The Media Data Box, also known as MDAT, is a box in the ISO Base Media File Format (MP4) used to store media data such as audio, video, or other types of multimedia content. The MDAT box contains the actual payload of the multimedia content, and its contents are generally compressed using a compression algorithm such as H.264 or AAC. The MDAT box is typically one of several boxes in an MP4 file, and its location and size are specified in other boxes such as the Movie Box (moov) or the Track Box (trak). The MP4 file format is widely used for multimedia content such as movies, music, and video games, and the MDAT box is an important component of this format for storing the actual multimedia data.
ISO/IEC 14496-12 - https://standards.iso.org/ittf/PubliclyAvailableStandards/c051533_ISO_IEC_14496-12_2015.zip
QuickTime File Format Specification - https://developer.apple.com/library/archive/documentation/QuickTime/QTFF/QTFFChap2/qtff2.html
MP4 Format - https://en.wikipedia.org/wiki/MPEG-4_Part_14
MP4 Tools - https://www.mp4tools.com/
File Format Wiki - https://fileformats.fandom.com/wiki/Media_Data_Box