Free online OGG to M4B converter

Apple Books and some audiobook players require or work best with M4B for chapter navigation and saved listening positions. Convert an OGG recording when the receiving app rejects OGG or when you need one MPEG-4 audiobook file with compatible metadata.

What the OGG format is

OGG is an open multimedia container maintained by the Xiph.Org Foundation. Files ending in .ogg most commonly contain Vorbis audio, although Ogg containers can also hold Opus and other codecs. Audacity, Linux audio tools, game engines, recording software, and media players commonly create or use OGG files.

The .ogg extension does not identify the exact codec or its bitrate. Use FFmpeg or MediaInfo to inspect the source if you need to choose a particular output quality.

What the M4B format is

M4B is an MPEG-4 audio file normally containing AAC audio. It is used for audiobooks, lectures, podcasts, and other long spoken-word recordings. The MP4 container can store title, author, album, cover-art, and chapter metadata; compatible players can also save the current listening position.

M4B is preferable to a generic M4A extension when the target application identifies audiobook files by the .m4b extension or exposes audiobook-specific chapter and bookmark features. Support is not universal: some older players accept AAC in an MP4 container but reject files with the M4B extension.

Convert OGG to M4B with FFmpeg

FFmpeg is the most direct desktop method on Windows, macOS, and Linux. Install FFmpeg, open a terminal in the folder containing the source file, and run:

ffmpeg -i input.ogg -map 0:a:0 -map_metadata 0 -map_chapters 0 -c:a aac -profile:a aac_low -b:a 96k -movflags +faststart output.m4b

Replace input.ogg and output.m4b with the actual filenames. The command selects the first audio stream, copies readable source metadata and chapters, encodes AAC-LC, and places it in an MP4 container with an M4B extension. Source OGG files usually have no chapter data, so -map_chapters 0 will not create chapters that are not already present.

For speech, 64k–96k AAC is often adequate. Use 128k or 160k for music or recordings where higher fidelity matters. These settings are not lossless.

Combine several OGG files

For a split audiobook, create files.txt with one file per line, in playback order:

file 'part01.ogg'
file 'part02.ogg'
file 'part03.ogg'

Then run:

ffmpeg -f concat -safe 0 -i files.txt -c:a aac -profile:a aac_low -b:a 96k -movflags +faststart audiobook.m4b

The source files should have compatible stream properties. This creates one continuous M4B; it does not automatically turn each source file into a chapter. Add chapter metadata separately with an FFmpeg metadata file or an audiobook editor that supports MP4 chapters.

Convert without installing software

You can convert an OGG file for free on 101convert.com: upload the file, choose M4B as the output format, start the conversion, and download the result. Do not upload private or confidential recordings unless the service’s storage and deletion terms are acceptable.

Quality and compatibility limits

OGG Vorbis or Opus to AAC is a lossy-to-lossy re-encode. The M4B cannot restore details removed by the original OGG compression, so keep the source file and avoid repeated conversions.

Renaming .ogg to .m4b does not convert the audio. A valid M4B requires an MP4 container and an audio codec supported by the target player.

Metadata handling varies by application. A converted file may retain title and artist tags while losing cover art, chapters, or reliable resume behavior. Test the output in the intended audiobook app, phone, car system, or dedicated player.