VOB is a DVD-based multimedia container video file format developed by the DVD Forum. It is based on MPEG-2. A file with the .VOB extension can have video and audio streams, audio and video data, subtitles, disc menus, and navigation content. And all this is combined into a common stream. In this case, video playback is carried out in MPEG-2 format, and audio in various audio formats. Most often, the AC-3 format is used for this, since it provides the most favorable ratio of bitrate and sound quality. The VOB format has gained popularity as files in which you can store video and sound on DVD discs. As a rule, if they have such an extension, then the files have a place in the VIDEO_TS DVD folder in the DVD root directory. Typically, .VOB format videos are opened using any video player that supports MPEG-2 compression. There are many free players that support the .VOB format. In particular, Zoom Player, Media Player Classic VLC, Media Player, Light Alloy and others. Now popular is the paid player CyberLink PowerDVD, which has rich functionality. He specializes in playing DVD videos. VOB video files, originally called DVD Video Object File, can be accompanied by .IFO and .BUP information files.
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.