FLAC is an acronym that stands for Free Lossless Audio Codec, a file format for storing audio data with no data loss. The format is well known among music lovers, who often prefer to listen to music files stored in FLAC format due to the higher sound quality that these files provide. The latest browser maker to add FLAC support is Google, who recently started adding it in the desktop version of Chrome 56, expected to launch on January 31. Firefox 51 and Chrome 56 are due to be released on January 23.
Source: https://www.bleepingcomputer.com/news/software/flac-support-coming-to-chrome-56-firefox-51/