As you may have gathered from the last few design articles,
audio and other multi-media components are not a strong
point in HTML. Not only does it appear that they were added
as an afterthought, they probably where. Multi-media support
directly from the HTML document is consequently very
limited. Where it does exist, it was added to the major
browsers in a manner that was almost intended to spite the
other browser.
The HTML 4.1 standard from the W3C supports inserted
components such as Audio and Video through the Object tag.
This is a new catchall tag that provides the ability to do
many things that the Browser developers wish to add.
Unfortunately the specification almost reads that way. "The
Object tag is intended to add many things that Browser
developers would like to add!", whatever they may be.
OK I'm being a little cynical. But why don't Audio and Video
Tags exist? It is not as if these are really esoteric
concepts. HTML is esoteric but audio/video has been around a
long time now. I recall being taught how to thread a 16mm
film through a projector. Does anyone still use those 16mm
films?
The closest A/V Tag is BGSOUND in Internet Explorer. This
adds background (B-back G-ground Sound) audio to a HTML
document. Even though it is far better than Netscape's use
of the Embed (In Bed?) tag, it is hardly a sound engineers
concept of advanced audio. Video does not exist at all
within HTML whether sanctioned by the W3C or not. Even so,
as you have probably gathered it is possible to add Audio
and Video to your web site, either through the Object Tag,
Embed Tag, BGSOUND tag or through a Streaming Server.
As you will quickly discover however, there is no such
format as Audio or Video. What we have instead is a plethora
of file formats including Wave, Midi, AVI, MPEG, AU, RA, MOV
etc. What is the difference and which ones should you use?
Here is a list of some of the more common formats. I have
not attempted to list them all because they are changing
quickly and would require more space than I have available.
Audio Formats:
MIDI (.mid,.midi) Music Instrument Digital Interface
Midi is a pure digital format. It essentially stores digital
information to represent notes from Musical Instruments. You
could if you wanted to, create a MIDI music file using a
text editor. Midi files however are usually created with
specialized authoring programs and a digital keyboard. Since
it is a pure digital format you cannot use a MIDI file to
record real world sounds such as a person talking or a dog
barking. The output quality of a MIDI file is also very
dependent on the quality of the audio card that is playing
it back. Old cheap audio cards would reproduce a midi file
so badly that even finger nails on a blackboard or a crying
baby would sound more pleasant. Fortunately today's audio
cards are significantly better. Due to their extremely small
file sizes, MIDI files are the best choice for playing back
digitally authored music on a web page.
WAVE (.wav) Wave Form Audio File Format
Wave files are used to sample real analogue audio into a
digital file format. The frequency of the sample will
determine the quality of the recording and the size of the
resulting file. At 44,000 Hz and 16-bits a WAVE file will be
close to CD quality but will generate a huge file. Since
their source is real, they can store a good representation
of the original sound. You could for example, distinguish
Ringo Starr's northern English accent in a recording of his
voice or the nuance of a good violin.
MP3 (.mp3) "Moving Pictures Expert Group" Layer 3
This is not a new format but it has significantly gained in
popularity lately. Unlike WAVE, MP3 uses a "lossy" algorithm
in order to compress the audio into smaller files. This type
of compression essentially throws information away so that a
side-by-side comparison between a high quality WAVE file and
a highly compressed MP3 file will be quite noticeable. Even
so, the loss of quality is not very pronounced while the
gain in compression is significant. A 1.0 Meg WAVE file for
example, can be compressed into as little as 50K using MP3.
RA G2 (.ra,.rm) Real Audio
Real Audio is one of the oldest formats for distributing
audio over the Internet. Their initial objective was to
provide voice transmission over low bandwidth telephone
lines. With G2 they are now moving toward distribution of
music. Real Audio can also be streamed so that the visitor
can start listening before the entire file has downloaded.
Unlike MP3, Real Audio is a proprietary format but the
Player is free and already installed on many computer
systems.
Audio/Video Formats:
Video compression has been undergoing significant
development in recent years. The formats that are now
available are significantly smaller than in the past while
still maintaining reasonably good quality. Even so, there is
really no such thing as a small video file. They all require
a significant amount of bandwidth. When a typical movie on
DVD requires over a Gigabyte of space you will quickly
realize that even short videos are going to demand a
significant amount of time to download even with a fast
connection.
There is a lot of talk about providing TV, Movies and Video
feeds over the Internet. The fact is the technology is just
not ready for it yet. In order to get real time video over a
fast connection, the quality has to be so low that it is the
equivalent of a penny whistle compared to a major symphony
orchestra. It may be able to carry the tune from Beethoven's
9th but wait until you hear what passes for the Choral
Orchestra.
For those of you that have a valid reason to add video to
your web pages, these are the primary choices you have.
AVI (.avi) Audio Video Interleave -Microsoft
AVI was developed by Microsoft to add Multi-Media
capabilities to Windows. It is the most common Multi-Media
format if for no other reason than it is included on every
PC running any version of Windows. It is capable of
combining both Audio and Video into a relatively high
quality file.
QUICKTIME (.gt,.mov) ISO standard -Apple.
QuickTime is a mature format that combines both audio and
video into a file that is significantly smaller than AVI at
a slight expense in quality. Apple was able to make the
format popular by offering a free player on PC's.
MPEG (.mpg,.mpeg) "Moving Pictures Expert Group"
This is one of the oldest and most popular Audio/Video
formats. MPEG is available on most platforms and probably
offers the best compromise between file size and quality.
There are many other formats either in use, outdated but
still available or in active development. I have not
attempted to list them all since the topic is too extensive
for a single article. Some of the links below will provide
additional information for those of you that are interested
in doing more research. You can also try your favorite
Search Engine or Index. I have also not included a links to
sites that provide players for these formats. The formats
and players change often and are widely available.
Here are just a very few links to sites with additional
information on these formats. There are many more.
This is a wrap on my introduction to Internet Multimedia. I
hope it has helped some of you to get an idea of what it is
all about. As you will have no doubt discovered, it is only
the tip of the iceberg on this quite extensive and complex
topic. I will no doubt look at different aspects of it in
more detail in the future.
"IMS Web Tips" is a weekly news letter for all web site managers regardless of experience who are looking for detailed information on creating, maintaining and promoting their web sites.
