Streaming video is a sequence of "moving
images" that are sent in compressed form over the Internet and
displayed by the viewer as they arrive.
Streaming media is streaming video with sound. With streaming video
or streaming media, a Web user does not have to wait to download a large
file before seeing the video or hearing the sound. Instead, the media
is sent in a continuous stream and is played as it arrives. The user
needs a player, which is a special program that uncompresses and sends
video data to the display and audio data to speakers. A player can be
either an integral part of a browser or downloaded from the software
maker's Web site.
Major streaming video and streaming media
technologies include RealSystem G2 from RealNetwork, Microsoft Windows
Media Technologies (including its NetShow Services and Theater Server),
and VDO.
Microsoft's approach uses the standard MPEG compression algorithm for
video. The other approaches use proprietary algorithms. (The program
that does the compression and decompression is sometimes called the
codec.) Microsoft's technology offers streaming audio at up to 96 Kbps
and streaming video at up to 8 Mbps (for the NetShow Theater Server).
However, for most Web users, the streaming video will be limited to
the data rates of the connection (for example, up to 128 Kbps with an
ISDN connection). Microsoft's streaming media files are in its Advanced
Streaming Format (ASF).
Streaming video is usually sent from prerecorded
video files, but can be distributed as part of a live broadcast
"feed." In a live broadcast, the video signal is converted
into a compressed digital signal and transmitted from a special Web
server that is able to do multicast, sending the same file to multiple
users at the same time.
Streaming media is audio and video that are
transmitted on the Internet in a streaming or continuous fashion, using
data packets.
The most effective reception of streaming media requires some form of
broadband technology such as cable modem or DSL. A packet is the unit
of data that is routed between an origin and a destination on the Internet
or any other packet-switched network. When any file (e-mail message,
HTML file, Graphics Interchange Format file, URL - Uniform Recourse
Locater request, and so forth) is sent from one place to another on
the Internet, the Transmission Control Protocol (TCP) layer of TCP/IP
divides the file into "chunks" of an efficient size for routing.
Each of these packets is separately numbered and includes the Internet
address of the destination. The individual packets for a given file
may travel different routes through the Internet. When they have all
arrived, they are reassembled into the original file (by the TCP layer
at the receiving end).
A packet-switching scheme is an efficient
way to handle transmissions on a connectionless network such as the
Internet.
An alternative scheme, circuit-switched, is used for networks allocated
for voice connections. In circuit-switching, lines in the network are
shared among many users as with packet-switching, but each connection
requires the dedication of a particular path for the duration of the
connection. "Packet" and "datagram" are similar
in meaning. A protocol similar to TCP, the User Datagram Protocol (UDP)
uses the term datagram.
MPEG, the Moving Picture Experts Group, develops
standards for digital video and digital audio compression.
It operates under the auspices of the International Organization for
Standardization (ISO). The MPEG standards are an evolving series, each
designed for a different purpose. To use MPEG video files, you need
a personal computer with sufficient processor speed, internal memory,
and hard disk space to handle and play the typically large MPEG file
(which has a file name suffix of .mpg). You also need an MPEG viewer
or client software that plays MPEG files. (Note that .mp3 file suffixes
indicate MP3 (MPEG-1 audio layer-3) files, not MPEG-3 standard files.)
You can download shareware or commercial MPEG players from a number
of sites on the Web.
The term codec is an acronym that stands
for "compression/decompression."
A codec is an algorithm, or specialized computer program, that reduces
the number of bytes consumed by large files and programs. In order to
minimize the amount of storage space required for a complicated file,
such as a video, compression is used. Compression works by eliminating
redundancies in data. Compression can be done for any kind of file,
including text, programs, images, audio, video, and virtual reality
(VR). Compression can reduce the size of a file by a factor of 100 or
more in some cases. For example, a 15-megabyte video might be reduced
to 150 kilobytes. The uncompressed file would be far too large to download
from the Web in a reasonable length of time, but the compressed file
could usually be downloaded in a few seconds. For viewing, a decompression
algorithm, which "undoes" the compression, would have to be
used.
There are numerous standard codec schemes.
Some are used mainly to minimize file transfer time, and are employed
on the Internet. Others are intended to maximize the data that can be
stored in a given amount of disk space, or on a CD-ROM. Codec’s
are used in many popular Internet products, including QuickTime, Netmeeting,
Cu-Seeme, and VDOphone.
Flash, is a popular authoring software developed
by Macromedia, and is used to create vector graphics-based animation
programs with full-screen navigation interfaces, graphic illustrations,
and simple interactivity in an antialiased, resizable file format that
is small enough to stream across a normal modem connection. The
software is ubiquitous on the Web, both because of its speed (vector-based
animations, which can adapt to different display sizes and resolutions,
play as they download) and for the smooth way it renders graphics. Flash
files, unlike animated but rasterized GIF and JPEG, are compact, efficient,
and designed for optimized delivery. Known as a do-it-yourself animation
package, Flash 4 gives Web designers the ability to import artwork using
whatever bitmap or illustration tool they prefer, and to create animation
and special effects, and add sound and interactivity. The content is
then saved as file with a .SWF file name extension.
Web users with Intel Pentium or Power Macintosh
processors can download Flash Player to view Flash content, which performs
across multiple browsers and platforms. Flash is lauded for being one
of the Web's most accessible plug-in. According to an independent study
cited by Macromedia, over 90 percent of Web users already have Flash
Player installed. Macromedia was recently acquired by Adobe in a 3.4
billion dollar deal.
About the Author: Ole Arndt is President of Global
Media LLC, in Branchburg NJ.
Correspondence to: oarndt@streamingmediabiz.com
Article Source: http://EzineArticles.com/
