When I was about to let myself into the bed at the late night on the same day that I searched on the .mkv media file; I surfed Mr. Danh Hong's blog, http://khmertype.blogspot.com, I was interested on many articles he's posted on (he is the person who makes a revolution of Khmer Unicode); in here I noted and found more details of WebM.
WebM is an audio-video format designed to provide a royalty-free, open video compression format for use with HTML5 video. The project's development is sponsored by Google.
A WebM file consists of VP8 video and Vorbis audio streams, in a container based on a profile of Matroska. The project releases WebM related software under a BSD license and all users are granted a worldwide, non-exclusive, no-charge, royalty-free patent license. Despite this, some in the industry have called upon Google to provide indemnification against patent suits.
# A key factor in the web’s success is that its core technologies such as HTML, HTTP, TCP/IP, etc. are open and freely implementable. Though video is also now core to the web experience, there is unfortunately no open and free video format that is on par with the leading commercial choices. To that end, we are excited to introduce WebM, a broadly-backed community effort to develop a world-class media format for the open web.
# File name extension: .webm
# Internet media type: video/webm, audio/webm
# Developed by: Google, based on developments of On2, Xiph, and Matroska
# Container for: VP8 (video), Vorbis (audio)
# Website: webmproject.org