background music: Tween volume_linear not volume_db #1897
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Previously we tweened the `volume_db` property between linear_to_db(0.00001) and linear_to_db(1.0). The reason for the strange lower bound was given in a comment but to expand on it: linear_to_db(0.0) is -inf. linear_to_db maps the (logarithmic) decibel scale between -inf and 0.0 onto a linear scale between 0.0 and 1.0. Here is a table of some sample values that I found helpful, rounded to 1dp: | x | linear_to_db(x) | | ------- | --------------- | | 0.0 | -inf | | 0.00001 | -100.0 | | 0.05 | -26.0 | | 0.1 | -20.0 | | 0.25 | -12.0 | | 0.5 | -6.0 | | 0.75 | -2.5 | | 1.0 | 0.0 | It's not meaningful to tween a value between 0.0 and -inf: there's no such thing as "halfway between 0.0 and -inf". AudioStreamPlayer has a volume_linear property. Setting it just sets volume_db to the result of linear_to_db() on its input. By tweening this property instead, then we can actually tween between the two bounds that we want. It also sounds better to my ears than what we were doing before, which was tweening between 0.0 dB and -100 dB. The human ear perceives a reduction of 10 dB as a halving of volume. Previously, halfway through the fade-out (between -0.0 dB and -100 dB) the volume would be -50 dB, which is a five-fold reduction in volume and means that the sound is essentially inaudible. With this change, the fade-out is smoother.
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Play this branch at https://play.threadbare.game/branches/endlessm/wjt/background-music-tween-volume-linear-not-volume-db. (This launches the game from the start, not directly at the change(s) in this pull request.) |
manuq
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Sounds better to my ears as well.
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Previously we tweened the
volume_dbproperty betweenlinear_to_db(0.00001)andlinear_to_db(1.0). The reason for the strangelower bound was given in a comment but to expand on it:
linear_to_db(0.0)is-inf.linear_to_dbmaps the (logarithmic) decibelscale between -inf and 0.0 onto a linear scale between 0.0 and 1.0. Here
is a table of some sample values that I found helpful, rounded to 1dp:
It's not meaningful to tween a value between 0.0 and -inf: there's no
such thing as "halfway between 0.0 and -inf".
AudioStreamPlayerhas avolume_linearproperty. Setting it just setsvolume_dbto the result oflinear_to_db()on its input. By tweening thisproperty instead, then we can actually tween between the two bounds that
we want.
It also sounds better to my ears than what we were doing before, which
was tweening between 0.0 dB and -100 dB. The human ear perceives a
reduction of 10 dB as a halving of volume. Previously, halfway through
the fade-out (between -0.0 dB and -100 dB) the volume would be -50 dB,
which is a five-fold reduction in volume and means that the sound is
essentially inaudible. With this change, the fade-out is smoother.