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