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.
AMR is a sound file format with a specific focus. Created a long time ago, before the advent of MP3. some sources call the developer Ericsson. The name of the format is an abbreviation for Adaptive Multi Rate. Sound files of this format are intended for mobile devices and in GSM cellular networks. Using this format provides a small file size due to the technology of signal coding in the speech frequency range. Effectively compressing audio recordings of human speech makes this format often used in voice recorders on mobile phones, for voice recordings, and for MMS messages.