WMV9

WMV9, or Windows Media Video 9, is a video compression format developed by Microsoft as part of the Windows Media framework. It was introduced in the early 2000s as part of Windows Media Player 9 and related components, with the goal of delivering higher compression efficiency and improved visual quality at a given bitrate compared to its predecessors, while supporting a wide range of resolutions, including high-definition content.

WMV9 is an implementation of the VC-1 video compression standard. VC-1 was standardized by SMPTE as 421M and has been used in various broadcasting and disc formats. The WMV9 codec integrates features of VC-1, including support for interlaced and progressive coding, multiple profiles for different performance and quality levels, and capability for variable bitrate and error resilience suitable for streaming.

Technical notes: WMV9 supports standard-definition and high-definition resolutions, commonly up to 1080p, and employs advanced motion compensation and prediction techniques to improve image quality at lower bitrates compared with earlier WMV codecs. It is designed to work within the Windows Media Video 9 family and the .wmv container format.

Usage and compatibility: The codec is primarily used in Windows-based media workflows, stored in .wmv files, and supported by Windows Media Player and related streaming services. It has also seen third-party decoder and player implementations, providing cross-platform playback in various software and some hardware devices.

Licensing and status: WMV9 is a Microsoft-proprietary codec, while the underlying VC-1 standard is publicly specified and licensable through SMPTE. As a result, WMV9 playback remains common on Windows and in certain services, though other formats such as H.264/AVC and newer codecs have become more prevalent in many applications.