Does this tool actually convert my video?

No. This is a command generator — it produces the FFmpeg command you run yourself in your own terminal. Your video files are never uploaded anywhere.

Do I need to install anything?

You need FFmpeg installed on your computer. It is free and available for Windows, macOS, and Linux at ffmpeg.org. Most Linux distributions can install it via apt or dnf.

What is CRF and what value should I use?

CRF (Constant Rate Factor) controls quality vs file size. For VP9, values range from 0 (lossless, huge) to 63 (very poor). A CRF of 28–33 is a good starting point for web video. Lower = better quality, larger file.

VP8 vs VP9 — which should I choose?

VP9 is newer and produces significantly better quality at the same file size. Choose VP9 unless you need compatibility with very old browsers. Both are supported in WebM.

How do I run the command on Windows?

Open Command Prompt or PowerShell, navigate to the folder containing your WMV file with the cd command, then paste and run the generated FFmpeg command.

Can I convert multiple WMV files at once?

On Linux/macOS, wrap the command in a for loop: for f in *.wmv; do ffmpeg -i "$f" "${f%.wmv}.webm"; done. On Windows PowerShell: Get-ChildItem *.wmv | ForEach-Object { ffmpeg -i $_.Name "$($_.BaseName).webm" }.

WMV to WebM Converter

Generate the correct FFmpeg command to convert WMV video files to WebM (VP9/Opus) with your chosen quality and audio settings.

Command Builder

Input filename

Output filename

Video codec

Video quality (CRF): 33

4 — best quality (large) 63 — smallest (low quality)

Resolution (optional)

Audio codec

Audio bitrate

Two-pass encoding (better quality, slower)

FFmpeg Command

Click "Generate Command" to build your FFmpeg command.

Quick Reference

-c:v libvpx-vp9 VP9 video encoder (best quality for WebM)

-crf 33 Constant rate factor — quality target

-b:v 0 Required alongside -crf for VP9 VBR mode

-c:a libopus Opus audio — standard for WebM

-vf scale=W:H Resize video to width W and height H

Install FFmpeg

Ubuntu sudo apt install ffmpeg

macOS brew install ffmpeg

Windows winget install ffmpeg

Summary

WMV (Windows Media Video) is a Microsoft-proprietary format that is not natively supported by most modern browsers and Linux systems. WebM is an open, royalty-free container using VP8/VP9 video and Opus/Vorbis audio, making it ideal for web playback. This tool generates the correct FFmpeg command so you can convert WMV files to WebM locally on your machine with full control over quality and file size.

How it works

Enter your input WMV filename and desired output filename.
Choose a video codec — VP9 is recommended for best quality-to-size ratio.
Set the CRF (Constant Rate Factor) — lower numbers mean higher quality and larger files.
Select an audio codec and bitrate.
Optionally set a target resolution or leave blank to keep the original.
Click "Generate Command" and copy the FFmpeg command to run in your terminal.

Use cases

Convert old WMV recordings to WebM for use on websites without a plugin.
Prepare video files for HTML5 <video> tags that require WebM format.
Reduce file size of WMV screencasts for sharing or uploading.
Batch-convert a folder of WMV files to WebM using the generated command as a template.
Convert WMV files on Linux or macOS where WMV playback support is limited.
Prepare video assets for web projects that require open, royalty-free formats.

Frequently Asked Questions

Last updated: 2026-06-11 · Reviewed by Nham Vu