Convert M4B to FLAC — Free Online Converter

Converting M4B audiobooks to FLAC decodes the compressed AAC speech audio and stores it in the Free Lossless Audio Codec. Since M4B uses lossy AAC at low bitrates (32-64 kbps for spoken word), the FLAC output preserves the decoded signal losslessly but does not recover quality lost during the original AAC encoding. The resulting FLAC file is substantially larger than the M4B with no audible improvement. Chapter markers and bookmarking are not preserved.

Archival-minded users may want a lossless copy of the decoded audiobook to prevent further generational loss during future re-encoding. Audio producers editing audiobook content prefer working with lossless formats to avoid cascading lossy-to-lossy degradation when processing and re-exporting. FLAC also serves as a vendor-neutral archival format compared to Apple's M4B.