MP4's audio is usually lossy AAC, so FLAC won't restore lost quality either — it extracts the track into a compact, lossless container.
About MP4
Common video container format
MP4 is the most widely used video container, bundling video, audio (usually AAC), and subtitles together; this tool extracts the audio track and converts it to common audio formats.
- Excellent compatibility — plays on nearly every device and platform
- Requires extracting the audio track first; the full video file is much larger than the audio alone
About FLAC
Lossless compressed format
FLAC uses lossless compression, cutting file size roughly in half while keeping the original audio quality. It is widely used by audiophiles and for archiving.
- Lossless, identical to the source
- Much smaller than WAV
- Some older players lack support
MP4 to FLAC FAQ
Will converting MP4 to FLAC lose quality?
MP4 is already a lossy format, so converting to lossless FLAC introduces no additional quality loss — existing compression artifacts remain but nothing new is degraded.
Will the file size change after conversion?
Converting to a lossless format (WAV) usually increases size, while converting to a lossy format (MP3, AAC) usually decreases it, depending on the chosen bitrate and sample rate.
How do I batch convert MP4 to FLAC?
Just drop multiple MP4 files in; they are converted to FLAC one by one via a queue. You can download them individually or as a single ZIP.