r4031 - trunk/bse

[stw svn gnome org]

Author: stw
Date: 2006-10-25 18:29:42 -0400 (Wed, 25 Oct 2006)
New Revision: 4031

Modified:
   trunk/bse/ChangeLog
   trunk/bse/gslfilter.c
Log:
Thu Oct 26 00:15:53 2006  Stefan Westerfeld  <stefan space twc de>

	* gslfilter.c (gsl_filter_sine_scan): More comments.



Modified: trunk/bse/ChangeLog
===================================================================
--- trunk/bse/ChangeLog	2006-10-25 19:39:27 UTC (rev 4030)
+++ trunk/bse/ChangeLog	2006-10-25 22:29:42 UTC (rev 4031)
@@ -1,3 +1,7 @@
+Thu Oct 26 00:15:53 2006  Stefan Westerfeld  <stefan space twc de>
+
+	* gslfilter.c (gsl_filter_sine_scan): More comments.
+
 Tue Oct 24 23:52:58 2006  Tim Janik  <timj gtk org>
 
 	* bseblockutils.hh, bseblockutils.cc: provide an block utils 

Modified: trunk/bse/gslfilter.c
===================================================================
--- trunk/bse/gslfilter.c	2006-10-25 19:39:27 UTC (rev 4030)
+++ trunk/bse/gslfilter.c	2006-10-25 22:29:42 UTC (rev 4031)
@@ -1334,6 +1334,8 @@
 		      gdouble	     freq,
 		      gdouble	     mix_freq)
 {
+  /* we usually use mix_freq / 10, because 0.1 seconds is the resolution for
+   * volume perception by human listeners */
   const guint     block_size = MAX (256, (guint) (mix_freq / 10));
   const gdouble	  phase_inc = freq / mix_freq * 2 * PI;
   const gdouble	  volume_epsilon = 1e-8;
@@ -1364,6 +1366,9 @@
    * signal. The advantage is that for each sample the absolute value can be
    * determined exactly as complex absolute value (whereas for a single sine
    * signal, the absolute value oscillates).
+   *
+   * The (complex) input signal volume is always 1, as sqrt (cos(x)^2 +
+   * sin(x)^2) == 1.
    */
   do
     {