Windows MediaVideo (WMV) is a video codec for compressing and decompressing video signals. WMV is a video file format for streaming video, it has high compression ratios and offers CIF display format at transfer rates of 250 kbit/s. It is a streaming format for playing audio and video. WMV is a series of audio codecs and video codecs optimized for specific applications.
The WMV format supports copy protection using digital rights management (DRM). There are several versions of Windows Media Video, but their version names are not clearly used: WMV1, WMV3, WMV7, and WMV9, with versions 1 and 7, and 3 and 9 being identical.Windows Media Video 9 (WMV9) version is an advanced video codec that offers optimal advantages for streaming over IP networks. WMV9 has implemented Video Codec 1 (VC-1) and supports half and quarter pixel interpolation, which has an immediate impact on picture quality, it reduces artifacts that occur during quantization, it can work with both Discrete Cosine Transform (DCT) and Inverse Discrete Cosine Transform (IDCT), and it supports block sizes of 8x8, 8x4, 4x8, and 4x4 pixels.
Compared to MPEG-2, WMV9 offers higher coding efficiency and lower computational overhead compared to H.264/AVC. WMV9 has also been adopted for HD-DVD and Blu-Ray disc.
WMV is the main streaming media format for Windows Media Player (WMP). The media player and codec can be downloaded for free from Microsoft. The extension of WMV files is *.wmv.