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IDX File - What is an .idx file and how do I open it?
Learn about .IDX files and view a list of programs that open them.
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Overview
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 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.
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Popularity3.1 | 32 Votes
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.IDX File Extension
5 file types use the .idx file extension.
VobSub Subtitles Index File
| Developer | The VobSub Team |
| Popularity |
3.6 | 235 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
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:
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
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Platform
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Windows
VobSub
Free
DirectVobSub
Free
VideoLAN VLC media player
Free
Any text editor
Mac
MPlayer
Free
VideoLAN VLC media player
Free
Any text editor
Linux
SMPlayer
Free
VideoLAN VLC media player
Free
Any text editor
Android
J2 Interactive MX Player
Free
Category: Video Files
Updated: April 27, 2022
Navigation POI File
| Developer | VDO Dayton |
| Popularity |
3.6 | 43 Votes |
Contains points of interest (POI) for a VDO Dayton GPS portable navigation device (PND); includes a header and a set of POIs; each POI consists of a 3 byte index, then 8 bytes for the coordinates and 46 bytes for name and type.
More Information
IDX files can be transferred to VDO Dayton PNDs via USB.
Programs that open or reference IDX files
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Windows
Transfer to a VDO Dayton device
Category: Data Files
Updated: December 31, 2008
Index File
| Developer | N/A |
| Popularity |
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:
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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Windows
ESRI ArcGIS for Desktop
Free Trial
ICQ
Free
Intuit Quicken
Free Trial
Mac
Intuit Quicken
Free Trial
Category: System Files
Updated: March 22, 2021
HMI Historical Log Index File
| Developer | Wonderware |
| Popularity |
3.2 | 33 Votes |
An IDX file may also be an index file created by InTouch Human-Machine Interface (HMI) software used to monitor and control industrial systems. It contains index data that references historical log ( .LGH ) files generated by the HMI system. The log files IDX files reference record system activity and process values over time, allowing operators and engineers to review past performance or troubleshoot issues.
More Information
An example of a program that uses IDX files is ReportBuilder, which uses the InTouch ODBC (Open Database Connectivity) Connector Pack to organize and access logged data. When generating reports, the software uses the information in IDX files to locate and retrieve specific data points from large historical log sets. This allows users to efficiently produce trend analyses, performance summaries, and system reports without having to read large log files.
How to open an IDX file
IDX files are not meant to be opened manually. Instead, AVEVA InTouch HMI and WorkSmart Automation ReportBuilder reference IDX files to access and display historical information stored in the accompanying log files located in the same directory.
Programs that open or reference IDX files
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AVEVA InTouch HMI
Free Trial
WorkSmart Automation ReportBuilder
Free Trial
Category: Data Files
Updated: November 6, 2025
Outlook Express Mailbox Index File
| Developer | N/A |
| Popularity |
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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Windows
Microsoft Outlook Express
—
Discontinued
Free
Category: Text Files
Updated: December 16, 2006