This page is intended to support you in creating or editing caption files on your own.

Disclaimer: You should finalize all edits to your media before adding captions. If captioned content is edited or replaced with an edited version at a later date, the captions will no longer be accurate.

Please contact Captioning@Colorado.EDU with any questions or if you would like to schedule a training.  

To request professional post-production captioning, please fill out the Captioning Request Form.

There are four steps to creating captions:

  1. Transcribe the content
  2. Break it into caption blocks and sync to the audio
  3. Review for quality and accuracy
  4. Save or export your file

Transcribe the Content

If you create your own videos, it’s recommended to plan out a script in advance. You can use the script to easily create captions later. Auto-generated captions are not accurate enough on their own, so you must review and correct the output of any auto-generated transcription.

Software and Programs for Auto-Generated Transcription

Note: With the exception of YouTube, if you are using any of the above software to transcribe pre-recorded audio, you may need to route your computer’s audio output back into the computer as audio input for better transcription quality. Suggestions are available for routing audio output on Mac and routing audio output on Windows.

Software and Programs for Manual Transcription

Note: Amara is a group work captioning option. Any user can contribute to an existing captioning file. Please note that if you use the free version of Amara, your content will be publicly available.

Break it into Caption Blocks & Sync to the Audio

The next step is to split your transcript into separate captioning blocks that will appear on-screen, one after the other. The caption blocks are assigned start and end times so they appear at the correct part of the video. 

Many captioning tools require you to do this manually. If you are manually transcribing your audio in a captioning program like Amara, you can create each caption block in the software as you transcribe. 

If you provide YouTube with a transcript of a video, it can automatically split it into caption blocks and set the timings for you. The results may not be perfectly accurate; check any long gaps in time or blocks with non-speech sounds to ensure they are aligned accurately.

Review for Quality & Accuracy

Once you create your caption file, please review it for quality and accuracy. A short summary of issues to check for is listed below. Please reference the Captioning Quality Guidelines for a more extensive list.

  • Identify all changes in speaker (e.g. "Sarah:", "Person:”, or “>>” if the speaker name is unknown.)
  • Add any meaningful non-speech sounds in brackets (e.g. [car honks])
  • Ensure all spoken content is transcribed exactly, not paraphrased.
  • Do not include more than 2 lines of text per caption block.
  • Ensure the caption blocks appear long enough to be easily read; generally, they should appear for at least 1 second.

Save or Export Your File

If you are creating your captions in a different tool from the media player they will be displayed in, you must save or export a caption file. You will then upload the caption file to where you are storing the video.

Caption files are typically saved with one of the following extensions: .srt, .vtt, .sbv, .dfxp, .sami, or .ttml. SRT files are the simplest format and can easily be edited by anyone using a text editor. However, they do not support features like vertical caption placement or text markup. If those features are required, VTT is recommended for ease of editing.

If you create your captions in a caption editor like YouTube or Amara, you can export your file to a variety of caption formats which can then be uploaded to any other player that accepts standard caption formats.

Note: Typically, it is appropriate to add closed captions (can be turned on and off) to your media content. However, in some situations, it is appropriate to add open captions (cannot be turned off).