From ee97942165fbbd82eb7453f2e74f6f06a1974a44 Mon Sep 17 00:00:00 2001 From: Robin Gareus Date: Tue, 9 Jul 2013 13:13:27 +0200 Subject: use accurate log10 for meter (fast_log2 is unsuitable inaccurate) fast_coefficient_to_dB() returns a lower bound value, unsuitable to catch audio peaks. The difference to 20*log10 is as large as 0.4 dB! The effective speedup of fast_log10 compared to log10f is marginal (sweep of all 24bit values) i686 (1.6GHz Intel core): 2.36 [times faster] x86_64 (core2 2.4GHz): 1.63 x86_64 (I3 2.80GHz): 2.03 the execution time of one log10f() averaged over a sweep of all 24 bit values i686 (1.6GHz Intel core): 0.131 usec x86_64 (core2 2.4GHz): 0.033 usec x86_64 (I3 2.80GHz): 0.044 usec PeakMeter::run() is called from dedicated non-rt, no harm done. --- libs/ardour/meter.cc | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) (limited to 'libs/ardour/meter.cc') diff --git a/libs/ardour/meter.cc b/libs/ardour/meter.cc index 41500c7cb0..f239a1c4b7 100644 --- a/libs/ardour/meter.cc +++ b/libs/ardour/meter.cc @@ -55,6 +55,8 @@ PeakMeter::~PeakMeter () * Input acceptance is lenient - the first n buffers from @a bufs will * be metered, where n was set by the last call to setup(), excess meters will * be set to 0. + * + * (runs in jack realtime context) */ void PeakMeter::run (BufferSet& bufs, framepos_t /*start_frame*/, framepos_t /*end_frame*/, pframes_t nframes, bool) @@ -95,7 +97,7 @@ 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) { _peak_signal[n] = compute_peak (bufs.get_audio(i).data(), nframes, _peak_signal[n]); - if (/* TODO use separate bit-flags for mixer,meterbridge,.. */ /* 1 || */ _meter_type & MeterKrms) { + if (_meter_type & MeterKrms) { _kmeter[i]->process(bufs.get_audio(i).data(), nframes); } } @@ -239,11 +241,7 @@ PeakMeter::meter () ; } else { /* empirical WRT to falloff times , 0.01f ^= 100 Hz update rate */ -#if 1 - new_peak = _visible_peak_power[n] - _visible_peak_power[n] * Config->get_meter_falloff() * 0.01f * 0.05f; -#else new_peak = _visible_peak_power[n] - sqrt(_visible_peak_power[n] * Config->get_meter_falloff() * 0.01f * 0.0002f); -#endif if (new_peak < (1.0 / 512.0)) new_peak = 0; } _visible_peak_power[n] = new_peak; @@ -257,7 +255,7 @@ PeakMeter::meter () _max_peak_signal[n] = std::max(new_peak, _max_peak_signal[n]); if (new_peak > 0.0) { - new_peak = fast_coefficient_to_dB (new_peak); + new_peak = accurate_coefficient_to_dB (new_peak); } else { new_peak = minus_infinity(); } @@ -283,7 +281,11 @@ PeakMeter::meter_level(uint32_t n, MeterType type) { { const uint32_t n_midi = current_meters.n_midi(); if ((n - n_midi) < _kmeter.size() && (n - n_midi) >= 0) { +#if 0 return fast_coefficient_to_dB (_kmeter[n-n_midi]->read()); +#else + return accurate_coefficient_to_dB (_kmeter[n-n_midi]->read()); +#endif } return minus_infinity(); } @@ -304,6 +306,7 @@ PeakMeter::meter_level(uint32_t n, MeterType type) { } } } + void PeakMeter::set_type(MeterType t) { @@ -329,5 +332,3 @@ PeakMeter::state (bool full_state) node.add_property("type", "meter"); return node; } - - -- cgit v1.2.3