[Gambas-devel] gb.sdl.sound channel volume bug

[Kevin Fishburne]

When setting the Volume property (type float according to the 
documentation) of a channel, the assignable values are of a lower 
resolution than advertised resulting in audibly abrupt changes in 
amplitude. Here's an example:

' Audio effects.
Public Struct Audio_Effect  ' Structure containing one effect's data.
   Current As Single   ' Current amplitude.
   Target As Single    ' Target amplitude.
   Velocity As Single  ' Speed at which current amplitude is moving 
toward target amplitude.
   Scale As Single     ' Audible amplitude coefficient.
   Chan As Channel     ' Default channel to play on.
   Name As String      ' Name of sample.
   Sample As Sound     ' Sample data (file).
End Struct

Public Environment[16] As Struct Audio_Effect ' Environmental effects.

' Start wind effect.
Environment[7].Sample = New Sound(Render.BasePath & "/sound/Wind.wav")
Environment[7].Name = "Wind"
Environment[7].Chan = Environment[7].Sample.Play(-1)
Environment[7].Chan.Volume = 0

Environment[7].Chan.Volume = 0.01
Print Environment[7].Chan.Volume
0

Environment[7].Chan.Volume = 0.02
Print Environment[7].Chan.Volume
0.01333477219943

This has been plaguing me for a while but I just now zeroed in on what 
was actually happening. I've noticed that when performing a calculation 
if you use the wrong datatype in the wrong place it can cause overflows 
or otherwise invalidate the equation. Maybe something like this is 
responsible?

-- 
Kevin Fishburne
Eight Virtues
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