Adding VA offline simulation / recording example with impulse responses

applications/VirtualAcoustics/VA/itaVA_example_offline_simulation_ir.m

+%% itaVA offline simulation/auralization example that uses impulse responses
+
+% Requires VA to run with a virtual audio device that can be triggered by
+% the user. Also the generic path prototype rendering module(s) has to record the output
+% to hard drive.
+
+buffer_size = 64;
+sampling_rate = 44100;
+
+
+%% Connect and set up simple scene
+va = itaVA( 'localhost' );
+
+L = va.create_sound_receiver( 'itaVA_Listener' );
+va.set_sound_receiver_position( L, [ 0 1.7 0 ] )
+H = va.create_directivity( '$(DefaultHRIR)' );
+va.set_sound_receiver_directivity( L, H );
+
+S = va.create_sound_source( 'itaVA_Source' );
+X = va.create_signal_source_buffer_from_file( '$(DemoSound)' );
+va.set_signal_source_buffer_playback_action( X, 'play' )
+va.set_signal_source_buffer_looping( X, true );
+va.set_sound_source_signal_source( S, X )
+
+
+%% Example for a synchronized scene update & audio processing simulation/auralization
+
+timestep = buffer_size / sampling_rate; % here: depends on block size and sample rate
+manual_clock = 0;
+va.set_core_clock( 0 );
+
+spatialstep = 0.01;
+disp( [ 'Resulting sound source speed: ' num2str( spatialstep / timestep ) ' m/s' ] )
+
+numsteps = 3400;
+disp( [ 'Simulation result duration: ' num2str( numsteps * timestep ) ' s' ] )
+
+x = linspace( -1, 1, numsteps ) * 5; % motion from x = -5m to x = 5m
+
+h = waitbar( 0, 'Hold on, running auralization' );
+for n = 1:length( x )
+    
+    % Modify scene as you please (position has no real effect for prototype generic path renderer)
+    pos = [ x( n ) 1.7 -1 ];
+    distance = sum( abs( pos - [ 0 1.7 0 ] ) );
+    va.set_sound_source_position( S, pos );    
+    
+    brir = itaAudio();
+    brir.timeData = zeros( 1024, 2 );
+    brir.timeData( 1, 1 ) = 1.0 / distance;
+    brir.timeData( 1, 2 ) = 0.5 / distance; % just make inbalanced and distance dependent for fun
+    
+    path_update = struct();
+    path_update.source = S;
+    path_update.receiver = L;
+    path_update.ch1 = brir.timeData( :, 1 );
+    path_update.ch2 = brir.timeData( :, 2 );
+    path_update.delay = distance / va.get_homogeneous_medium_sound_speed(); % will generate smooth Doppler even for fast motion
+    va.set_rendering_module_parameters( 'MyGenericRenderer', path_update );
+    
+    % Increment core clock
+    manual_clock = manual_clock + timestep;
+    va.call_module( 'manualclock', struct( 'time', manual_clock ) );
+    
+    % Process audio chain by incrementing one block
+    va.call_module( 'virtualaudiodevice', struct( 'trigger', true ) );
+    
+    waitbar( n / numsteps )
+    
+end
+close( h )
+
+va.disconnect
+
+disp( 'Stop VA to export simulation results from rendering module(s)' )