[linux-audio-dev] Re: LADSPA plugin parameters realtime control

[Tom Szilagyi]

On Sat, 9 Jul 2005 15:24:20 +0300, Artemio <artemio at kdemail.net> wrote:

> Hello all!
>
> I am here to ask you one thing. If I want sample-precise realtime
> control for the plugin, should I be getting all the parameters inside
> the cycle which travels through the buffer contents?
> [...]

Hi,

LADSPA hosts refresh control data on a per buffer basis. Of course you
can read the control data while processing a buffer as many times you
want, but you won't get any different values.

>From ladspa.h:
    Control data is communicated using single LADSPA_Data values. Control
    data has a single value at the start of a call to the `run()' or
    `run_adding()' function, and may be considered to remain this value
    for its duration.

However, you may want to do simple interpolation/filtering of the
incoming control stream, so user interaction results in no audible
pops/clicks (due to abrupt changes in incoming control values on buffer
boundaries). It depends on the DSP you perform if this is needed.

Tom