Closed Captions create an overlay displayed on the video through Idomoo's player. This is great to support hard of hearing customers, but also ensures videos played while muted are also understood.
You can setup captions in many languages, so captions can also be used as translation.

Closed captions are currently supported only through API and professional services, not through the Generate Videos section.


Setting Up Closed Captions

Caption files are there to follow the narration. Therefor you create a caption text file for each narration audio file you have. The timing of the caption runs the length of the audio file.
To setup closed captions follow these steps:

  1. Prepares a text file in a text editor of your choice with the caption.
  2. Name the text file the same as the audio file it corresponds to. For example, name a caption text file for narration_01.wav: narration_01-en.txt.
  3. Specify languages by adding a suffix of the language after a dash, for example: narration_01-en.txt, narration_01-fr.txt.
    You can use the standard ISO 639-1 codes, but as long as you're consistant in your definition over the text file, API request, and player definition, any text can work.
  4. Instructions for how to author the text file can be found below. In order to not have to create many files, the content of the file can also have parameter.
  5. Next, upload the text file to the same location of the narration audio files. This can be on Idomoo's media libraries (scene library or user) or your own storage, as long as it's accessible.
  6. You've now finished configuring captions.
  7. To render with captions add the accessibility output object and specify the languages you're after in the API call.
  8. Make sure you configure the Idomoo player to accept the captions, language by language


If using AWS Polly for narration, a text file is not needed at all, but captions are only going to be created for the text used in the narration - no translation.


How To Author a Caption Text File

To author a text file you must use a text editor rather than a word processor. You can use Notepad++, Sublime Text, Atom and so on.

The caption file can be in one of two ways, simple or manual timing. For the simple file, just write the text you want displayed. This works well with short sentences of narration, where you can fit the whole caption in one slide.

Just a line of narration.

The manually timed file is there for longer narration sentences or paragraphs, when you want to control what slide appears when. The syntax, then, is like so:

//00:00:00.000 --> 00:00:04.220
First line of narration.
//00:00:04.953 --> 00:00:12.288
Second line of narration.

Here are some tips about the manually timed caption file:

  1. Start with two backslashes, then write the starting timecode, counting from the beginning of the audio file.
  2. Add two dashes and a greater than symbol (-->), followed by the end time code.
  3. The timecode structure is HH:MM:SS.FFF - hours, minutes, seconds, and milliseconds.
  4. In the next line write the caption text. The player decides when to split this caption into several lines by length.


Using Defaults with Parameters to Reduce Number of Text Files

When mapping parameters to audio files to create complex personalized narration such as "Hi Jim, how are you?" you create many different audio files, one for each name. One way to create captions for these is to create a caption text file per audio file. This means, though, that if you recorded 800 names, you'll also need to create 800 text files. Possible, but not fun.
To avoid this you can use the default option instead. We recommend to always record a default options, such as "Hi there". Learn about default here. Once you have the default audio file selected, follow these steps to setup the caption file:

  1. For a default audio file called default.wav, the caption text files should be called default-en.txt (for English).
  2. Use a parameter inside the text for the name. The syntax to create a parameter is: <<%parameter name%>>. In this case, if the parameter you are using for the names is called "first name" the caption file's content will be:
    Hi <<%first name%>>
    The parameter must also be defined in the storyboard.
  3. Upload the file to the same location as you audio file.
  4. When you render with the first name parameter receiving the data "Jim", for example, Idomoo's platform will first look for a file called jim-en.txt. When it doesn't find it, it will check if there's a default and take that route, replacing the data instead of the parameter. The text presented in the caption will then be "Hi Jim".
  5. You can use several parameters in one text file. Also, parameters work on any file, not just one used as default.