Apple

On Mon, Mar 7, 2016 at 2:01 PM, Charles Constant <email@hidden> wrote:

Hi Paul,

Okay, I gather the 64 bit AudioUnit support I read about just referred to the OS transition (max buffer size, etc)... not the audiofile bitdepth.

That still leaves me with the same question though. I'm still not sure if the ASBD I'm getting back means "I'm currently at 32Bit because it's a reasonable default for me" or "My maximum bit depth is 32Bit"

My app has support for both 32 and 64 bit audio (not much reason for 64 bit, but it's not much more code). If the AudioUnit supports it, I'd prefer not to degrade quality.

(1) 64 bit is more quality than you need for the signal pathway BETWEEN plugins (there is an argument for using it inside certain synthesis and effect processing, but that's entirely down to your own plugin internals)

(2) If you start specifying that your AU only handles 64 bit audio data, then you're just imposing the need for implicit conversion on the (non-human) user of the plugin (the host, the graph, whatever).

Since almost all AU's and AU hosts work with 32 bit floating point data, that's the format you're going to see by default in an ABSD. The format in an ABSD is a absolute description, not a maximum.

References:
	>Best practice for checking 64-bit AU support? (From: Charles Constant <email@hidden>)
	>Re: Best practice for checking 64-bit AU support? (From: Paul Davis <email@hidden>)
	>Re: Best practice for checking 64-bit AU support? (From: Charles Constant <email@hidden>)