Convert M4B to MKA

Turn M4B recordings into MKA. The AAC audio is moved into Matroska as it is, so nothing is lost and a cut lands on the nearest frame; any other option re-encodes it as 16-bit FLAC.

Converted in an isolated sandbox on our serversDeleted after 24 hours

Drop M4B files on the dialor turn it to pick what to do

M4B and MKA

From

M4B Audiobook

AAC audiobooks in an MP4 container with chapters. What Apple Books and most audiobook apps play.

Extensions: .m4b
MIME type: audio/mp4
Kind: Audio

To

Matroska Audio

Audio-only Matroska. Any codec, with chapters and tags.

Extensions: .mka
MIME type: audio/x-matroska
Kind: Audio

Options for M4B to MKA

audio.channels: Number of audio channels. 1 is mono, 2 is stereo.
audio.denoise: Reduce steady background noise.
audio.normalize: Normalize loudness to -16 LUFS as streaming services do.
audio.sample_rate: Audio sample rate in Hz.
speed: Playback speed multiplier. 2 plays twice as fast.
trim_end: Second at which the audio or video stops.
trim_start: Seconds to cut from the start of audio or video.