well as standard desktop software.
Developers can count on a certain level of multimedia functionality on
every desktop.
The Network
Powerful networking capabilities provide access to people and
information across not only the enterprise, but cross-platform and
globally as well. People and information must also be accessible when
you are not at your desk through portable computing and remote access.
For instance, you could call your workstation from a public phone and
have important information read to you.
Powerful Platform for Powerful Communication
The networked multimedia desktop is a prerequisite for collaborative
multimedia; powerful communication depends on a powerful platform. This
platform must be multimedia-ready, with bundled multimedia technology
supported by a multimedia development environment and adherence to
standards. Connectivity (networking), speed (workstation performance),
multi- tasking, and a client/server architecture are all necessary to
enable this level of communication power.
Empowering Teams with Information
Collaborative multimedia enables new levels of multimedia solutions for
individuals, workgroups and corporations as a whole. Personal
multimedia solutions provide new ways of delivering information to
individuals. Group multimedia involves new ways of working together.
Corporate multimedia enables whole new ways of doing business.
The more powerful communication that collaborative multimedia enables
can provide a real competitive advantage. Collaborative multimedia is
much more than just presentations and entertainment: it enables faster
development of higher quality products, better customer service, more
efficient corporate processes, and increased group productivity and
creativity. See the Multimedia on Sun Workstations brochure for
examples of how Sun customers are benefitting from multimedia today.
Personal Multimedia
In the 1990s, information must be accessible in many forms. Personal
multimedia involves new ways to deliver information to the individual.
Typically the communication is one way - experts create/author the
materials, and the individuals view (play back) the materials. Prepared
materials, such as presentations or multimedia documents, may be viewed
from media (CD- ROM, video disc, VCR) or from on-line files. Examples
include employee training, sales presentations, or customer service
kiosks. Network access means that the information can be distributed
over the network and located away from the individual user.
Group Multimedia
Group multimedia enables real-time, interactive collaboration among
members of a project team, customer service group or other work group.
Communication is two-way: team members are both authors and viewers of
the shared materials.
Functionality includes screen-sharing so team members can view each
other's work, shared whiteboard capability enabling interactive mark up
of documents, and video conferencing for real-time interactive
exchange. Everything you need during your conference is already
available from your workstation, ready to be shared.
Typical uses of group multimedia would be for collaborative business
analysis and decision making, or for concurrent engineering.
Corporate Multimedia
Corporate multimedia centers around the impact of multimedia on
applications that are critical to the nature of the corporation's
products or services. Examples are
o Collaborative medical diagnosis and treatment in a healthcare facility
o Customer service, such as order processing in a manufacturing company
o Intercompany cooperation, such as insurance claims settlement
Typically these types of applications are developed in-house by MIS
departments, or by vertical independent software vendors or system
integrators. They are applications that directly affect the bottom line
of the business.
Sun's 3-Point Multimedia Strategy
Sun's multimedia strategy involves:
o Delivering multimedia-ready workstations
o Providing an open development environment
o Forming key strategic partnerships
The Multimedia-Ready Workstation
Sun workstations are multimedia-ready today. SPARCstations have
included voice-quality audio since their introduction in 1989. They
also support large screen displays, high-resolution color graphics, and
a CD-ROM interface. The multitasking capability of the operating system
and extensive networking support are fundamental enabling technologies
required for true collaborative multimedia.
The OpenWindows V3 multimedia mail tool and Calendar Manager are the
first DeskSet applications to begin to address collaborative work and
multimedia communications. As time goes by the level of multimedia
support bundled in Sun Workstations will increase.
Over 100 third-party solutions related to multimedia are available
today. These encompass products in the areas of:
o Multimedia documents and multimedia mail
o Image manipulation and animation
o Video hardware and software
o Audio and speech recognition
o Multimedia presentations and hypermedia
o ISDN and fax
These third-party products make Sun fully equipped for multimedia. See
the Multimedia Portfolio for a complete listing of Sun and third-party
products that support multimedia.
An Open Development Environment
The Sun multimedia platform will provide a unified multimedia
programming interface for developers. It will be based on industry
standards, and will be cross-platform.
Sun participates in a number of key standards organizations:
o Interactive Multimedia Association (IMA), which deals with
cross-platform multimedia standards
o International Standards Organization (ISO) and International
Telecommunications Standards Organization (CCITT) which deal
with video compression
o National ISDN User's Forum (NIU)
o CCITT also deals with fax
o SPARC International (SPARC compliance definition)
o UNIX" International (multimedia team)
The standards that Sun is tracking for cross-platform interoperability
are in the areas of:
o Video
o Video and audio compression
o Communications
o Fax
o CD-ROM
o Graphics and imaging
o File formats
o Device control
Key Strategic Partnerships
Partnerships are critical to the development of Sun's multimedia
strategy. Sun is undertaking several types of partnerships:
o Technology partnerships. These focus on joint platform development,
including joint applications programming interface (API) development,
cross-platform development and standards efforts.
o Software and hardware developers. These focus on complete solutions
including applications software. The goal is to move beyond multimedia-
ready to actual multimedia solutions
o Customers. The focus is on requirements identification and
development of multimedia solutions. Customers provide feedback on the
platform work, proof-of-concept for significant solutions and success
stories.
Sun's Differentiation
Sun's collaborative multimedia strategy provides a powerful competitive
advantage for corporations.
o Multimedia-ready workstations from Sun provide standard multimedia
capabilities that will track emerging industry and de facto standards.
In addition, an open multimedia development environment will facilitate
the development of key multimedia solutions.
o Sun's speed, connectivity, multi-tasking capabilities, and
client-server architecture provide the infrastructure to support
collaborative multimedia.
o Sun's multimedia-ready workstations enable corporate-wide solutions
that can provide a competitive advantage and positively affect the
bottom line.
The Florida SunFlash
Multimedia: Key Concepts (3 of 6)
SunFLASH Vol 40 #27 April 1992
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3 Key Multimedia Concepts
Before reading about the more technical aspects of multimedia, you
should be familiar with some of the key concepts that apply to
multimedia technology.
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Key Processes
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Authoring
Authoring is the process of using multimedia applications to create
multimedia materials for others to view. Multimedia authoring utilizes
a wide variety of tools, from the more familiar text editor or desktop
publishing application, to tools for capturing and manipulating video
images or editing audio files. Authors might include specialized
creators of training, sales, or corporate applications such as
insurance claims processing. Or, they might be creators of everyday
business communications like voice-annotated email. Over time, everyone
involved in business communications will probably have some level of
multimedia authoring capability.
Playback
Playback is the process of viewing multimedia materials created by an
author. Playback can include a range of activities, from viewing a
single video clip to participating in a series of interactive
multimedia training modules. Some playback applications (for example
many training and presentation applications) are sold separately from
their authoring applications. However, many developers are selling
authoring and playback capabilities in a single product.
Collaboration
Collaboration involves two or more people working together in
real-time, or in a "store-and-forward" mode (defined in the next
section). Applications in development will enable a group of people to
collaborate in real-time over the network using shared screens, shared
whiteboards, and video conferencing. Collaboration can range from two
people reviewing a slide set on-line to a conference of doctors at
different locations sharing patient files and discussing treatment
options.
Editing
Editing is the familiar process of changing the content of files to
achieve more effective communication by cutting, pasting, cropping,
resizing, or copying. Multimedia editing can be done on all types of
media: voice annotations, music, still images, motion video, graphics
and text. Tools for editing vary from simple tools for email voice
annotations to more sophisticated tools for video manipulation.
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Key Concepts
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Real-Time
Operating in real-time means that there is little time delay in the
communication of information. You make a change to a screen display,
and your colleagues at different workstations see the change almost
immediately. This is in contrast to the concept of
"store-and-forward".
Store-and-Forward
The concept of store-and-forward means a time delay between the
creation and receipt of multimedia materials. This is the process that
most people currently use. It does not accommodate live interaction
between people. The information is created at one point in time, and
received at another. An example of this is today's electronic mail.
Synchronization
Synchronization is very precise real-time processing, down to the
milli-second. Some forms of multimedia, such as audio and video, are
time-critical. Time delays that might not be noticeable in text or
graphics delivery are unacceptable for audio and video. Workstations
and networks must be capable of transmitting this kind of data in a
synchronized manner. Where audio and video are combined, they must be
time-stamped so that they can both play back at the same time.
One-way Communication
One-way communication goes from an author to a playback user, but not
the other way around. Examples of one-way communication include
training and documentation materials, and presentations. The material
is authored specifically for playback by the end user and not for a
collaborative work effort. One-way communication materials remain
unchanged until the master is updated by the author.
Multi-way Communication
Multi-way communication goes between two people, or between groups of
people in all directions. Multi-way communication can be in real-time,
or in store-and-forward mode. Examples of multi-way communication
include a video conference, where one individual is giving a
presentation to a group of people who listen and ask questions from
their workstations; and group conferencing, where several people
collaborate, supported by audio, video, and graphics on their
workstation screens.
Compound Documents
A compound document is one that enables incorporation of different
kinds of media - audio, video, images, text, and graphics.
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Key Applications
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Videoconferencing
Videoconferencing is communication with others using video and audio
applications to see and hear each other. Audio can be provided
through specialized videoconferencing equipment, through the telephone,
or through the computer. Videoconferencing has traditionally been done
with dedicated equipment. The use of computers for conferencing is very
recent. Synchronized, real-time audio and video is required.
Shared Screens
Shared screen applications enable two or more workstations to display
the same screen simultaneously. For example, two users sharing a screen
can work on the same spreadsheet. Changes made by one user can be seen
by the other as they are made. Shared screens can be implemented in two
ways. One way enables people to view each other's screen while one
person makes changes. The other way enables people to run the same
application on both screens so that both users can make changes
simultaneously.
Shared Whiteboards
Shared whiteboards enable you to "mark-up" a screen using a mouse or
stylus input device and have the results show on other screens. The
concept is similar to a traditional whiteboard mark-up process where
everyone has a different color marking pen to circle, write, or cross
out items. The background board can be a window from the workstation
such as a spreadsheet, image, or blank canvas, or it can be the entire
workstation screen. The shared whiteboard can be used for either
real-time or store-and-forward collaboration. In the store- and-forward
scenario, the mark-ups can be implemented in a time-delayed fashion so
everyone can follow the entire step-by-step process.
Software-only Video Playback
Video software playback displays a stream of video without any
specialized chips or boards. The playback is done through a software
application. The video is usually compressed to minimize the storage
space required.
Hypermedia
Hypermedia is a type of authoring and playback software through which
you can access multiple layers of multimedia information related to a
specific topic. The information can be in the form of text, graphics,
images, audio, or video. For example, suppose you received a
hypermedia document about the Sun file system. You could click on a
hotspot (such as the words file system) and then read a description.
You could then click an icon to see an illustration of a file
structure, and then click the file icon to see and hear more
information in a video explaining the file system.
Runtime
A runtime environment is the software that plays back multimedia
materials. The runtime material is created by the author. Examples of
runtime applications are presentations and training, where the material
cannot be edited but only viewed. The runtime software could be a slide
show viewer, a software-only video playback application, or a
hypermedia runtime document.
Device Control
Device control enables you to control different media devices over the
network through software. The media devices include VCRs, laser disc
players, video cameras, CD players, and so on. Control capabilities are
available on the workstation through a graphical user interface. They
are similar to the controls on the device itself, such as play, record,
reverse, eject, and fast forward. Device control is important because
it enables you to control video and audio remotely - without requiring
physical access.
Telephony
Telephony refers to the integration of the telephone into the
workstation. For instance, making or forwarding a call will be as easy
as pointing to an address book entry. Caller identification (if
available from the telephone company) could be used to automatically
start an application or bring up a database file. Voicemail and
incoming faxes can be integrated with email. Users can have all the
features of today's telephones accessible through their workstations,
plus the added benefits provided by integrating the telephone with
other desktop functions.
Titles
When an author sells what he or she has created, it is called a title.
For instance, the various encyclopedias, dictionaries, musical works,
and games available on CD are all "titles". Someone authors the
material, and sells it to users who can play it back but not change the
content.
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The Florida SunFlash
Multimedia: Audio (4 of 6)
SunFLASH Vol 40 #28 April 1992
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4 Audio
Audio plays an important role in multimedia applications. When a
service representative adds a voice note to a credit record, when
executives hold a video conference, when travelers listen to voice mail
or have their email read to them over the phone, or when new employees
complete training modules, they all use desktop audio.
Audio Applications
Audio can be used in many applications, including voice annotation,
voice conferencing, voice mail, training and presentations,
text-to-speech, and speech recognition. The following paragraphs
describe some of these applications.
Voice Annotation
A voice annotation application enables audio comments to be added to
documents, data base records, and so on. These applications can be
built using fairly simple record and playback capabilities. For
example, someone records a voice comment and attaches it to a certain
spot in a document. The document then displays an indicator, showing
that an audio note is attached. While viewing the document, the reader
can select the indicator to play back the audio recording. Voice
annotation applications may also provide some simple audio editing
capabilities for message creation.
Voice Conferencing
Voice conferences enable people to speak to each other in real-time
over the network. Voice conferencing is an alternative to video
conferencing since both parties do not always have to see each other.
Often, voice conferencing would be used in a collaborative environment,
where two people can sit at their workstations, look at the same
document at the same time, and make verbal comments about it.
Voice Mail
Voice mail provides a way to send and receive voice-quality audio
recordings in a multimedia email message. Audio messages can be
recorded, sent as attachments to a multimedia email message, and played
back by the recipient. With the integration of telephony into the
desktop, messages could be recorded automatically by a
telephone-answering application, and forwarded as email to the
telephone owner.
Training and Presentations
Audio can be very effective in training applications. It can provide a
soundtrack for video segments, or for illustrations of any form. It can
also provide help and feedback to the student with a more personal
feel, and without interrupting the student's focus. Audio can also
provide richer, more interesting, and more effective presentations.
Audio in combination with other multimedia technologies enables authors
to create presentations of a quality that meet the expectations of
today's consumers.
Text-to-Speech
Text-to-speech technology enables information stored as text to be
converted to speech - effectively to be read aloud. Applications can
use text-to-speech to provide verbal help, or to read your calendar,
address file information, email message or other information. When
integrated with telephony capabilities, text-to-speech technology can
provide remote access to information. For example, you could telephone
your computer and have it read your mail or appointments. This
technology can also provide spoken desktop messages, such as a reminder
of a pending appointment, without imposing a pop-up window into the
middle of your current work. These desktop alerts could include
announcing an incoming email message or, with telephone integration, an
incoming phone call. They can also provide spoken status messages or
warnings from the system.
Speech Recognition
Speech recognition enables you to speak to your computer through a
microphone or telephone. The workstation translates the voice input
into text that the system can understand. This technology enables the
use of voice as an additional input channel to supplement the keyboard
and mouse. For example, radiologists save valuable time by dictating
their x-ray reports into the computer for immediate viewing. They can
be edited by voice or by keyboard. You could also give commands to
open and close windows or start applications without moving away from
your current work. With telephony integration, speech recognition would
enable you to give commands to your workstation verbally over the
telephone, for example, "Read the headers of any mail messages from
William Tell." Speech recognition technology in the near future will be
limited in the size of its vocabulary, and will typically require you
to train your system to your own voice. Eventually, these restrictions
should disappear.
Key Audio Concepts
Multimedia audio applications depend on the interaction of a number of
variables such as the type of audio and how it can be digitized,
edited, stored, and played back. The following paragraphs describe some
of these key concepts.
Types of Audio
Workstations generally support two types of audio input and output:
o Music quality audio (often called CD-quality audio or 16-bit audio)
o Voice quality audio (also known as telephone quality or 8-bit audio)
MIDI data, which specifies music, is also often included in the audio
category.
CD-quality Audio
CD-quality audio requires both higher sample rates and greater sampling
precision (more bits of data), thus making greater storage and
processing demands on the workstation. Today, applications requiring
CD-quality audio are found primarily in the music industry. The use of
CD-quality audio for business training and presentations, while
currently limited, is expected to expand considerably throughout the
corporate marketplace. CD-quality audio is typically input from a CD
player or DAT (Digital Audio Tape) player, and is output through a
high-quality speaker.
Voice-quality Audio
Voice-quality audio can reproduce the comparatively limited dynamic
range of the human voice. Voice-quality audio is standard on every Sun
desktop workstation, enabling multimedia applications ranging from
electronic voice mail to voice annotation of documents to voice control
of your workstation. Voice-quality audio is commonly input from a
microphone or over a telephone, and can be output through a speaker
built into or attached to the workstation, or using a telephone handset
or speaker phone.
MIDI
MIDI (Musical Instrument Digital Interface) is a note-oriented control
language for specifying music. MIDI data consists of codes specifying
notes and timing. These codes can be generated by or output to
MIDI-compatible devices such as keyboards or synthesizers. MIDI
applications are generally found in the computer music industry, used
for studio control and audio production.
Audio Editing and Manipulation
You can perform various operations to audio data stored in a file in
addition to playing it back. Probably the most common operation is to
edit the audio data. Programs that do audio editing typically generate
a display of the waveform representing the data, and then enable you to
specify sections of data to cut out or relocate. Editing can be used to
isolate segments of interest (for example, to create a "sound bite"),
or remove leading or trailing noise, silence, or pauses.
Another common operation is the mixing of sound files, for example to
combine a voice overlay on top of a music background for a training
application or in a presentation.
Audio Playback
Playing back stored audio data requires regenerating the analog audio
signal from the digital data. This is done by a digital to analog
converter or DAC. The analog signal can then be output to a speaker
built into or attached to your workstation, to the speaker in a
telephone handset, or to a speakerphone.
Capturing and Digitizing Audio
Sound, or audio, is analog data. To store, manipulate, and enhance it
using a computer, it must be digitized - converted to a
computer-readable format. Audio starts as a complex analog waveform
coming from some form of input device, such as a microphone, telephone
handset, or CD player connected to your workstation. An audio signal is
characterized by its bandwidth, the highest frequency in cycles per
second or hertz (Hz) that can be represented in the waveform.
Digitizing this signal involves two processes, sampling and
quantization. These functions are generally performed by a chip known
as an analog-to-digital converter, or ADC. Today the ADC and its
counterpart, the DAC, are sometimes combined into a single chip called
a Coder-Decoder or CODEC. The quality of audio a workstation supports
is primarily determined by the capabilities of the ADC and DAC
components.
Audio Data Storage
Once the audio input stream has been captured and digitized, it can be
stored in a data file for later playback or for editing or other
processing. Even voice- quality audio is data intensive; one minute of
voice-quality audio on a SPARCstation takes almost half a megabyte of
storage space. One minute of uncompressed CD-quality audio (16-bit 44.1
Khz stereo) would require close to 10 Mbytes of storage space.
Besides the raw data, you also need to store information about the
data, such as its sampling rate, the number of bits per sample, and the
encoding algorithm used. This information is necessary in order to be
able to reproduce the original signal. Thus, audio data is commonly
stored in files with a special format that includes this data, often in
some sort of header structure. This often requires special routines to
write the data to these files and to read it back properly.
Multi-Channel Audio
Many workstations, such as today's SPARCstation family, support one
channel of audio, or monaural sound. Multiple channels are also
possible. Supporting two channels (stereo) requires two input and two
output ports, independent ADC/DAC components for each data stream (or
components designed to handle two channels), and a data representation
format for the storage of multiple channels of data.
Challenges
There are still some challenging issues to tackle before audio will
become commonplace on the desktop. One of the most significant is the
development of more effective ways to handle the volume of data that
audio involves. Development of compression algorithms to minimize
storage space and network bandwidth to allow transmission across
computer networks is an area for further research.
Ongoing research in the area of text-to-speech and speech recognition
is another challenge. More human-sounding speech generation, and more
flexible and accurate speech recognition are important goals for the
future.
The Florida SunFlash
Multimedia: Video (5 of 6)
SunFLASH Vol 40 #29 April 1992
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5 Video
Desktop, full-motion digital video brings a new level of collaboration
and communication to corporations. Just as visual communication,
through pictures, can provide vastly more information than words alone,
moving pictures can offer more and in some cases better, information
than still images.
Video Applications
Full-motion digital video means a continuous sequence of video images
integrated in the workstation. The ability to capture, archive, edit,
display, and transmit digital, full-motion video provides both new and
better internal corporate communication, and innovative,
attention-getting, external communication with customers.
Collaboration
The shared workstation video-window will redefine workgroup computing.
The networked video-capable workstation will provide a new level of
collaboration among working groups. The current workgroup collaborates
by sharing email and documents. The workgroup of the 1990's will also
share images, video and audio.
Multimedia Mail
Just as email can include images and sound, it can also include a
sequence of images. A mail application could enable users to place, and
possibly edit, digitized video in a standard email message. The video
might have been captured from a television broadcast, an in-house talk
or trade show demonstration, or synthetic images generated on the
workstation.
Video Conferencing
Video conferencing using special equipment not associated with the
workstation has become both commonplace and a necessity for corporate
communication. Current implementations are expensive (both for
equipment and dedicated high-speed phone links) and typically available
in very few locations within a corporation.
Video conferencing on the workstation will fundamentally change the
role it plays in corporate communications. Individual workstations,
with video capture capability and inexpensive cameras, will capture,
compress and transmit video (and audio) over local networks or ISDN
lines to one or many workstations. You will be able to start up this
application in a window as easily as you send email. You will also be
able to share data from your workstation with others - for instance,
engineering drawings or presentations and spreadsheets.
A variation of videoconferencing is broadcast video. One person gives a
presentation and broadcasts it to many people, while the audience can
interactively ask questions through video conferencing capabilities.
Software-only Video Playback
Video software playback displays stored video without any additional
hardware. Generally, the video is compressed to ease the storage
requirements. This type of application is very useful for training and
presentations or whenever someone only needs to play back video, rather
than capture, edit, or store it.
Video Editing
Video editing enables you to capture video clips, then manipulate and
store them. Different aspects include dropping and duplicating frames,
creating special effects, synchronizing audio with the video, splicing
clips together, and so on. This capability is very important for
high-quality video production, but also for creating presentations,
demos, training applications, and so on.
Education and Training
Full-motion digital video can transform computer-based training from a
slide presentation into a live presentation. Opportunities abound for
sales training, just-in-time technical training, occupational training,
on-line documentation, and computer-based education courses. There are
two categories of customers for these applications, each with different
requirements.
o Users of video authoring software, such as developers of
training materials. need the software plus the video capture and
compression capability.
o Users of training materials may only need the developed
materials, with video decompression and display capability.
Interactive Presentations and Information Access
Multimedia presentations are very similar to the applications described
under education and training. Specific opportunities include
interactive kiosks in public locations (such as instructions in a train
station showing how to purchase and use tickets) and interactive
commercial presentations (such as video presentations of a cruise ship
in a travel agency where the customer can pick an activity or
port-of-call and see a video of the selection). Once again there will
be users requiring authoring capability (including video capture) and
others requiring only display capability.
Professional Video Productions
Video productions, for broadcast video (such as television commercials
and flying logos) or for distribution on CD-ROM (video games and sales
material), can be planned, created, and edited using workstation video
capability.
Corporate Custom Applications
As full-motion video on the workstation becomes more accessible, its
use in corporate applications will become more commonplace. An initial
application includes remote medical imaging for diagnosis and surgical
planning.
Key Video Concepts
Full-motion digital video is actually a combination of several,
related, hardware and software technologies for video capture, video
compression and decompression, video transmission over a network, video
display in a workstation window, and video archiving on disk or other
storage media.
Video Capture (input)
The video we are all used to seeing on our televisions and VCRs is an
analog signal. To capture the video signal, the video data must be
digitized and stored in memory or in the frame buffer. The digitization
requires special purpose (but commonly available) hardware and produces
a digital image similar to a Sun raster file. For the image to be saved
it must be transmitted across the available buses to memory. Capturing
and storing or transmitting a continuous video sequence at 640 x 480
resolution requires from 9 to 27 Mbytes/second of bandwidth for 8-bit
or 24-bit images. This stretches or exceeds many system buses such as
SBus, LANs (Ethernet), or WANs (ISDN). Therefore, real-time video
capture will generally also include real-time video compression to
reduce the bandwidth required. (This is discussed further below.)
Compression is also required to save video data. Without compression,
one minute of video data requires almost a gigabyte of storage.
Video capture is needed for many, but not all, full-motion video
applications. It is obviously necessary for every workstation used for
video-conferencing. It is also required for many video authoring
situations (though the video capture capability can often be a shared
resource).
Full Motion Digital Video Display
Display of full-motion digital video generally means starting with
video that has already been digitized and compressed and is received
from some network connection (Ethernet or ISDN), from a live video
capture device (camera or VCR), or from some storage media (disk or
CD-ROM). To display the video must be decompressed (preferably in
real-time, e.g. 30 frames per second) and sent to the frame buffer for
display in a window.
Full Motion Digital Video Compression/Decompression
Video compression and decompression is one of the areas of technology
currently receiving the greatest amount of attention. As discussed
earlier, video compression is a requirement for reducing network and
bus bandwidth needs and for reducing space for video archiving. There
are many ways to compress and decompress video, with different costs
and benefits, both monetary and performance. The many techniques
available or under development differ in a variety of characteristics.
Characteristics of Compression/Decompression Techniques
Some of the characteristics of compressing and decompressing
full-motion video include lossless vs. lossy compression, compression
ratio, intraframe vs. interframe compression, computation cost, and
symmetric vs. non-symmetric compression.
o Lossless vs. Lossy Compression
Lossless compression means there is no information lost when an image
is compressed and then decompressed; that is, the decompressed image is
identical to the original image. Lossless decompression is often used
for saving space on disk storage text and binary data. Lossless
algorithms tend to provide only a small amount of compression - perhaps
a 2:1 uncompressed-to-compressed ratio. Certain applications, such as
medical imaging or satellite data interpretation, require lossless
compression.
The video compression algorithms used for full-motion digital video are
generally lossy algorithms, that is, not identical to the original
image. The amount of information loss, and thus the final image
quality, varies considerably with the different techniques and within a
single technique according to the parameters chosen. As a general rule,
the greater the compression ratio, the greater the information loss.
o Compression Ratio
Compression ratio describes the change in size, or amount of storage
space required, one achieves in compressing the image or video.
o Intraframe vs. Interframe Compression
Intraframe compression compresses a single image at a time, without
regard to the previous or succeeding images. Other algorithms do
intraframe compression and then do additional interframe compression.
This technique is much more costly to encode but, for a given
compression ratio, provides a higher quality sequence of images. This
provides the very high compression needed for video conferencing over
LANs and WANs. Techniques that are intraframe-only are more appropriate
for still images.
o Computation Cost
Different compression techniques vary considerably in the amount of
computation required to compress and decompress images. Some
decompression techniques are relatively low cost (measured in time and
money) and can be computed in software on standard workstations at
reasonable speeds (for example 10-30 fps). Other techniques currently
require special purpose hardware to perform compression or
decompression at rates close to full-motion video.
o Symmetric vs. Non-symmetric Compression
A symmetric compression is one in which the computation cost for
compression is roughly the same as the computation cost for
decompression. A non-symmetric technique is one in which compression
typically is significantly more expensive than decompression. Symmetric
techniques have the advantage that specific hardware can be developed
to provide both the compression and the decompression. Asymmetric
techniques have the advantage of providing inexpensive playback without
additional hardware.
Compression Techniques
As mentioned previously, there are a great many compression techniques
in existence or currently under development. Some of the more common
ones are described in the following paragraphs.
o JPEG
Joint Photographic Experts Group (JPEG) is close to being endorsed as
an industry standard for still picture compression. It is an intraframe
compression standard that achieves a ratio of about 20:1 r
o MPEG
Moving Pictures Experts Group (MPEG) is a video compression standard
for full-motion video. It is an interframe method that can compress to
a ratio of about 100:1.
o Px64
Px64 is also known as H.261. This technique is a standard proposed
specifically for video transmission over ISDN lines: that is, for video
conferencing and videophone.
o DVI
Digital Video Interactive (DVI) is a proprietary video software
architecture developed by Intel to run on their hardware.
o RPZ - RPZ
RPZ - RPZ is the Apple" proprietary compression/decompression technique
and is part of their QuickTime` software for multimedia applications.
Other Techniques
There are also several lossless compression algorithms, including
Run-Length Encoding and Huffman encoding. These tend to provide much
less image compression. They are also often used in conjunction with
the above techniques to provide some additional compression.
Challenges
Full-motion digital video on the workstation is currently possible and
no longer a research question, but it is far from commonplace. The
greatest challenge is to make video on the workstation inexpensive
enough to have on every workstation, and easy enough to use so that it
is no more complicated than email.
The challenge of low cost is the easier one to meet. As CPUs become
more powerful and as workstations are becoming multiprocessors, more
video functions can be computed on a standard workstation. Furthermore,
special- purpose chips to aid in video compression are becoming
available and will advance along the price curve until they are on
every system. Additional hardware, including cameras and higher speed
networks, are also becoming more accessible.
The challenge of ease-of-use is not so predictable. Widespread use is
not likely to occur until multimedia presentations are as easy to
produce as creating slides or displaying analog video on a VCR. Video
conferencing will not be widely used until one can point and click and
bring up a video conference window on the workstation. Furthermore,
full-motion video must integrate seamlessly with the other aspects of
multimedia - documents, fax, and audio.
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The Florida SunFlash
Multimedia: ISDN (6 of 6)
SunFLASH Vol 40 #30 April 1992
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6 ISDN
Integrated Services Digital Network (ISDN) is a new service offered by
many telephone companies that provides fast, high-capacity digital
transmission of voice, data, still images and full-motion video over
the worldwide telephone network.
ISDN will soon be to wide area networking what Ethernet is to local
area networking today. It will enable multimedia communication - voice,
video, images and data combined - over the existing telephone network.
ISDN will help workstation users integrate their telephone with
workstation applications in a seamless way, increasing their
productivity. In addition, ISDN will provide an alternate channel
enabling customers to transmit information from one point to another in
real-time at a reasonable cost. ISDN offers many times the speed of
current analog modems, and twice the bandwidth of the leased lines
commonly used today to carry video conferencing.
ISDN Applications
ISDN applications fall into two categories:
o Basic applications in which ISDN replaces or enhances existing
applications
o New types of applications that integrate voice, images, video
and data in ways that don't exist today
Basic Applications of ISDN
The basic application of ISDN is for wide area networking. When
workstations come with an ISDN interface built in, just as they have an
Ethernet interface today, your reach will not be limited just to the
local network but will extend to the whole world. Some of the
applications this basic capability enables are described in the
following paragraphs.
Replacement or Backup for Private, Leased,
or Public Packet Switched Lines
For most customers, the cost of an ISDN line is much less than that of
a private line or leased line. For customers that can afford private
lines, ISDN will provide a cost-effective alternative as a backup line.
Most leased lines are 56 kilobits per second (Kbps), compared to ISDN
speeds of up to 128 Kbps (aggregated) for basic rate ISDN.
For customers that cannot afford the substantial fixed charges for
leased lines, ISDN for the first time offers them equivalent bandwidth
at a cost they can afford. The cost of ISDN will also be much less than
public switched network access (X.25), especially in Japan and Europe.
Telecommuting
Working from home on a networked workstation will become a reality when
ISDN becomes available at home. ISDN provides data transmission speeds
that enable true client-server computing over a wide area network,
making access from home practical. Workstations will require an ISDN
terminal adapter (or an SBus card for SPARCstations) and software that
allows TCP/IP (communication protocols used in the UNIX environment)
over ISDN.
Replacement of Data and Fax Modems
Currently, 9600-baud modems are becoming a standard. However, the price
range for such modems is $500-$1000. The price for ISDN adapters is
currently in the $1000-$1500 range but they offer speeds that are about
seven times greater than 9600-baud modems.
New Applications of ISDN
New applications made possible by ISDN technology can be discussed in
three categories. These categories are not all-inclusive. Customers
will find many more applications of the technology as it becomes widely
available. Some of these applications are described in the following
paragraphs.
Telephone-Workstation Integration
Telephones used in proprietary PBX systems currently provide
functionality such as caller identification with a liquid crystal
display (LCD). A workstation with a graphical user interface could
provide a much more flexible and powerful display. This type of
integration enables the following applications:
o An automatic phone dialer linked with an address file or
calendar application
o A customizable answering machine application that can take
messages or forward calls based on the identity of the caller
o The integration of voice messaging (voicemail) with electronic mail
Multimedia Communication/Collaboration
A conference call between people at different locations that includes
sharing each others' screens in a collaborative work environment will
require point-to- point connections with real-time response. ISDN can
enable this type of connection. Some of the applications in this
category are:
o Collaborative work environments. This could involve real-time
screen-sharing between two or more people working on the same
project.
o Concurrent engineering. This would enable everyone involved in
a project (including suppliers) access to shared work even if they are
not connected to the same local area network.
o Video conferencing. With proper compression/decompression, a
reasonable quality video conference can be carried over the ISDN lines.
For example, some of the video conferencing systems available today use
two 56 Kbps switched lines, for 112 Kbps total.
Vertical Applications
There are certain market segments such as customer service, where
computer users spend a lot of time on the phone. Any degree of
automation that can integrate the phone and the computer will help
improve service and increase efficiency. Some of the examples in this
category are:
o Customer service applications. ISDN's caller ID feature enables
immediate access to the customer's records when a customer's call is
received.
o Technical support. A support person could easily look at a
workstation screen and provide support remotely.
o Voice response applications.
o Intelligent operator terminals in telephone companies.
Benefits of ISDN
ISDN will benefit workstation users, system administrators, companies
of all sizes, and the telephone company as well.
o Workstation users will get better access speeds and higher
transmission quality of voice and data. ISDN will make wide area
networking and communications as easy as plugging a phone into the wall
jack. It will also allow a viable telecommuting environment. Wide area
networking will provide users with the functionality of today's local
area network, but with the added benefit of access to people on other
networks as well.
o Telecommunication system administration can more easily
accommodate changes when office moves occur. It will also reduce the
network wiring requirements and maintenance costs. ISDN will make
troubleshooting from remote locations easier.
o Company benefits include reduced transmission costs resulting
in enhanced employee productivity. There will be faster dial-up
transmission at lower cost and higher profits in the long run.
o For the telephone company, ISDN will reduce maintenance and
upgrade costs and provide an increase in the data communication
business for the telephone companies. These benefits will ultimately
result in higher profitability.
Key ISDN Concepts
The following paragraphs describe some of the technical aspects of ISDN.
Current Telephone Network
In order to understand ISDN technology, you should first understand the
current telephone network.
Voice Call Routing
Voice is analog in nature and so are most telephones today. When you
make a call, your analog signal goes through the telephone company's
central office (CO) switch which converts it to a digital signal. If it
is a long-distance call, the switch routes the digital signal to an
inter-exchange carrier (IEC) such as AT&T, US Sprint or MCI. The IEC
then routes the call to the appropriate local central office which
converts the digital signal back to an analog signal so that it can be
used by the telephone on the receiving end.
Data Call Routing
Computers generate digital signals instead of analog signals, so two
additional steps are required. A modem must convert the computer's
digital signal into analog form before sending it to the telephone
company's CO switch, and another modem must convert the analog signal
back to digital so the receiving computer can understand it.
In this process the data is converted between analog and digital forms
at least four times in one transmission, thereby under-utilizing the
network capacity. When voice is converted into digital form, a bit
rate of 56 Kbps (kilobits per second) is often used to maintain the
sound quality. Most modems today transmit data at 1200 or 2400 bps
(with 9600 bps modems becoming more common). At 1200 bps, less than 2%
of the 56 Kbps network capacity is used.
ISDN Telephone Network
Computer equipment is currently at a disadvantage because the telephone
network was designed for voice. ISDN will remove this limitation,
enabling companies and individuals to access a variety of multimedia
services (voice, textual data, images, video) over a single
international phone system serving as a global network.
Integrated Services Digital Network (ISDN) is a worldwide public
telecommunications network that will deliver a wide variety of data and
voice transmission services. The first set of standards for ISDN were
issued by the International Telecommunications Standards Organization
(CCITT) in 1984. As ISDN becomes established globally, a variety of
multimedia services (voice, textual data, images, video) can be
supported over a single, homogeneous infrastructure. Digital
communication will eventually prevail, resulting in enhanced quality
and reduced costs of telecommunication. In addition, ISDN promises to
make wide area networking as economical and accessible as local area
networking is today.
There are various types of ISDN that cater to different requirements.
Unlike the current telephone network's in-band signalling, all ISDN
services offer out-of- band signalling (signalling information and data
are carried on different channels). This provides more flexibility in
network operations and control.
D Channels and B Channels
There are two types of ISDN channels, D channels and B channels.
o D Channel
A D (or Delta) channel is a control channel.
o B Channels
B (or Bearer) channels are 64 Kbps clear channels for carrying data.
Depending on the service offerings of the telephone companies, a number
of B channels can be concatenated to provide higher bandwidths.
BRI, PRI, and BISDN
There are three types of ISDN, Basic Rate Interface (BRI), Primary Rate
Interface (PRI), and Broadband ISDN (BISDN).
o Basic Rate Interface (BRI)
BRI is the interface that will eventually replace the current
single-line telephones in residences and many businesses. BRI will be
the standard interface to connect desktop devices such as telephones,
fax machines and computers to the ISDN network. It normally provides
two B channels and one D channel and is commonly referred to as a 2B+D
interface.
o Primary Rate Interface (PRI)
PRI will become the standard interface between a PBX and a central
office switch, or between two PBX switches. In the US and Japan, this
service provides 23 B channels and one D channel (23B+D) with an
aggregate rate of 1.544 Mbps. In Europe, the primary rate interface is
30B+D with an aggregate rate of 2.048 Mbps. These rates are different
due to the requirement of maintaining compatibility with the existing
digital systems in each country. Most phone companies in the US have
applied to their regulatory agencies for rate approval for both BRI and
PRI services. This means that ISDN will soon be available in most
metropolitan areas in the US.
o Broadband ISDN (BISDN)
Broadband ISDN is the telephone companies' solution to the bandwidth
limitations associated with BRI and PRI. As video and high-quality
images become commonplace on desktops, their bandwidth requirements
will exceed the capabilities of BRI and PRI. BISDN will offer a rates
as high as 150 Mbps. However, BISDN is at least 2-3 years away from a
trial stage in the USA.
Signalling System #7 (SS7)
For ISDN services to be useful, a user must be able to communicate to
the rest of the world. SS7 is an international standard for common
channel signalling that enables internetworking between the various
ISDN exchanges. It is called "common channel signalling". The
signalling information is sent on a separate, shared signalling
channel. AT&T has been using a proprietary common channel signalling
scheme, but is migrating its switches to SS7 to permit easy
internetworking.
Challenges
ISDN's promise for integrating voice and data over a wide area network
opens up possibilities for a universal network with a cost structure in
line with current telephone service. ISDN does not require any change
in our current wirings except for some minor additional investments in
equipment. The US has been slow to implement ISDN so far, but the new
aggressive plans published by telephone companies call for ISDN
availability in all metropolitan areas by 1994.
In contrast, ISDN is already available today in most of the European
countries and in Japan. In fact, most of the developing countries are
also migrating to ISDN. Japan, Australia, France, Germany, and Great
Britain have ISDN available today for all businesses and many
residential customers. Providing ISDN support as a standard feature
will be a requirement for computer companies doing business in Europe
and Japan.
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