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More => Old Versions => Media Center 11 (Development Ended) => Topic started by: datdude on June 11, 2005, 07:24:18 pm

Title: Album Gain discrepancies
Post by: datdude on June 11, 2005, 07:24:18 pm
I have several duplicate tracks that are associated with the exact same album.  Verified using album thumbnail view. 

Replay gain values are almost identical to each duplicate track only varying by .1 - .2 dB.
Album gian values however vary by .5 - 2.5 dB which is audibly different and the reason why I checked so it does make a difference.

Why is this happening?

Im not sure what to make of this.  I like album gain but if this discrepancie occurs frequently(in my library?), then doesn't it defeat the purpose of it?
Title: Re: Album Gain discrepancies
Post by: Alex B on June 12, 2005, 05:26:28 am
Album Gain is based on the track gain values of the tracks that are in the same folder and have the same Album tag. It works only with imported files and it updates dynamically. If the folder contents are changed the value changes respectively.

You can try this by moving the duplicates into the same folder. They will have exactly the same Album Gain value if the Album fields are identical.

The only thing that is not clear to me is why it does not simply take the gain value from the track that has the greatest track gain attenuation. The Album Gain attenuation seems to be always a bit less. I wonder if that means that the loudest album tracks may clip in some cases.
Title: Re: Album Gain discrepancies
Post by: Alex B on June 13, 2005, 10:02:28 am
The only thing that is not clear to me is why it does not simply take the gain value from the track that has the greatest track gain attenuation. The Album Gain attenuation seems to be always a bit less. I wonder if that means that the loudest album tracks may clip in some cases.

For example, this album has quite diverse track gains:

(http://kotisivu.mtv3.fi/alexb/pix/albumgain.png)

The loudest track has a track gain value of -14,56 dB, but the album gain is only -8,28 dB. Why is that?

Also, the tracks 1 and 2 have the same Peak Level and Intensity values, but the track gains are different. How does MC calculate the Replay Gain values?
Title: Re: Album Gain discrepancies
Post by: datdude on June 13, 2005, 07:27:14 pm
Why is album gain Folder dependent?

Shouldn't be too big of a deal no that I know.
Title: Re: Album Gain discrepancies
Post by: paulr on June 13, 2005, 10:24:01 pm
Replay gain is calculated according to the proposed standard posted here:  http://replaygain.hydrogenaudio.org/

Take a look at the "Equal Loudness Filter" portion of the proposal and it should be more clear.  In short - perceived loudness varies by frequency, so simple "Peak Level" measurements or "Intensity" values would not result in a consistent replay gain values.