FLV is a video file format developed by Adobe Systems. The name is an abbreviation of the full name Flash Video File. FLV format video files are Flash-compatible and usually contain various metadata (titles, audio, video, etc.). FLV-files are widely spread on the global network, in this format they make streaming video for YouTube, MySpace and other video hosting sites. Compared with similar formats, video files have a higher compression ratio. FLV files are easily converted to more common video formats.
ALAC is the format of a small specialized program called an audio codec. Its main task is to compress a file with digital music without losing its quality. The name of the format created by Apple's IT giant is Apple's abbreviation Lossless Audio Codec. This format may also be called ALE (from Apple Lossless Encoder). Files in this format can play devices even with limited computing resources - such as an iPod. When compressing a file in this format, it is approximately 40-60% of the original file. Now almost every multimedia player based on the libavcodec library is able to play ALAC format files.