jack_mixer/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 logging
  19 import math
  20
  21 from ._jack_mixer import Scale
  22
  23
  24 log = logging.getLogger(__name__)
  25
  26
  27 class Mark:
  28     """Encapsulates scale linear function edge and coefficients for scale = a * dB + b formula"""
  29
  30     def __init__(self, db, scale, text=None):
  31         self.db = db
  32         self.scale = scale
  33         if text is None:
  34             # TODO: l10n
  35             self.text = "%.0f" % math.fabs(db)
  36         else:
  37             self.text = text
  38
  39
  40 class Base:
  41     """Scale abstraction, various scale implementation derive from this class"""
  42
  43     def __init__(self, scale_id, description):
  44         self.marks = []
  45         self.scale_id = scale_id
  46         self.description = description
  47         self.scale = Scale()
  48
  49     def add_threshold(self, db, scale, is_mark, text=None):
  50         self.scale.add_threshold(db, scale)
  51         if is_mark:
  52             self.marks.append(Mark(db, scale, text))
  53
  54     def calculate_coefficients(self):
  55         self.scale.calculate_coefficients()
  56
  57     def db_to_scale(self, db):
  58         """Convert dBFS value to number in range 0.0-1.0 used in GUI"""
  59         # log.debug("db_to_scale(%f)", db)
  60         return self.scale.db_to_scale(db)
  61
  62     def scale_to_db(self, scale):
  63         """Convert number in range 0.0-1.0 used in GUI to dBFS value"""
  64         return self.scale.scale_to_db(scale)
  65
  66     def add_mark(self, db):
  67         self.marks.append(Mark(db, -1.0))
  68
  69     def get_marks(self):
  70         return self.marks
  71
  72     def scale_marks(self):
  73         for i in self.marks:
  74             if i.scale == -1.0:
  75                 i.scale = self.db_to_scale(i.db)
  76
  77
  78 # IEC 60268-18 Peak programme level meters - Digital audio peak level meter
  79 # Adapted from meterbridge, may be wrong, I'm not buying standards, even if they cost $45
  80 # If someone has the standard, please either share it with me or fix the code.
  81 class IEC268(Base):
  82     """IEC 60268-18 Peak programme level meters - Digital audio peak level meter"""
  83
  84     def __init__(self):
  85         Base.__init__(
  86             self,
  87             "iec_268",
  88             _("IEC 60268-18 Peak programme level meters - Digital audio peak level meter"),
  89         )
  90         self.add_threshold(-70.0, 0.0, False)
  91         self.add_threshold(-60.0, 0.05, True)
  92         self.add_threshold(-50.0, 0.075, True)
  93         self.add_threshold(-40.0, 0.15, True)
  94         self.add_mark(-35.0)
  95         self.add_threshold(-30.0, 0.3, True)
  96         self.add_mark(-25.0)
  97         self.add_threshold(-20.0, 0.5, True)
  98         self.add_mark(-15.0)
  99         self.add_mark(-10.0)
 100         self.add_mark(-5.0)
 101         self.add_threshold(0.0, 1.0, True)
 102         self.calculate_coefficients()
 103         self.scale_marks()
 104
 105
 106 class IEC268Minimalistic(Base):
 107     """IEC 60268-18 Peak programme level meters - Digital audio peak level meter,
 108     fewer marks"""
 109
 110     def __init__(self):
 111         Base.__init__(
 112             self,
 113             "iec_268_minimalistic",
 114             _(
 115                 "IEC 60268-18 Peak programme level meters - "
 116                 "Digital audio peak level meter, fewer marks"
 117             ),
 118         )
 119         self.add_threshold(-70.0, 0.0, False)
 120         self.add_threshold(-60.0, 0.05, True)
 121         self.add_threshold(-50.0, 0.075, False)
 122         self.add_threshold(-40.0, 0.15, True)
 123         self.add_threshold(-30.0, 0.3, True)
 124         self.add_threshold(-20.0, 0.5, True)
 125         self.add_mark(-10.0)
 126         self.add_threshold(0.0, 1.0, True)
 127         self.calculate_coefficients()
 128         self.scale_marks()
 129
 130
 131 class Linear70dB(Base):
 132     """Linear scale with range from -70 to 0 dBFS"""
 133
 134     def __init__(self):
 135         Base.__init__(self, "linear_70dB", _("Linear scale with range from -70 to 0 dBFS"))
 136         self.add_threshold(-70.0, 0.0, False)
 137         self.add_mark(-60.0)
 138         self.add_mark(-50.0)
 139         self.add_mark(-40.0)
 140         self.add_mark(-35.0)
 141         self.add_mark(-30.0)
 142         self.add_mark(-25.0)
 143         self.add_mark(-20.0)
 144         self.add_mark(-15.0)
 145         self.add_mark(-10.0)
 146         self.add_mark(-5.0)
 147         self.add_threshold(0.0, 1.0, True)
 148         self.calculate_coefficients()
 149         self.scale_marks()
 150
 151
 152 class Linear30dB(Base):
 153     """Linear scale with range from -30 to +30 dBFS"""
 154
 155     def __init__(self):
 156         Base.__init__(self, "linear_30dB", _("Linear scale with range from -30 to +30 dBFS"))
 157         self.add_threshold(-30.0, 0.0, False)
 158         self.add_threshold(+30.0, 1.0, True)
 159         self.calculate_coefficients()
 160         self.scale_marks()
 161
 162
 163 class K20(Base):
 164     """K20 scale"""
 165
 166     def __init__(self):
 167         Base.__init__(self, "K20", _("K20 scale"))
 168         self.add_mark(-200, "")
 169         self.add_mark(-60, "-40")
 170         self.add_mark(-55, "")
 171         self.add_mark(-50, "-30")
 172         self.add_mark(-45, "")
 173         self.add_mark(-40, "-20")
 174         self.add_mark(-35, "")
 175         self.add_mark(-30, "-10")
 176         self.add_mark(-26, "-6")
 177         self.add_mark(-23, "-3")
 178         self.add_mark(-20, "0")
 179         self.add_mark(-17, "3")
 180         self.add_mark(-14, "6")
 181         self.add_mark(-10, "10")
 182         self.add_mark(-5, "15")
 183         self.add_mark(0, "20")
 184
 185     def db_to_scale(self, db):
 186         v = math.pow(10.0, db / 20.0)
 187         return self.mapk20(v) / 450.0
 188
 189     def add_mark(self, db, text):
 190         self.marks.append(Mark(db, self.db_to_scale(db), text))
 191
 192     def mapk20(self, v):
 193         if v < 0.001:
 194             return 24000 * v
 195         v = math.log10(v) + 3
 196         if v < 2.0:
 197             return 24.3 + v * (100 + v * 16)
 198         if v > 3.0:
 199             v = 3.0
 200         return v * 161.7 - 35.1
 201
 202
 203 class K14(Base):
 204     """K14 scale"""
 205
 206     def __init__(self):
 207         Base.__init__(self, "K14", _("K14 scale"))
 208         self.add_mark(-200, "")
 209         self.add_mark(-54, "-40")
 210         self.add_mark(-35 - 14, "")
 211         self.add_mark(-30 - 14, "-30")
 212         self.add_mark(-25 - 14, "")
 213         self.add_mark(-20 - 14, "-20")
 214         self.add_mark(-15 - 14, "")
 215         self.add_mark(-10 - 14, "-10")
 216         self.add_mark(-6 - 14, "-6")
 217         self.add_mark(-3 - 14, "-3")
 218         self.add_mark(-14, "0")
 219         self.add_mark(3 - 14, "3")
 220         self.add_mark(6 - 14, "6")
 221         self.add_mark(10 - 14, "10")
 222         self.add_mark(14 - 14, "14")
 223
 224     def db_to_scale(self, db):
 225         v = math.pow(10.0, db / 20.0)
 226         return self.mapk14(v) / 448.3
 227
 228     def add_mark(self, db, text):
 229         self.marks.append(Mark(db, self.db_to_scale(db), text))
 230
 231     def mapk14(self, v):
 232         if v < 0.002:
 233             return int(12000 * v)
 234         v = math.log10(v) + 2.7
 235         if v < 2.0:
 236             return int(20.3 + v * (80 + v * 32))
 237         if v > 2.7:
 238             v = 2.7
 239         return int(v * 200 - 91.7)
 240
 241
 242 def scale_test1(scale):
 243     for i in range(-97 * 2, 1, 1):
 244         db = float(i) / 2.0
 245         print("%5.1f dB maps to %f" % (db, scale.db_to_scale(db)))
 246
 247
 248 def scale_test2(scale):
 249     for i in range(101):
 250         s = float(i) / 100.0
 251         print("%.2f maps to %.1f dB" % (s, scale.scale_to_db(s)))
 252
 253
 254 def print_db_to_scale(scale, db):
 255     print("%-.1f dB maps to %f" % (db, scale.db_to_scale(db)))
 256
 257
 258 def scale_test3(scale):
 259     print_db_to_scale(scale, +77.0)
 260     print_db_to_scale(scale, +7.0)
 261     print_db_to_scale(scale, 0.0)
 262     print_db_to_scale(scale, -107.0)
 263
 264
 265 def _test(*args, **kwargs):
 266     scale = Linear30dB()
 267     scale_test1(scale)
 268     scale_test2(scale)
 269     scale_test3(scale)
 270
 271
 272 if __name__ == "__main__":
 273     _test()