scale.py

   1 # This file is part of jack_mixer
   2 #
   3 # Copyright (C) 2006 Nedko Arnaudov <nedko@arnaudov.name>
   4 #
   5 # This program is free software; you can redistribute it and/or modify
   6 # it under the terms of the GNU General Public License as published by
   7 # the Free Software Foundation; version 2 of the License
   8 #
   9 # This program is distributed in the hope that it will be useful,
  10 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 # GNU General Public License for more details.
  13 #
  14 # You should have received a copy of the GNU General Public License
  15 # along with this program; if not, write to the Free Software
  16 # Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  17
  18 import math
  19 import jack_mixer_c
  20
  21 class Mark:
  22     '''Encapsulates scale linear function edge and coefficients for scale = a * dB + b formula'''
  23     def __init__(self, db, scale):
  24         self.db = db
  25         self.scale = scale
  26         self.text = "%.0f" % math.fabs(db)
  27
  28 class Base:
  29     '''Scale abstraction, various scale implementation derive from this class'''
  30     def __init__(self, scale_id, description):
  31         self.marks = []
  32         self.scale_id = scale_id
  33         self.description = description
  34         self.scale = jack_mixer_c.Scale()
  35
  36     def add_threshold(self, db, scale, is_mark):
  37         self.scale.add_threshold(db, scale)
  38         if is_mark:
  39             self.marks.append(Mark(db, scale))
  40
  41     def calculate_coefficients(self):
  42         self.scale.calculate_coefficients()
  43
  44     def db_to_scale(self, db):
  45         '''Convert dBFS value to number in range 0.0-1.0 used in GUI'''
  46         #print "db_to_scale(%f)" % db
  47         return self.scale.db_to_scale(db)
  48
  49     def scale_to_db(self, scale):
  50         '''Convert number in range 0.0-1.0 used in GUI to dBFS value'''
  51         return self.scale.scale_to_db(scale)
  52
  53     def add_mark(self, db):
  54         self.marks.append(Mark(db, -1.0))
  55
  56     def get_marks(self):
  57         return self.marks
  58
  59     def scale_marks(self):
  60         for i in self.marks:
  61             if i.scale == -1.0:
  62                 i.scale = self.db_to_scale(i.db)
  63
  64 # IEC 60268-18 Peak programme level meters - Digital audio peak level meter
  65 # Adapted from meterpridge, may be wrong, I'm not buying standards, event if they cost $45
  66 # If someone has the standart, please eighter share it with me or fix the code.
  67 class IEC268(Base):
  68     '''IEC 60268-18 Peak programme level meters - Digital audio peak level meter'''
  69     def __init__(self):
  70         Base.__init__(self, "iec_268",
  71                       "IEC 60268-18 Peak programme level meters - Digital audio peak level meter")
  72         self.add_threshold(-70.0, 0.0, False)
  73         self.add_threshold(-60.0, 0.05, True)
  74         self.add_threshold(-50.0, 0.075, True)
  75         self.add_threshold(-40.0, 0.15, True)
  76         self.add_mark(-35.0)
  77         self.add_threshold(-30.0, 0.3, True)
  78         self.add_mark(-25.0)
  79         self.add_threshold(-20.0, 0.5, True)
  80         self.add_mark(-15.0)
  81         self.add_mark(-10.0)
  82         self.add_mark(-5.0)
  83         self.add_threshold(0.0, 1.0, True)
  84         self.calculate_coefficients()
  85         self.scale_marks()
  86
  87 class IEC268Minimalistic(Base):
  88     '''IEC 60268-18 Peak programme level meters - Digital audio peak level meter,
  89        fewer marks'''
  90     def __init__(self):
  91         Base.__init__(self, 'iec_268_minimalistic',
  92                       'IEC 60268-18 Peak programme level meters - Digital audio peak level meter, fewer marks')
  93         self.add_threshold(-70.0, 0.0, False)
  94         self.add_threshold(-60.0, 0.05, True)
  95         self.add_threshold(-50.0, 0.075, False)
  96         self.add_threshold(-40.0, 0.15, True)
  97         self.add_threshold(-30.0, 0.3, True)
  98         self.add_threshold(-20.0, 0.5, True)
  99         self.add_mark(-10.0)
 100         self.add_threshold(0.0, 1.0, True)
 101         self.calculate_coefficients()
 102         self.scale_marks()
 103
 104 class Linear70dB(Base):
 105     '''Linear scale with range from -70 to 0 dBFS'''
 106     def __init__(self):
 107         Base.__init__(self, "linear_70dB", "Linear scale with range from -70 to 0 dBFS")
 108         self.add_threshold(-70.0, 0.0, False)
 109         self.add_mark(-60.0)
 110         self.add_mark(-50.0)
 111         self.add_mark(-40.0)
 112         self.add_mark(-35.0)
 113         self.add_mark(-30.0)
 114         self.add_mark(-25.0)
 115         self.add_mark(-20.0)
 116         self.add_mark(-15.0)
 117         self.add_mark(-10.0)
 118         self.add_mark(-5.0)
 119         self.add_threshold(0.0, 1.0, True)
 120         self.calculate_coefficients()
 121         self.scale_marks()
 122
 123 class Linear30dB(Base):
 124     '''Linear scale with range from -30 to +30 dBFS'''
 125     def __init__(self):
 126         Base.__init__(self, "linear_30dB", "Linear scale with range from -30 to +30 dBFS")
 127         self.add_threshold(-30.0, 0.0, False)
 128         self.add_threshold(+30.0, 1.0, True)
 129         self.calculate_coefficients()
 130         self.scale_marks()
 131
 132 def scale_test1(scale):
 133     for i in range(-97 * 2, 1, 1):
 134         db = float(i)/2.0
 135         print "%5.1f dB maps to %f" % (db, scale.db_to_scale(db))
 136
 137 def scale_test2(scale):
 138     for i in range(101):
 139         s = float(i)/100.0
 140         print "%.2f maps to %.1f dB" % (s, scale.scale_to_db(s))
 141
 142 def print_db_to_scale(db):
 143     print "%-.1f dB maps to %f" % (db, scale.db_to_scale(db))
 144
 145 def scale_test3(scale):
 146     print_db_to_scale(+77.0)
 147     print_db_to_scale(+7.0)
 148     print_db_to_scale(0.0)
 149     print_db_to_scale(-107.0)
 150
 151 #scale = linear_30dB()
 152 #scale_test2(scale)
 153 #scale_test3(scale)