MyMediaTools

Convert WMV to AVI — Free Online Tool

Convert WMV files to AVI by re-encoding the Microsoft proprietary WMV video stream into H.264 (libx264) and the WMA audio into MP3, producing a widely compatible AVI container. This is especially useful for getting WMV content out of the Windows ecosystem and into a format that legacy editing software, older media players, and hardware devices can reliably open.

FFmpeg Command

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Estimated output:

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How It Works

WMV uses Microsoft's proprietary MPEG-4 variant (msmpeg4 or msmpeg4v2) for video and Windows Media Audio (WMA/wmav2) for audio — neither of which is natively supported by the AVI container in most players. During this conversion, FFmpeg fully re-encodes the video stream from the WMV codec into H.264 using libx264, and transcodes the WMA audio into MP3 using the LAME encoder. Because both streams must be decoded and re-encoded rather than simply copied, this is a full transcode — not a remux — meaning some quality loss is inherent, but the output H.264/MP3 AVI is broadly compatible with a far wider range of software and hardware than the original WMV.

What Each Flag Does

Flag What it does
ffmpeg Invokes the FFmpeg program. In the browser-based version of this tool, FFmpeg runs locally via WebAssembly (FFmpeg.wasm) — no data leaves your device.
-i input.wmv Specifies the input WMV file. FFmpeg automatically detects the ASF/WMV container and identifies the contained msmpeg4 video and WMA audio streams for decoding.
-c:v libx264 Re-encodes the WMV video stream (originally msmpeg4 or msmpeg4v2) into H.264 using the libx264 encoder, which is the default and most compatible video codec for AVI output.
-c:a libmp3lame Transcodes the WMA audio stream from the source WMV into MP3 using the LAME encoder — the standard audio codec for AVI files, ensuring compatibility with virtually all media players and editing tools that open AVI.
-crf 23 Sets the Constant Rate Factor for the H.264 encoder to 23, which is the libx264 default and delivers a good balance of visual quality and file size for typical WMV source material. Lower values (e.g., 18) mean higher quality and larger files; higher values (e.g., 28) mean smaller files with more compression.
-b:a 128k Sets the MP3 audio bitrate to 128 kbps, which is sufficient for most speech and general-purpose audio from WMV sources. Raise this to 192k or 320k if your original WMV contained high-quality music or audio that warrants a higher bitrate.
output.avi Defines the output filename and instructs FFmpeg to write the re-encoded H.264 video and MP3 audio into an AVI container — no special flags are needed since AVI is a straightforward legacy container format.

Common Use Cases

  • Opening WMV files recorded by older Windows systems or cameras in video editing software like Premiere Pro or Vegas that works better with H.264 AVI timelines
  • Playing WMV content on older DVD players, media streamers, or smart TVs that support AVI but not Windows Media formats
  • Archiving corporate training videos or presentations originally distributed as DRM-free WMV files into a more future-proof container
  • Importing WMV screen recordings into legacy tools like VirtualDub, which reads AVI natively but has limited WMV support
  • Sharing video clips with colleagues or clients on non-Windows machines where Windows Media Player is unavailable and WMV codec packs are not installed
  • Stripping WMV-specific metadata and container quirks before re-editing or re-encoding footage for distribution

Frequently Asked Questions

Yes, there will be some quality loss because both the video and audio streams must be fully re-encoded — the WMV codec (msmpeg4) is decoded and re-encoded as H.264, and WMA audio is decoded and re-encoded as MP3. The default CRF value of 23 for libx264 produces good visual quality for most content, but if your original WMV was already heavily compressed at a low bitrate, the output quality is bounded by that source quality. Lowering the CRF value (e.g., to 18) in the FFmpeg command will produce a higher-quality output at the cost of a larger file size.
WMA (Windows Media Audio) is a proprietary Microsoft codec that is not widely supported outside the Windows ecosystem. The AVI container can technically hold WMA audio, but MP3 (libmp3lame) is the standard audio codec for AVI files and is supported by virtually every media player, editing tool, and hardware device that can open AVI. FFmpeg therefore transcodes the WMA stream to MP3 to ensure maximum compatibility with the output file.
File size differences are driven by the difference in bitrate settings between the source WMV and the output H.264 AVI. H.264 is generally more efficient than the older msmpeg4 codec used in WMV, so at the same visual quality the H.264 output is often smaller. However, if your original WMV was encoded at a low bitrate and your AVI output settings are more generous, the AVI could be larger. The CRF-based encoding used for H.264 targets quality rather than a fixed bitrate, so file size will vary depending on the complexity of your video content.
WMV files can carry some metadata but do not support embedded subtitle tracks or chapter markers in a standard way, and neither does the AVI container. Neither format supports these features in this conversion pipeline, so there is nothing to lose on that front. However, any ASF-level metadata embedded in the WMV (such as title, author, or copyright fields) will not be automatically carried over to the AVI output, as the two containers use incompatible metadata structures.
The video quality is controlled by the -crf flag. The default value of 23 is a good balance for most WMV source material, but you can lower it toward 18 for higher quality (larger file) or raise it toward 28 for smaller file size with more compression. For example: ffmpeg -i input.wmv -c:v libx264 -c:a libmp3lame -crf 18 -b:a 128k output.avi. You can also increase the audio bitrate by changing -b:a 128k to -b:a 192k or -b:a 320k if your WMV source had high-quality WMA audio you want to preserve as faithfully as possible.
Yes. On Linux or macOS you can loop over files in a directory with a shell one-liner: for f in *.wmv; do ffmpeg -i "$f" -c:v libx264 -c:a libmp3lame -crf 23 -b:a 128k "${f%.wmv}.avi"; done. On Windows Command Prompt, use: for %f in (*.wmv) do ffmpeg -i "%f" -c:v libx264 -c:a libmp3lame -crf 23 -b:a 128k "%~nf.avi". This browser-based tool processes one file at a time, so the FFmpeg command is especially handy for batch jobs or for files larger than 1GB.

Technical Notes

WMV is built on Microsoft's Advanced Systems Format (ASF) container, which requires the special -f asf flag when creating WMV output in FFmpeg, though this is not needed when reading WMV as input. The video codec in WMV files is almost always msmpeg4 or msmpeg4v2, both of which are Microsoft's proprietary derivations of the MPEG-4 Part 2 standard — they are not the same as standard MPEG-4 ASP and are not compatible with ISO-standard decoders without specific codec support. Converting to H.264 in AVI resolves this compatibility gap entirely. One notable limitation of this conversion is that if your WMV was protected with Windows Media DRM, FFmpeg cannot decrypt it and the conversion will fail — only DRM-free WMV files can be processed. The AVI container does not support multiple audio tracks in practice (despite the format technically allowing it), so if your WMV has multiple WMA audio streams, only the first stream will be mapped to the output by default. Additionally, AVI has a 2GB file size limit in its original specification, though modern players using the OpenDML AVI extension handle larger files — be aware of this if converting long or high-bitrate WMV recordings.

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