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 a lot 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 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.

http://www.lib.rochester.edu/multimed/music.htm
http://www.math.auth.gr/~axonis/studies/audio.htm
http://www.communicator.com/mp3itva.html
http://homerecording.com
http://www.lib.rochester.edu/multimed/movies.htm
http://www.wotsit.org/

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.


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