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Topic: MPC replaygain data; how to covert peak from dB to float? (Read 7065 times) previous topic - next topic

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  • DrTwox
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MPC replaygain data; how to covert peak from dB to float?
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)
  • Last Edit: 23 January, 2010, 01:34:29 AM by DrTwox

  • r2d
  • [*]
  • Developer
MPC replaygain data; how to covert peak from dB to float?
Reply #1
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

  • DrTwox
  • [*]
MPC replaygain data; how to covert peak from dB to float?
Reply #2
Awesome! Thank you for the help.