The MKV file holds an unlimited number of video, audio, picture and subtitle tracks within the file. It is a convenient video file where you can fit in the highest amount of data possible. It is a raw format that you can easily flip and turn all of the separate data tracks.
File saved into the MKV format more often than not save each track (subtitle, picture, audio and video) into a different dataline. This is similar to other container formats such as AVI or MP4 although generally when packaging an MKV file people rarely bundle all the tracks within the file. Most media players do not natively support MKV files, you would have to use a special media playing software to access its content normally such as VLC.
MP4 files (MPEG-4 Part 14) are multimedia files. MP4 is a container format that can store video, audio and subtitle data (as well as more depending on content). Since stores like iTunes uses this container format, and it is used with iPod and PlayStation Portable (PSP), MP4 files have become more common.
MPEG-4 Part 14 or MP4, formally ISO/IEC 14496-14:2003, is a multimedia container format standard specified as a part of MPEG-4. It is most commonly used to store digital video and digital audio streams, especially those defined by MPEG, but can also be used to store other data such as subtitles and still images. Like most modern container formats, MPEG-4 Part 14 allows streaming over the Internet. A separate hint track is used to include streaming information in the file. The only official filename extension for MPEG-4 Part 14 files is .mp4.
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