I spent quite a long time playing with various types of attack/decay filtering on the rectified audio input, but eventually I gave up on it. I find the instantaneous response is actually the best - the brightness of the LEDs gives you an idea how often that level is being hit. Obviously I also needed to know what the very highest level was to avoid clipping, and that's why I added the peak hold feature.
I thought initially "Oh, I need a VU meter!" but then when I started looking into it, I discovered that I didn't really need a "VU" meter, I needed a "PPM" (Peak Program Meter) and furthermore that I was most interested in one that was scaled with full-scale at 0dB and then down from there. That's only one of the about-a-hundred types of meter that have been designed and specified over the years for all sorts of uses.
That said, most of those are different lin/log/summat else scales and different attack/decay specifications, so they don't provide what you'd call "different displays", rather just the same display, but with a different response speed. But yeah, as soon as it's software, you've got free rein to do whatever display suits you best. I did!
Tom
