Convert WMV to MP3 - extract audio
WMV files carry WMA audio inside a Microsoft container. Wave discards the video, decodes the WMA - v1, v2, or Pro - and re-encodes it to a portable 192 kbps MP3 that plays on any device. WMA vs MP3 vs the rest is covered in Audio codecs explained.
What actually changes
A WMV file is an Advanced Systems Format container holding WMV video plus a WMA audio track. WMA v1 (rare, pre-2000), WMA v2 (the common consumer format from around 2000 onward), and WMA Pro (higher-bitrate, sometimes multi-channel) are all decodable by Wave's LGPL-clean wasm ffmpeg core. WMA Voice - a narrow-band variant used for lectures and dictation - is also handled.
Because the video track is discarded entirely, extract is fast - often ten times faster than converting the same WMV to MP4. An hour-long lecture WMV typically re-encodes to MP3 in under a minute on a modern laptop. Wave uses LAME (libmp3lame) at VBR around 190 kbps average, which is transparent for speech and for the vast majority of music content.
Windows Media Audio came in several distinct flavours. WMA v2 (WMA9 Standard) is the workhorse - the codec inside 90%+ of consumer WMV video files, targeting 96-192 kbps stereo for general-purpose audio. WMA Pro (WMA9 Professional) is the higher-bitrate variant used for surround audio in Windows Media Center and some broadcast archives; it supports 6-channel 5.1 layouts at 128-768 kbps. WMA Voice (WMA9 Voice) is the narrow-band variant used for corporate voicemail systems and lecture-recording tools, capped around 20 kbps and roughly voice-quality only.
The re-encode preserves whatever the source WMA carried. A WMA Voice-narrated tutorial produces a small MP3 that sounds exactly as clear as the source (bandwidth-limited); a WMA Pro music file produces a stereo MP3 that captures the source at MP3's transparency threshold. Multi-channel WMA Pro downmixes to stereo since MP3 has no surround.
Three steps.
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Step 1
Drop the WMV file onto the card.
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Step 2
Pick MP3 as the output format.
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Step 3
Convert and save the MP3.
Answers, specifically.
DRM-protected WMV - does it work?
No. Windows Media DRM (PlaysForSure) can only be decoded by Microsoft's own player. Wave, running purely in the browser, has no way around that. Unprotected WMV - which is nearly everything not from a paid store - converts fine.
Will my old lecture recording sound tinny?
Some lecture WMVs use WMA Voice, a narrow-band codec designed for speech that caps audio bandwidth around 4 kHz. Wave decodes it correctly, but the source bandwidth is what it is - the MP3 will sound as clear as the WMA did, no better and no worse.
Is 5.1 WMA Pro downmixed?
Yes. Wave downmixes multi-channel WMA Pro to stereo before encoding to MP3. If you need the surround field preserved, MP3 is the wrong target - it doesn't hold multi-channel audio at all.
How long does an hour-long WMV take?
Typically 30–60 seconds on a modern laptop. Because there's no video decode at all, extract runs several times faster than a full WMV-to-MP4 conversion.
What if my file is audio-only (a .wma)?
Wave rejects audio-only sources up front - it's a video-to-audio extractor, not an audio-to-audio converter. For a plain .wma, a dedicated audio-conversion tool is the right fit.
Do my Camtasia / Snagit WMV recordings work?
Yes. Camtasia and Snagit both used WMV output as their default for many years, with WMA2 or WMA Voice audio - exactly Wave's path. Modern versions of both tools default to MP4 output, but archives from before 2015 are typically WMV.
Windows Media Center recorded TV files (.wtv) - can Wave extract those?
Not directly. WTV is a related but different Microsoft format that ASF-based Wave paths do not currently target. Convert WTV to WMV first through Windows Media Center's built-in export or through a desktop ffmpeg ('ffmpeg -i recording.wtv -c copy recording.wmv'), then drop the WMV here.
The MP3 is much smaller than the WMV. Is that expected?
Yes - the video track is discarded entirely. A WMV that was 500 MB (video + audio) typically produces an MP3 in the 20-80 MB range depending on the source audio bitrate and duration. All the file-size difference comes from removing the video track, not from any additional audio compression.