What FLAC does
FLAC (Free Lossless Audio Codec) compresses audio the way a ZIP file compresses documents: the file gets smaller, but when it is played back, every sample is exactly the same as before. A FLAC file is usually 40 to 60 percent of the size of the same audio in WAV. Unlike WAV, it stores tags and cover art reliably. FLAC plays in VLC, foobar2000, Windows 10 and 11, Android, recent iPhones and most hi-fi streamers.
Lossless from a lossy source
It is important to understand what you get when you convert WMV to FLAC. Most WMV files carry WMA Standard audio, which is lossy. FLAC stores the decoded WMA sound perfectly, but it cannot bring back what the WMA encoder removed. So why use FLAC at all?
- Editing without further loss. If you will cut, mix or process the audio and save it several times, a lossless copy avoids adding new compression damage each time.
- Archiving. FLAC is an open format with long-term support. You can make MP3 or AAC copies from it at any time.
- WMA Lossless sources. A small number of WMV files, mostly music and concert videos, use WMA Lossless. In that case FLAC keeps every bit of the original quality in an open, widely supported format.
Compression level
The level only changes the file size and the time needed to save it. Level 5 is a common default. Level 8 makes files a few percent smaller. The sound is identical at every level, so pick a higher level only if storage matters.
How it works here
The WMA track is decoded by the converter engine built into the page, because browsers cannot read WMA. The FLAC file is then written in your browser. Nothing is uploaded, which matters for private recordings such as interviews or family videos.
If you only want to listen on a phone, a lossy format is more practical. WMV to M4A gives much smaller files. If your editor does not accept FLAC, use WMV to WAV.