.QT File Extension
What is a QT file?
A QT file is a movie file saved in the QuickTime File Format (QTFF), which is a multimedia container format developed by Apple. It contains one or more audio, video, or text (subtitle) tracks and typically uses the MPEG-4 codec for compression. QT files are most often used for storing movies.
The QTFF was developed and released by Apple in 1991, and led to the formation of the MPEG-4 standard. It is designed to support various types of media in order to accommodate the transfer of multimedia between applications, operating systems, and devices.
Video files saved in the QTFF may use the .qt or .mov file extensions. However, .MOV files are much more common than QT files. Since MOV and QT files often store video compressed with the MPEG-4 codec, they are commonly interchanged with .MP4 video files.
More information about the QuickTime File Format
QTFF is object-oriented and is forward-compatible, allowing it to support new object types introduced over time. The format supports media data, which is the video, audio, or text data, and metadata, which includes the media compression utilized, timing information, number of media tracks, and an index of where the media data is located.