The M4V file format was developed by Apple. It is very similar to the MP4 file type, with the main difference being that M4V may contain Apple's DRM protection, Fairplay. Video content downloaded from the iTunes store is likely to be in M4V format. If M4V file does have DRM enabled then the iTunes account used to procure the file will need to be authenticated on the computer playing the file.
The M4V format was developed by Apple and it is much more similar to the MP4 format with a slight difference in DRM protection. If M4V format has DRM protection than the iTunes account used to process the file will have to be authenticated on the computer playing the file.
The M4V file is a container that allows audio and video. In certain circumstances where Apple's DRM has not be applied to the file, it is possible to play the file from a different unauthenticated computer by amending the file extension from .m4v to .mp4. Additionally m4v provides the functionality to create chapter information which is not possible with MP4.
The M4V supported files have both the audio as well as the video data, the file extension M4V can be converted into the MP4 file extension in order for it to play on an unauthenticated computer because the M4V files are protected by Apples DRM. MP4 files do not provide with the functionality to create chapter information while M4V file does that.
Similar to the MKV file extension, WEBM is a file format developed by a number of parties, including Google. Launched in 2010, it is open source format designed to deliver video through the web. It can be used for a variety of types of video, from video calls to high definition movies. WebM is growing, and by using the HTML5 version of YouTube, it is possible to watch video encoded in WebM.
Like the MKV file extension, the WEBM extension is developed by various online parties such as Google, it is a freeware offering streaming of online video content and it was first developed in 2010. By using the HTML5 version of YouTube one can watch video encoded in WEBM.
WebM benefits from being designed for use on the modern web, rather than for local use. This means the format is specifically designed for the wide range of devices that are used to access the web, from Smart Phones to Powerful PCs. The video element of the file is encoded using VP8 video codec and the audio element of the file is encoded using the Vorbis audio codec.
Encoding and deciding in WEBM format is possible while using the ffvp8 software or libvpx from the Google support. When it comes to the Android support a version of 2.3 (Gingerbread) and above allowing playback of WEBM format can be used for encoding and decoding. Back in 2001 using Rockchip a full hardware implementation of 1080p VO8 encoding was made possible.
Google (Previously developed by On2, Xiph, and Matroska)