WMV (Windows Media Video)
Microsoft's internet-streaming video format, built in 1999 to compete with RealVideo and still found in millions of Windows recordings today.
| Full name | Windows Media Video |
| Extension | .wmv |
| MIME type | video/x-ms-wmv |
| Developer | Microsoft |
| Released | 1999 (WMV 7) |
| Type | Video codec and format |
| Container | Advanced Systems Format (ASF) |
| Standardized as | SMPTE 421M (VC-1), approved March 2006 |
What is a WMV file?
WMV is a video codec and file format developed by Microsoft and first released in 1999. It was designed for internet streaming on Windows and bundled into Windows Media Player for years. The format is closely tied to the ASF container and can be found in screen recordings, camcorder output, and older Windows video libraries.
WMV is both a codec family and a file format. The codec compresses video data; the file wraps that compressed video together with audio in an ASF container. Microsoft released three main codec versions: WMV 7, WMV 8, and WMV 9. WMV 9, the most capable version, was later standardized as VC-1 by SMPTE in 2006, making it an open standard. The format also includes two specialized variants: WMV Screen (optimized for screen recordings) and WMV Image (a slideshow format using still images).
History
Microsoft introduced WMV 7 in 1999, building it on top of Microsoft's implementation of MPEG-4 Part 2. The goal was to challenge RealVideo as the dominant format for low-bandwidth internet video. WMV 8 followed with incremental improvements, and WMV 9 (released in 2003) added native interlaced video support, non-square pixels, and better compression at high bit rates. In March 2006, the SMPTE standardized WMV 9 as SMPTE 421M, also known as VC-1, opening the codec for third-party implementations.
Container vs codec
A WMV file uses the Advanced Systems Format (ASF) container, a binary format organized into objects with globally unique identifiers (GUIDs). The header object describes the streams, codec details, and playback properties. The data object holds the actual interleaved audio and video packets. An index object at the end of the file allows players to seek to any point without reading the whole file. While WMV content can technically be placed in MKV or AVI containers, the .wmv extension always signals an ASF wrapper.
What it is used for
- Playing back screen recordings made with older Windows tools like Expression Encoder or Camtasia
- Storing corporate training videos and presentations originally captured on Windows workstations
- Streaming video over Windows Media Services in intranet environments
- Archiving consumer camcorder footage recorded by older Windows-based devices
How to open it
WMV files open natively in Windows Media Player and Movies and TV on Windows 10 and 11. On macOS and Linux, VLC Media Player handles WMV files without any extra codec installation.
Pros and cons
Strengths
- Built into every version of Windows, so no extra software is needed on Windows machines
- WMV Screen variant achieves very small file sizes for desktop recordings
- WMV 9 / VC-1 is an open SMPTE standard, not purely proprietary
- Supports DRM, which made it the format of choice for early digital video stores
Trade-offs
- Poor compatibility on macOS, iOS, and Android without third-party players or conversion
- Modern codecs like H.264 and H.265 deliver better quality at the same file size
- Microsoft stopped actively developing the format; WMV 9 has not been updated since 2003
- DRM-protected WMV files can become permanently unplayable if the license server goes offline
Convert WMV files
Free, in your browser, no signup. Start at the WMV converter, or jump straight to a popular conversion below.
From WMV
Curious how fast and how small? See our measured conversion benchmarks.
WMV FAQ
Can I play a WMV file on a Mac or iPhone?
Not natively. Apple's QuickTime and iOS do not support WMV. VLC for Mac can play most WMV files. For iPhones, your best option is to convert the WMV to MP4 first, since MP4 plays everywhere without any extra app.
Is WMV better than MP4?
No, not for general use today. MP4 with H.264 gives smaller files at the same quality and works on every device and browser. WMV only has an advantage in specific Windows-only workflows or when you need Windows Media DRM.
Why does my WMV file say 'license required' and refuse to play?
The file has Windows Media DRM applied. It needs a license from the original server to unlock playback. If that server no longer exists, the file cannot be played. There is no way to recover a DRM-locked WMV file whose license server is gone.
Does converting WMV to MP4 lose quality?
It depends on the settings. Re-encoding the video stream introduces some quality loss because both WMV and H.264 are lossy formats. To minimize loss, use a high-quality preset or, if the target player accepts it, do a container-only remux when the codec allows it.