3 Feb
2003
3 Feb
'03
10:49 a.m.
On Monday 03 February 2003 15.12, Sami P Perttu wrote:
On Mon, 3 Feb 2003, David Olofson wrote:
I think this is bad.
It's a primitive performance hack. Once upon a time, these things
actually mattered... ;-)
As a
plugin author, having to implement
both is a pain. I use code generation to make both functions.
You don't necessarily *have* to implement both. Even the
primitive FX plugin API of Audiality have these variants:
void (*process)(struct ADY_plugin *p,
int *buf, unsigned frames);
void (*process_r)(struct ADY_plugin *p,
int *in, int *out, unsigned frames);
void (*process_m)(struct ADY_plugin *p,
int *in, int *out, unsigned frames);
...and you only *have* to provide *one* - any variant will do. If
you don't provide all of them, the host "SDK" will emulate the
others using the ones that are provided. There should be just one process() function,
which could be given two gain values, one for previous output and
another for the plugin's own output. Plugins would do
out[i] = previous_gain * out[i] + gain * myoutput;
When previous gain is zero this is almost equivalent to replace
except that NANs and maybe some other values will screw you.
Solution: forbid NANs as output and maybe cleanse buffers
periodically. And initially, of course.
Well, that cover's all the cases, and you *can* still optimize with
alternative inner loops if you like. Just check for 0.0 gains - but
remember that the gain controls will most probably be normal *ramped*
controls, so you can't just check the initial value.
Looks like a great idea.
As to NANs, I think you're pretty screwed if you get them in an audio
stream anyway. Plugins that generate NANs are broken, as are hosts
that allow plugins to operate on garbage buffers.
//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 -'
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