On 2/1/21 4:32 PM, Jaroslav Kysela wrote:
Dne 01. 02. 21 v 16:03 Camel Guo napsal(a):
From: Camel Guo <camelg@xxxxxxxx>
In order for external software components to adjust ladspa plugin
dynamically, this commit adds an option to exposes the control array of
input control ports of a ladspa plugin to a file, through which any
applications with proper permission can control this plugin.
It looks like a pure hack (although the implementation is interesting). The
controls may be exposed via the ctl (control) API like we do in
src/pcm/pcm_softvol.c for example. The floats can be mapped to integer64
or we
may discuss to add the float type to the control API elements.
If there are not so many input controls of a ladspa plugin, I think it
is okay to implement it like pcm_softvol.c. But the problem is that some
plugins might have more than 100 input controls. For every input
control, there will be a system call ioctl in order to get its value.
This will make performance really bad. If a ladspa plugin like this
needs to support per-channel control, that will make it even worst.
But with shared memory like this, it will become a pure memory read,
this will make performance acceptable.
Another benefit of exposing ladspa control array to shared memory is
that it makes it possible for any algorithms to connect with these
ladspa plugins. The ladspa control array is basically a float-array,
which is exactly the input, output of lots of machine learning, deep
learning algorithm. Imagine an algorithm listening to the audio stream
automatically applies privacy masks on audio stream to mask human voice
via ladspa plugins.
Jaroslav
--
Jaroslav Kysela <perex@xxxxxxxx>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.
