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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WMV files are a type of video file (usually containing audio) from Microsoft. These files can be played on a variety of video players on both Mac and PC machines. Some WMV files may have digital rights management (DRM) protection which prevents users from making unauthorized copies of files purchased in online stores.
Windows Media Video (WMV) is a compressed video file format for several proprietary codecs developed by Microsoft. These files are based on the Microsoft Advanced Systems Format (ASF) container format encoded using the Windows Media Video (WMV) codec.
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