Extract Audio from WMV to FLAC — Free Online Tool
Extract lossless audio from WMV files by converting the WMA (wmav2) audio stream to FLAC — an open, lossless format that preserves every bit of the original audio with no quality degradation. Ideal for archiving audio from Windows Media Video files in a universally compatible, high-fidelity format.
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FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
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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
WMV files store audio using Microsoft's proprietary WMA codec (typically wmav2), which is a lossy format. During this conversion, FFmpeg discards the video stream entirely using the -vn flag, then decodes the wmav2 audio to raw PCM and re-encodes it using the FLAC codec. Because the source audio is already lossy (WMA), the FLAC output is a lossless capture of what the WMA decoder produces — no further quality is lost in the extraction process, but the conversion cannot recover detail that was lost when the WMV was originally encoded. The result is a .flac file that faithfully represents the audio as it exists in the source file, with lossless compression that typically reduces file size compared to uncompressed PCM.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg multimedia processing tool. In this browser-based tool, FFmpeg runs locally via WebAssembly (FFmpeg.wasm) — your WMV file never leaves your device. |
-i input.wmv
|
Specifies the input WMV file. FFmpeg automatically detects the ASF container and identifies the audio codec (typically wmav2) and any video streams inside the file. |
-vn
|
Disables video output entirely, discarding the video stream from the WMV. This ensures the output FLAC file contains only the extracted audio with no attempt to process the WMV's video data. |
-c:a flac
|
Decodes the source WMA audio stream and re-encodes it using the FLAC codec. FFmpeg first decodes the lossy wmav2 audio to raw PCM, then losslessly compresses it into the FLAC format. |
-compression_level 5
|
Sets FLAC's compression effort to level 5 (the default and a sensible midpoint on a 0–8 scale). This controls only the encode speed and output file size — all compression levels produce bit-identical audio, so the extracted audio quality is unaffected by this setting. |
output.flac
|
Specifies the output filename and container. The .flac extension tells FFmpeg to write a standard FLAC file, which is widely supported by audio players, DAWs, and music library tools on all major platforms. |
Common Use Cases
- Archive audio commentary or narration from WMV training videos or screencasts into a future-proof, lossless format that isn't tied to Microsoft's proprietary WMA codec
- Extract music or sound effects from WMV files for use in audio editing software like Audacity or Adobe Audition, which handles FLAC better than WMA
- Convert a library of old Windows Media Video recordings to FLAC for playback on devices or players (such as hi-fi DACs and audiophile music players) that support FLAC but not WMA
- Strip the audio from a WMV presentation or lecture recording to produce a clean FLAC file for distribution as a podcast or audio-only download
- Preserve original audio from WMV home videos in a lossless container before further processing, ensuring no additional generation loss during editing workflows
- Extract audio from WMV files received from legacy Windows systems where the WMA format is inconvenient for cross-platform tools or streaming services that require open formats
Frequently Asked Questions
The FLAC file will be a lossless representation of the audio as decoded from the WMA stream, but it cannot recover quality that was discarded when the WMV was originally encoded with the lossy wmav2 codec. Think of it as a lossless snapshot of the current audio — no further degradation occurs during extraction. If the original WMV was encoded at a low WMA bitrate (e.g., 64k), that quality ceiling is fixed and the FLAC will simply preserve it perfectly from that point forward.
WMV stores audio using the lossy WMA codec, which achieves small file sizes by permanently discarding audio data. FLAC uses lossless compression, which retains all decoded audio data — resulting in a much larger file. Additionally, the WMV file also contains a compressed video stream, so comparing the two file sizes directly is misleading; the FLAC contains only audio. For reference, a FLAC file at compression level 5 is typically 50–60% the size of uncompressed PCM WAV, but still significantly larger than a lossy WMA or MP3 equivalent.
FFmpeg will attempt to map metadata from the ASF/WMV container to FLAC's Vorbis comment tags during conversion, and common fields like title and artist often transfer correctly. However, WMV uses Microsoft's ASF metadata format with Windows Media-specific tag names, so some fields may not map cleanly or may be dropped. After conversion, it's worth checking and editing tags in a tool like MusicBrainz Picard or foobar2000 to ensure accuracy.
The -compression_level flag controls how aggressively FLAC compresses the audio data. Level 5 is the default and a balanced midpoint — it produces smaller files than levels 0–4 with only a modest increase in encoding time. Levels 6–8 offer diminishing file size returns at the cost of significantly longer encoding times, while levels 0–1 encode very fast but produce larger files. Crucially, all compression levels produce bit-identical audio output — the setting only affects file size and encode speed, not audio quality.
The command as shown processes a single file, but you can batch process on the command line using a shell loop. On Linux or macOS, run: for f in *.wmv; do ffmpeg -i "$f" -vn -c:a flac -compression_level 5 "${f%.wmv}.flac"; done. On Windows Command Prompt, use: for %f in (*.wmv) do ffmpeg -i "%f" -vn -c:a flac -compression_level 5 "%~nf.flac". This is particularly useful when you have a large archive of WMV files to convert, especially since the browser-based tool handles files one at a time.
WMV/ASF does support multiple audio tracks, and FFmpeg will select the default audio stream automatically. To target a specific stream, add -map 0:a:1 to select the second audio track (zero-indexed), for example: ffmpeg -i input.wmv -vn -map 0:a:1 -c:a flac -compression_level 5 output.flac. The browser-based tool extracts the default audio track, so use the desktop FFmpeg command for multi-track WMV files where you need precise stream selection.
Technical Notes
WMV files use Microsoft's Advanced Systems Format (ASF) container, which is why FFmpeg requires the -f asf flag when writing WMV output — though for reading (input), FFmpeg auto-detects the format. The default audio codec in WMV is wmav2, a proprietary lossy codec; less commonly, WMV files may contain AAC or MP3 audio. Regardless of which lossy codec is in the source, FFmpeg decodes it to PCM before re-encoding to FLAC, so the extraction process is consistent. FLAC supports sample rates up to 655,350 Hz and bit depths up to 32-bit, so it can faithfully represent any audio quality present in the source WMV without truncation. One known limitation is that FLAC does not support multiple audio tracks in a single file — if your WMV has several audio streams, each must be extracted to a separate FLAC file. Additionally, DRM-protected WMV files (a feature of the ASF container) cannot be processed by FFmpeg or this tool; the file must be free of copy protection for extraction to succeed.