WMV to MKV Converter

How to Convert WMV to MKV Online

1. Upload Your WMV File: Drag and drop your .wmv clip onto the page, or click "+ Add Files" to pick one from your computer. Batch uploads work — drop a folder of WMVs and they share the same settings.
2. Pick Video Codec and Quality Preset: The default is Very High (Recommended), which re-encodes to H.264 for broad device support. Switch the codec to H.265/HEVC for ~40% smaller files at the same visual quality, VP9 or AV1 for royalty-free codecs, or leave WMV2/MSMPEG4 inside MKV if you only want a container swap. Choose Constant Bitrate, Variable Bitrate, Constant Quality, or Constraint Quality under File Compression to control rate behaviour.
3. Resize, Trim, or Set a Specific File Size (Optional): Use Preset Resolutions (480p through 4320p / 8K) or enter Width x Height with aspect ratio locked. Trim by Time Range to cut intros. Set Specific file size in MB, or Resolution Percentage to scale by ratio.
4. Convert and Download: Click Convert. Files are uploaded over an encrypted connection, processed on our servers, and deleted automatically after a few hours — no sign-up, no watermark, never shared.

Why Convert WMV to MKV?

WMV is Microsoft's video format from 1999 (WMV7) and 2003 (WMV9 / SMPTE VC-1), wrapped in the proprietary Advanced Systems Format (ASF) container. MKV (Matroska), announced in December 2002, is a free, open EBML-based container that can hold an unlimited number of video, audio, picture, and subtitle tracks in one file. Moving a WMV stream into MKV gives you a portable, future-proof envelope without re-compressing the picture if you choose codec copy.

• Plays in VLC, MPV, PotPlayer, Kodi, and Plex without a Windows Media codec pack — MKV is the native container most cross-platform players assume. WMV/ASF support outside Microsoft has been thinning since Telestream ended Flip4Mac in 2019.
• Multi-track audio and subtitles in one file — MKV lets you bundle English, commentary, and dubs as selectable audio tracks plus SRT/ASS subtitle tracks. ASF has audio-track support but is rarely used for it, and most WMV files ship single-track.
• Lossless container swap is possible — pick codec Copy (or leave WMV2/MSMPEG4 selected) and the converter remuxes the original video bitstream into MKV without re-encoding, preserving every pixel of the source.
• Modern codec re-encoding — re-encode to H.264 for the widest hardware decode support, H.265/HEVC for storage savings on Apple Silicon and Intel 7th-gen-or-later chips, or VP9/AV1 for browsers (Chrome, Firefox, Edge support both natively).
• Archive raw camera or screen-recorder output — old Windows Movie Maker exports, Camtasia legacy projects, and security-camera WMVs become unwieldy. MKV is the de-facto archive container for the digital-preservation community.
• Chapters, attachments, and metadata — MKV stores chapter markers, fonts, cover art, and arbitrary file attachments alongside video, which ASF cannot.

WMV vs MKV — Format Comparison

Codec & Quality Preset Quick Guide

Quality presets map roughly to CRF: Lowest ≈ 32, Low ≈ 28, Medium ≈ 23, High ≈ 20, Very High (Recommended) ≈ 18, Highest ≈ 15. Lower CRF means larger files and better picture.

Frequently Asked Questions

Will converting WMV to MKV reduce video quality?

It depends on what you choose. If you select codec Copy (or leave WMV2/MSMPEG4 as the codec), the original bitstream is remuxed into MKV with zero quality loss — same pixels, new container. If you re-encode to H.264, H.265, VP9, or AV1, quality depends on the preset: Very High (Recommended) is visually transparent for most footage; Highest is near-lossless. Lowest visibly degrades. For archival, pick Copy or Highest.

Should I pick H.264 or H.265 for MKV output?

H.264 if you care about compatibility — every smart TV, phone, and browser made since 2010 decodes it in hardware. H.265 if you care about file size: it gives the same visual quality at roughly 40-50% smaller files, but older Intel CPUs (pre-6th gen), AMD GPUs (pre-Polaris), and budget TVs may software-decode and stutter. For a home-server (Plex, Jellyfin) archive on modern hardware, H.265 is the sweet spot. For sending files to others, H.264.

Why is my MKV bigger than the original WMV?

Old WMV files are often heavily compressed (1-3 Mbps for 720p). Re-encoding at default Very High quality targets a higher visual standard, which inflates the file. To keep the MKV similar in size: drop the codec to H.265, use Constraint Quality at CRF 24, or set a Specific file size matching the WMV. For zero growth, use codec Copy — pure container swap.

Can MKV embed subtitles from a separate SRT file?

The xConvert converter does not currently mux external subtitle files during this conversion — it preserves any subtitle tracks that already exist inside the WMV. To add an SRT after conversion, use MKVToolNix (free) to mux the SRT into the MKV without re-encoding. MKV natively carries SRT, ASS/SSA, PGS (Blu-ray), and VobSub (DVD) subtitle formats.

Will my old Windows Movie Maker or Camtasia WMV files convert correctly?

Yes. Legacy WMV7 (MSMPEG4-based) and WMV9 (VC-1) bitstreams are both supported. Very old WMVs sometimes have unusual frame rates (15, 23.976, or NTSC-pulldown variants) — these are preserved automatically. If a file refuses to play after conversion, try re-encoding to H.264 at Very High preset instead of copying the codec; old WMV streams occasionally have header oddities that re-encoding cleans up.

Why use MKV instead of MP4?

MKV is more flexible: unlimited tracks, embedded chapters, attachments (fonts, posters), and any codec. MP4 is more compatible: native to Safari, iOS, most TVs, and required for HTML5 <video> everywhere. Rule of thumb — MKV for archive and home-media libraries; MP4 for sharing, streaming, and mobile playback. If MKV doesn't work where you need it, see MKV to MP4.

Does converting strip Microsoft DRM from a WMV file?

No. If a WMV is protected by Windows Media DRM (PlayReady / WMRM), the original cannot be decoded by anyone who doesn't hold the license — neither xConvert nor any other converter can read the encrypted video. Most personal or screen-recorded WMVs are not DRM-protected and convert normally. Files from older online stores (early-2000s purchases) often are protected and will fail.

What about audio — does the AAC/WMA track come through?

The audio track is preserved by default. Original WMV files typically contain WMA Pro or WMA 2 audio. MKV happily carries both. If you want to re-encode the audio to AAC or Opus for better compatibility, the converter exposes Audio Codec selection under Advanced Options (AAC, AC3, Opus, FLAC, Vorbis, and PCM variants are available).

Can I also go the other way — MKV back to WMV?

Yes, see MKV to WMV. That said, WMV is a legacy format with declining player support outside the Microsoft ecosystem; most workflows now use MKV or MP4. For a more universal target, MKV to MP4 is usually a better choice.