Subject: [linux-audio-dev] [ANN] VLevel 0.5
From: Tom Felker (tcfelker_AT_mtco.com)
Date: Mon Jul 07 2003 - 01:12:08 EEST
Hello all,
I've been working on VLevel, a LADSPA plugin to keep me from having to
fiddle with the volume, and it's now in a useful state, so I'm looking
for some feedback. Basically, VLevel keeps track of the peak
amplitudes, and adjusts the volume smoothly to make the quiet parts
louder. Since it looks ahead a few seconds, the gain change is always
smooth.
<http://vlevel.sourceforge.net>
VLevel is written in C++. I have two questions. First, why do most
other plugins allocate and free copies of their strings and structures,
instead of just passing the literal (as I do)? The declarations in
ladspa.h don't allow the host to modify what the pointers reference.
Second, I keep a buffer of length n in my code, so the first n seconds
of data I return is useless, and after the audio is sent, I need n more
seconds of input before all the audio is returned. Is there any way of
informing the host about this?
In the future I plan to make some performance improvements, and perhaps
a nice cross-platform GUI for applying VLevel to files. I may also try
to get XMMS-LADSPA to save its state, which would be very useful to me.
I suppose VLevel could use RMS or a psychoacoustic model to estimate
volume, but that would make it very complex, and more difficult to avoid
clipping. Despite that, it serves my purpose, to play classical music
on the road, quite well.
Have fun,
-- Tom Felker <tcfelker_AT_mtco.com>
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