The decay rate of the audio meters can now be selected in the audio
settings. The values are:
- "Fast" (OBS default, 40 dB / 1.7s)
- "Medium" (Type I PPM, 20 dB / 1.7s)
- "Slow" (Type II PPM, 24 dB / 2.8s)
Closesjp9000/obs-studio#1143
The following features have been added to the audio-meters:
* Stereo PPM-level meter, with 40 dB/1.7s decay rate.
* Stereo VU-level meter, with 300 ms integration time.
* Stereo Peak-hold meter, with 20 second sustain.
* Input peak level color-squares in front of every meter.
* Minor-ticks for each dB.
* Major-ticks for every 5 dB.
* Meter is divided in sections at -20 dB and -9 dB.
The ballistic parameters chosen here where taken from:
* https://en.wikipedia.org/wiki/Peak_programme_meter (SMPTE RP.0155)
* https://en.wikipedia.org/wiki/VU_meter
In the rework I have removed any ballistic calculations from
libobs/obs-audio-controls.c making the calculations here a lot more
simple doing only MAX and RMS calculations for only the samples in
the current update. The actual ballistics are now done by just
the UI/volume-control.cpp because ballistics need to be updated
based on the repaint-rate of the user-interface.
The dB to pixel conversion has been moved from
libobs/obs-audio-controls.c to UI/volume-control.cpp as well to reduce
coupling between these two objects, especially when implementing the
major- and minor-ticks and the sections.
All colors and ballistic parameters are adjustable via QT style sheets.
There are slight differences in colors for each of the themes.
