Digitizing Audio
(This primer is for Mac users. The concepts will be the same for PC users,
though you'll have to adjust.)
Setting the Input Source
Use the Sound (or Monitors and Sound) control panel to set the Sound In to
your desired audio source.
 
Choosing an Application for Digitizing
You can find shareware sound recording utilities on the net, or you can use
one of several commercial sound editing or video editing packages. Since
Adobe Premiere is readily available around campus and has a great deal of
flexibility, I'll use it for this demonstration. After you've set the sound
source, open Premier and choose File/Capture/Audio Capture to display the
audio recorder window.
Then set the sampling rate and format for the audio recording. The
higher the sampling rate and format (44 kH, 16-bit stereo) the better
quality of sound you will record. Higher quality sound, however, also
requires more disk space to record and store and may not play well on most
computers. You will generally get fine sound with 22 kH, 8-bit mono or
less, but you can alway save the audio file in a lower sampling than you
recorded. See the page of audio sampling
comparisons to get an idea of how various formats effect the sound you
hear.
Saving audio files in Premiere
Once you've digitized an audio clip in Premiere, you have a couple of
different options. You can Export the file in AIFF format (this is
not the same as AIFC) by selecting Export from the File
menu and then choose AIFF Audio File.... You can also save the file in
Quicktime format, but it's a litle more complicated. (The size of the file is
almost exactly the same.)
To save the file in Quicktime format, you'll have to create a movie
file. To do this, start a New Project in Premiere (any of the
preselect choices will do). Import the audio file that you just created
(you'll have to save the audio clip first) by selecting Import File
from the file menu. Select the audio clip that you just created. That
clip will now appear in the Project window (usually located in the
lower left corner of the screen). Drag the audio clip from the Project
window to the Construction window. It will look something like
this:
Drag the right red arrow in the yellow work area bar to the right until it
stops at the end of the clip. (You can adjust the length of the clip by
changing the yellow work area bar. To learn more about Premiere, read the
manual.)
Before making a Quicktime movie (Quicktime movies can contain only
audio), you'll have to set the output options. Select Make and
then Output Options... to bring up the following dialog box:
There are several things you'll want to set:
- Select Work Area if you only want to record what's between the
two red arrows. Select Entire Project if you want to record
the... entire project. (Stay with me here. :-) )
- Select Quicktime Movie
- Deselect Video if you want to generate an audio-only file.
- Make sure that Audio is selected and set the Rate, Format and
Blocks for the audio quality you want. (See the Audio Quality page for examples of the various
sampling rates and formats. Blocks are used to tell Premiere how much
audio to stick into the video at a time. I don't think you have to worry
about it for an audio-only file.)
- Make sure you select Flatten if you want to be able to use this
on the web or play it on different platforms!
Once you've set the options you want, select OK. To make the
movie, select Make and then Movie. This file can now be used
in a web page. Why did I go through all of this if you can just save the
audio file as an AIFF file directly from Premiere? Because someone's bound
to want to know and there are a couple of things you have to know. (Like
making sure you flatten it.) Besides, the Quicktime plug-in has a cute
control panel for controlling playback of your audio.
Including audio in HTML files
Audio files can easily be included in HTML files by linking to them, using
the <EMBED> tag, or (don't do it!) by making them background sounds
for your web page. (Seriously. 95% of the people out there will grow
tired of your background sound before it finishes loading. This feature
rates right up there with the overused <BLINK> tag.)
Linking to an audio file:
Use a standard anchor link to point to an audio file. Your viewers will
have to set their browsers to use an appropriate helper application to
open the files. Here is an example. The
code used to create the link is:
<A HREF="audio/m-22-8-s.mov">example</A>
and my Netscape browser
is set to use the Quicktime Plug-in to open the audio file in a blank
browser window.
Embedding an audio file
The audio quality page uses the Netscape
extension <EMBED> to embed the audio file in the web page. Again,
my browser has the Quicktime Plug-in installed and Netscape has been set
to use it when opening Quicktime files.
(To set Netscape to use a particular plug-in or application to read a
certain file type, open the Options menu and select General. In the General
dialog box, select Helpers and then select the appropriate tool to open the
appropriate file type. See your browser's documentation to see how to set
helpers for your particular browser.)
Using an audio file as a background sound
I'm not helping you out on this one! Check the Netscape helpers page or
find a site you like and take a look at the source. What can I say?
You've gotta draw the line somewhere. :-)
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