Streaming Audio Primer
(Part 5):
If you have come this far, then you have accomplished
the most difficult part. If you already have your own web page,
then you have probably done this next step: putting the file on
the Internet. To do this simply upload the audio file to your
web page and provide an appropriate link for someone to download
the file. Check out my site for an example that allows you to
pseudo-stream MP3 as well as download them. You might encapsulate
your files into a ZIP archive, since it is much easier to download
ZIP files in some browsers. Shareware versions programs that create
ZIP archives are available, such as WinZIP.
However, the pseudo-streaming techniques will not work with ZIPped
files. They must be posted as *.MP3 or *.VQF. The last key is
the *.M3U and *.VQL files which point to the actual MP3 or VQF
files, which will be discussed in more detail below.
If you want to do this right, I would suggest
making a separate page just for these downloads. On this page
you should include links for people downloading shareware
versions of players that will play either the MP3 or VQF files.
I would suggest the Microsoft Windows Media Player or the
Sonique player for MP3 files. The Microsoft Media Player will
probably become the most widely player, while sonique is a much
more aesthetically pleasing and functional player. One of these
functions include the unique ability to both play a stream and
save the file, all at the same time.
The VQF player can be downloaded from Yamaha.
It is actually a browser plug-in; although, it can be operated
without your browser.
Pseudo-Streaming Audio
Pseudo-Streaming Audio is a technique that
lets someone listen to an audio file immediately without having
to download the entire file. In this respect it is similar to
Real Audio. Although this label is not technically correct
because this technique does really stream audio, it is called
pseudo-streaming to distinguish it from RealAudio's dynamically
compensated streaming, which is what many people think of as
streaming.
Streaming works by downloading the file as
normal, but decoding and playing the file on the fly. As long as
the file info is downloaded faster than it can be played, then
the listener can detect no difference whatsoever between
pseudo-streaming and dynamic streaming (Real Audio). This
requires a modem connection to be greater than the bit rate
which was set during encoding. However, if the listener has a
slower connection, then their computer does not play until it
has downloaded enough information to begin playing with a buffer
to spare. This may result in some pauses during playing. But,
the tests that I have run show that this never occurs with a
28.8 kbps modem if the stream's bit rate is equal to or less
than 20 kbps.
Real Audio is different in that the files are
posted on a special server that adjusts the audio quality (lower
quality means less information must be transmitted) to
accommodate slower connections. However, for a given rate, the
MP3 and VQF sound much better than Real Audio! The true
difference between Real Audio and MP3 streams is that a Real
Audio file actually contains information for multiple bit rates.
This redundancy makes the file huge; however, it allows a single
file to support multiple connection speeds. This is the only
true drawback to this MP3 pseudo-streaming technique - high
bandwidth listeners must listen to the same quality as used by
listeners with the slowest connection speeds. But, for voice and
speech audio, a quality can be chosen that sounds pleasant at
even low connection speeds.
Both VQF and MP3 can accommodate
pseudo-streaming. In both cases, the key to this magic is a
small file called a "locator file". This file contains nothing
more than the http address of the audio file. However, this
special locator file directs a listener's player to the audio
files location and instructs the media player to play the audio
stream as it is downloading.
All locator files for the MP3 format have the
extension M3U. Files with this extension typically contain a
"play-list" of files in a given location. If only a single file
is included, then only that file will be played, but if multiple
files are included, then the player will continue and play the
additional "tracks" after the first one is completed. Using the
"track seek" buttons, a listener can jump from one track to the
next. The following line is the only contents of a simple M3U
file located on our site:
http://www.auburn.edu/truthseekers/audio/mount1.mp3
The name of this file is "mount1.m3u".
Double-clicking or linking to the M3U file will automatically
open the default MP3 player and begin streaming the audio file,
"mount1.mp3" from our web-site. As a simple test, try making a
similar file using "Notepad" or any other simple text editor.
Copy the above contents, paste it into the new text file, and
save it to the desktop as "test.m3u". Finally, connect to the
Internet, if you haven't already, and double-click the newly
created icon for "test.m3u". If you have a MP3 player, such as
Sonique, Microsoft Media Player, etc., then your default media
player should automatically open and begin streaming it from our
site.
Once you are comfortable with this test, then
you are ready to upload your own MP3 and matching M3U files.
Please note that links to the M3U file will begin streaming the
MP3 file, but links to the MP3 will prompt for its download
without playing it until it is completely downloaded.
VQF is very similar to MP3 in that it uses a
locator file. Official directions for how to do this are
provided on Yamaha's web site. These are the best directions.
Please refer to them for details.
Server Configuration?
A good ISP server will probably have the
server configured properly, but if you have any trouble, then
you may have to contact your ISP provider or web-master. A
typical problem with server configurations would be clicking on
a link and a browser window popping up, filled with garbage
text.
The server configuration revolve around one
issue - application association. Before a server directs ANY
file to your computer through the web, it first tells your
computer what kind of file it is and if any specific program
should be used to open the file. For example, your server tells
your computer that all files with extension HTML or HTM should
be opened using your web-browser. A few low-budget ISP's may not
have configured their server to recognize files of extension
MP3, M3U, VQF, etc.
If you have trouble with either one, be sure
to contact your ISP provider or webmaster. They may ask you to
post an additional file labeled ".htaccess". The period in front
is important. (You could try posting this on your on.) This file
tells the server how to handle files with specific extensions
and whether or not to associate a browser plug-in or application
with them. The file must be posted in the same directory, or
higher, as the audio files. Any subdirectories within the same
directory as the .htaccess file, will "inherit" the same
settings. My .htaccess file looks like this:
AddType
application/octet-stream mp3
AddType audio/x-mpegurl m3u
AddType audio/x-twinvq vqf
AddType audio/x-twinvq vql
AddType audio/x-twinvq vqe
The first line tells the server that files
with the extension MP3 are applications that must be downloaded
in binary form - they are not ASCII text or HTML code. The
second line associates files with the extension M3U with the
default audio player. The last 3 lines tell the browser that the
files of those extensions are associated with file type "audio"
and to use the plugin "twinvq" to play them. These last 3 lines
are very similar to the code provided on Yamaha's site.
Although, you may not have to do this, I have
included it for the few who may need it. Again, first ask your
webmaster and ISP if you have any problems. It won't hurt to add
the above ".htaccess" file, even if the server doesn't recognize
it.
Concluding Thoughts
The bottom line is that the MP3/VQF setup is
less complicated, sophisticated, and expensive than streaming
audio. Moreover, it works almost as well as Real Audio; and for
some performance parameters, it is even better, such as smaller
file size for the same quality. The MP3 format is already
extremely popular with those who trade and share music over the
Internet, and its popularity is continuing to grow. Eventually,
as modem speeds increase, formats like MP3 and VQf will topple
the entire Real Audio regime because of the complexity of
setting up Real Audio files, thereby removing the only advantage
that Real Audio has over MP3 and VQF. |