.IDX File Extension

VobSub Subtitles Index File

Developer The VobSub Team
3.6  |  232 Votes

What is an IDX file?

An IDX file is a subtitles index file created and used by VobSub, a program that allows users to extract subtitles from DVDs. It contains a list of plain text settings and timestamps used to show the subtitles that a .SUB (VobSub Subtitles) file contains. IDX files are always paired with accompanying SUB files.

More Information

Screenshot of a .idx file in GitHub Atom
IDX file open in GitHub Atom

VobSub is a free program that allows users to extract and play the subtitles stored on DVDs. When VobSub extracts subtitles from a DVD, it creates two subtitles files: a SUB file and an IDX file. The SUB file contains images that are shown as subtitle text. The IDX file contains metadata that tells a media player what color the subtitle text should appear in, where the subtitles should appear on-screen, and when and in what order to show the images the SUB file contains. Subtitle settings typically appear at the beginning of an IDX file, on lines that begin with #, and timestamps and image references appear later in the file, on lines that begin with timestamp:.

Using VobSub's DirectVobSub component or a media player that supports the SUB / IDX subtitle format, users can play back DVD-format subtitles alongside the movie they were meant to be used with. This can be useful if, for example, you acquire an .MP4 copy of a movie and want to watch the movie with subtitles. If you can locate a SUB and IDX file for the movie, you can load and play them as subtitles. SUB and IDX files can also be used to embed subtitles in .MKV files.

How to open an IDX file

When paired with its accompanying SUB file, an IDX file can be used to play subtitles alongside a movie using DirectVobSub (Windows) or VideoLAN VLC media player (multiplatform).

To use an IDX file as a subtitles file in VLC media player:

  1. Make sure your SUB and IDX file are stored in the same directory.
  2. Begin playing the movie you want to use your IDX file with.
  3. From VLC's menu bar, select Subtitles → Add Subtitle File...
  4. Navigate to and open your IDX file.

Because they are plain text files, you can also open and edit IDX files in any text editor. However, editing an IDX file may cause the subtitles it is linked with to play incorrectly.

How to convert an IDX file

The .SRT subtitle format is more common than the VobSub format. Therefore, you might want to convert your VobSub subtitles to the SRT format so you can use them more easily. SubtitleTools.com has a SUB / IDX to SRT converter, called Convert Sub/Idx to Srt, that you can use to convert VobSub subtitles to the SRT format. Keep in mind that you must have both a .SUB file and an IDX file to convert VobSub subtitles to the SRT format.

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Programs that open IDX files

Index File

Developer N/A
3.6  |  25 Votes

An IDX file stores an index of files used by various programs. It is used by search functions to speed up searches. After a hard disk, directory, or database is indexed within an IDX file, programs can search and sort the data more efficiently.

More Information

Some examples of programs that use IDX files include:

  • Microsoft FoxPro
  • Corel QuickFinder
  • ESRI ArcView
  • ICQ
  • Intuit Quicken (whose IDX file is named qdata.idx)

Common IDX Filenames

qdata.idx - An IDX file used by Intuit Quicken.

How to open an IDX file

IDX files are not meant to be opened. If you accidentally delete an IDX file, the program that created the IDX file should re-create the file the next time you perform a function that requires re-indexing.

Programs that open or reference IDX files

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HMI Historical Log Index File

Developer N/A
3.2  |  33 Votes

Index for log files created by InTouch Human-Machine Interface (HMI) software or ReportBuilder with ODBC Connector pack for InTouch; used for running reports from collected data

Programs that open IDX files

Wonderware InTouch
WorkSmart Automation ReportBuilder

Outlook Express Mailbox Index File

Developer N/A
3.1  |  32 Votes

Stores an index of mail messages stored in an Outlook Express mailbox (.MBX file); should be located in the same folder as the mailbox files; required for importing old Outlook Express mailboxes into Outlook Express 5 or later.

Programs that open IDX files

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