path: root/doc/pddp/all_about_acoustic_conversions.pd

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#X text 19 36 [mtof] will convert MIDI note numbers to Wave Freqeuency.
This object exists in Pd for the sake of convenience and speed of processing.
;
#X obj 45 195 mtof;
#X floatatom 45 173 5 0 0 0 - - -;
#X text 85 172 Select a MIDI note: (Middle C is 60).;
#X floatatom 45 218 5 0 0 0 - - -;
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#X restore 45 262 pd output;
#X msg 116 239 MUTE;
#X text 133 217 <-- Turn up your volume here.;
#X text 19 85 MIDI notes usually range between 0 and 127 from an incoming
MIDI controller. However \, in Pd negative numbers to -1500 and positive
numbers to 1499 are also supported and decimal places can be used to
achive microtonal pitches.;
#X text 19 145 CONVENIENT? YES!;
#X obj 1 1 cnv 15 425 20 empty \$0-pddp.cnv.subheading empty 20 10
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#X text 7 1 Understanding [mtof];
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#X text 25 36 HERE IS THE ALTERNATIVE;
#X obj 46 97 mtof;
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#X floatatom 133 237 0 0 0 0 - - -;
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#X obj 171 295 realtime;
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#X obj 418 118 loadbang;
#X obj 375 184 exp;
#X obj 375 204 *;
#X floatatom 375 224 0 0 0 0 - - -;
#X obj 407 207 r zero;
#X text 89 53 Select a MIDI note here.;
#X text 172 332 Arithmetic is __?__ milliseconds slower than [mtof].
;
#X text 169 368 [expr] is __?__ milliseconds slower than [mtof].;
#X text 22 139 RESULT A;
#X text 133 252 RESULT B;
#X text 374 241 RESULT C;
#X msg 418 139 0.0577623;
#X msg 418 179 8.1758;
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#X text 7 1 An alternative to [mtof];
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#X restore 22 452 pd mtof_patches;
#X text 19 121 The examples at the botton left are Pd structures which
emulate the source code of the [mtof] object. In one case \, I have
used the [expr] object to perform the necessary calculation. In the
other case \, I used Pd's Arithmetic objects to perform the calculation.
;
#X text 19 268 Secondly \, the incoming MIDI note number is translated
into a frequency value by the simple equation:;
#X text 19 332 For curiosity's sake \, I included a timer to show how
much faster the [mtof] object is compared to the two alternative methods.
;
#X text 20 37 The [mtof] object is really just a function defined in
Pd's source code - which is programmed in "C".;
#X text 20 74 As such \, it operates very quickly. If a similar function
were to be created using Pd's arithmetic objects \, the process would
be quite a bit slower. How much slower?;
#X text 19 376 As well \, notice that RESULT C (the output from Pd's
basic arithmetic objects) is not as accurate as the other two methods:
[mtof] and/or [expr]. This is because the message boxes and the [*]
object round off the operands because they cannot handle enough decimal
places.;
#X text 19 190 The first order of business performed by these examples
is the filtering out of all numbers less than -1500 and greater than
1499 (Just like the [mtof] source code). In other words \, "overflows
and underflows are clipped" as Miller Puckette stated in the original
documentation for this object.;
#X text 19 302 (8.17579891564 * exp(0.0577622650 * MIDI_note)) = frequency
;
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#X text 7 1 Alternatives to [mtof];
#X restore 22 302 pd Alternatives_to_mtof;
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#X floatatom 21 109 5 0 0 0 - - -;
#X floatatom 21 154 5 0 0 0 - - -;
#X text 19 89 CONVENIENT? YES!;
#X text 19 37 [ftom] will convert Wave/Signal Frequency to MIDI note
numbers. This object exists in Pd for the sake of convenience and speed
of processing.;
#X text 61 108 Select a Frequency: (i.e. 440 hz is an "A" above middle
C);
#X obj 21 131 ftom;
#X obj 21 181 makenote 100 500;
#X obj 21 204 noteout;
#X text 37 225 Note that fractional values have no effect. MIDI controllers
only accept integers. Perhaps a subroutine could be designed to parse
the decimal places and manipulate the pitch bend controller to achieve
microtonal control?;
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#X text 7 1 Understanding [ftom];
#N canvas 14 48 428 488 Alternatives_to_ftom 0;
#X text 19 71 As such \, it operates very quickly. If a similar function
were to be created using Pd's arithmetic objects \, the process would
be quite a bit slower. How much slower?;
#X text 19 37 The [ftom] object is really just a function defined in
Pd's source code - which is programmed in "C".;
#X text 19 117 The examples at the botton left are Pd structures which
emulate the source code of the [ftom] object. In one case \, I have
used the [expr] object to perform the necessary calculation. In the
other case \, I used Pd's Arithmetic objects to perform the calculation.
;
#X text 19 184 Firstly \, the Pd source code "clips" overflows and
underflows. This means simply that frequencies LESS THAN zero cannot
be tranlated into a MIDI note value - so they're ignored completely
and the object responds with "-1500".;
#X text 19 255 Secondly \, the incoming frequency is translated into
a MIDI note value by the simple equation:;
#X text 19 310 For curiosity's sake \, I included a timer to show how
much faster the [ftom] object is compared to the two alternative methods.
;
#X text 19 364 As well \, notice that RESULT C (the output from Pd's
basic arithmetic objects) is not as accurate as the other two methods:
[ftom] and/or [expr]. This is because the message boxes and the [*]
object round off the operands because they cannot handle enough decimal
places.;
#X text 19 285 (17.3123405046 * log(0.12231220585 * Frequency)) = MIDI_note
;
#N canvas 14 48 428 416 ftom_patches 0;
#X text 19 39 HERE IS THE ALTERNATIVE;
#X floatatom 40 60 5 0 0 0 - - -;
#X floatatom 19 124 0 0 0 0 - - -;
#X text 16 142 RESULT A;
#X text 83 56 Select a FREQUENCY here.;
#X obj 40 100 ftom;
#X obj 71 80 moses 0;
#X msg 71 101 -1500;
#X floatatom 71 232 0 0 0 0 - - -;
#X floatatom 121 170 0 0 0 0 - - -;
#X obj 121 137 * 17.3123;
#X obj 121 97 * 0.122312;
#X obj 121 117 log;
#X obj 108 209 expr (17.3123405046*log(.12231220585*$f1));
#X text 71 247 RESULT B;
#X text 120 183 RESULT C;
#X obj 100 273 bang;
#X obj 40 270 bang;
#X obj 40 290 realtime;
#X floatatom 165 364 0 0 0 0 - - -;
#X obj 208 287 bang;
#X obj 165 287 bang;
#X obj 165 307 realtime;
#X floatatom 165 328 0 0 0 0 - - -;
#X text 196 344 Arithmetic is __?__ milliseconds slower than [mtof].
;
#X text 163 380 [expr] is __?__ milliseconds slower than [mtof].;
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#X text 7 1 An alternative to [ftom];
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#X restore 22 442 pd ftom_patches;
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#X text 7 1 Alternatives to [ftom];
#X restore 21 297 pd Alternatives_to_ftom;
#X connect 0 0 5 0;
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#X connect 5 0 1 0;
#X connect 6 0 7 0;
#X connect 6 1 7 1;
#X restore 23 110 pd understanding_ftom;
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#X obj 180 189 dbtorms;
#X obj 180 236 rmstodb;
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#X text 24 94 The difficulty in measuring the volume of an instrument
however is caused by 'distance'. For example \, at one metre away from
a door bell \, the amplitude might be 70 Decibels \, while at 50 metres
away the same door bell is just a fraction of that amplitude.;
#X text 25 33 DECIBELS are units by which we measure amplitude. A human
voice is approximately 70 Decibels - a snare drum is approximately
120 Decibels - the threshold of pain for the human ear is approximately
110 Decibels (poor drummers!);
#X text 23 174 Literally \, a Decibel is one-tenth of a Bel. A Bel
\, according to a medical dictionary is approximately the threshold
of the human ear at 1000 hz. I know that this seems a little vague
\, and perhaps this isn't the best way to explain it - we might as
well be measuring "fortnights" and "bunches" and "Alens"! Anyways...I'm
not an acoustician.;
#X restore 20 350 pd What_is_a_decibel?;
#N canvas 5 174 440 242 What_does_RMS_mean? 0;
#X text 24 21 RMS is an acronym meaning "Root Mean Square".;
#X text 23 43 In the analog realm \, RMS is the result of an equation
performed on electrical flow. It is used to measure voltage or current.
It is important to note however \, that it does NOT measure "power".
It's also important to recognize that our ears perceive changes in
amplitude (decibels) more than we perceive changes in RMS levels.;
#X text 23 133 In the digital realm \, i.e. Pd! \, RMS is better defined
as "a measurement of a signal taken by squaring data points along the
curve \, finding the mean \, and then determining the square root of
that mean value.;
#X restore 20 373 pd What_does_RMS_mean?;
#X text 17 158 Example:;
#X floatatom 20 210 0 0 0 0 - - -;
#X obj 20 230 moses 0;
#X msg 20 250 0;
#X obj 82 269 min 485;
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#X obj 147 227 dbtorms;
#X floatatom 147 247 0 0 0 0 - - -;
#X obj 82 289 expr (exp((2.302585092994*0.05)*($f1-100)));
#X text 18 116 On a scale of zero to 100 decibels \, the [dbtorms]
produces exponential values between 0 and 1;
#X msg 20 181 0;
#X msg 53 181 100;
#X obj 57 249 sel 0;
#X obj 1 1 cnv 15 425 20 empty \$0-pddp.cnv.subheading empty 20 10
1 18 -261106 -33289 0;
#X text 7 1 Understanding [dbtorms];
#X text 18 92 (exp((2.302585092994 * 0.05) * (db_value - 100)) = RMS
;
#X text 18 37 [dbtorms] in Pd performs the following equation to convert
the data: Note that incoming values less than 0 or greater than 485
are considered overflow or underflow and are clipped/ignored.;
#X connect 3 0 4 0;
#X connect 3 0 8 0;
#X connect 4 0 5 0;
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#X restore 23 189 pd understanding_dbtorms;
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#X obj 180 362 powtodb;
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#X text 24 94 The difficulty in measuring the volume of an instrument
however is caused by 'distance'. For example \, at one metre away from
a door bell \, the amplitude might be 70 Decibels \, while at 50 metres
away the same door bell is just a fraction of that amplitude.;
#X text 25 33 DECIBELS are units by which we measure amplitude. A human
voice is approximately 70 Decibels - a snare drum is approximately
120 Decibels - the threshold of pain for the human ear is approximately
110 Decibels (poor drummers!);
#X text 23 174 Literally \, a Decibel is one-tenth of a Bel. A Bel
\, according to a medical dictionary is approximately the threshold
of the human ear at 1000 hz. I know that this seems a little vague
\, and perhaps this isn't the best way to explain it - we might as
well be measuring "fortnights" and "bunches" and "Alens"! Anyways...I'm
not an acoustician.;
#X restore 21 383 pd What_is_a_decibel?;
#N canvas 3 246 440 242 What_does_RMS_mean? 0;
#X text 24 21 RMS is an acronym meaning "Root Mean Square".;
#X text 23 43 In the analog realm \, RMS is the result of an equation
performed on electrical flow. It is used to measure voltage or current.
It is important to note however \, that it does NOT measure "power".
It's also important to recognize that our ears perceive changes in
amplitude (decibels) more than we perceive changes in RMS levels.;
#X text 23 133 In the digital realm \, i.e. Pd! \, RMS is better defined
as "a measurement of a signal taken by squaring data points along the
curve \, finding the mean \, and then determining the square root of
that mean value.;
#X restore 21 406 pd What_does_RMS_mean?;
#X text 18 157 Example:;
#X floatatom 21 179 0 0 0 0 - - -;
#X floatatom 21 345 0 0 0 0 - - -;
#X floatatom 148 279 0 0 0 0 - - -;
#X msg 65 201 0;
#X text 18 107 On a scale of zero to 1 decibels \, the [rmstodb] produces
logarithmic values between 0 and 100 \, although higher values can
also be produced.;
#X obj 148 257 rmstodb;
#X obj 21 279 max 0;
#X obj 21 323 max 0;
#X obj 21 301 expr (100+((20/2.302585092994)*log($f1)));
#X obj 21 201 / 1000;
#X floatatom 21 233 0 0 0 0 - - -;
#X msg 98 201 1;
#X obj 1 1 cnv 15 425 20 empty \$0-pddp.cnv.subheading empty 20 10
1 18 -261106 -33289 0;
#X text 7 1 Understanding [rmstodb];
#X text 18 82 (100 + ((20/2.302585092994) * log(RMS_value)));
#X text 18 37 [rmstodb] in Pd performs the following equation to convert
the data: Note that incoming values less than 0 is consider underflow
and is clipped/ignored.;
#X connect 3 0 12 0;
#X connect 6 0 13 0;
#X connect 8 0 5 0;
#X connect 9 0 11 0;
#X connect 10 0 4 0;
#X connect 11 0 10 0;
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#X connect 13 0 9 0;
#X connect 14 0 13 0;
#X restore 23 236 pd understanding_rmstodb;
#N canvas 7 22 428 333 understanding_dbtopow 0;
#N canvas 0 46 452 302 What_is_a_decibel? 0;
#X text 24 94 The difficulty in measuring the volume of an instrument
however is caused by 'distance'. For example \, at one metre away from
a door bell \, the amplitude might be 70 Decibels \, while at 50 metres
away the same door bell is just a fraction of that amplitude.;
#X text 25 33 DECIBELS are units by which we measure amplitude. A human
voice is approximately 70 Decibels - a snare drum is approximately
120 Decibels - the threshold of pain for the human ear is approximately
110 Decibels (poor drummers!);
#X text 23 174 Literally \, a Decibel is one-tenth of a Bel. A Bel
\, according to a medical dictionary is approximately the threshold
of the human ear at 1000 hz. I know that this seems a little vague
\, and perhaps this isn't the best way to explain it - we might as
well be measuring "fortnights" and "bunches" and "Alens"! Anyways...I'm
not an acoustician.;
#X restore 22 267 pd What_is_a_decibel?;
#X floatatom 22 128 0 0 0 0 - - -;
#X floatatom 22 234 0 0 0 0 - - -;
#X floatatom 149 167 0 0 0 0 - - -;
#N canvas 3 96 442 209 What_does_power_mean? 0;
#X text 30 25 What does power mean? I really don't know? I can't determine
from my own research or from Pd's documentation why or how this data
is used. All that I do know \, is that Pd provides these objects for
a good reason -- I just don't know the reason.;
#X text 27 103 Having said that \, I would enjoy learning from somebody
who DOES know more about these objects and their usage. All that I
can offer is an explanation of the equation used to perform these conversions.
;
#X restore 22 290 pd What_does_power_mean?;
#X obj 149 145 dbtopow;
#X obj 22 150 max 0;
#X obj 22 172 min 870;
#X text 19 92 exp((2.302585092994 * 0.1) * (db_value - 100)) = Power
;
#X obj 22 194 expr exp((2.302585092994*0.1)*($f1-100));
#X obj 1 1 cnv 15 425 20 empty \$0-pddp.cnv.subheading empty 20 10
1 18 -261106 -33289 0;
#X text 7 1 Understanding [dbtopow];
#X text 19 37 [dbtopow] in Pd performs the following equation to convert
the data: Note that incoming values less than 0 or greater than 870
are considered overflow or underflow and are clipped/ignored.;
#X connect 1 0 5 0;
#X connect 1 0 6 0;
#X connect 5 0 3 0;
#X connect 6 0 7 0;
#X connect 7 0 9 0;
#X connect 9 0 2 0;
#X restore 23 315 pd understanding_dbtopow;
#N canvas 13 22 428 336 understanding_powtodb 0;
#N canvas 0 22 452 302 What_is_a_decibel? 0;
#X text 24 94 The difficulty in measuring the volume of an instrument
however is caused by 'distance'. For example \, at one metre away from
a door bell \, the amplitude might be 70 Decibels \, while at 50 metres
away the same door bell is just a fraction of that amplitude.;
#X text 25 33 DECIBELS are units by which we measure amplitude. A human
voice is approximately 70 Decibels - a snare drum is approximately
120 Decibels - the threshold of pain for the human ear is approximately
110 Decibels (poor drummers!);
#X text 23 174 Literally \, a Decibel is one-tenth of a Bel. A Bel
\, according to a medical dictionary is approximately the threshold
of the human ear at 1000 hz. I know that this seems a little vague
\, and perhaps this isn't the best way to explain it - we might as
well be measuring "fortnights" and "bunches" and "Alens"! Anyways...I'm
not an acoustician.;
#X restore 22 274 pd What_is_a_decibel?;
#X text 19 110 Example:;
#X floatatom 22 131 0 0 0 0 - - -;
#X floatatom 22 237 0 0 0 0 - - -;
#X floatatom 149 170 0 0 0 0 - - -;
#N canvas 2 68 442 244 What_does_power_mean? 0;
#X text 30 25 What does power mean? I really don't know? I can't determine
from my own research or from Pd's documentation why or how this data
is used. All that I do know \, is that Pd provides these objects for
a good reason -- I just don't know the reason.;
#X text 27 103 Having said that \, I would enjoy learning from somebody
who DOES know more about these objects and their usage. All that I
can offer is an explanation of the equation used to perform these conversions.
;
#X restore 22 297 pd What_does_power_mean?;
#X text 18 37 [powtodb] in Pd performs the following equation to convert
the data: Note that incoming values less than 0 are considered underflow
and are clipped/ignored.;
#X text 17 84 (100 + ((10/2.302585092994) * log(POWER_value))) = Debibels
;
#X obj 149 148 powtodb;
#X obj 22 153 max 0;
#X obj 22 193 expr (100 + ((10/2.302585092994)*log($f1)));
#X obj 22 215 max 0;
#X obj 1 1 cnv 15 425 20 empty \$0-pddp.cnv.subheading empty 20 10
1 18 -261106 -33289 0;
#X text 7 1 Understanding [powtodb];
#X connect 2 0 8 0;
#X connect 2 0 9 0;
#X connect 8 0 4 0;
#X connect 9 0 10 0;
#X connect 10 0 11 0;
#X connect 11 0 3 0;
#X restore 23 362 pd understanding_powtodb;
#X text 215 63 - MIDI note number to frequency;
#X text 215 110 - Frequency to MIDI note number;
#X text 234 190 - Decibels to RMS;
#X text 234 237 - RMS to Decibels;
#X text 234 316 - Decibels to power;
#X text 234 363 - power to Decibels;
#X text 21 412 Please note: I have no idea why it's necessary for Pd
to measure decibels \, rms \, or power. It seems to me that RMS and
Power are extremely important in the analog world (so that an engineer
doesn't blow up a transistor)...but in Pd \, these things are just
numbers which have been abstracted from their original analog counterparts.
I would really appreciate if somebody could help me understand these
concepts and finish this document. Why are these objects present in
Pd? WHY should they be used and what benefits to they produce in a
digital process?;
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14 -233017 -33289 0;
#N canvas 323 229 494 344 META 0;
#X text 12 115 HELP_PATCH_AUTHORS Dave Sabine \, May 5 \, 2003 . Jonathan
Wilkes revised the patch to conform to the PDDP template for Pd version
0.42.;
#X text 12 45 KEYWORDS conversion;
#X text 12 95 LIBRARY PDDP;
#X text 12 5 GENRE all_about_pd;
#X text 12 25 NAME mtof ftom dbtorms rmstodb dbtopow powtodb;
#X text 12 65 DESCRIPTION examples of objects that do conversions between
acoustic units;
#X restore 392 550 pd META;
#N canvas 12 355 428 212 Related_objects 0;
#X obj 23 42 dbtopow~;
#X obj 77 42 dbtorms~;
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