MP4 to FLAC Converter — Free, Online, No Upload

You have a video recording of a concert, a studio session, or a live radio broadcast as an MP4. The performance is exactly what you want to preserve, but storing it as video is wasteful — you'll never watch it, only listen. More importantly, your audiophile media player (Roon, Plex, Naim, Bluesound) wants FLAC, not MP4, in its music library.

This converter extracts the audio track from your MP4 and outputs it as FLAC — the lossless archival audio format preferred by hi-fi systems, music servers, and audio archivists. One important caveat: FLAC is lossless from the point of extraction forward, but it cannot undo the original AAC compression that was already applied to the audio inside the MP4. If the MP4 was encoded at 256 kbps AAC — common for modern recordings — the FLAC output will sound excellent and contain every decoded sample. If the source was low-bitrate (96 kbps or less), the quality ceiling is set by that original encoding.

The FLAC file will be several times larger than the audio-only equivalent in AAC or MP3, but smaller than a WAV, because FLAC compresses losslessly. For archival and hi-fi playback, this is the right trade-off: every streaming player, NAS music server, and audiophile DAC that supports FLAC will import it directly.

Typical sizes: MP4 100–300 MB (1 minute 1080p); FLAC 20–40 MB (3-minute song).

FLAC will not restore detail the MP4 encoder removed, and the file gets bigger.