Zap's MUSIC-ON-THE-NET Tutorial: MIME Types

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Zap's MUSIC-ON-THE-NET Tutorial!

MIME types

Note: These pages, while still "true", are fairly outdated by todays standard. They still contain correct information but it's somewhat dated.

Intro

This page tells you about MIME types, how they work, and what to do when it doesn't work.

File types - on and off the Web

Every file, in one way or the other, has a "type", i.e. it is in some format or other.

In Windows, the file type is "defined" by the extension, i.e. .EXE, .TXT or .WRI.

On a Mac, the file type is defined by the files "Resource Fork" (I think, I'm no Mac guru?)

On the Web, the file type is defined by the files MIME type.

What's MIME?

MIME stands for Multipart Internet Mail Extension, and is an attempt to make the "stupid", text-only Internet mail system understand complicated mails containing several parts in different formats (rich text, pictures, file attachments...).

When the WWW was developed, part of MIME was lifted over to the Web technology, especially the concept of a "mime type".

A mime-type is often written as two strings with a slash between them. This is the major and minor MIME types. For instance:

text/plain

is the MIME type of generic text. And

text/html

is the type of a HTML web document!

MIME and http-servers

On the Web, documents are fetched with the "http" (HyperText Transfer Protocol). This protocol sends not only the file, but it's MIME type too.

That means, that the definition of the type of a file on the Web is done by the server!!

That's important, better say it again, louder:

The type is defined by the server

Not only that - when the http server (your webserver) finds a file that it doesn't know what it is, it serves it as text/plain (the default)!!!

The Problem

Now as you see, MIME is only used when on the web i.e. when using http.

That means, that when you are off the web - i.e. testing on your local harddisk at home - the situation is quite different.

When not using http, the file extension is used, just like in Windows!

The classic Symptom

Classic symptom for links

Let's say you have a link to a MIDI file from a HTML file on your local harddisk. When you try it at home, everything works.

But when you upload it to the webserver, and try the link on your HTML page, the music doesn't play. Instead, the browser window is filled by garbage! This is the MIDI file being sent to you as text/plain, and the browser always shows files of type text/plain in the browser window!!

Classic symptom for embedded files

Let's say you have a embedded a MIDI file on a HTML file on your local harddisk. When you try it at home, everything works, and you see the embedded MIDI player

But when you upload it to the webserver, the HTML file displays OK. But where the embedded MIDI player is supposed to be, there is a strange icon, with the filename! This is the MIDI file that was sent to you as text/plain, and the Windows Netscape browser has a strange and undocumente behavior of embedding the Windows Media-player for unknown datatypes!

The Cure

It's simple, really. The webmaster (the keeper of your webserver) must configure the correct MIME-types. How this is done for a few different servers, can be seen in the document http://www.liveupdate.com/mimetypes.html, available at the Crescendo website. [Please take note that I don't like the new way the new Crescendo player works - see my flame]

These are the MIME-types needed:

Format	Description	MIME-type	Extension(s)
MIDI	General MIDI music files	audio/midi	.mid, .midi
RealAudio	RealAudio files	audio/x-pn-realaudio	.ra, .ram
RealAudio	RealAudio files	audio/x-pn-realaudio-plugin	.rpm

Be Warned of Netscapes very persisten Cache!!!

Netscape caches the files, but also the MIME-type of files. So if your webmaster has changed the MIME-types, it's quite possible you won't notice this when you try the same file again!

If Netscape has downloaded a file with the wrong mimetype once, and it's still in Netscape's cache, the file will still look wrong even if your Webmaster fixes the mime types!! Even if you hit the RELOAD button!!!

To fix this:

..either clear Netscape's cache
..or hit Shift+RELOAD, which is a kind of "super reload". This might help.

If you do not know about this odd behavior of Netscape, you could otherwise loose more then one chunk of hair...

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Page accessed 1112 times since November 2019 and was last modified September 2006

Zap's MUSIC-ON-THE-NET Tutorial!

MIME types

Intro

File types - on and off the Web

What's MIME?

MIME and http-servers

The Problem

The classic Symptom

Classic symptom for links

Classic symptom for embedded files

The Cure

These are the MIME-types needed:

Be Warned of Netscapes very persisten Cache!!!