Libsndfile-1.0.18pre7 has some regression w.r.t. earlier prereleases. - When writing a WAVEX it always writes the Ambisonic GUID, and sets the channel mask to 0. Since it can also read this and you can't get the channel mask value, this will go unnoticed until you use some other lib to read the file. - When reading it always tells you the file is not Ambisionic. The attached patch will fix this AFAICS. Ciao, -- FA Laboratorio di Acustica ed Elettroacustica Parma, Italia Wie der Mond heute Nacht aussieht ! Ist es nicht ein seltsames Bild ?