I've got Linux Ubuntu and ffmpeg version 4.3-2. It converts monochannel 16kHz 16kbit/s amr-wb files to wav without any problems, but when it comes to amr-wb multichannel files the output is:
filename.amr: Operation not permitted
I've already tried for test purposes to encode a stereo.wav file into an amr-wb file, but without success. The ffmpeg codec converts it into a normal monofile with just one channel. Seems that the multichannel mode is unknown for it.
Any idea?
Thanks in advance.