Audio Stream Recording - Audio Stream Capture

Many music web sites offer 'streaming' audio that you can listen to by clicking a link. Streaming allows you to hear the audio as the file is being transferred rather than waiting for the complete file to download before it can be used.

Downloading a music file can take several minutes or even hours depending on the size of the file and the speed of your Internet connection, but sound from a streamed file can begin a few seconds after clicking the link.

The process is called streaming because it works by delivering a constant flow of data to your computer - a stream. The data is usually buffered to prevent pauses in the case of data flow interruption, but the buffer is small enough that the sound can begin almost immediately after the stream starts.

Streamed audio, however, is not meant to be saved as a computer file that can be used at a later time. It's a one time deal, similar to listening to a radio broadcast. This is partly to prevent the unauthorized copying of audio content, as most music streams have copyright protection.

But just as you can record audio from the radio, you can also record audio streams from the Internet. There are several ways to do this.

Audio Stream Capture

The low tech way to capture streaming audio is to simply record the actual audio. Sound from speakers can be recorded, but this will introduce a lot of background noise - not a method recommended for the 21st century.

A step above this is to connect the output of your soundcard back to the input. This is a background noise-free option, but the sound must pass through two converters - the Digital to Analog converter on the way out, and the Analog to Digital converter on the way back in. This can create digital distortion that is noticeable on playback.

Digital Capture

It is far better to keep the audio stream in the digital domain. This way the sound can be reproduced exactly as it was heard the first time.

Some sound cards can be set up to route the output to the input without passing through the digital to analog converter. This option allows you to use any audio recording software to record the audio stream as it is received, entirely in the digital domain.

Most consumer audio cards don't have this routing function, however, so if you are using the standard audio connections that are included with your motherboard this may not be possible.

Audio Stream Capture Software

Finally we have the software solution. Most audio stream capture software works by redirecting the audio stream from the output to the input, the same as our re-routing option mentioned above. This keeps the sound in the digital domain and the captured audio can usually be converted into one of several formats such as MP3, WAV or OGG.

Some software can automatically divide the audio stream into individual tracks and even add tag information such as artist, song and album.

Legalities

Many Internet sites that offer streaming audio do not want their music to be recorded and may have license agreements for using their sites. This is especially true of online music vendors such as the iTunes Music Store or Rhapsody. Many of these sites are aware of how easy it is to record audio streams, and for this reason usually limit song previews to 30 seconds.