Convert WMV to FLAC — Free Online Tool
Convert WMV video files to FLAC audio by extracting and losslessly compressing the audio stream from Microsoft's proprietary ASF container. This tool strips the video and re-encodes the WMV audio (typically WMA or AAC) into FLAC, preserving every bit of audio fidelity in an open, universally supported format.
to
FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
Drop your WMV file here
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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 use Microsoft's Advanced Systems Format (ASF) container, which most commonly carries Windows Media Audio (WMAv2) or AAC audio alongside the video stream. During this conversion, FFmpeg discards the video stream entirely and decodes the audio — whether WMAv2, AAC, or MP3 — to a raw PCM representation in memory. That PCM audio is then re-encoded using the FLAC codec at compression level 5, which applies lossless compression. Because FLAC is lossless by definition, the output perfectly represents the decoded audio signal; however, since WMV itself is a lossy format, any quality loss that existed in the original WMV's audio encoding is already baked in. You are not losing any additional quality in this conversion, but you are also not recovering quality lost during the original WMV encoding.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg command-line tool, which handles all media decoding, stream selection, and re-encoding. In the browser version of this tool, FFmpeg runs via WebAssembly (FFmpeg.wasm) entirely client-side — no data leaves your device. |
-i input.wmv
|
Specifies the input file in WMV format. FFmpeg reads the ASF container, identifies the available video and audio streams (typically an msmpeg4 video stream and a WMAv2 audio stream), and makes them available for processing. |
-c:a flac
|
Sets the audio codec for the output to FLAC (Free Lossless Audio Codec). FFmpeg decodes the WMV's audio stream — whether WMAv2, AAC, or another codec — to raw PCM and then re-encodes it using the native FLAC encoder. No video codec is specified because FLAC is an audio-only format and the video stream is automatically discarded. |
-compression_level 5
|
Controls how aggressively FLAC compresses the audio data, on a scale from 0 (fastest, largest file) to 8 (slowest, smallest file). Level 5 is the FLAC default and provides a good balance between encoding speed and file size. All levels decode to identical audio — this flag has no effect on audio quality whatsoever. |
output.flac
|
Defines the output filename and format. The .flac extension tells FFmpeg to wrap the encoded FLAC audio stream in a standard FLAC file. This is a standalone audio file with no video, compatible with virtually all modern media players, DAWs, and lossless audio platforms. |
Common Use Cases
- Archiving the audio from a Windows Media Player library of old WMV music videos or concert recordings in a lossless, future-proof format
- Extracting a high-fidelity audio track from a WMV screen recording or webinar to use as a clean podcast or voiceover source
- Recovering audio from WMV files received from Windows-based production environments and converting it to FLAC for use in DAWs like Audacity, Reaper, or Logic Pro
- Preparing audio content originally distributed in WMV format for upload to lossless music platforms or personal lossless streaming servers like Plex or Navidrome
- Stripping DRM-free WMV audio tracks from corporate training videos or presentations to create searchable, archivable audio files
- Converting a collection of WMV files from an old Windows Media Center recording setup into FLAC for long-term storage on a NAS device
Frequently Asked Questions
The FLAC output is lossless relative to what was stored in the WMV file, meaning no additional quality is lost during this conversion. However, WMAv2 is itself a lossy codec, so any artifacts introduced when the WMV was originally created are already present in the audio data. FLAC perfectly preserves that decoded signal — it just cannot undo the lossy encoding that happened upstream.
WMV files use lossy compression for both video and audio, which can produce very small file sizes. FLAC, while compressed, stores the full decoded audio signal losslessly — with no data discarded. When you strip a compact WMAv2 audio track from a WMV and encode it as FLAC, the resulting file reflects the true uncompressed size of the audio waveform minus only lossless compression savings, which is inherently larger than a lossy-compressed equivalent.
FFmpeg will attempt to map metadata from the ASF container's attribute fields to FLAC's Vorbis comment tags. Common fields like title and artist often transfer correctly. However, ASF uses Microsoft-specific tag names that do not always map 1:1 to FLAC's tagging standard, so some tags may be missing or renamed in the output. It is worth verifying tags in a tool like fre:ac or Kid3 after conversion.
Yes. The -compression_level flag accepts values from 0 to 8. Lower values like 0 or 1 compress faster and produce slightly larger files, while 8 achieves the smallest possible FLAC file at the cost of slower encoding. Crucially, all compression levels produce bit-identical decoded audio — this setting only affects file size and encoding speed, not audio quality. For example, replace '5' with '8' in the command: ffmpeg -i input.wmv -c:a flac -compression_level 8 output.flac.
WMV (ASF) supports multiple audio tracks, but FLAC does not — it is a single-stream format. By default, FFmpeg will select the first (or best-ranked) audio track for conversion. If you need a specific audio track, add the -map flag to the command, for example: ffmpeg -i input.wmv -map 0:a:1 -c:a flac -compression_level 5 output.flac to select the second audio track.
On Linux or macOS, you can loop through files in a directory with: for f in *.wmv; do ffmpeg -i "$f" -c:a flac -compression_level 5 "${f%.wmv}.flac"; done. On Windows Command Prompt, use: for %f in (*.wmv) do ffmpeg -i "%f" -c:a flac -compression_level 5 "%~nf.flac". This applies the exact same conversion settings to every WMV file in the current folder.
Technical Notes
The ASF container used by WMV carries audio in one of several codecs — most commonly WMAv2 (wmav2), but sometimes AAC or MP3 depending on how the file was produced. In all cases, FFmpeg fully decodes the compressed audio to PCM before re-encoding to FLAC, so the conversion process is a full transcode of the audio stream, not a remux. The -f asf flag is not needed on the output side since we are producing a FLAC file, and no special container flags are required for FLAC. FLAC does not support multiple audio streams in a single file, so only one audio track will be present in the output. WMV files sometimes carry DRM (Digital Rights Management) protection using Microsoft's PlayReady or older WMDRM systems; FFmpeg cannot process DRM-protected WMV files, and attempting to do so will result in an error or a silent/corrupted audio output. Subtitles and chapter markers present in the WMV are silently dropped, as FLAC supports neither. Replay Gain tags and cue sheet embedding, which FLAC supports natively, are not automatically generated during conversion but can be added afterward with tools like mp3gain or foobar2000.