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# how do I convert from linear to logarithmic

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How do I convert a linear volume scale 0->64 to the logarithmic dB scale 0->10000(hundredths of a decibel).
Message from above: Damn, my hair is grey!

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Using the log function. C''s log() function is the natural logarithm, and you want base 2, but it''s easy to convert betwen the two. E.g. you can use

#define logbase2(a) (log(a) / log(2))

and then you just need

hundredths_of_a_decibel = 100 * 10 * logbase2(volume);

[the ''100'' comes from wanting hundredths, while the 10 comes from wanting _deci_bels]

Note that this may not work for a volume of zero: it may crash or produce an infinite result. If you expect 0 volumes you should probably handle them seperately.

Thanks johnb!

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