MPEG is a special standard for compressing audio files and video files into a different format, which is most convenient for downloading or forwarding, say, over a global network. The specified standard was developed by the Moving Picture Experts Group. It was created by the international organization ISO just in order to develop a standard for the compression and transmission of digital video and audio data. The official designation for this group is ISO / IEC JTC1 / SC29 WG11. The first time she met in Ottawa in May 1988. By 2005, up to 350 people became participants in the meetings. MPEG, that is, Moving Picture Experts Group, consists of 3 components: Audio, Video, System (combining and synchronizing the other two). There are different MPEG standards, which are also called phases: MPEG-1, MPEG-2, MPEG-3, MPEG-4, MPEG-7. According to the MPEG-1 standard, for example, streams of video and audio data are sent at a speed of 150 kilobytes per second. The speed of a single-speed CD-ROM player is similar. Streams are managed by sampling key video frames and filling in areas that change between frames. This standard ensures the quality of the video image is significantly lower compared to the video that is transmitted on the television standard.
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.