Audacity is an open source multi-platform application that is the ultimate tool for all your audio recording and editing requirements. It will record the input from your microphone, line-in (used to connect an external audio device output to your computer system, unfortunately not available in laptops) and also stereo mix, that will record what ever you get to hear from your computer speakers.

Beginning with this post is a series on Audacity. It will show you how a simple hack device, which you can prepare yourself for less than the cost of four compact discs, can convert your computer into a digital sound recorder. You will be able to use your desktop or laptop as a personal audio recording and editing device, converting your room into a sound recording room for your solo guitar performance or a band performance with your friends.

What to expect in this series?

1. How to record streaming audio using Audacity?
2. Simple hack to record streaming audio even without "Stereo Mix" option in Audacity
3. How to convert your music cassettes collection into digital mp3 music library?

Though the tutorial will give explain how to do things on Windows, it also applies to Linux and other operating systems with some minor modifications.

How to record streaming audio using Audacity? If you have installed Audacity, you must have tried recording your own voice using microphone. It is very simple. Audacity can be used to record audio being streamed over the Web, particularly live audio streams as well as those which do not allow you to download the audio. [PS: It is recommended that you take care of copyright issues before recording any streaming music or radio programme.]

Disable system noises: In order to record streaming audio, your computer's audio output should not be dotted with the noises of the system, such as beeps and notification sounds and clicking noises. Go to audio settings of your computer and mute all those possible annoyances that will ruin your efforts of creating a high-quality mp3 music or audio recording. If you are using Windows XP, you need to go to Control Panel -> Sound and Audio Devices -> Sounds and set sound scheme to No Sound.

Enable MP3 encoding: After you record your music, it would be preferable to save it as mp3, and not in default wav format. For this you need to include LAME MP3 Encoder with Audacity (Lame Encoder Website). For Windows, it needs to be downloaded as a zip file and then unzipped, preferably in a folder inside Audacity application folder. Audacity will ask you to locate LAME MP3 Encoder when you choose to export your recording as a mp3 file.

Now you have a computer that is equipped with Audacity and has been trained not to make noise that can spoil sound recordings. It's time to start experimenting to achieve audio nirvana.

Enable stereo recording: In Audacity, go to Edit -> Preferences and select appropriate input and output devices. Also, set the recording channels to two. This is required for stereo recording that involves left and right tracks.

Choose the input: In the main panel of Audacity, you will find a dropdown listing such as Mic, Line In, Wave Out and Stereo Mix. Select the appropriate input.

Line In option should be selected if you wish to the output of another device such as a cassette player or radio to be recorded.

Wave Out or Stereo Mix option will record the output coming from the speakers of your computer. This should be selected when you want to record some audio being played on your computer, maybe any music that you are composing using some DJ mixer or the radio programme being streamed on the website of your favourite radio station.

P.S: This is a three-part series on using Audacity to convert your computer into a powerful audio recorder. Next in the series is a simple hack device that will allow you to directly record your computer's output, or stereo mix. It will allow you to record streaming audio without losing any quality, as happens in case a microphone is used to pick the sound coming from speakers. Thereafter comes the cheapest way of transferring you music collection from cassettes to digital mp3 collection.

Additional resources:
Record streaming audio even without "Stereo Mix" option in Audacity
Convert your music cassettes collection into digital mp3 music library
Audacity Help
Audacity Wiki
MouseBlog (Defunct)