Unfortunately the term "buffer" is too vague. In most of the audio framework we use circular buffers to pass data between threads or processes. We can read and write into the buffers. Generally the amount we write is less than the full size of the buffer. If we can fit two writes into the buffer then, traditionally, we might say "the buffer is double buffered", which is inherently confusing.
In the AudioTrack API we refer to the BufferSizeInFrames. But we also refer to the AudioManager.PROPERTY_OUTPUT_FRAMES_PER_BUFFER. That is the optimal size for writing into the buffer. Many people confuse these two uses of the word "buffer" so we wanted to avoid that confusion in AAudio.
In AAudio, "buffer" means the large circular buffer that is written by one thread and read by another.
A "burst" is the number of frames processed at one time by the side closest to the hardware. For an output stream the framesPerBurst is the number of frames read by the system mixer or DSP at one time. If an app writes the same size as the mixer reads then we can optimize the latency.
Traditionally people might say "the buffer is double buffered". In AAudio they would say that the buffer can contain two bursts.
We want to avoid confusion so please let us know what we can do to clarify this.
Thanks,
Phil Burk