level plugin by thomas <thomas@apestaart.org>
this plugin signals:
- running time since last EOS/start
- channel
- RMS level
- peak level
- decaying peak level
over the given interval.
This is useful for a VU meter display and for plotting out the signal graph.
The VU meter can either display RMS, or display immediate peak level and
have the falloff decaying peak level displayed as a line.
The interval for signal emission, ttl of decay peak, and falloff of decay peak
can all be set.
The element only takes unsigned data in; it could be extended to signed as
well, if separate fast chain functions are made that displaces the incoming
data to its midpoint (ie, 0,65535 should be mapped to -32768, 32767)
There are two demo apps, apps and plot. apps will create some GTK sliders
to display the volume. plot will output data readable by gnuplot.
Here is a sample plot script to plot output of the plot command that was
stored to plot.dat
set xlabel "Seconds"
set ylabel "dB"
set yrange [-60:0]
plot 'plot.dat' using 1:2 title 'L RMS' with lines, \
'plot.dat' using 1:3 title 'L peak' with lines, \
'plot.dat' using 1:4 title 'L decay' with lines
plot 'plot.dat' using 1:5 title 'R RMS' with lines, \
'plot.dat' using 1:6 title 'R peak' with lines, \
'plot.dat' using 1:7 title 'R decay' with lines
