dbtopow(), dbtorms(), powtodb(), powtorms() off by 100 db
In chuck 1.2.1.2, the family of db conversion functions appear to be broken, or at least have a unconventional interpretation of db -- they all seem have an offset of 100 db: for example: Std.powtodb(1.0) => 100.0 (expected 0.0) Std.powtodb(10.0) => 110.0 (expected 10.0) Std.dbtopow(0) => 0 (expected 1.0) Std.dbtopow(100) => 1.0 (expected 10000000000) (Similar comments apply to rmstodb() and dbtorms()) OTOH they are self-consistent, in that Std.dbtopow(Std.powtodb(x)) == x, so maybe someone thinks that's how they're supposed to behave? - Rob
Hi, This is intentional. This is the same convention that Pure Data uses, the reason being is that it is easy to use MIDI velocity numbers to change volume. Std.dbopow(MIDI_VEL) => mysynth.volume; Or some similar line of code. It is nice because a MIDI value of 100 means full volume (1.0) and anything above that jacks up the volume if you have a quiet synth or sample loaded. Remember that decibels are a logarithmic scale that is relative to some value, in this case 1.0. --art
From: rdpoor@gmail.com To: chuck-users@lists.cs.princeton.edu Date: Sun, 3 May 2009 08:28:24 -0700 Subject: [chuck-users] dbtopow(), dbtorms(), powtodb(), powtorms() off by 100 db
In chuck 1.2.1.2, the family of db conversion functions appear to be broken, or at least have a unconventional interpretation of db -- they all seem have an offset of 100 db:
for example:
Std.powtodb(1.0) => 100.0 (expected 0.0) Std.powtodb(10.0) => 110.0 (expected 10.0)
Std.dbtopow(0) => 0 (expected 1.0) Std.dbtopow(100) => 1.0 (expected 10000000000)
(Similar comments apply to rmstodb() and dbtorms())
OTOH they are self-consistent, in that Std.dbtopow(Std.powtodb(x)) == x, so maybe someone thinks that's how they're supposed to behave?
- Rob
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participants (2)
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Adam Tindale
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Robert Poor