Let’s talk about the definition of scopes first. Scopes refers to an area inside which something operates or acts. When talking about scopes in the context of AlsaPlayer, it’s more about the concept of music visualization. Music visualization is a feature that is found in media player software and electronic music visualizers wherein an animated imagery is generated based on the piece of music that is playing. This imagery is normally generated and rendered in real-time, implying that it keeps changing with the music as it’s synchronized with whatever’s playing. These visualization techniques can vary from the simple ones, for instance simulation of oscilloscope display to the more elaborate ones including multiple composite effects. The variances in the music’s frequency spectrum and loudness are two of the many properties that are utilized as input for such visualization.

For instance if you use Windows media player, you can get a first-hand idea about the different visualizations available in the form of geometric shapes and splashes of colors whose patterns keep moving with the music that is currently playing. The visualizations get grouped into collections, based on specific themes like bars or ambience.

In case of AlsaPlayer, the users can employ couple of available scope plug-ins as follows:
FFTScope – This is a visualization plug-in meant for AlsaPlayer and its main purpose is demonstration of how a visualization plug-in must be written for the AlsaPlayer’s visualization API.
Nebulus – This is a full screen OpenGL or SDL plug-in and you can get its AlsaPlayer version (known as alsaplayer-nebulus) from its homepage. Nebulus is nothing but a compilation of different OpenGL effects which conceptually depend on the music that is playing.