At a fundamental level, you can specify the type of a media file using a simple MIME type, such as video/mp4 or audio/mpeg. However, many media types—especially those that support video tracks—can benefit from the ability to more precisely describe the format of the Data within them. For instance, just describing a video in an MPEG-4 file with the MIME type video/mp4 doesn't say anything about what format the actual media within takes....precisely describe the format of the data within them. For instance, just...plane. Otherwise, the video data is entirely in the Y plane and...