Memory operations are indirected through function pointers. The AL_Allocator default implementation simply wraps malloc and free, etc.
Two higher level techniques are used for memory management: reference counted buffers, and buffer pools. A reference counted buffer is created with a zero reference count. The AL_Buffer_Ref and AL_Buffer_Unref functions increment and decrement the reference count, respectively. The AL_Buffer interface separates the management of buffer metadata from the management of the data memory associated with the buffer. Usage of the reference count is optional.
The AL_TBufPool implementation manages a buffer pool with a ring buffer. Some ring buffers have sizes fixed at compile time. Exceeding the buffer pool size results in undefined behavior. See AL_Decoder_PutDisplayPicture.