Convert M4V to WMV — Free Online Tool
Convert M4V files from iTunes or iOS devices into WMV format using the Microsoft MPEG-4 v3 (msmpeg4) video codec and WMA v2 audio — making your Apple-sourced video compatible with Windows Media Player and legacy Windows-based media workflows. Processing happens entirely in your browser with no file uploads required.
to
FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
Drop your M4V file here
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Free — no uploads, no signups. Your files never leave your browser.
Settings
Note: Browser-based encoding uses approximate quality targets. For precise CRF compression, copy the FFmpeg command above and run it on your desktop.
Estimated output:
Conversion Complete!
DownloadHow It Works
M4V is an Apple container closely related to MP4, typically carrying H.264 (libx264) video and AAC audio. WMV uses Microsoft's Advanced Systems Format (ASF) container, which requires its own proprietary video codec — in this case msmpeg4 (Microsoft MPEG-4 version 3). Because neither the video nor audio codec is compatible between these containers, this conversion is a full transcode: the H.264 video stream is decoded and re-encoded to msmpeg4, and the AAC audio is decoded and re-encoded to WMA v2 (wmav2). This means every frame is processed, so encode time is longer than a simple remux, and there is inherent generational quality loss since both the source and target are lossy formats.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg program. In the browser version, this runs as a WebAssembly (FFmpeg.wasm) instance entirely within your browser — no data leaves your machine. |
-i input.m4v
|
Specifies the input file in M4V format — an Apple MPEG-4 container typically holding H.264 video and AAC audio, as used by iTunes and iOS devices. |
-c:v msmpeg4
|
Sets the video codec to Microsoft MPEG-4 version 3 (msmpeg4), the proprietary codec required for genuine WMV compatibility with Windows Media Player. This triggers a full re-encode of the H.264 video from the M4V source. |
-c:a wmav2
|
Sets the audio codec to Windows Media Audio version 2 (wmav2), re-encoding the original AAC audio from the M4V into WMA format, which is natively supported by Windows Media Player without additional codecs. |
-b:v 2000k
|
Sets the video bitrate to 2000 kilobits per second for the msmpeg4 output stream. Because WMV uses constant bitrate rather than quality-based encoding, this is the primary lever for balancing file size against visual quality. |
-b:a 128k
|
Sets the WMA v2 audio output to 128 kilobits per second, a standard bitrate that provides acceptable stereo audio quality for most speech and music content in a WMV file. |
-f asf
|
Forces the output container to Advanced Systems Format (ASF), the Microsoft container format that underpins WMV. This flag is required because WMV is ASF with video content, and explicitly setting it ensures correct muxing of the msmpeg4 and wmav2 streams. |
output.wmv
|
The name of the resulting output file in WMV format, ready for playback in Windows Media Player or import into Windows-based video workflows. |
Common Use Cases
- Playing iTunes-purchased or Apple TV video downloads on a Windows PC using Windows Media Player, which natively supports WMV but not M4V
- Submitting video content to legacy enterprise content management systems or intranets that only accept ASF/WMV files
- Importing Apple-recorded video into older Windows-based video editing software that lacks H.264 or AAC decoder support
- Archiving iOS screen recordings or Apple-exported video in a format compatible with Windows Media Services or legacy Microsoft streaming infrastructure
- Preparing video assets for Windows-centric kiosk or digital signage systems that use Windows Media Player as their playback engine
- Stripping Apple-specific container metadata and DRM-free M4V content into a neutral, Windows-native format for redistribution within a corporate Windows environment
Frequently Asked Questions
Yes, some quality loss is unavoidable. Your M4V file already uses lossy H.264 compression, and re-encoding to msmpeg4 introduces a second generation of lossy compression. The msmpeg4 codec is also technically older and less efficient than H.264, so at the same bitrate it will generally produce lower visual quality. The default bitrate of 2000k is acceptable for standard-definition content, but for HD M4V files you should increase -b:v to 4000k or higher to reduce visible degradation.
WMV's ASF container does support multiple audio tracks, so multi-language audio from your M4V can technically be preserved. However, WMV does not support chapters at all — any chapter markers embedded in your M4V file will be lost during conversion. If chapter navigation is important, WMV is not a suitable target format.
Subtitles will be dropped entirely. M4V supports embedded subtitle tracks, but the WMV/ASF container does not support subtitle streams in the way FFmpeg handles them for this conversion. If you need subtitles, you would need to burn them into the video stream using a filter (such as -vf subtitles) before or during conversion, making them a permanent part of the image.
No. iTunes M4V files with FairPlay DRM are encrypted and cannot be decoded by FFmpeg or any browser-based tool. FFmpeg will report an error or produce a blank/corrupt output. This tool can only convert DRM-free M4V files, such as those exported from iMovie, Final Cut Pro, Apple Compressor, or iTunes purchases that have had DRM removed through authorized means.
WMV uses constant bitrate (CBR) control via the -b:v flag rather than the CRF quality scale used by H.264. To increase quality, raise the value — for example, replace -b:v 2000k with -b:v 4000k for better quality at a larger file size, or use -b:v 1000k to reduce file size at the cost of quality. Similarly, audio bitrate can be adjusted with -b:a, for example changing 128k to 192k for higher-fidelity WMA audio output.
Yes. On Windows you can use a simple batch script: for %f in (*.m4v) do ffmpeg -i "%f" -c:v msmpeg4 -c:a wmav2 -b:v 2000k -b:a 128k -f asf "%~nf.wmv". On macOS or Linux, use: for f in *.m4v; do ffmpeg -i "$f" -c:v msmpeg4 -c:a wmav2 -b:v 2000k -b:a 128k -f asf "${f%.m4v}.wmv"; done. The browser-based tool processes one file at a time, so the desktop FFmpeg command is the recommended approach for batch jobs.
Technical Notes
The msmpeg4 codec (Microsoft MPEG-4 version 3, sometimes called MS-MPEG4v3) is a proprietary variant of the MPEG-4 Part 2 specification developed by Microsoft in the late 1990s. It is distinct from the ISO-standard MPEG-4 ASP codec (libxvid or mpeg4 in FFmpeg) and is not interchangeable with modern H.264 or H.265. The ASF container (-f asf) is mandatory for WMV output because the .wmv extension is simply an ASF file with video content — FFmpeg uses this flag to force the correct container structure rather than inferring it from the extension alone. WMA v2 (wmav2) is a reasonable default audio codec for WMV and is natively decoded by Windows Media Player without additional codecs. Note that M4V-specific metadata such as iTunes tags (album, artist, show name, episode number), chapter markers, and Apple-specific UUID atoms will not be preserved in the ASF container. If your M4V was encoded in H.265 (HEVC), the source is even further in quality terms from the msmpeg4 target, so increasing -b:v is especially recommended. Files over 1GB should be processed using the desktop FFmpeg command rather than the browser tool due to browser memory constraints.