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MPC replaygain data; how to covert peak from dB to float?
DrTwox
post Jan 23 2010, 07:07
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Hi all,

I'm seeking some help with replaygain and musepack files...

MPC stores the peak level as a 16 bit integer representing the loudness. How do I convert this value to a 32 bit float? e.g. A peak value of 23225 (read from the .mpc file) shows as a peak of 1.048776 in foobar; what's the calculation to go from one to the other?

I've read the specs, but it might as well be in another language!
http://trac.musepack.net/trac/wiki/SV8Spec...eplaygainPacket
QUOTE
Replay gain finds that this title has a loudness of 78.56 dB. It will be encoded as 78.56 * 256 ~ 20111 = 0x4E8

For float output (range [-1 1]), the max is 0.96. It will be encoded as 20 * log10(0.96 * 215) * 256 ~ 23029 = 0x59F5 (for peak values it is suggested to round to nearest higher integer)


This post has been edited by DrTwox: Jan 23 2010, 07:34
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r2d
post Jan 23 2010, 22:43
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QUOTE (DrTwox @ Jan 23 2010, 08:07) *
e.g. A peak value of 23225 (read from the .mpc file) shows as a peak of 1.048776 in foobar; what's the calculation to go from one to the other?


20 * log10(1.048776 * 2^15) * 256 = 23225

10^(23225/(20*256)) / 2^15 = 1,04877633098761506451

with ^ the power operator, so 2^15 = 32768
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DrTwox
post Jan 24 2010, 02:34
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Awesome! Thank you for the help.
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