Subject: [linux-audio-dev] Reference amplitudes and LADSPA (again)
From: Steve Harris (S.W.Harris_AT_ecs.soton.ac.uk)
Date: Fri Feb 01 2002 - 17:35:58 EET
Hi,
I think its time for me to go on about the lack of reference amplitudes in
LADSPA again. This still bites people on a regular basis.
In a nutshell I think that there should be a reference 0dB (LADSPA) level,
defined as 1.0f.
<rant>
That doesn't meant that abs(signal) can't go above 1.0f, just as it
doesn't meant that analogue signals can't go above 0dB in analogue
hardware. Its just a reference level.
It matters because, as it is, some hosts (notably applyplugin) send
signals in that are at 32768.0f, which renders any waveshaping or dynamics
processing code useless*, resulting in heavy distortion or silence.
Reasons why its a good idea:
o ...reasons given above
o It is confusing for newbies writing plugins, who don't know why thier
trivial dsp code doens't work in applyplugin
o Changing any existing hosts that don't use 1.0 is really easy
(I allready have a patch for applyplugin)
o It doesn't require modification to the api, just a note in the spec.
o Compatibility with VST, jmax, matlab... and 99% of all example dsp code
o I will shut up about it
Reasons why its a bad idea:
o Requires a new package of the LADSPA SDK (with note and patched
applyplugin)
* Unless you ask the user what the 0dB level for thier hosts is, but how
the hell are they going to know that?
</rant>
- Steve
This archive was generated by hypermail 2b28 : Fri Feb 01 2002 - 17:28:23 EET