AUDIO RECORDING AND EDITING
|File Extension||Brief Description of Format|
|aiff||Audio Interchange File Format - am older file format developed by Apple for storing uncompressed audio data.|
|avi||Audio Video Interleave - an older file format that may store compressed audio or video file format.|
|cda||CD Audio - format for audio files on CD-ROMs such as music CDs and thus cannot be played on iPods or mp3 players.|
|midi||Musical Instrument Digital Interface - this file format was originally used to store music generated by MIDI devices connected to computers; cannot be played on iPods or mp3 players.|
|mp3||Moving Picture Exerts Group standards file format - comes in other versions also, but mp3 is the most popular audio file format in these standards.|
|wav||Waveform Audio - the old Microsoft format that usually stores uncompressed audio data.|
|wma||Windows Media Audio - the current standard file type used by Microsoft; it uses a fairly robust compression algorithm resulting in small files appropriate for posting on the Internet; cannot be played on iPods or mp3 players.|
Note: More information about audio file formats may be found at the following sites.
Note: The various players can be downloaded from the following sites.
|Contact the IT Center to request a microphone for your office computer. You should also request a set of speakers, if none are presently
attached to your computer.
If you need a microphone for your home computer and are planning on doing only voice recording, there is no need to purchase a high quality microphone. In fact a simple microphone such as pictured at left can be obtained for under $30 and works great.
To connect the microphone, move to the back of your computer and locate the sound card with a jack for a microphone and plug the microphone into the jack. Presto! All is ready. Position the microphone such that you are talking fairly directly into it.
Then make a trial recording with Windows built-in sound recorder. (See the next section) If it sounds well in play back, then you are ready to go. If there is distortion, it may be for any of the following reasons.
1. Windows Sound Recorder
Windows come with a built-in sound recorder. It is very basic, but it reproduces voice sounds very adequately.
In Windows XP the sounds recorder is limited to recording only one minute of audio and outputs by default in wav format. There are a few items that may be changed and a few effects that might be interesting to explore. (See the next section for details on how to access the properties that may be changed in this program.) If you want to see how a particular microphone works or want to begin exploring audio recordings, this sound recorder will do the job. It may be accessed by clicking on All Programs in the Start Menu and then on Accessories. Finally choose the Entertainment folder and click on Sound Recorder. It will show up looking like the image below.
Windows Vista has a sound recorder that can record longer files and it saves the audio files as wma files. Thus this is a much better option to use for many basic situations in which faculty would need a recorder than its predecessor in Windows XP. However, it has few options to change. (See the next section for the few that may be changed.) It can be located by going to the Start button and then All Programs and finally Accessories. There click on Sound Recorder. There is a Start Recording button and a volume level display next to an elapsed time clock. After recording, pressing the Stop Recording button brings up the usual Save As dialogue box.
For more advanced recordings, use one of the many audio recording and editing programs that are available for purchase or as freeware. Three of these are described below.
2. Free Sound Recorder
A somewhat more advanced program may be accessed at http://www.freesoundrecorder.net/ . Download the latest program from cnet (a reliable source for free software), save the file to your computer, and then double-click on the file icon where you have saved it to begin the installation process. (A free-to-try sound editor will also be installed, but this can be ignored and its icon deleted from the desktop.)
When the program starts it should look something like the picture below, after closing the Device drop-down box below the main program graphic.
Note: While you are at the Free Sound Recorder web site, download and save the Overview file from its link at the bottom of the page. It is a very good tutorial on many aspects of working with audio recording on a Windows computer.
For more flexibility, install and use the open-source recorder and editor, Audacity. It may be accessed at http://audacity.sourceforge.net/ . Generally the best advice is to download the latest version and not a beta version, which may still have bugs in it. Save the file to your computer and then double-click on the file icon to begin the installation process.
To save an mp3-format recorded file, Audacity needs the file, “lame_enc.dll”. Follow these instructions for locating and installing this file
Since normal voice recordings do not require a lot of high-fidelity (quality), in the recorder you have installed select a recording speed that is on the order of 28 kbps and a mono sound (not stereo). Each recorder is somewhat different in where these options are located, but try looking for Settings, Preferences, or Options. Below are the procedures for the three porgams discussed here.
Note: The size of file that results from the differing bit rates approximately depends upon the factor that one speed is larger or smaller than another rate. For example, recording at 24 kbps makes a file that is about 5 times smaller than if the same message was recorded at 128 kbps.
Recording and saving an audio file is fairly straight-forward in each program, but there are some significant differences.
1. Windows Sound Recorder
2. Free Sound Recorder
In many of the sections already introduced in this tutorial, hints have been given about how to ensure that the size of the resulting audio file will be small enough for use on the web or in Moodle while retaining reasonable quality.
However, what can be done to a file that was recorded and is larger than desired? (Such a file could be several megabytes (MB) but only one to three minutes in playing length.) There are several software packages that may accomplish such a compression, but one of the simplest I have found that is freeware is Free Mp3 Wma Converter. At the writing of this tutorial, I am using version 1.8 of this program on my home computer.
Free Mp3 Wma Converter may be obtained by searching for it at www.downloads.com . When installing Free Mp3 Wma Converter, you will see a dialogue box with four items checked for installation. Leave the checks by the Converter and the installation of Wma runtime files, but remove the checks by the other two items.
The highest saving in size is from the conversion between a high-quality mp3 recording to a wma-format file. However, even reducing the qualtiy of the mp3 file can make a significant size difference. To do this add the mp3 file to the list of files at the top of the program window and then select the output format to also be mp3 with a 16,000 Hz sampling rate (the main skin incorrectly lists this as 16,000 kHz but the settings window has it correct), mono, and a bit rate of 32 (or even 24) kbit (this is really kb/s).
As an example, I converted a CD-quality mp3 file (44 kHz stereo) to one of lower quality (16 kHz mono) and the file went from 2360 KB to 614 KB--almost a decrease by 1/4. When I saved the original file as a wma (16 kHz mono), the file size went down to 326 KB--almost 1/8 the size of the original file. Remember, iPods and other mp3 players can also play wma-formatted files. So going to a wma file is safe as far as user-friendliness is concerned.
After saving your audio file, locate it and double click on it to open it in your default player. If it sounds OK, then it can be copied to your web directory.
Remember that this file cannot be found by students in a course unless it has been added to the appropriate location.
In addition to this tutorial, the reader will probably find several other resources helpful.
A. Help Menus
All of the above programs have some associated help files available through their Help menus. Browse all of them, even if you are only going to use one of them. Some of their information is very generic and very useful for making any sound recording.
B. Other Tutorials through Academic Computing at Bridgewater College
C. Other Resources
|©2007-09, Richard L. Bowman
Last modified: 9-Aug-09; by R. Bowman, firstname.lastname@example.org