Apple

On Wed, Jun 18, 2014 at 9:11 AM, James Walker-Hall <email@hidden> wrote:

Hi All

I am an audio unit plugin developer, developing a plugin with multiple output configurations (specifically up to 8 stereo outputs). For optimization reasons I would like to be able to find out the following before rendering begins:
(a) the number of used elements/busses
(b) whether or not the host is providing output buffers and
(c) if it is providing the output buffers, then the buffer addresses.

So i would like to get that information before render is called on my audio unit, ie so sometime after it is instantiated but before the first audio render callback is called...

your plugin will have its kAudioUnitProperty_StreamFormat set by the host for both input and output, before any render call.

you don't know about the buffer situation until render occurs. it is probably safe to assume that any realtime host will provide buffers. you cannot know these in advance because the host may use different buffers every time it renders (unlikely, but entirely legal).

by the way, unless there is a *compelling* reason to do it, please don't split your outputs into different busses.

References:
	>Get number of used busses before render begins (From: James Walker-Hall <email@hidden>)