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livetrax/gtk2_ardour/plugin_eq_gui.cc
Sampo Savolainen bcd217ec8e Improvements to the plugin eq gui:
- phase correction for analysis
 - move gui elements to a more common location so that it's available for VSTs
   (needs packing in each PluginUI derived class though)


git-svn-id: svn://localhost/ardour2/branches/3.0@4745 d708f5d6-7413-0410-9779-e7cbd77b26cf
2009-03-07 11:17:06 +00:00

790 lines
20 KiB
C++

/*
Copyright (C) 2008 Paul Davis
Author: Sampo Savolainen
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "plugin_eq_gui.h"
#include "fft.h"
#include "ardour_ui.h"
#include "gui_thread.h"
#include "ardour/audio_buffer.h"
#include "ardour/data_type.h"
#include <gtkmm/box.h>
#include <gtkmm/button.h>
#include <gtkmm/checkbutton.h>
#include <iostream>
#include <cmath>
PluginEqGui::PluginEqGui(boost::shared_ptr<ARDOUR::PluginInsert> pluginInsert)
: _min_dB(-12.0),
_max_dB(+12.0),
_step_dB(3.0),
_impulse_fft(0),
_signal_input_fft(0),
_signal_output_fft(0),
_plugin_insert(pluginInsert)
{
_signal_analysis_running = false;
_samplerate = ARDOUR_UI::instance()->the_session()->frame_rate();
_plugin = _plugin_insert->get_impulse_analysis_plugin();
_plugin->activate();
set_buffer_size(4096, 16384);
//set_buffer_size(4096, 4096);
_log_coeff = (1.0 - 2.0 * (1000.0/(_samplerate/2.0))) / powf(1000.0/(_samplerate/2.0), 2.0);
_log_max = log10f(1 + _log_coeff);
// Setup analysis drawing area
_analysis_scale_surface = 0;
_analysis_area = new Gtk::DrawingArea();
_analysis_width = 500.0;
_analysis_height = 500.0;
_analysis_area->set_size_request(_analysis_width, _analysis_height);
_analysis_area->signal_expose_event().connect( sigc::mem_fun (*this, &PluginEqGui::expose_analysis_area));
_analysis_area->signal_size_allocate().connect( sigc::mem_fun (*this, &PluginEqGui::resize_analysis_area));
// dB selection
dBScaleModel = Gtk::ListStore::create(dBColumns);
dBScaleCombo = new Gtk::ComboBox(dBScaleModel);
dBScaleCombo -> set_title("dB scale");
#define ADD_DB_ROW(MIN,MAX,STEP,NAME) \
{ \
Gtk::TreeModel::Row row = *(dBScaleModel->append()); \
row[dBColumns.dBMin] = (MIN); \
row[dBColumns.dBMax] = (MAX); \
row[dBColumns.dBStep] = (STEP); \
row[dBColumns.name] = NAME; \
}
ADD_DB_ROW( -6, +6, 1, "-6dB .. +6dB");
ADD_DB_ROW(-12, +12, 3, "-12dB .. +12dB");
ADD_DB_ROW(-24, +24, 5, "-24dB .. +24dB");
ADD_DB_ROW(-36, +36, 6, "-36dB .. +36dB");
ADD_DB_ROW(-64, +64,12, "-64dB .. +64dB");
#undef ADD_DB_ROW
dBScaleCombo -> pack_start(dBColumns.name);
dBScaleCombo -> set_active(1);
dBScaleCombo -> signal_changed().connect( sigc::mem_fun(*this, &PluginEqGui::change_dB_scale) );
Gtk::Label *dBComboLabel = new Gtk::Label("dB scale");
Gtk::HBox *dBSelectBin = new Gtk::HBox(false, 5);
dBSelectBin->add( *manage(dBComboLabel));
dBSelectBin->add( *manage(dBScaleCombo));
// Phase checkbutton
_phase_button = new Gtk::CheckButton("Show phase");
_phase_button->set_active(true);
_phase_button->signal_toggled().connect( sigc::mem_fun(*this, &PluginEqGui::redraw_scales));
// populate table
attach( *manage(_analysis_area), 1, 3, 1, 2);
attach( *manage(dBSelectBin), 1, 2, 2, 3, Gtk::SHRINK, Gtk::SHRINK);
attach( *manage(_phase_button), 2, 3, 2, 3, Gtk::SHRINK, Gtk::SHRINK);
// Connect the realtime signal collection callback
_plugin_insert->AnalysisDataGathered.connect( sigc::mem_fun(*this, &PluginEqGui::signal_collect_callback ));
}
PluginEqGui::~PluginEqGui()
{
if (_analysis_scale_surface) {
cairo_surface_destroy (_analysis_scale_surface);
}
delete _impulse_fft;
delete _signal_input_fft;
delete _signal_output_fft;
_plugin->deactivate();
// all gui objects are *manage'd by the inherited Table object
}
void
PluginEqGui::on_hide()
{
stop_updating();
Gtk::Table::on_hide();
}
void
PluginEqGui::stop_updating()
{
if (_update_connection.connected()) {
_update_connection.disconnect();
}
}
void
PluginEqGui::start_updating()
{
if (!_update_connection.connected() && is_visible()) {
_update_connection = Glib::signal_timeout().connect( sigc::mem_fun(this, &PluginEqGui::timeout_callback), 250);
}
}
void
PluginEqGui::on_show()
{
Gtk::Table::on_show();
start_updating();
Gtk::Widget *toplevel = get_toplevel();
if (!toplevel) {
std::cerr << "No toplevel widget for PluginEqGui?!?!" << std::endl;
}
if (!_window_unmap_connection.connected()) {
_window_unmap_connection = toplevel->signal_unmap().connect( sigc::mem_fun(this, &PluginEqGui::stop_updating));
}
if (!_window_map_connection.connected()) {
_window_map_connection = toplevel->signal_map().connect( sigc::mem_fun(this, &PluginEqGui::start_updating));
}
}
void
PluginEqGui::change_dB_scale()
{
Gtk::TreeModel::iterator iter = dBScaleCombo -> get_active();
Gtk::TreeModel::Row row;
if(iter && (row = *iter)) {
_min_dB = row[dBColumns.dBMin];
_max_dB = row[dBColumns.dBMax];
_step_dB = row[dBColumns.dBStep];
redraw_scales();
}
}
void
PluginEqGui::redraw_scales()
{
if (_analysis_scale_surface) {
cairo_surface_destroy (_analysis_scale_surface);
_analysis_scale_surface = 0;
}
_analysis_area->queue_draw();
// TODO: Add graph legend!
}
void
PluginEqGui::set_buffer_size(uint32_t size, uint32_t signal_size)
{
if (_buffer_size == size && _signal_buffer_size == signal_size)
return;
FFT *tmp1 = _impulse_fft;
FFT *tmp2 = _signal_input_fft;
FFT *tmp3 = _signal_output_fft;
try {
_impulse_fft = new FFT(size);
_signal_input_fft = new FFT(signal_size);
_signal_output_fft = new FFT(signal_size);
} catch( ... ) {
// Don't care about lost memory, we're screwed anyhow
_impulse_fft = tmp1;
_signal_input_fft = tmp2;
_signal_output_fft = tmp3;
throw;
}
delete tmp1;
delete tmp2;
delete tmp3;
_buffer_size = size;
_signal_buffer_size = signal_size;
// These are for impulse analysis only, the signal analysis uses the actual
// number of I/O's for the plugininsert
uint32_t inputs = _plugin->get_info()->n_inputs.n_audio();
uint32_t outputs = _plugin->get_info()->n_outputs.n_audio();
// buffers for the signal analysis are ensured inside PluginInsert
uint32_t n_chans = std::max(inputs, outputs);
_bufferset.ensure_buffers(ARDOUR::DataType::AUDIO, n_chans, _buffer_size);
_collect_bufferset.ensure_buffers(ARDOUR::DataType::AUDIO, n_chans, _buffer_size);
ARDOUR::ChanCount chanCount(ARDOUR::DataType::AUDIO, n_chans);
_bufferset.set_count(chanCount);
_collect_bufferset.set_count(chanCount);
}
void
PluginEqGui::resize_analysis_area(Gtk::Allocation& size)
{
_analysis_width = (float)size.get_width();
_analysis_height = (float)size.get_height();
if (_analysis_scale_surface) {
cairo_surface_destroy (_analysis_scale_surface);
_analysis_scale_surface = 0;
}
}
bool
PluginEqGui::timeout_callback()
{
if (!_signal_analysis_running) {
_signal_analysis_running = true;
_plugin_insert -> collect_signal_for_analysis(_signal_buffer_size);
}
run_impulse_analysis();
return true;
}
void
PluginEqGui::signal_collect_callback(ARDOUR::BufferSet *in, ARDOUR::BufferSet *out)
{
ENSURE_GUI_THREAD(bind (mem_fun (*this, &PluginEqGui::signal_collect_callback), in, out));
_signal_input_fft ->reset();
_signal_output_fft->reset();
for (uint32_t i = 0; i < _plugin_insert->input_streams().n_audio(); ++i) {
_signal_input_fft ->analyze(in ->get_audio(i).data(_signal_buffer_size, 0), FFT::HANN);
}
for (uint32_t i = 0; i < _plugin_insert->output_streams().n_audio(); ++i) {
_signal_output_fft->analyze(out->get_audio(i).data(_signal_buffer_size, 0), FFT::HANN);
}
_signal_input_fft ->calculate();
_signal_output_fft->calculate();
_signal_analysis_running = false;
// This signals calls expose_analysis_area()
_analysis_area->queue_draw();
}
void
PluginEqGui::run_impulse_analysis()
{
uint32_t inputs = _plugin->get_info()->n_inputs.n_audio();
uint32_t outputs = _plugin->get_info()->n_outputs.n_audio();
// Create the impulse, can't use silence() because consecutive calls won't work
for (uint32_t i = 0; i < inputs; ++i) {
ARDOUR::AudioBuffer &buf = _bufferset.get_audio(i);
ARDOUR::Sample *d = buf.data(_buffer_size, 0);
memset(d, 0, sizeof(ARDOUR::Sample)*_buffer_size);
*d = 1.0;
}
uint32_t x,y;
x=y=0;
_plugin->connect_and_run(_bufferset, x, y, _buffer_size, (nframes_t)0);
nframes_t f = _plugin->signal_latency();
// Adding user_latency() could be interesting
// Gather all output, taking latency into account.
_impulse_fft->reset();
// Silence collect buffers to copy data to, can't use silence() because consecutive calls won't work
for (uint32_t i = 0; i < outputs; ++i) {
ARDOUR::AudioBuffer &buf = _collect_bufferset.get_audio(i);
ARDOUR::Sample *d = buf.data(_buffer_size, 0);
memset(d, 0, sizeof(ARDOUR::Sample)*_buffer_size);
}
if (f == 0) {
//std::cerr << "0: no latency, copying full buffer, trivial.." << std::endl;
for (uint32_t i = 0; i < outputs; ++i) {
memcpy(_collect_bufferset.get_audio(i).data(_buffer_size, 0),
_bufferset.get_audio(i).data(_buffer_size, 0), _buffer_size * sizeof(float));
}
} else {
//int C = 0;
//std::cerr << (++C) << ": latency is " << f << " frames, doing split processing.." << std::endl;
nframes_t target_offset = 0;
nframes_t frames_left = _buffer_size; // refaktoroi
do {
if (f >= _buffer_size) {
//std::cerr << (++C) << ": f (=" << f << ") is larger than buffer_size, still trying to reach the actual output" << std::endl;
// there is no data in this buffer regarding to the input!
f -= _buffer_size;
} else {
// this buffer contains either the first, last or a whole bu the output of the impulse
// first part: offset is 0, so we copy to the start of _collect_bufferset
// we start at output offset "f"
// .. and copy "buffer size" - "f" - "offset" frames
nframes_t length = _buffer_size - f - target_offset;
//std::cerr << (++C) << ": copying " << length << " frames to _collect_bufferset.get_audio(i)+" << target_offset << " from bufferset at offset " << f << std::endl;
for (uint32_t i = 0; i < outputs; ++i) {
memcpy(_collect_bufferset.get_audio(i).data(_buffer_size, target_offset),
_bufferset.get_audio(i).data(_buffer_size, 0) + f,
length * sizeof(float));
}
target_offset += length;
frames_left -= length;
f = 0;
}
if (frames_left > 0) {
// Silence the buffers
for (uint32_t i = 0; i < inputs; ++i) {
ARDOUR::AudioBuffer &buf = _bufferset.get_audio(i);
ARDOUR::Sample *d = buf.data(_buffer_size, 0);
memset(d, 0, sizeof(ARDOUR::Sample)*_buffer_size);
}
x=y=0;
_plugin->connect_and_run(_bufferset, x, y, _buffer_size, (nframes_t)0);
}
} while ( frames_left > 0);
}
for (uint32_t i = 0; i < outputs; ++i) {
_impulse_fft->analyze(_collect_bufferset.get_audio(i).data(_buffer_size, 0));
}
// normalize the output
_impulse_fft->calculate();
// This signals calls expose_analysis_area()
_analysis_area->queue_draw();
}
bool
PluginEqGui::expose_analysis_area(GdkEventExpose *evt)
{
redraw_analysis_area();
return false;
}
void
PluginEqGui::draw_analysis_scales(cairo_t *ref_cr)
{
// TODO: check whether we need rounding
_analysis_scale_surface = cairo_surface_create_similar(cairo_get_target(ref_cr),
CAIRO_CONTENT_COLOR,
_analysis_width,
_analysis_height);
cairo_t *cr = cairo_create (_analysis_scale_surface);
cairo_set_source_rgb(cr, 0.0, 0.0, 0.0);
cairo_rectangle(cr, 0.0, 0.0, _analysis_width, _analysis_height);
cairo_fill(cr);
draw_scales_power(_analysis_area, cr);
if (_phase_button->get_active()) {
draw_scales_phase(_analysis_area, cr);
}
cairo_destroy(cr);
}
void
PluginEqGui::redraw_analysis_area()
{
cairo_t *cr;
cr = gdk_cairo_create(GDK_DRAWABLE(_analysis_area->get_window()->gobj()));
if (_analysis_scale_surface == 0) {
draw_analysis_scales(cr);
}
cairo_copy_page(cr);
cairo_set_source_surface(cr, _analysis_scale_surface, 0.0, 0.0);
cairo_paint(cr);
if (_phase_button->get_active()) {
plot_impulse_phase(_analysis_area, cr);
}
plot_impulse_amplitude(_analysis_area, cr);
// TODO: make this optional
plot_signal_amplitude_difference(_analysis_area, cr);
cairo_destroy(cr);
}
#define PHASE_PROPORTION 0.5
void
PluginEqGui::draw_scales_phase(Gtk::Widget *w, cairo_t *cr)
{
float y;
cairo_font_extents_t extents;
cairo_font_extents(cr, &extents);
char buf[256];
cairo_text_extents_t t_ext;
for (uint32_t i = 0; i < 3; i++) {
y = _analysis_height/2.0 - (float)i*(_analysis_height/8.0)*PHASE_PROPORTION;
cairo_set_source_rgb(cr, .8, .9, 0.2);
if (i == 0) {
snprintf(buf,256, "0\u00b0");
} else {
snprintf(buf,256, "%d\u00b0", (i * 45));
}
cairo_text_extents(cr, buf, &t_ext);
cairo_move_to(cr, _analysis_width - t_ext.width - t_ext.x_bearing - 2.0, y - extents.descent);
cairo_show_text(cr, buf);
if (i == 0)
continue;
cairo_set_source_rgba(cr, .8, .9, 0.2, 0.6/(float)i);
cairo_move_to(cr, 0.0, y);
cairo_line_to(cr, _analysis_width, y);
y = _analysis_height/2.0 + (float)i*(_analysis_height/8.0)*PHASE_PROPORTION;
// label
snprintf(buf,256, "-%d\u00b0", (i * 45));
cairo_set_source_rgb(cr, .8, .9, 0.2);
cairo_text_extents(cr, buf, &t_ext);
cairo_move_to(cr, _analysis_width - t_ext.width - t_ext.x_bearing - 2.0, y - extents.descent);
cairo_show_text(cr, buf);
// line
cairo_set_source_rgba(cr, .8, .9, 0.2, 0.6/(float)i);
cairo_move_to(cr, 0.0, y);
cairo_line_to(cr, _analysis_width, y);
cairo_set_line_width (cr, 0.25 + 1.0/(float)(i+1));
cairo_stroke(cr);
}
}
void
PluginEqGui::plot_impulse_phase(Gtk::Widget *w, cairo_t *cr)
{
float x,y;
int prevX = 0;
float avgY = 0.0;
int avgNum = 0;
// float width = w->get_width();
float height = w->get_height();
cairo_set_source_rgba(cr, 0.95, 0.3, 0.2, 1.0);
for (uint32_t i = 0; i < _impulse_fft->bins()-1; i++) {
// x coordinate of bin i
x = log10f(1.0 + (float)i / (float)_impulse_fft->bins() * _log_coeff) / _log_max;
x *= _analysis_width;
y = _analysis_height/2.0 - (_impulse_fft->phase_at_bin(i)/M_PI)*(_analysis_height/2.0)*PHASE_PROPORTION;
if ( i == 0 ) {
cairo_move_to(cr, x, y);
avgY = 0;
avgNum = 0;
} else if (rint(x) > prevX || i == _impulse_fft->bins()-1 ) {
avgY = avgY/(float)avgNum;
if (avgY > (height * 10.0) ) avgY = height * 10.0;
if (avgY < (-height * 10.0) ) avgY = -height * 10.0;
cairo_line_to(cr, prevX, avgY);
//cairo_line_to(cr, prevX, avgY/(float)avgNum);
avgY = 0;
avgNum = 0;
}
prevX = rint(x);
avgY += y;
avgNum++;
}
cairo_set_line_width (cr, 2.0);
cairo_stroke(cr);
}
void
PluginEqGui::draw_scales_power(Gtk::Widget *w, cairo_t *cr)
{
static float scales[] = { 30.0, 70.0, 125.0, 250.0, 500.0, 1000.0, 2000.0, 5000.0, 10000.0, 15000.0, 20000.0, -1.0 };
float divisor = _samplerate / 2.0 / _impulse_fft->bins();
float x;
cairo_set_line_width (cr, 1.5);
cairo_set_font_size(cr, 9);
cairo_font_extents_t extents;
cairo_font_extents(cr, &extents);
// float fontXOffset = extents.descent + 1.0;
char buf[256];
for (uint32_t i = 0; scales[i] != -1.0; ++i) {
float bin = scales[i] / divisor;
x = log10f(1.0 + bin / (float)_impulse_fft->bins() * _log_coeff) / _log_max;
x *= _analysis_width;
if (scales[i] < 1000.0) {
snprintf(buf, 256, "%0.0f", scales[i]);
} else {
snprintf(buf, 256, "%0.0fk", scales[i]/1000.0);
}
cairo_set_source_rgb(cr, 0.4, 0.4, 0.4);
//cairo_move_to(cr, x + fontXOffset, 3.0);
cairo_move_to(cr, x - extents.height, 3.0);
cairo_rotate(cr, M_PI / 2.0);
cairo_show_text(cr, buf);
cairo_rotate(cr, -M_PI / 2.0);
cairo_stroke(cr);
cairo_set_source_rgb(cr, 0.3, 0.3, 0.3);
cairo_move_to(cr, x, _analysis_height);
cairo_line_to(cr, x, 0.0);
cairo_stroke(cr);
}
float y;
//double dashes[] = { 1.0, 3.0, 4.5, 3.0 };
double dashes[] = { 3.0, 5.0 };
for (float dB = 0.0; dB < _max_dB; dB += _step_dB ) {
snprintf(buf, 256, "+%0.0f", dB );
y = ( _max_dB - dB) / ( _max_dB - _min_dB );
//std::cerr << " y = " << y << std::endl;
y *= _analysis_height;
if (dB != 0.0) {
cairo_set_source_rgb(cr, 0.4, 0.4, 0.4);
cairo_move_to(cr, 1.0, y + extents.height + 1.0);
cairo_show_text(cr, buf);
cairo_stroke(cr);
}
cairo_set_source_rgb(cr, 0.2, 0.2, 0.2);
cairo_move_to(cr, 0, y);
cairo_line_to(cr, _analysis_width, y);
cairo_stroke(cr);
if (dB == 0.0) {
cairo_set_dash(cr, dashes, 2, 0.0);
}
}
for (float dB = - _step_dB; dB > _min_dB; dB -= _step_dB ) {
snprintf(buf, 256, "%0.0f", dB );
y = ( _max_dB - dB) / ( _max_dB - _min_dB );
y *= _analysis_height;
cairo_set_source_rgb(cr, 0.4, 0.4, 0.4);
cairo_move_to(cr, 1.0, y - extents.descent - 1.0);
cairo_show_text(cr, buf);
cairo_stroke(cr);
cairo_set_source_rgb(cr, 0.2, 0.2, 0.2);
cairo_move_to(cr, 0, y);
cairo_line_to(cr, _analysis_width, y);
cairo_stroke(cr);
}
cairo_set_dash(cr, 0, 0, 0.0);
}
inline float
power_to_dB(float a)
{
return 10.0 * log10f(a);
}
void
PluginEqGui::plot_impulse_amplitude(Gtk::Widget *w, cairo_t *cr)
{
float x,y;
int prevX = 0;
float avgY = 0.0;
int avgNum = 0;
// float width = w->get_width();
float height = w->get_height();
cairo_set_source_rgb(cr, 1.0, 1.0, 1.0);
cairo_set_line_width (cr, 2.5);
for (uint32_t i = 0; i < _impulse_fft->bins()-1; i++) {
// x coordinate of bin i
x = log10f(1.0 + (float)i / (float)_impulse_fft->bins() * _log_coeff) / _log_max;
x *= _analysis_width;
float yCoeff = ( power_to_dB(_impulse_fft->power_at_bin(i)) - _min_dB) / (_max_dB - _min_dB);
y = _analysis_height - _analysis_height*yCoeff;
if ( i == 0 ) {
cairo_move_to(cr, x, y);
avgY = 0;
avgNum = 0;
} else if (rint(x) > prevX || i == _impulse_fft->bins()-1 ) {
avgY = avgY/(float)avgNum;
if (avgY > (height * 10.0) ) avgY = height * 10.0;
if (avgY < (-height * 10.0) ) avgY = -height * 10.0;
cairo_line_to(cr, prevX, avgY);
//cairo_line_to(cr, prevX, avgY/(float)avgNum);
avgY = 0;
avgNum = 0;
}
prevX = rint(x);
avgY += y;
avgNum++;
}
cairo_stroke(cr);
}
void
PluginEqGui::plot_signal_amplitude_difference(Gtk::Widget *w, cairo_t *cr)
{
float x,y;
int prevX = 0;
float avgY = 0.0;
int avgNum = 0;
// float width = w->get_width();
float height = w->get_height();
cairo_set_source_rgb(cr, 0.0, 1.0, 0.0);
cairo_set_line_width (cr, 2.5);
for (uint32_t i = 0; i < _signal_input_fft->bins()-1; i++) {
// x coordinate of bin i
x = log10f(1.0 + (float)i / (float)_signal_input_fft->bins() * _log_coeff) / _log_max;
x *= _analysis_width;
float power_out = power_to_dB(_signal_output_fft->power_at_bin(i));
float power_in = power_to_dB(_signal_input_fft ->power_at_bin(i));
float power = power_out - power_in;
// for SaBer
/*
double p = 10.0 * log10( 1.0 + (double)_signal_output_fft->power_at_bin(i) - (double)
- _signal_input_fft ->power_at_bin(i));
//p *= 1000000.0;
float power = (float)p;
if ( (i % 1000) == 0) {
std::cerr << i << ": " << power << std::endl;
}
*/
if (std::isinf(power)) {
if (power < 0) {
power = _min_dB - 1.0;
} else {
power = _max_dB - 1.0;
}
} else if (std::isnan(power)) {
power = _min_dB - 1.0;
}
float yCoeff = ( power - _min_dB) / (_max_dB - _min_dB);
y = _analysis_height - _analysis_height*yCoeff;
if ( i == 0 ) {
cairo_move_to(cr, x, y);
avgY = 0;
avgNum = 0;
} else if (rint(x) > prevX || i == _impulse_fft->bins()-1 ) {
avgY = avgY/(float)avgNum;
if (avgY > (height * 10.0) ) avgY = height * 10.0;
if (avgY < (-height * 10.0) ) avgY = -height * 10.0;
cairo_line_to(cr, prevX, avgY);
avgY = 0;
avgNum = 0;
}
prevX = rint(x);
avgY += y;
avgNum++;
}
cairo_stroke(cr);
}