AMR – Adaptive Multi-Rate audio
AMR is a speech codec used for voice recordings and voicemail on mobile phones. Files are very small and tuned for speech, not music.
More AMR conversionsAMR to M4B is coming soon
We list every conversion we plan to support so you can find it later, but we only switch one on once it really works. APE, DSS and SHN can be read but not written.
M4B – MPEG-4 Audiobook
M4B is an MPEG-4 audio file for audiobooks. It supports chapters and remembers where you stopped listening.
More M4B conversionsHow this works: your file is uploaded over HTTPS and converted on this server with open-source engines (libvips for images, FFmpeg for audio and video, LibreOffice and Pandoc for documents, Calibre for ebooks, Ghostscript and Inkscape for PDF and vector files). Images are processed in memory; other files use a private temporary folder that is deleted as soon as the conversion finishes.