Panalysis delay analysis

Author: geraintluff

Panalysis-delay.png

@@ -19,6 +19,12 @@ freemem = (buffer0 = freemem) + buffer_length;
 freemem = (buffer1 = freemem) + buffer_length;
 buffer_index = 0;
 
+delay_fftsize = 2048;
+delay_bufferlength = delay_fftsize;
+freemem = (delay_bufferA = freemem) + delay_bufferlength*2;
+freemem = (delay_bufferB = freemem) + delay_bufferlength*2;
+freemem = (delay_bufferSum = freemem) + delay_bufferlength;
+
 DISPLAY_SCREEN = 5;
 ui_reserve_image(DISPLAY_SCREEN);
 
@@ -49,6 +55,74 @@ buffer_index >= buffer_length ? (
 	buffer_index = 0;
 );
 
+// Delay analysis
+
+function perform_delay_analysis() local(i, ratio, window, rA, iA, rB, iB, mag2, factor, max_abs, max_index, max_phase) (
+	action_delay_analysis_reset ? (
+		i = 0;
+		while (i < delay_bufferlength) (
+		  delay_bufferSum[i] = 0;
+		  i += 1;
+		);
+		action_delay_analysis_reset = 0;
+	);
+
+	ratio = (delay_bufferindex/delay_bufferlength);
+	window = 0.5 - 0.5*cos(ratio*2*$pi);
+
+	delay_bufferA[delay_bufferindex*2] = spl0*window;
+	delay_bufferA[delay_bufferindex*2 + 1] = 0;
+	delay_bufferB[delay_bufferindex*2] = spl1*window;
+	delay_bufferB[delay_bufferindex*2 + 1] = 0;
+
+	delay_bufferindex += 1;
+	delay_bufferindex >= delay_bufferlength ? (
+		delay_bufferindex = 0;
+
+		fft(delay_bufferA, delay_fftsize);
+		fft(delay_bufferB, delay_fftsize);
+		i = 0;
+		while (i < delay_bufferlength) (
+			rA = delay_bufferA[2*i];
+			iA = delay_bufferA[2*i + 1];
+			rB = delay_bufferB[2*i];
+			iB = delay_bufferB[2*i + 1];
+			mag2 = (rA*rA + iA*iA)*(rB*rB + iB*iB);
+			factor = 1/(max(mag2, 0.000001))/delay_fftsize;
+			delay_bufferA[2*i] = (rA*rB + iA*iB)*factor;
+			delay_bufferA[2*i + 1] = (-rA*iB + iA*rB)*factor;
+			i += 1;
+		);
+		ifft(delay_bufferA, delay_fftsize);
+
+		max_abs = 0;
+		max_phase = 1;
+		max_index = 0;
+
+		i = 0;
+		while (i < delay_bufferlength) (
+			i2 = (i + delay_bufferlength/2)%delay_bufferlength;
+			value = delay_bufferSum[i2] += delay_bufferA[2*i];
+			abs(value) >= max_abs ? (
+				max_abs = abs(delay_bufferSum[i2]);
+				max_index = i;
+				max_phase = delay_bufferSum[i2] < 0 ? -1 : 1;
+			);
+			i += 1;
+		);
+
+		delay_samples = max_index;
+		delay_samples > delay_bufferlength/2 ? (
+			delay_samples -= delay_bufferlength;
+		);
+		delay_phase = max_phase;
+	);
+);
+
+delay_analysis_active ? (
+	perform_delay_analysis();
+);
+
 @gfx 510 660
 
 function update_display() local(dest, imgW, imgH, t, dt, i, x, y, cx, cy, cr, mag, alpha) (
@@ -63,17 +137,17 @@ function update_display() local(dest, imgW, imgH, t, dt, i, x, y, cx, cy, cr, ma
 			gfx_rect(0, 0, imgW, imgH);
 		);
 		gfx_dest = DISPLAY_SCREEN;
-		
+
 		t = time_precise();
 		dt = t - last_update_time;
 		debug.dt = dt;
 		last_update_time = t;
-	
-		// Fade     
+
+		// Fade
 		alpha = 1 - exp(-dt/fade_time);
 		gfx_gradrect(0, 0, imgW, imgH, 0, 0, 0, alpha);
 		gfx_a = sqrt(alpha);
-	
+
 		mag = pow(10, reference_db/20);
 		cx = imgW*0.5;
 		cy = imgH*0.5;
@@ -91,7 +165,7 @@ function update_display() local(dest, imgW, imgH, t, dt, i, x, y, cx, cy, cr, ma
 			i += 1;
 		);
 		buffer_index = 0;
-		
+
 		gfx_dest = dest;
 		gfx_x = ui_left();
 		gfx_y = ui_top();
@@ -154,8 +228,19 @@ function labelled_switch_vertical(value, label, valuestring) (
 
 control_start("main", "tron");
 
+delay_analysis_active = (ui_screen() == "delay-analysis");
+
 ui_screen() == "main" ? (
 	ui_split_top(150);
+		ui_split_righttext("Delay");
+			ui_split_bottomtext();
+				control_button("Delay") ? (
+					ui_screen_open("delay-analysis");
+					action_delay_analysis_reset = 1;
+					g_zoom = 1;
+				);
+			ui_pop();
+		ui_pop();
 		ui_split_rightratio(2/5);
 			control_group("display");
 			ui_split_leftratio(1/2);
@@ -164,23 +249,68 @@ ui_screen() == "main" ? (
 				fade_time = labelled_dial_vertical(fade_time, 0.01, 1, 4.6, "Fade", floor(fade_time*1000 + 0.5), "%ims", 0.1, 1000000);
 			ui_pop();
 		ui_pop();
-		
+
 		control_group("stereo field");
 		ui_split_leftratio(1/3);
 			default_width = (rot_cos + rot_sin > 0) ? (rot_cos - rot_sin)/(rot_cos + rot_sin) : 0;
 			default_width > 1 ? default_width = 1/default_width;
 			slider1 = labelled_dial_vertical(slider1, 0, 2, 0, "Width", floor(slider1*100 + 0.5), "%i%%", default_width, default_width);
 		ui_split_next();
-			slider2 = labelled_dial_vertical(slider2, -1, 1, 0, "Pan (rotate)", abs(slider2*100), slider2 < 0 ? "%i%% L" : slider2 > 0 ? "%i%% R" : "0%%", 0, 1000000);
+			slider2 = labelled_dial_vertical(slider2, -1, 1, 0, "Rotate", abs(slider2*100), slider2 < 0 ? "%i%% L" : slider2 > 0 ? "%i%% R" : "0%%", 0, 1000000);
 		ui_split_next();
 			slider3 = labelled_switch_vertical(slider3, "Invert", slider3 ? "on" : "off");
 		ui_pop();
 	ui_pop();
-	
+
 	update_display();
+) : ui_screen() == "delay-analysis" ? (
+	control_dialog("Delay analysis", gfx_w*0.9, gfx_h*0.5, "done", -1);
+
+	/*
+	ui_split_left(60);
+		ui_padright();
+		ui_split_bottom(100);
+			g_zoom = labelled_dial_vertical(g_zoom, 1, 0.01, 0, "Zoom", 0, "", 1, 1);
+		ui_pop();
+	ui_pop();
+	*/
+
+	control_background_technical();
+       ui_graph_step(delay_bufferSum, delay_bufferlength, 1, 0, 0);
+       ui_hover() ? (
+		mouse_sample = ceil((ui_mouse_xratio() - 0.5)*delay_bufferlength);
+		ui_align(1, 1);
+		ui_textnumber(mouse_sample, "%i samples");
+		ui_align(0, 1);
+		ui_textnumber(mouse_sample/srate*1000, "%fms");
+
+		ui_colora(255, 255, 255, 0.5);
+		gfx_line(mouse_x, ui_top(), mouse_x, ui_bottom());
+       );
+
+	ui_push();
+		ui_color(255, 255, 255);
+		ui_align(delay_samples >= delay_bufferlength*0.1 ? 0 : 1, 0);
+		ui_split_top(gfx_texth);
+			g_ms = delay_samples/srate*1000;
+			g_ms >= 0 ? (
+				ui_textnumber(g_ms, "Ch1 is %fms ahead");
+			) : (
+				ui_textnumber(-g_ms, "Ch0 is %fms ahead");
+			);
+		ui_pop();
+		ui_split_top(gfx_texth);
+			ui_textnumber(delay_samples, "(peak at %i samples)");
+		ui_pop();
+		ui_split_top(gfx_texth);
+			ui_text(delay_phase > 0 ? "Phase: aligned" : "Phase: inverted");
+		ui_pop();
+	ui_pop();
+
+       control_finish_technical();
 ) : control_system();
 
 @serialize
 
 file_var(0, fade_time);
-file_var(0, reference_db);
+file_var(0, reference_db);

Panalysis.jsfx

@@ -117,6 +117,10 @@ It's possible to rotate the field such that hard-left or hard-right inputs will
 
 ![screenshot](Panalysis 2.png)
 
+It also includes a delay analyser, for when one channel is ahead/behind or out of phase with the other - this can be useful when trying to get phases to agree in a multi-mic setup.
+
+![screenshot](Panalysis-delay.png)
+
 ## Learning Sampler
 
 This sampler records samples from the incoming audio when in learning mode (selected by a controller switch), and plays them back when in playback mode.

Panalysis.png

@@ -294,6 +294,8 @@ <h2 id="padsynth">PadSynth</h2><div class="section section2">
 <p><img src="Panalysis.png" alt="screenshot"></p>
 <p>It&#39;s possible to rotate the field such that hard-left or hard-right inputs will output &quot;inside out&quot; (opposite phase in both output channels).  In this case, the Width dial will turn red - double-click the dial to reset it to the maximum &quot;safe&quot; width:</p>
 <p><img src="Panalysis 2.png" alt="screenshot"></p>
+<p>It also includes a delay analyser, for when one channel is ahead/behind or out of phase with the other - this can be useful when trying to get phases to agree in a multi-mic setup.</p>
+<p><img src="Panalysis-delay.png" alt="screenshot"></p>
 </div><h2 id="learning-sampler">Learning Sampler</h2><div class="section section2">
 <p>This sampler records samples from the incoming audio when in learning mode (selected by a controller switch), and plays them back when in playback mode.</p>
 <p>To record the samples, set the appropriate controller to a value of 64 or above.  While this controller is down, when you play a MIDI note the sampler will remember the start/end positions in the buffer.  When you have recorded all the samples, reset the controller to 0, and it will enter playback mode.</p>