The term Crossfading is a technique that creates a smooth transition from one sound to another -- this effect is not to be confused with simple fading which involves a single sound fading in or out. This audio effect is often used in audio engineering to fill in the silence between two tracks, or even blend multiple sounds in the same song to create smooth changes rather than abrupt ones. DJ's (short for Disc Jockeys) often make use of the crossfading effect between tracks to enhance their music performance and to make sure that there aren't any sudden silent gaps that could annoy the audience or the people on the dance floor!
Analog versus Digital Crossfading
With the invention of digital music,it has become relatively easy to apply crossfading effects to your collection of songs without needing any special hardware or audio engineering knowledge. It is also much simpler to do compared to crossfading using analog equipment -- if you are old enough to remember analog tapes, then crossfading required three cassette decks (two input sources and one for recording the mix). Crossfading digital audio sources can also be done automatically rather than having to manually control the input levels of the sound sources in order to achieve gapless playback on the recording. In fact, when the right type of software is used, there is very little user input required to achieve professional sounding results.
Examples of Software Applications That can be Used for Crossfading Digital Music
Depending on what you want to achieve, there are several types of software applications (many of them free) that you can use to apply crossfading to your digital music library. The categories of audio programs that often have the facility to create crossfades include:
- DJ Mixing Software -- as well as gapless playback of your digital music files using crossfading, DJ programs also have other sound processing tools that you can use such as: beat matching (BPM detection), time stretching, sample looping, etc.
- Software media players -- many jukebox software programs like iTunes, Windows Media Player, and others come with an automatic crossfading feature that can be used not only for music files, but also for your playlists too. For ease-of-use, software media players are probably as simple as it gets.
- CD Burning Software -- Some DVD/CD burning software applications can be used to burn digital audio files on audio CDs that have crossfading. This is a type virtual crossfading which is added to the music during the burning session. The process does not alter any of your original files which therefore remain unchanged on your computer's hard drive.
- Audio Editors -- audio editing software such as the free Audacity program can be used to create new mixes that have crossfaded tracks. This type of software is a bit different from the other examples above (excluding audio CD burning) as you are actually creating a new digital audio file, rather than just adding a non-permanent effect.
- Apps from Online Music Services -- some online music services provide free applications that can be downloaded which can crossfade streaming audio using extra buffering. Spotify is one example of a streaming music service that provides this facility in its desktop software; at the time of writing, you can set the overlap between songs from 1 to 12 seconds.