For interleaved stereo audio buffers (for example when the Left and Right audio packets are in a single stream) there is a single AudioBuffer which contains both the left and right sample in the buffer. For non-interleaved stereo buffers, there are two buffers, the left samples are stored in one buffer and the right samples are stored on the other one.

This is an immutable data structure, if you are looking for a mutable version, see the noMac.AudioToolbox.MutableAudioBufferList.