What Is a VOB File?
A VOB file, short for Video Object, stores media used on DVDs. It can contain video, audio, bitmap subtitles, and navigation data. These files normally sit inside a DVD’s VIDEO_TS folder alongside files that control playback.
VOB is based on the MPEG program stream structure. It packages different streams together so a DVD player can decode and present them in synchronization. The video is typically MPEG-2, while the audio can use formats such as Dolby Digital AC-3 or linear PCM.
How VOB Files Work
A DVD player uses more than the video files themselves and often encrypts some or all VOB files. Three file types work together:
- VOB: Holds video, audio, subtitle streams, and some navigation data.
- IFO: Describes playback and navigation information.
- BUP: Provides a backup of the corresponding IFO information.
A longer program may span several VOB files because DVD-Video limits individual VOB file sizes to approximately 1 GB. Opening one file can therefore show only part of a program.
Playback order also depends on the authored DVD structure. Processing the complete source through software that understands DVD titles is more reliable than treating every numbered VOB as an independent video.
How to Open a VOB File
A player with MPEG program stream and MPEG-2 support, such as VLC, can play many individual VOB files. For the full disc experience, open the DVD through its disc-opening function so the player can interpret the surrounding structure.
Check whether you need a single clip or the complete DVD presentation. Playing one VOB does not necessarily reproduce the intended menus, title sequence, or chapter navigation.
Copy protection can also affect access. A converter’s support for VOB does not guarantee that it can process an encrypted DVD, and the majority of DVD-Video titles will have some sort of copy protections that cannot be circumvented.
