X-Git-Url: https://scm.cri.ensmp.fr/git/Faustine.git/blobdiff_plain/1059e1cc0c2ecfa237406949aa26155b6a5b9154..66f23d4fabf89ad09adbd4dfc15ac6b5b2b7da83:/interpreter/preprocessor/faust-0.9.47mr3/tools/faust2pd/examples/synth/amp.dsp

diff --git a/interpreter/preprocessor/faust-0.9.47mr3/tools/faust2pd/examples/synth/amp.dsp b/interpreter/preprocessor/faust-0.9.47mr3/tools/faust2pd/examples/synth/amp.dsp
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+
+/* Stereo amplifier stage with bass, treble, gain and balance controls and a
+   dB meter. */
+
+declare name "amp -- stereo amplifier stage";
+declare author "Albert Graef";
+declare version "1.0";
+
+import("math.lib");
+import("music.lib");
+
+/* Fixed bass and treble frequencies. You might want to tune these for your
+   setup. */
+
+bass_freq	= 300;
+treble_freq	= 1200;
+
+/* Bass and treble gain controls in dB. The range of +/-20 corresponds to a
+   boost/cut factor of 10. */
+
+bass_gain	= nentry("bass", 0, -20, 20, 0.1);
+treble_gain	= nentry("treble", 0, -20, 20, 0.1);
+
+/* Gain and balance controls. */
+
+gain		= db2linear(nentry("gain", 0, -96, 96, 0.1));
+bal		= hslider("balance", 0, -1, 1, 0.001);
+
+/* Balance a stereo signal by attenuating the left channel if balance is on
+   the right and vice versa. I found that a linear control works best here. */
+
+balance		= *(1-max(0,bal)), *(1-max(0,0-bal));
+
+/* Generic biquad filter. */
+
+filter(b0,b1,b2,a0,a1,a2)	= f : (+ ~ g)
+with {
+	f(x)	= (b0/a0)*x+(b1/a0)*x'+(b2/a0)*x'';
+	g(y)	= 0-(a1/a0)*y-(a2/a0)*y';
+};
+
+/* Low and high shelf filters, straight from Robert Bristow-Johnson's "Audio
+   EQ Cookbook", see http://www.musicdsp.org/files/Audio-EQ-Cookbook.txt. f0
+   is the shelf midpoint frequency, g the desired gain in dB. S is the shelf
+   slope parameter, we always set that to 1 here. */
+
+low_shelf(f0,g)		= filter(b0,b1,b2,a0,a1,a2)
+with {
+	S  = 1;
+	A  = pow(10,g/40);
+	w0 = 2*PI*f0/SR;
+	alpha = sin(w0)/2 * sqrt( (A + 1/A)*(1/S - 1) + 2 );
+
+	b0 =    A*( (A+1) - (A-1)*cos(w0) + 2*sqrt(A)*alpha );
+	b1 =  2*A*( (A-1) - (A+1)*cos(w0)                   );
+	b2 =    A*( (A+1) - (A-1)*cos(w0) - 2*sqrt(A)*alpha );
+	a0 =        (A+1) + (A-1)*cos(w0) + 2*sqrt(A)*alpha;
+	a1 =   -2*( (A-1) + (A+1)*cos(w0)                   );
+	a2 =        (A+1) + (A-1)*cos(w0) - 2*sqrt(A)*alpha;
+};
+
+high_shelf(f0,g)	= filter(b0,b1,b2,a0,a1,a2)
+with {
+	S  = 1;
+	A  = pow(10,g/40);
+	w0 = 2*PI*f0/SR;
+	alpha = sin(w0)/2 * sqrt( (A + 1/A)*(1/S - 1) + 2 );
+
+	b0 =    A*( (A+1) + (A-1)*cos(w0) + 2*sqrt(A)*alpha );
+	b1 = -2*A*( (A-1) + (A+1)*cos(w0)                   );
+	b2 =    A*( (A+1) + (A-1)*cos(w0) - 2*sqrt(A)*alpha );
+	a0 =        (A+1) - (A-1)*cos(w0) + 2*sqrt(A)*alpha;
+	a1 =    2*( (A-1) - (A+1)*cos(w0)                   );
+	a2 =        (A+1) - (A-1)*cos(w0) - 2*sqrt(A)*alpha;
+};
+
+/* The tone control. We simply run a low and a high shelf in series here. */
+
+tone		= low_shelf(bass_freq,bass_gain)
+		: high_shelf(treble_freq,treble_gain);
+
+/* Envelop follower. This is basically a 1 pole LP with configurable attack/
+   release time. The result is converted to dB. You have to set the desired
+   attack/release time in seconds using the t parameter below. */
+
+t		= 0.1;			// attack/release time in seconds
+g		= exp(-1/(SR*t));	// corresponding gain factor
+
+env		= abs : *(1-g) : + ~ *(g) : linear2db;
+
+/* Use this if you want the RMS instead. Note that this doesn't really
+   calculate an RMS value (you'd need an FIR for that), but in practice our
+   simple 1 pole IIR filter works just as well. */
+
+rms		= sqr : *(1-g) : + ~ *(g) : sqrt : linear2db;
+sqr(x)		= x*x;
+
+/* The dB meters for left and right channel. These are passive controls. */
+
+left_meter(x)	= attach(x, env(x) : hbargraph("left", -96, 10));
+right_meter(x)	= attach(x, env(x) : hbargraph("right", -96, 10));
+
+/* The main program. */
+
+process		= hgroup("0-amp", hgroup("1-tone", tone, tone) :
+				  hgroup("2-gain", (_*gain, _*gain)))
+		: vgroup("3-balance", balance)
+		: vgroup("4-meter", (left_meter, right_meter));