audio content and the internet
For true audio there are a large number of file formats, a few of which are commonly found on the internet, including AIF, WAV, Windows® Media Audio and MP3. For these to be heard they have to be fully downloaded first and then played using an appropiate player - if one can be found for the users operating system.
Luckily there are a few audio formats for which players are available for most computer operating systems. One of these is RealPlayer™ which has a free player available for most computer operating systems. This satisfies the criterion of portability, so what about file size?
Well the argument is covered in the size comparisons box.
The audio compression abilities offered by the Real™ system is really pretty impressive, reducing file sizes by a factor of 10. This has a big impact on download time, as well as file space on the server.
but that is not all...
So we have a highly portable format that is very compact.
What could be better?
How about a format that does not even need the file to be fully downloaded before it starts playing?
A 30 minute talk saved as a WAV file would be about 68 megabytes in size, which would take a considerable time to download before you could start listening to it. Even when encoded as a RealAudio™ file it is 6.5 megabytes which would take a short while to download by convential means.
We have prepared several audio files of this length and greater, and they only take a few seconds to start playing. That is the beauty of streaming.
Examples of large audio files streamed via the internet are available ›››
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size comparisons
For this exercise we have a 30 second clip of music. This was taken from a song composed and recorded by Marcus Mitchell onto an audio cassette using a four channel mixer.
In the first step this was digitised as a stereo WAV file. This file was then edited and optimised. For this comparison exercise this was converted to an MP3 file. Finally the WAV file was encoded as a Real™ audio file.
so what are the size differences?
The differences are illustrated in the following table. You can compare the download times for yourself with the example files being available from the links in the table.
format |
size (kb) |
down load time
(seconds) at: |
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44K/s1 |
200K/s2 |
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5254 |
119 |
26 |
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478 |
11 |
2.4 |
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129 |
3 |
0.6 |
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1) a typical speed achieved via a 56K modem connection
2) a typical speed achieved via a LAN connection
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If you already had RealPlayer then in some respects the above download experiment would have been unfair. This is because RealPlayer does not need to fully download a file before it can start playing it.
RealPlayer uses a system called streaming which allows audio/video files to start playing as soon as a small proportion of a file is received. Because the server takes part in the process it does mean that you can't use any old server or site hosting account for making these available.
more on hosting ›››
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audio off the net
If you are considering making the audio content available by other means, such as from within a multimedia presentation on CD or video then a higher quality of audio would be appropiate. The audio compression that is a feature of the Real™ system does result in some loss of audio quality.
If this is a consideration then it is important that this is made apparent at the outset to whoever you use to digitize, edit and encode your audio, and video, content.
This could save you a lot of time and money.
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