The phrase that best describes this is broadcatching. It was coined by a professor at MIT to explain the server/client communication necessary on the web. The forms of cybercasting that are becoming popular for transmission on the web are beginning be received in a more traditional real time playback format but, they must still be initiated by the client. The fact that the playback and interfaces are getting to be more traditional is good for the user - we like things to look like what we know.
I'm getting ahead of myself here. How did we get this far? Let's look at where cybercasting started and how we got to where we are today.
The idea seems simple enough to the non-techno nerd but, the differences
in transmission methods, media, and protocols makes it much more
difficult. The first transmission of images and sound was simply the FTP
of a file that, once received, could be processed by some application on
the clients machine.
In 1992 a format for the identification of file type was proposed by
Nathaniel S.
Borenstein at the ULPAA '92 Conference in Vancouver. Borenstein
thought that it would be a great idea for people to be able to do
"multimedia email." He proposed the creation of MIME
(Multipurpose Internet Mail Extensions) extensions. These extensions
allow browsers to know what kind of file to interpret.
As browsers became more powerful they could process
more of the information within the program. Netscape now
includes a
player for .au and .aif audio files. When combined with the ability to
display .gif and .jpg images in a document, this makes for a better, but
still very basic, multimedia experience.
In the Beginning...
The addition of the programming language Java has
further increased the
capability of web browsing. It enables the browsers to update images,
trigger sounds, react to user input, and more. And now there is Shockwave from Macromedia. This
new plugin for browsers enables clients to view Director movies. All
these improvements add versatility for the presentation of materials on
the web but the key question is:
There is one fundamental aspect that separates these forms of viewing and
listening from cybercasting. Whether it is FTP or a browser that gets
the files, they must be received and stored, at least temporarily, by the
client. Then they can be processed into something useful to the client.
Even Java must load all the information it will need to carry out its
duties as an applet (a miniature program).
This is a major shortcoming with Shock wave as well. The client must
wait for
the information to be received, temporarily stored, and then processed by
the plugin program. In fact, at present (Dec. 8, 1995), Shockwave doesn't
support linked files. This makes it unable to include Quicktime
movies because it treats them as linked files in all Director movies.
On the client end, the user, there needs to be a player. This player can
be designed to decode video, audio, or both. The players are usually free
to the user and can be downloaded and installed with relative ease. The
companies that support cybercasting ventures are giving the players
away. Their revenues will come from the server end through sales and
support of their systems.
The servers stream the data to the client upon request. The data is a
digitized and compressed video or audio signal that may be a stored file
or a real time translation. The compression format used is one that each
specific player is designed to interpret. The most popular currently in
use is a form of MPEG.
A likely reason for stored files to be served is in the case of archived
material. The Internet Multicasting
Service is good example of this. They use a player called Real Audio to serve a weekly
interview program. They now support Xing Technologies
Streamworks player as well.
The serving of real time audio or video is much more complex process. It
requires the encoding and compression of the information
instantaneously. This requires expensive hardware in addition to the
serving hardware. Video encoding requires a great deal of information in
comparison to audio so it suffers more degradation with the current
schemes. Real time audio encoding is getting very good with little loss
of quality and greatly reduced bandwidth requirements.
The Streamworks
system made great improvements with their last update. The realtime
audio from radio stations like WXYC come through with relatively
few dropouts and at very low bandwidth. If bandwidth isn't a
consideration they can serve great stereo music sampled at 44Khz (that's
CD sampling rate), again with little dropout.
Real Audio is a another player
that claims it can play streams back at quality equal to FM radio
signals. It is a scalable system that allows the server to adjust for
the available bandwidth. The Streamworks server can do this as well.
Truespeechis a more basic
player that is meant to be used as an alternative to putting traditional
audio files in a web page. The page will link to the Truespeech file and
the clients browser spawns the player that decodes the file as it comes
in.
There are two companies that are currently providing video streaming
servers and players on the web. The first was mentioned above from Xing
Technologies. Streamworks will also stream video but not as nicely as
the audio. The second video streaming company is VDOnet with their player called
VDOLive. VDOLive looks like the best at the low bandwidth video
transmission game. They have the problems listed above but, improved
compression, increased computation speeds, and increased bandwidth will
all help this situation improve quickly.
The most common method of upstream cybercasting on the web is CU SeeME. It is a basic
teleconferencing package that was created at Cornell University and is
available for free. It allows users to send audio and video at about 4
frames per second, depending on bandwidth, to a reflector. The reflector
is a server that puts the image and the audio up as if it were a bulletin
board. The users that are logged onto the reflector can see and/or hear
the others on the reflector. The number of participants is limited by
the administrator of the reflector.
This technology was used in a project by the people at SunSITE to cybercast WXYC. This
was the first full time cybercasting of a radio station on the web.
Users could logon to the reflector and hear WXYC from anywhere in the
world. The audio quality was poor compared to the cybercasting
capabilities available today but, it focussed attention on the new
possibilities and sparked a number of legal questions for communication
lawmakers.
CUSeeMe has illustrated the enthusiasm for this type of upstream
communication. There is a CUSeeME event guide
that list what's happening on the web. There's also a program that can
connect two users directly.
In the words of its creator,
The new devices that are bound shake up the communications industry are
those are specifically made to allow person to person communication over
the web.
The Internet Phone is an
intriguing device that has tremendous implications.
Another similar device is the Mac
Phone. These devices allow transmission of audio between two parties
using no more bandwidth than a medium speed modem.
The impact of these
systems and those that will surely follow them will not be fully realized
for some time but, it could be significant.
The MBONE
is a multicasting backbone that was set aside in 1992 for video and audio
conferencing. It requires an extremely large bandwidth connection. The
MBONE is relatively exclusive as an
interactive medium. Those wanting to cybercast their information make a
sort of reservation. For those with right machine and connection,
monitoring the MBONE is easy. A key benefit is that
many machines can monitor the transmission using the same amount of
bandwidth as a single machine. It also allows the transmitter to control
the dissemination of information by controlling how far the packets of
information can travel. In spite of its current
shortcomings, the potential for cybercasting is enormous. It already lets
parties communicate orally from anywhere around the world. It allows
users to listen to high quality audio from anywhere. And it allows us to
see video images - not very good, but understandable - from anywhere.
Cybercasting has overcome the dilemna of storage limitations through real
time players. The user no longer has to store the file so the server can
retain the quality that is desired. Combined with more effective
streaming methods, user can enjoy beautifully clean, stereo audio with
little drop out. The issue of bandwidth is still a limiting factor and
is now the primary limiting factor. The bandwidth issue is being attacked
in a number of ways that have allowed for impressive progress. The new
hardware and software compression/decompression schemes are becoming more
efficient, reducing the need for bandwidth. The amount of bandwidth that
is physically available is constantly growing and will substantially
increase for the general public in the near future. All of this makes
for an exciting future for cybercasting. The future for cybercasting has
the potential to be great. Whether it can fulfill that promise will
depend on many factors; regulation, bandwidth, dissemination, and the
capability for upstream communication. These issues will dictate whether
cybercasting is a triumph for world communication and tool that empowers
individuals, or just a new way to catch a "Happy Days" rerun.
Is this cybercasting?
No. Not really.Cybercasting Proper
The Client
The Server
The Players
Audio
There are several players available and the numbers are growing. Those
companies that currently have players and servers are constantly updating
them every time they find a more efficient solution. The updates can
definitely show marked improvement.
Video
Video streaming on the web has a lot of improvement to make. There have
been tremendous improvements but, picture quality, size, and frame rate
are still inadequate.
The amount
of information that must be encoded from each frame of video creates a
great deal of difficulty. The compression process includes a number of
tricks in order to reduce the amount of information
that is streamed. The image size is reduced and the number of frames per
second are reduced. This makes the video small and jumpy. Combined with
the blockiness caused by the compression algorithm, the video has a way
to go.
Two Way Communications
your soul-mate. (Well, OK, the odds of that
are infinitesimal, but at least you will have
CUSeeMe in common with that other person)."
The Bottom Line
On Cybercasting