properly handle meter channel count changes

* reset peak when switching type (audio/midi) or total count
* clamp to +40dBFS to prevent endless falloff for HUGE signals

diff --git a/libs/ardour/meter.cc b/libs/ardour/meter.cc
index bb6e3eb29ce67356c1e6982f7fb3e50ca8335d42..430306c91a00c8cb9b40c497b15f581111f22194 100644 (file)
--- a/libs/ardour/meter.cc
+++ b/libs/ardour/meter.cc
@@ -137,11 +137,12 @@ PeakMeter::run (BufferSet& bufs, framepos_t /*start_frame*/, framepos_t /*end_fr
        // Meter audio in to the rest of the peaks
        for (uint32_t i = 0; i < n_audio; ++i, ++n) {
                if (bufs.get_audio(i).silent()) {
-                       ;
+                       _peak_buffer[n] = 0;
                } else {
                        _peak_buffer[n] = compute_peak (bufs.get_audio(i).data(), nframes, _peak_buffer[n]);
+                       _peak_buffer[n] = std::min (_peak_buffer[n], 100.f); // cut off at +40dBFS for falloff.
                        _max_peak_signal[n] = std::max(_peak_buffer[n], _max_peak_signal[n]); // todo sync reset
-                       _combined_peak =std::max(_peak_buffer[n], _combined_peak);
+                       _combined_peak = std::max(_peak_buffer[n], _combined_peak);
                }
 
                if (do_reset_max) {
@@ -236,14 +237,23 @@ PeakMeter::can_support_io_configuration (const ChanCount& in, ChanCount& out)
 bool
 PeakMeter::configure_io (ChanCount in, ChanCount out)
 {
+       bool changed = false;
        if (out != in) { // always 1:1
                return false;
        }
 
+       if (current_meters != in) {
+               changed = true;
+       }
+
        current_meters = in;
 
        set_max_channels (in);
 
+       if (changed) {
+               reset_max();
+       }
+
        return Processor::configure_io (in, out);
 }