summaryrefslogtreecommitdiffstats
path: root/arts/modules/synth/synth_compressor_impl.cc
diff options
context:
space:
mode:
authortoma <toma@283d02a7-25f6-0310-bc7c-ecb5cbfe19da>2009-11-25 17:56:58 +0000
committertoma <toma@283d02a7-25f6-0310-bc7c-ecb5cbfe19da>2009-11-25 17:56:58 +0000
commite2de64d6f1beb9e492daf5b886e19933c1fa41dd (patch)
tree9047cf9e6b5c43878d5bf82660adae77ceee097a /arts/modules/synth/synth_compressor_impl.cc
downloadtdemultimedia-e2de64d6f1beb9e492daf5b886e19933c1fa41dd.tar.gz
tdemultimedia-e2de64d6f1beb9e492daf5b886e19933c1fa41dd.zip
Copy the KDE 3.5 branch to branches/trinity for new KDE 3.5 features.
BUG:215923 git-svn-id: svn://anonsvn.kde.org/home/kde/branches/trinity/kdemultimedia@1054174 283d02a7-25f6-0310-bc7c-ecb5cbfe19da
Diffstat (limited to 'arts/modules/synth/synth_compressor_impl.cc')
-rw-r--r--arts/modules/synth/synth_compressor_impl.cc139
1 files changed, 139 insertions, 0 deletions
diff --git a/arts/modules/synth/synth_compressor_impl.cc b/arts/modules/synth/synth_compressor_impl.cc
new file mode 100644
index 00000000..54c7648e
--- /dev/null
+++ b/arts/modules/synth/synth_compressor_impl.cc
@@ -0,0 +1,139 @@
+/*
+
+ Copyright (C) 2001 Matthias Kretz <kretz@kde.org>
+
+ 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+
+ */
+
+#include "artsmodulessynth.h"
+#include "stdsynthmodule.h"
+#include "debug.h"
+
+#include <math.h>
+#include <string.h>
+
+#ifndef LN2
+# define LN2 0.69314718
+#endif
+
+#ifndef MAX
+# define MAX(a,b) (((a) > (b) ? (a) : (b)))
+#endif
+
+using namespace std;
+namespace Arts {
+
+class Synth_COMPRESSOR_impl : virtual public Synth_COMPRESSOR_skel,
+ virtual public StdSynthModule
+{
+protected:
+ float _attack, _release, _threshold, _ratiominus1, _output;
+ float _attackfactor, _releasefactor;
+ float _volume;
+ float _compfactor;
+ bool _autooutput;
+
+public:
+ float attack() { return _attack; }
+ float release() { return _release; }
+ float threshold() { return _threshold; }
+ float ratio() { return _ratiominus1 + 1.0; }
+ float output() { return _output; }
+
+ Synth_COMPRESSOR_impl()
+ : _threshold( 1 )
+ , _ratiominus1( -0.2 )
+ , _output( 0 )
+ , _autooutput( true )
+ {
+ newCompFactor();
+ attack( 10 );
+ release( 10 );
+ }
+
+ void newCompFactor()
+ {
+ _compfactor = _output / pow( _threshold, _ratiominus1 );
+ }
+
+ void streamInit()
+ {
+ _volume = 0;
+ }
+
+ void calculateBlock(unsigned long samples)
+ {
+ for( unsigned long i = 0; i < samples; i++ ) {
+ float delta = fabs( invalue[i] ) - _volume;
+ if( delta > 0.0 )
+ _volume += _attackfactor * delta;
+ else
+ _volume += _releasefactor * delta;
+
+ if( _volume > _threshold )
+ // compress
+ // this is what it does:
+ // UtodB(x) = 20 * log( x )
+ // dBtoU(x) = pow( 10, x / 20 )
+ // outvalue[i] = dBtoU( ( UtodB( volume ) - UtodB( threshold ) ) * ratio + UtodB( threshold ) ) / volume * output * invalue[ i ];
+ // showing that it's equal to the formula below
+ // is left as an exercise to the reader.
+ outvalue[i] = pow( _volume, _ratiominus1 ) * _compfactor * invalue[ i ];
+ else
+ outvalue[i] = invalue[i] * _output;
+ }
+ }
+
+ void attack( float newAttack )
+ { // in ms
+ _attack = newAttack;
+ // _attackfactor has to be <= 1, that's why we need the MAX here
+ _attackfactor = LN2 / MAX( _attack / 1000 * samplingRateFloat, LN2 );
+ attack_changed( newAttack );
+ }
+
+ void release( float newRelease )
+ { // in ms
+ _release = newRelease;
+ // _releasefactor has to be <= 1, that's why we need the MAX here
+ _releasefactor = LN2 / MAX( _release / 1000 * samplingRateFloat, LN2 );
+ release_changed( newRelease );
+ }
+
+ void threshold( float newThreshold )
+ { // in V not in dB
+ _threshold = newThreshold;
+ newCompFactor();
+ threshold_changed( newThreshold );
+ }
+
+ void ratio( float newRatio )
+ {
+ _ratiominus1 = newRatio - 1;
+ newCompFactor();
+ ratio_changed( newRatio );
+ }
+
+ void output( float newOutput )
+ { // in V not in dB
+ _output = newOutput;
+ newCompFactor();
+ output_changed( newOutput );
+ }
+};
+
+REGISTER_IMPLEMENTATION(Synth_COMPRESSOR_impl);
+}