AC3 is an audio format designed by Dolby Digital to offer surround sound listening. This format is available on most Blu-ray and DVD media files and is played using a Dolby Digital DVD Player. Interestingly, AC3 can be output in up to six speakers of a home stereo system. On a computer, AC3 can be opened on VLC Media Player, Apple QuickTime Player, and Windows Media Player.
VLC Media Player Apple QuickTime Player Windows Media Player
FLAC (Free Lossless Audio Codec) is a free lossless digital audio format developed by Xiph.Org. A compressed FLAC file can be reduced by between 50-70% of the original size and decompress back to the original sound data. This file format supports metadata like ID3 tags, cover art, and album title.