Add the LFO plotting tool

tests/CMakeLists.txt

@@ -94,6 +94,9 @@ target_link_libraries(sfizz_plot_curve PRIVATE sfizz::sfizz)
 add_executable(sfizz_plot_wavetables PlotWavetables.cpp)
 target_link_libraries(sfizz_plot_wavetables PRIVATE sfizz::sfizz)
 
+add_executable(sfizz_plot_lfo PlotLFO.cpp)
+target_link_libraries(sfizz_plot_lfo PRIVATE sfizz::sfizz)
+
 add_executable(sfizz_file_instrument FileInstrument.cpp)
 target_link_libraries(sfizz_file_instrument PRIVATE sfizz::sfizz)
 

tests/PlotLFO.cpp

@@ -0,0 +1,100 @@
+// SPDX-License-Identifier: BSD-2-Clause
+
+// This code is part of the sfizz library and is licensed under a BSD 2-clause
+// license. You should have receive a LICENSE.md file along with the code.
+// If not, contact the sfizz maintainers at https://github.com/sfztools/sfizz
+
+/**
+   This program generates the data file of a LFO output recorded for a fixed
+   duration. The file contains columns for each LFO in the SFZ region.
+   The columns are: Time, Lfo1, ... LfoN
+   One can use Gnuplot to display this data.
+   Example:
+     sfizz_plot_lfo file.sfz > lfo.dat
+     gnuplot
+     plot "lfo.dat" using 1:2 with lines
+ */
+
+#include "sfizz/Synth.h"
+#include "sfizz/LFO.h"
+#include "sfizz/LFODescription.h"
+#include <absl/types/span.h>
+#include <vector>
+#include <iostream>
+#include <cmath>
+
+//==============================================================================
+
+static constexpr double sampleRate = 44100.0; // sample rate used to compute
+static constexpr double duration = 5.0; // length in seconds
+
+/**
+   Print usage information
+ */
+static void usage()
+{
+    std::cerr << "Usage: sfizz_plot_lfo <file.sfz>" "\n";
+}
+
+static std::vector<sfz::LFODescription> lfoDescriptionFromSfzFile(const fs::path &sfzPath, bool &success)
+{
+    sfz::Synth synth;
+
+    if (!synth.loadSfzFile(sfzPath)) {
+        std::cerr << "Cannot load the SFZ file.\n";
+        success = false;
+        return {};
+    }
+
+    if (synth.getNumRegions() != 1) {
+        std::cerr << "The SFZ file must contain exactly one region.\n";
+        success = false;
+        return {};
+    }
+
+    success = true;
+    return synth.getRegionView(0)->lfos;
+}
+
+/**
+   Program which loads LFO configuration and generates plot data for the given duration.
+ */
+int main(int argc, char* argv[])
+{
+    if (argc < 2 || argc > 2) {
+        usage();
+        return 1;
+    }
+
+    fs::path sfzPath = argv[1];
+    bool success = false;
+    const std::vector<sfz::LFODescription> desc = lfoDescriptionFromSfzFile(sfzPath, success);
+    if (!success)
+        return 1;
+
+    size_t numLfos = desc.size();
+    std::vector<sfz::LFO> lfos(numLfos);
+
+    for (size_t l = 0; l < numLfos; ++l) {
+        lfos[l].setSampleRate(sampleRate);
+        lfos[l].configure(&desc[l]);
+    }
+
+    size_t numFrames = (size_t)std::ceil(sampleRate * duration);
+    std::vector<float> outputMemory(numLfos * numFrames);
+
+    std::vector<absl::Span<float>> lfoOutputs(numLfos);
+    for (size_t l = 0; l < numLfos; ++l) {
+        lfoOutputs[l] = absl::MakeSpan(&outputMemory[l * numFrames], numFrames);
+        lfos[l].process(lfoOutputs[l]);
+    }
+
+    for (size_t i = 0; i < numFrames; ++i) {
+        std::cout << (i / sampleRate);
+        for (size_t l = 0; l < numLfos; ++l)
+            std::cout << ' ' << lfoOutputs[l][i];
+        std::cout << '\n';
+    }
+
+    return 0;
+}

tests/TestFiles/lfo_subwave.sfz

@@ -0,0 +1,19 @@
+<region>
+sample=*noise
+lokey=0
+hikey=127
+cutoff=1000.0
+fil_type=brf_2p
+lfo1_cutoff=1200.0
+//
+lfo1_freq=1
+lfo1_phase=0.5
+lfo1_wave=3
+lfo1_delay=0.5
+lfo1_fade=0.5
+lfo1_wave2=1
+lfo1_offset2=0.2
+lfo1_ratio2=0.7
+lfo1_scale2=0.3
+//
+lfo2_freq=0.5