A caption file is a completely separate file from a video file. Caption files can be made in a wide variety of formats, and you can upload a caption file to accompany a video in order to create closed captioning (captions that can be turned on and off independently by each viewer). To ensure your videos can have closed captions, always choose a video platform that supports caption files.
Caption File Format Types
The two most common caption file formats are SRT and VTT. SRT and VTT caption files are relatively simple file formats that are compatible with many commonly used video platforms. 3Play Media has provided detailed information about SRT, VTT, and more complex caption file format options and their uses.
SRT (SubRip Subtitle)
SRT is a plain text file and can be used for captions or subtitles. An SRT file contains the text for all captions in sequential order and start/end timestamps for each caption. The timestamps ensure each section of caption text will align with the video.
VTT (Web Video Text Tracks)
All information provided in the SRT section also applies to VTT caption files (also referred to as WebVTT). However, VTT files contain information that allows the captioner to adjust caption formatting like font, color, and placement. VTT can offer a more robust and accessible experience.
Converting Caption File Formats
Some video platforms only accept certain caption file formats. Below are two tools that can be used to convert a caption file to a different format. Please note that these tools have not been evaluated for data security, so they should not be used for confidential data.
- CADET (Caption and Description Editing Tool) is a free downloadable tool that allows you to convert caption formats, including SRT and VTT.
- Subtitle Tools is a free online caption converter tool that allows you to convert caption files into SRT format.
If you need assistance with uploading or converting caption files, please contact Captioning@Colorado.EDU for support.
