Perian was an open-source QuickTime component that enabled Apple Inc.’s QuickTime to play several popular video formats not supported natively by QuickTime on macOS. It was a joint development of several earlier open source components based on the multiplatform FFmpeg project's libavcodec and libavformat, as well as liba52 and libmatroska.
Before it was discontinued, it was featured as the "Download of the Day" on Lifehacker, as well as on several popular blogs including Ars Technica and The Unofficial Apple Weblog.