[linux-audio-dev] XAP spec & PTAF comments [merge]

[David Olofson]

On Thursday 06 February 2003 22.56, Tim Hockin wrote:
[...]
> Now, based on recent arguments, I am rethinking my otiginal idea. 
> I had originally put this at the plugin granularity, then moved it
> to per-channel. This may be Good Enough, but not The Best.

I actually suspect that it might be *easier* to do it per audio port, 
as that eliminates the need for keeping track of which port belongs 
where.


[...]
> I'm starting to lean more towards David's idea which is that a
> buffer also has at least one flag - SILENT. All buffers start out
> silent (though they should be zeroed, I think).

Speaking of which, a host that can fill any SILENT buffers it sees 
with garbage would make a nice debugging tool for this feature. :-)

You could also abuse the MMU to trap reads from SILENT buffers, but 
that's not quite as trivial to implement.


>  If a plugin can
> optimize in the face of silent buffers, it should.  We should
> heavily recommend this, and code all examples to do this.

Yeah.


> This gives plugins a lot of granularity, and a lot of
> responsibility. However, it is easy to do, and doesn't require the
> host to participate at all.

This is what I do in Audiality FX when I'm feeling lazy and want 
buffers of zeroes for silence:

	if(!in)
		in = ady_silent_buffer;


This is an implication of the "silent input" feature not being 
optional - but it's not much to ask for, is it? (Though you'd have to 
loop over all your inputs, which makes it a *lot* harder! ;-)

If it's still too much, a plugin can just have a hint "I don't give a 
damn about silent input!", which would have hosts clear silent input 
buffers before run()ning that plugin.


//David Olofson - Programmer, Composer, Open Source Advocate

.- The Return of Audiality! --------------------------------.
| Free/Open Source Audio Engine for use in Games or Studio. |
| RT and off-line synth. Scripting. Sample accurate timing. |
`---------------------------> http://olofson.net/audiality -'
   --- http://olofson.net --- http://www.reologica.se ---