From 43a8f1a2c2f1c61861d9499b2fdb02d325fbc559 Mon Sep 17 00:00:00 2001
From: "Steinar H. Gunderson" <sgunderson@bigfoot.com>
Date: Sun, 8 Nov 2015 20:11:23 +0100
Subject: [PATCH] Hook up the lo-cut knob. A bit crude for now, though.

---
 mainwindow.cpp   | 10 ++++++++++
 mixer.cpp        |  2 +-
 mixer.h          |  9 ++++++++-
 ui_mainwindow.ui |  4 ++--
 4 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/mainwindow.cpp b/mainwindow.cpp
index d4e4d62..76293c8 100644
--- a/mainwindow.cpp
+++ b/mainwindow.cpp
@@ -91,6 +91,16 @@ void MainWindow::mixer_created(Mixer *mixer)
 		connect(ui_display->wb_button, &QPushButton::clicked, std::bind(&MainWindow::wb_button_clicked, this, i));
 	}
 
+	connect(ui->locut_cutoff_knob, &QDial::valueChanged, [this](int value) {
+		float octaves = value * 0.1f;
+		float cutoff_hz = 20.0 * pow(2.0, octaves);
+		global_mixer->set_locut_cutoff(cutoff_hz);
+
+		char buf[256];
+		snprintf(buf, sizeof(buf), "%ld Hz", lrintf(cutoff_hz));
+		ui->locut_cutoff_display->setText(buf);
+	});
+
 	mixer->set_audio_level_callback([this](float level_lufs, float peak_db, float global_level_lufs, float range_low_lufs, float range_high_lufs, float auto_gain_staging_db){
 		post_to_main_thread([=]() {
 			ui->vu_meter->set_level(level_lufs);
diff --git a/mixer.cpp b/mixer.cpp
index 506af4a..1e49407 100644
--- a/mixer.cpp
+++ b/mixer.cpp
@@ -544,7 +544,7 @@ void Mixer::process_audio_one_frame()
 	// Cut away everything under 150 Hz; we don't need it for voice,
 	// and it will reduce headroom and confuse the compressor.
 	// (In particular, any hums at 50 or 60 Hz should be dampened.)
-	locut.render(samples_out.data(), samples_out.size() / 2, 150.0 * 2.0 * M_PI / OUTPUT_FREQUENCY, 0.5f);
+	locut.render(samples_out.data(), samples_out.size() / 2, locut_cutoff_hz * 2.0 * M_PI / OUTPUT_FREQUENCY, 0.5f);
 
 	// Apply a level compressor to get the general level right.
 	// Basically, if it's over about -40 dBFS, we squeeze it down to that level
diff --git a/mixer.h b/mixer.h
index 312566d..e561a52 100644
--- a/mixer.h
+++ b/mixer.h
@@ -10,6 +10,7 @@
 
 #include <movit/effect_chain.h>
 #include <movit/flat_input.h>
+#include <atomic>
 #include <condition_variable>
 #include <cstddef>
 #include <functional>
@@ -130,6 +131,11 @@ public:
 		theme->set_wb(channel, r, g, b);
 	}
 
+	void set_locut_cutoff(float cutoff_hz)
+	{
+		locut_cutoff_hz = cutoff_hz;
+	}
+
 private:
 	void bm_frame(unsigned card_index, uint16_t timecode,
 		FrameAllocator::Frame video_frame, size_t video_offset, uint16_t video_format,
@@ -208,7 +214,8 @@ private:
 	// TODO: Implement oversampled peak detection.
 	float peak = 0.0f;
 
-	StereoFilter locut;  // Cutoff 150 Hz, 24 dB/oct.
+	StereoFilter locut;  // Default cutoff 150 Hz, 24 dB/oct.
+	std::atomic<float> locut_cutoff_hz;
 
 	// First compressor; takes us up to about -12 dBFS.
 	StereoCompressor level_compressor;
diff --git a/ui_mainwindow.ui b/ui_mainwindow.ui
index 9a7030b..4e43711 100644
--- a/ui_mainwindow.ui
+++ b/ui_mainwindow.ui
@@ -454,7 +454,7 @@
          </widget>
         </item>
         <item row="1" column="0">
-         <widget class="QDial" name="dial_2">
+         <widget class="QDial" name="locut_cutoff_knob">
           <property name="sizePolicy">
            <sizepolicy hsizetype="Preferred" vsizetype="Preferred">
             <horstretch>0</horstretch>
@@ -489,7 +489,7 @@
          </widget>
         </item>
         <item row="2" column="0">
-         <widget class="QLabel" name="label_4">
+         <widget class="QLabel" name="locut_cutoff_display">
           <property name="text">
            <string>150 Hz</string>
           </property>
-- 
2.39.2