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.
M4V is a video file format that has been downloaded from the Apple iTunes store. The format contains TV shows, videos, films, music. It looks like a .MP4 file, but it sometimes has copy protection when Apple's FairPlay DRM is used (technical copyright protection). The M4V format, i.e., MPEG-4 iTunes Video File, was developed by Apple. MP4 is a container format. Like the same formats as MOV, AVI, MKV, it provides the ability to combine a variety of multimedia streams into one file. Mostly it is audio and video. In order to play the protected M4V file, the computer must be authorized using the iTunes account from which the videos were purchased. In this case, it can be used in order to buy video. Unprotected M4V files can be played by other video players if the extension is changed from .M4v to .Mp4. Files with the M4V extension contain both sound and video data. You can convert M4V files to MP4 format. In this case, it will be possible to play them on other computers, since the M4V files are protected by DRM. MP4 files, compared to the M4V format, do not allow you to specify partition information.