From 24e4026778bfd87612d5bedce1bfa51455853bc3 Mon Sep 17 00:00:00 2001
From: "Steinar H. Gunderson" <sgunderson@bigfoot.com>
Date: Thu, 29 Oct 2015 00:48:08 +0100
Subject: [PATCH] Add the beginnings of a very simple VU meter, based on
 libebur128.

---
 Makefile         |  6 +++---
 glwidget.cpp     |  5 +++++
 mainwindow.cpp   |  2 ++
 mixer.cpp        | 11 +++++++++++
 mixer.h          | 10 ++++++++++
 ui_mainwindow.ui | 24 ++++++++++++++++++++----
 vumeter.cpp      | 33 +++++++++++++++++++++++++++++++++
 vumeter.h        | 31 +++++++++++++++++++++++++++++++
 8 files changed, 115 insertions(+), 7 deletions(-)
 create mode 100644 vumeter.cpp
 create mode 100644 vumeter.h

diff --git a/Makefile b/Makefile
index d056084..2355194 100644
--- a/Makefile
+++ b/Makefile
@@ -1,11 +1,11 @@
 CXX=g++
 PKG_MODULES = Qt5Core Qt5Gui Qt5Widgets Qt5OpenGLExtensions Qt5OpenGL libusb-1.0 movit lua5.2 libmicrohttpd
 CXXFLAGS := -O2 -march=native -g -std=gnu++11 -Wall -Wno-deprecated-declarations -Werror -fPIC $(shell pkg-config --cflags $(PKG_MODULES)) -pthread -DMOVIT_SHADER_DIR=\"$(shell pkg-config --variable=shaderdir movit)\"
-LDFLAGS=$(shell pkg-config --libs $(PKG_MODULES)) -lEGL -lGL -pthread -lva -lva-drm -lva-x11 -lX11 -lavformat -lavcodec -lavutil -lzita-resampler
+LDFLAGS=$(shell pkg-config --libs $(PKG_MODULES)) -lEGL -lGL -pthread -lva -lva-drm -lva-x11 -lX11 -lavformat -lavcodec -lavutil -lzita-resampler -lebur128
 
 # Qt objects
-OBJS=glwidget.o main.o mainwindow.o window.o
-OBJS += glwidget.moc.o mainwindow.moc.o window.moc.o
+OBJS=glwidget.o main.o mainwindow.o window.o vumeter.o
+OBJS += glwidget.moc.o mainwindow.moc.o window.moc.o vumeter.moc.o
 
 # Mixer objects
 OBJS += h264encode.o mixer.o bmusb/bmusb.o pbo_frame_allocator.o context.o ref_counted_frame.o theme.o resampler.o httpd.o
diff --git a/glwidget.cpp b/glwidget.cpp
index 3482a13..2118ffe 100644
--- a/glwidget.cpp
+++ b/glwidget.cpp
@@ -3,6 +3,7 @@
 #include <qtextstream.h>  // Needs to come before egl.h.
 #include <qcursor.h>  // Needs to come before egl.h.
 #include <qcoreevent.h>  // Needs to come before egl.h.
+#include <qevent.h>  // Needs to come before egl.h.
 #include <epoxy/gl.h>
 #include <epoxy/egl.h>
 #include <QSurfaceFormat>
@@ -17,6 +18,7 @@
 #include "context.h"
 #include "mixer.h"
 #include "ref_counted_gl_sync.h"
+#include "vumeter.h"
 
 class MainWindow;
 class QSurface;
@@ -46,6 +48,9 @@ void GLWidget::initializeGL()
 	static std::once_flag flag;
 	std::call_once(flag, [this]{
 		global_mixer = new Mixer(QGLFormat::toSurfaceFormat(format()));
+		global_mixer->set_audio_level_callback([this](float level){
+			global_vu_meter->set_level(level);
+		});
 		global_mixer->start();
 	});
 	global_mixer->set_frame_ready_callback(output, [this]{
diff --git a/mainwindow.cpp b/mainwindow.cpp
index 3ccc893..29a863b 100644
--- a/mainwindow.cpp
+++ b/mainwindow.cpp
@@ -79,6 +79,8 @@ MainWindow::MainWindow()
 	qRegisterMetaType<std::vector<std::string>>("std::vector<std::string>");
 	connect(ui->preview1, SIGNAL(transition_names_updated(std::vector<std::string>)),
 	        this, SLOT(set_transition_names(std::vector<std::string>)));
+
+	global_vu_meter = ui->vu_meter;  // global_mixer does not exist yet, so need to delay the hookup.
 }
 
 void MainWindow::resizeEvent(QResizeEvent* event)
diff --git a/mixer.cpp b/mixer.cpp
index 59f520a..226d57f 100644
--- a/mixer.cpp
+++ b/mixer.cpp
@@ -146,6 +146,8 @@ Mixer::Mixer(const QSurfaceFormat &format)
 		"    gl_FragColor = texture2D(cbcr_tex, tc0); \n"
 		"} \n";
 	cbcr_program_num = resource_pool->compile_glsl_program(cbcr_vert_shader, cbcr_frag_shader);
+
+	r128_state = ebur128_init(2, 48000, EBUR128_MODE_SAMPLE_PEAK | EBUR128_MODE_M | EBUR128_MODE_S | EBUR128_MODE_I | EBUR128_MODE_LRA);
 }
 
 Mixer::~Mixer()
@@ -161,6 +163,8 @@ Mixer::~Mixer()
 		}
 		cards[card_index].usb->stop_dequeue_thread();
 	}
+
+	ebur128_destroy(&r128_state);
 }
 
 namespace {
@@ -352,6 +356,7 @@ void Mixer::thread_func()
 					}
 				}
 				if (card_index == 0) {
+					ebur128_add_frames_float(r128_state, samples_out.data(), samples_out.size() / 2);
 					h264_encoder->add_audio(pts_int, move(samples_out));
 				}
 			}
@@ -362,6 +367,12 @@ void Mixer::thread_func()
 			}
 		}
 
+		if (audio_level_callback != nullptr) {
+			double loudness_s;
+			ebur128_loudness_shortterm(r128_state, &loudness_s);
+			audio_level_callback(loudness_s);
+		}	
+
 		// If the first card is reporting a corrupted or otherwise dropped frame,
 		// just increase the pts (skipping over this frame) and don't try to compute anything new.
 		if (card_copy[0].new_frame->len == 0) {
diff --git a/mixer.h b/mixer.h
index a177854..5b82b4e 100644
--- a/mixer.h
+++ b/mixer.h
@@ -7,6 +7,7 @@
 #undef Success
 #include <movit/effect_chain.h>
 #include <movit/flat_input.h>
+#include <ebur128.h>
 #include <functional>
 
 #include "bmusb/bmusb.h"
@@ -80,6 +81,12 @@ public:
 		output_channel[output].set_frame_ready_callback(callback);
 	}
 
+	typedef std::function<void(float)> audio_level_callback_t;
+	void set_audio_level_callback(audio_level_callback_t callback)
+	{
+		audio_level_callback = callback;
+	}
+
 	std::vector<std::string> get_transition_names()
 	{
 		return theme->get_transition_names(pts());
@@ -155,6 +162,9 @@ private:
 
 	std::thread mixer_thread;
 	bool should_quit = false;
+
+	audio_level_callback_t audio_level_callback = nullptr;
+	ebur128_state *r128_state = nullptr;
 };
 
 extern Mixer *global_mixer;
diff --git a/ui_mainwindow.ui b/ui_mainwindow.ui
index 90663b0..12e3864 100644
--- a/ui_mainwindow.ui
+++ b/ui_mainwindow.ui
@@ -6,8 +6,8 @@
    <rect>
     <x>0</x>
     <y>0</y>
-    <width>902</width>
-    <height>590</height>
+    <width>1089</width>
+    <height>664</height>
    </rect>
   </property>
   <property name="windowTitle">
@@ -27,7 +27,7 @@
     <item row="0" column="0">
      <layout class="QVBoxLayout" name="vertical_layout" stretch="0,0,0">
       <item>
-       <layout class="QHBoxLayout" name="me_displays" stretch="0,0,0">
+       <layout class="QHBoxLayout" name="me_displays" stretch="0,0,0,0">
         <item>
          <layout class="QVBoxLayout" name="verticalLayout_3">
           <property name="leftMargin">
@@ -137,6 +137,16 @@
           </item>
          </layout>
         </item>
+        <item>
+         <widget class="VUMeter" name="vu_meter" native="true">
+          <property name="minimumSize">
+           <size>
+            <width>30</width>
+            <height>0</height>
+           </size>
+          </property>
+         </widget>
+        </item>
        </layout>
       </item>
       <item>
@@ -221,7 +231,7 @@
     <rect>
      <x>0</x>
      <y>0</y>
-     <width>902</width>
+     <width>1089</width>
      <height>19</height>
     </rect>
    </property>
@@ -251,6 +261,12 @@
    <extends>QWidget</extends>
    <header>qglwidget.h</header>
   </customwidget>
+  <customwidget>
+   <class>VUMeter</class>
+   <extends>QWidget</extends>
+   <header>vumeter.h</header>
+   <container>1</container>
+  </customwidget>
  </customwidgets>
  <resources/>
  <connections/>
diff --git a/vumeter.cpp b/vumeter.cpp
new file mode 100644
index 0000000..03a93e7
--- /dev/null
+++ b/vumeter.cpp
@@ -0,0 +1,33 @@
+#include <QPainter>
+
+#include "vumeter.h"
+
+using namespace std;
+
+VUMeter *global_vu_meter = nullptr;
+
+VUMeter::VUMeter(QWidget *parent)
+	: QWidget(parent)
+{
+}
+
+void VUMeter::paintEvent(QPaintEvent *event)
+{
+	QPainter painter(this);
+
+	painter.fillRect(0, 0, width(), height(), Qt::black);
+
+	float level;
+	{
+		unique_lock<mutex> lock(level_mutex);
+		level = this->level;
+	}
+
+	const float min_level = 0.0f;    // y=0 is top of screen, so “min” is the loudest level.
+	const float max_level = -60.0f; 
+	int y = lrintf(height() * (level - min_level) / (max_level - min_level));
+	if (y >= 0 && y < height()) {
+		painter.setPen(Qt::white);
+		painter.drawLine(0, y, width(), y);
+	}
+}
diff --git a/vumeter.h b/vumeter.h
new file mode 100644
index 0000000..de27529
--- /dev/null
+++ b/vumeter.h
@@ -0,0 +1,31 @@
+#ifndef VUMETER_H
+#define VUMETER_H
+
+#include <QWidget>
+#include <QPaintEvent>
+
+#include <mutex>
+
+class VUMeter : public QWidget
+{
+	Q_OBJECT
+
+public:
+	VUMeter(QWidget *parent);
+
+	void set_level(float level) {
+		std::unique_lock<std::mutex> lock(level_mutex);
+		this->level = level;
+		update();
+	}
+
+private:
+	void paintEvent(QPaintEvent *event) override;
+
+	std::mutex level_mutex;
+	float level = -HUGE_VAL;
+};
+
+extern VUMeter *global_vu_meter;
+
+#endif
-- 
2.39.2