fix Dummy DSP load on win32 & low-pass filter load

g_get_monotonic_time() has millisecond granularity,
use performance Counter if available

diff --git a/libs/backends/dummy/dummy_audiobackend.cc b/libs/backends/dummy/dummy_audiobackend.cc
index fa512d96bf65822be86eaae52cb39e9326e4130f..9b99bf811e032b8065482552b3c01b4e0298dd14 100644 (file)
--- a/libs/backends/dummy/dummy_audiobackend.cc
+++ b/libs/backends/dummy/dummy_audiobackend.cc
@@ -37,6 +37,23 @@ size_t DummyAudioBackend::_max_buffer_size = 8192;
 std::vector<std::string> DummyAudioBackend::_midi_options;
 std::vector<AudioBackend::DeviceStatus> DummyAudioBackend::_device_status;
 
+#ifdef PLATFORM_WINDOWS
+static double _win_pc_rate = 0; // usec per tick
+#endif
+
+static int64_t _x_get_monotonic_usec() {
+#ifdef PLATFORM_WINDOWS
+       if (_win_pc_rate > 0) {
+               LARGE_INTEGER Count;
+               // not very reliable, but the only realistic way for sub milli-seconds
+               if (QueryPerformanceCounter (&Count)) {
+                       return (int64_t) (Count.QuadPart * _win_pc_rate);
+               }
+       }
+#endif
+       return g_get_monotonic_time();
+}
+
 DummyAudioBackend::DummyAudioBackend (AudioEngine& e, AudioBackendInfo& info)
        : AudioBackend (e, info)
        , _running (false)
@@ -1122,7 +1139,7 @@ DummyAudioBackend::main_process_thread ()
        manager.graph_order_callback();
 
        uint64_t clock1, clock2;
-       clock1 = g_get_monotonic_time();
+       clock1 = _x_get_monotonic_usec();
        while (_running) {
 
                // re-set input buffers, generate on demand.
@@ -1149,10 +1166,10 @@ DummyAudioBackend::main_process_thread ()
                }
 
                if (!_freewheeling) {
-                       clock2 = g_get_monotonic_time();
+                       clock2 = _x_get_monotonic_usec();
                        const int64_t elapsed_time = clock2 - clock1;
                        const int64_t nomial_time = 1e6 * _samples_per_period / _samplerate;
-                       _dsp_load = elapsed_time / (float) nomial_time;
+                       _dsp_load = _dsp_load + .05 * ((elapsed_time / (float) nomial_time) - _dsp_load) + 1e-12;
                        if (elapsed_time < nomial_time) {
                                Glib::usleep (nomial_time - elapsed_time);
                        } else {
@@ -1162,7 +1179,7 @@ DummyAudioBackend::main_process_thread ()
                        _dsp_load = 1.0f;
                        Glib::usleep (100); // don't hog cpu
                }
-               clock1 = g_get_monotonic_time();
+               clock1 = _x_get_monotonic_usec();
 
                bool connections_changed = false;
                bool ports_changed = false;
@@ -1231,6 +1248,14 @@ static int
 instantiate (const std::string& arg1, const std::string& /* arg2 */)
 {
        s_instance_name = arg1;
+#ifdef PLATFORM_WINDOWS
+       LARGE_INTEGER Frequency;
+       if (!QueryPerformanceFrequency(&Frequency) || Frequency.QuadPart < 1) {
+               _win_pc_rate = 0;
+       } else {
+               _win_pc_rate = 1000000.0 / Frequency.QuadPart;
+       }
+#endif
        return 0;
 }