BUP File Documentation

Summary

A DVD IFO Backup file is part of a DVD-Video disc: a byte-for-byte backup copy of the matching .ifo navigation file (VIDEO_TS.BUP backs up VIDEO_TS.IFO). A player reads it only when the real IFO is damaged. A .bup holds no video, so you do not play or convert it: open the whole VIDEO_TS folder (or the .vob files) in VLC instead. Its MIME type is application/octet-stream.

Technical details

FeatureValue
Full nameDVD IFO Backup File
File extension.bup
MIME typeapplication/octet-stream
Format typeBinary — exact backup copy of a DVD-Video IFO file
ContainsNavigation tables only (menus, chapters, titles) — no audio or video
DeveloperDVD Forum (DVD-Video specification)
Introduced1996 (DVD-Video specification)
LocationVIDEO_TS folder on a DVD-Video disc
Magic numberDVDVIDEO-VMG or DVDVIDEO-VTS (copied from the IFO)
Byte orderBig-endian (DVD-Video sector data)
Backs upVIDEO_TS.IFO (Video Manager) or VTS_xx_0.IFO (title set)
Safe to deleteNot recommended — it is the disc’s fallback navigation
Play / convertNo — use the VIDEO_TS folder / .vob files
Other meaningMcAfee/Trellix quarantine file (unrelated OLE compound format)
Related extensions.ifo, .vob
Open standardNo
File signature (magic bytes)
44 56 44 56 49 44 45 4F 2D 56 4D 47

Offset 0, 12 bytes, ASCII DVDVIDEO-VMG in VIDEO_TS.BUP, or DVDVIDEO-VTS (44 56 44 56 49 44 45 4F 2D 56 54 53) in a VTS_xx_0.BUP. A BUP is an exact copy of its paired IFO, so it carries the same header: VMG marks the disc-wide Video Manager, VTS marks one Video Title Set. Seeing this string confirms a DVD navigation-backup file rather than an unrelated .bup such as a McAfee quarantine container.

What is a BUP file?

A DVD IFO Backup file (.bup) is one of the three file types that make up a DVD-Video disc. On every disc, the VIDEO_TS folder holds .vob files (the actual video and audio streams), .ifo files (navigation information: menus, chapters, title lists) and .bup files. Each BUP is a byte-for-byte backup copy of its matching IFO. The DVD-Video specification, published by the DVD Forum in 1996, mandates this redundancy: the player uses the BUP only if it cannot read the primary IFO.

Because a BUP is a duplicate of an IFO, it begins with the same header (DVDVIDEO-VMG or DVDVIDEO-VTS) and contains only navigation tables. There is no video or audio inside it, which is the single most important fact about the format: a BUP is useless on its own, and every question about “playing” or “converting” one has the same answer, which is to work with the whole disc folder instead.

Why the backup exists: scratch protection

The point of the BUP is physical fault tolerance. When a disc is authored, each IFO is written once as the primary copy and again as a .bup, and the two copies are deliberately placed in different physical areas of the disc. If a scratch or a bad sector destroys the IFO, the player silently falls back to the BUP and the disc stays navigable. Losing the navigation data would make a disc unplayable even if all the video were intact, so the specification protects it with a full second copy rather than a checksum.

There are two kinds. VIDEO_TS.BUP backs up VIDEO_TS.IFO, the disc-wide Video Manager that holds the top menu and the list of titles. Each VTS_xx_0.BUP backs up the IFO of one Video Title Set, typically a single movie or feature, with that title’s program chains, chapter and cell pointers and its own menus. The VMG versus VTS in the header is what distinguishes the two.

What is inside a BUP (and what is not)

A BUP contains the same navigation tables as the IFO it mirrors: program chains (PGCs) that define playback order, chapter and cell pointers, menu structures, and pointers into the VOB files where the actual media lives. What it does not contain is any of that media. The video and audio are only ever in the .vob files; the IFO and its BUP just describe how to navigate them. This is why the three file types must stay together: the BUP is read for structure, but the picture always comes from the VOBs.

Playing and converting a DVD backup folder

Since a BUP has no media, you never open the BUP itself. To watch the movie, open the whole VIDEO_TS folder in VLC (Media → Open Folder), or open the largest .vob; VLC reads the IFO, or the BUP if the IFO is damaged, to reconstruct menus and chapters. To convert a DVD backup to MP4 or MKV, point HandBrake or MakeMKV at the VIDEO_TS folder, not at a BUP. Those tools read the navigation from the IFO/BUP for chapter marks but pull the video out of the VOB files. There is no such thing as “BUP to MP4”: the file you would be converting contains no video.

Using a BUP to repair a missing IFO

There is one legitimate operation that treats the BUP as data. Because a BUP is defined to be an exact copy of its IFO, if the IFO in a DVD backup folder is missing or corrupted you can restore the disc structure by copying the BUP and renaming the copy to the IFO’s name: VIDEO_TS.BUP → VIDEO_TS.IFO, or VTS_01_0.BUP → VTS_01_0.IFO. The contents are identical by specification, so players then read the navigation normally. Keep the original BUP as well; a compliant DVD-Video structure expects each IFO to still have a matching BUP.

Is a BUP file safe, and can I delete it?

DVD BUP files are inert navigation data. They contain no executable code and cannot harm a system. You can delete them from a backup, since a player reads the BUP only when the IFO is unreadable, but they cost almost nothing in space and are the disc’s only fallback navigation, so keeping them is the safer choice if you want the backup to stay playable. If you later burn the folder back to a disc, the BUP files should be present, because authoring tools expect every IFO to have its matching BUP and normally recreate them automatically.

One caution about identity: the .bup extension is also used by McAfee/Trellix antivirus for quarantine files, which are an unrelated OLE compound format holding a detected threat, and by a few programs for generic automatic backups. A quick header check settles it: a DVD navigation backup starts with the ASCII string DVDVIDEO-VMG or DVDVIDEO-VTS. Anything else with a .bup name is a different file type that this page does not cover.

Frequently asked questions

How do I play a BUP file?

You do not play the BUP itself, because it holds only backup navigation data and no video. Open the whole VIDEO_TS folder (or the .vob files) in VLC and the movie plays with its menus and chapters.

What is the difference between BUP, IFO and VOB files?

VOB files hold the actual video and audio streams; IFO files hold the navigation (menus, chapters, titles); and BUP files are exact backup copies of the IFO files, stored elsewhere on the disc in case a scratch damages the original.

How do I convert BUP to MP4?

You cannot, because a BUP contains no video. Convert the DVD instead: open the VIDEO_TS folder in HandBrake and encode to MP4, or use MakeMKV for a lossless MKV. Both read the VOB files for the actual media.

References