Skip to Content

Captioning Solutions for Handheld Media and Mobile Devices
M4V Subtitles

This page contains information about adding foreign-language subtitles to M4V movies targeted for the iPhone or iPod Touch. There is currently no single application or tool available to simplify the addition of subtitles to M4V files, so the process described below may take a considerable amount of time depending on the length of your movie. A Windows computer is required, and you should be comfortable using the command-prompt window.

Adding subtitles to M4V movies

Before beginning, download and install the following software:

  • MP4Box (Windows only). For simplicity, install it in the same directory as the source media and subtitle files.
  • Dumpster (Windows or Mac). For the Windows version, follow the "Legacy Windows QuickTime Tools" link, but you'll need to register an account with the Apple Developer Connection first. Mac users can download QuickTime Movie Atom Dumpster.
  • MAGpie, to write the initial subtitle files, and Subtitle Workshop (Windows only) to convert the files to the SubRip (SRT) format.
Once the software is installed, begin by creating the subtitle text file. The subtitle file must be in the SRT format.

  • Write the subtitle file by using MAGpie. Do not apply any styles (color, size, font type, italics, etc.) or positions.
  • Export the file as QuickTime.
  • Open the exported file (filename.qt.txt) in Subtitle Workshop and save it as an SRT file.
  • Copy the SRT file into the directory containing MP4Box.exe
  • Repeat this process for each track of subtitles, making sure to copy each SRT file into the directory containing MP4Box.exe.
Next, convert the source video to M4V. The easiest way to do this is to use QuickTime (Pro version required). Other conversion tools are available on the Web.

  • Open the movie in QuickTime.
  • Choose File/Export.
  • Select "Movie to iPhone" from the Export drop-down menu.
  • Give the movie a new name if necessary, then press the Save button.
  • Copy the M4V to a Windows computer and place it in the same directory as MP4Box.exe.
Now convert the SRT files to the TTXT format.

  • Open a command-prompt window and change to the directory that contains MP4Box.exe and the source video file.
  • Convert the SRT files to TTXT files: type (no quotes) "mp4box -ttxt".
  • Repeat for each SRT file.
Next, integrate each TTXT file into the source M4V.

When you have integrated all TTXT files into the movie, you must open the M4V in Dumpster (Windows or Mac) by dragging the M4V onto the Dumpster icon. The instructions below refer to Dumpster for Windows.

  • Open the M4V in Dumpster.
  • Double-click 'moov'.
The subtitle tracks you added to the movie can be found at the end of the 'trak' list. For example, if you added four subtitle tracks they will be the last four 'trak' entries. With this in mind...

  • Double-click the first 'trak' that corresponds to your first subtitle track.
  • Double-click 'tkhd'.
  • Change Flags to $000001.
  • Press the Apply button at the bottom of the window (note: press Apply after you make each change described below or else your changes will not be saved).
  • Change Alternate Group to $0002.
  • Double-click 'tkhd' to close.
  • Double-click 'mdia'.
  • Double-click 'hdlr'.
  • Change Component subtype to $7362746c (this will change the type to 'sbtl').
  • Double-click 'hdlr' to close.
Repeat the above steps for each 'trak' that corresponds to a subtitle track, but leave all other 'tkhd'/Flags set to $000000. When you have finished altering all tracks, close Dumpster and check your movie in iTunes:

  • Open the M4V in iTunes.
  • Hover the pointer over the player so that the control bar appears.
  • Click once on the bubble icon and you should see an alphabetical list of your subtitle tracks, as shown in the following image. If any subtitle tracks are missing from the menu, close iTunes, re-open the M4V in Dumpster and verify that you have set all the flags, groups and component subtypes as specified above.

iPhone subtitle menu (opened from the controller)

  • Transfer the M4V to the iPhone or iPod Touch.
  • Open the movie in the iPod.
  • Tap the screen once to reveal the control bar.
  • Tap the bubble icon. You should see a list of languages appear, as shown below.

iPhone subtitle menu

  • Chose a language and tap Done.
  • Play the movie; tap the screen to make the control bar disappear. The subtitles will appear at the bottom of the viewer, as shown below.
Italian subtitles on an iPhone movie