added simple way for plugins to process at lower sample-rates

git-svn-id: https://lmms.svn.sf.net/svnroot/lmms/trunk/lmms@967 0778d3d1-df1d-0410-868b-ea421aaaa00d

include/effect.h

@@ -173,8 +173,36 @@ public:
 protected:
 	virtual pluginView * instantiateView( QWidget * );
 
+	// some effects might not be capable of higher sample-rates so they can
+	// sample it down before processing and back after processing
+	inline void sampleDown( const sampleFrame * _src_buf,
+					sampleFrame * _dst_buf,
+					sample_rate_t _dst_sr )
+	{
+		resample( 0, _src_buf,
+				engine::getMixer()->processingSampleRate(),
+					_dst_buf, _dst_sr,
+					engine::getMixer()->framesPerPeriod() );
+	}
+
+	inline void sampleBack( const sampleFrame * _src_buf,
+					sampleFrame * _dst_buf,
+					sample_rate_t _src_sr )
+	{
+		resample( 1, _src_buf, _src_sr, _dst_buf,
+				engine::getMixer()->processingSampleRate(),
+			engine::getMixer()->framesPerPeriod() * _src_sr /
+				engine::getMixer()->processingSampleRate() );
+	}
+	void reinitSRC( void );
+
 
 private:
+	void resample( int _i, const sampleFrame * _src_buf,
+						sample_rate_t _src_sr,
+			sampleFrame * _dst_buf, sample_rate_t _dst_sr,
+					const fpp_t _frames );
+
 	descriptor::subPluginFeatures::key m_key;
 
 	ch_cnt_t m_processors;
@@ -189,6 +217,9 @@ private:
 	floatModel m_gateModel;
 	tempoSyncKnobModel m_autoQuitModel;
 
+	SRC_DATA m_srcData[2];
+	SRC_STATE * m_srcState[2];
+
 
 	friend class effectView;
 	friend class effectChain;

src/core/effect.cpp

@@ -47,6 +47,8 @@ effect::effect( const plugin::descriptor * _desc,
 	m_gateModel( 0.0f, 0.0f, 1.0f, 0.01f, this ),
 	m_autoQuitModel( 1.0f, 1.0f, 8000.0f, 100.0f, 1.0f, this )
 {
+	m_srcState[0] = m_srcState[1] = NULL;
+	reinitSRC();
 }
 
 
@@ -121,5 +123,53 @@ pluginView * effect::instantiateView( QWidget * _parent )
 	return( new effectView( this, _parent ) );
 }
 
+	
+
+
+void effect::reinitSRC( void )
+{
+	for( int i = 0; i < 2; ++i )
+	{
+		if( m_srcState[i] != NULL )
+		{
+			src_delete( m_srcState[i] );
+		}
+		int error;
+		if( ( m_srcState[i] = src_new(
+			engine::getMixer()->currentQualitySettings().
+							libsrcInterpolation(),
+					DEFAULT_CHANNELS, &error ) ) == NULL )
+		{
+			printf( "Error: src_new() failed in effect.cpp!\n" );
+		}
+	}
+}
+
+
+
+
+void effect::resample( int _i, const sampleFrame * _src_buf,
+							sample_rate_t _src_sr,
+				sampleFrame * _dst_buf, sample_rate_t _dst_sr,
+								fpp_t _frames )
+{
+	if( m_srcState[_i] == NULL )
+	{
+		return;
+	}
+	m_srcData[_i].input_frames = _frames;
+	m_srcData[_i].output_frames = engine::getMixer()->framesPerPeriod();
+	m_srcData[_i].data_in = (float *) _src_buf[0];
+	m_srcData[_i].data_out = _dst_buf[0];
+	m_srcData[_i].src_ratio = (double) _dst_sr / _src_sr;
+	m_srcData[_i].end_of_input = 0;
+	int error;
+	if( ( error = src_process( m_srcState[_i], &m_srcData[_i] ) ) )
+	{
+		printf( "effect::resample(): error while resampling: %s\n",
+							src_strerror( error ) );
+	}
+}
+
 
 #endif