Speaker Fill

Most music is produced with only two channels and is, therefore, not optimized for the multichannel audio equipment of the typical audio or video enthusiast. So having music emanate from only the front-left and front-right loudspeakers is a less-than-ideal audio experience. Speaker fill simulates a multichannel loudspeaker setup. It allows music that would otherwise be heard on only two speakers to be played on all of the loudspeakers in the room, enhancing the spatial sensation.

Speaker fill is used when there are more playback channels or loudspeakers than there are source channels. The effect is generated by a combination of channel manipulation and inserted delays. Speaker fill accepts stereo or multichannel input. Speaker fill is sometimes used when there are equal numbers of source and playback channels. This situation occurs when content is authored for a channel mask with a smaller number of channels than the physical configuration's channel mask. One example would be content with a quadraphonic channel mask that is played on a surround sound system.