Old 22nd December 2009, 22:01   #1
WhichOne
Junior Member
 
Join Date: Dec 2009
Posts: 9
Replay Gain - Winamp vs Foobar values.

Hi, I usually tag my songs with Foobar2000 but tried out to see how fast Winamp was at scanning them recently. Foobar was the winner, but what really suprised me was that the calculated Replay Gain values were often different! The amount they are off is really splitting hairs, but what I'm wondering is, how can this be possible? I thought that having a reference level would ensure any analyzer would comeback with the same gains and peaks if the song didn't change. And if the values can vary from analyzer to analyzer, how can we be sure what is correct? Picture below, Foobar on the left, Winamp on the right.



album gain difference: 0.04
album peak difference: 0.000945965

track differences
1: 0.02
2: 0.06
3: 0.13
4: 0.00
5: 0.07
6: 0.06
7: 0.05
8: 0.05

track peak differences:
1: 0.00000008
2: 0.00000008
3: 0.00000008
4: 0.000000021
5: 0.00000008
6: 0.00000008
7: 0.000000035
8: 0.00000008
WhichOne is offline   Reply With Quote
Old 22nd December 2009, 23:47   #2
J_Darnley
Forum King
 
J_Darnley's Avatar
 
Join Date: Apr 2004
Location: Belgium, Europe
Posts: 3,626
Send a message via ICQ to J_Darnley
Different decoders with different floating point and rounding errors. The MP3 format does not specify that a decode must be exactly the same, just within a certain difference.

As for the replay gain scanner, that too might have some slight errors.

Since the smallest difference between two sounds that a human can appreciate is 1dB, I don't think 0.1 and less is much to worry about.

Also, the track peak values are identical. If you round the Winamp value to the same number of places as the foobar value...

Winamp ATF ReferenceMy cPro timer widgetMy port of AVS
Do NOT email me with general tech support questions.
J_Darnley is offline   Reply With Quote
Old 23rd December 2009, 00:02   #3
WhichOne
Junior Member
 
Join Date: Dec 2009
Posts: 9
Quote:
Originally posted by J_Darnley
Different decoders with different floating point and rounding errors. The MP3 format does not specify that a decode must be exactly the same, just within a certain difference.

As for the replay gain scanner, that too might have some slight errors.

Since the smallest difference between two sounds that a human can appreciate is 1dB, I don't think 0.1 and less is much to worry about.

Also, the track peak values are identical. If you round the Winamp value to the same number of places as the foobar value...
I thought somebody would mention MP3, but these are actually lossless files, in flac. Yes, they are quite small error, I just didn't expect to get different results. Too bad there wasn't an official replay gain scanner that could be plugged into foobar and winamp so everybody could have the same gains. I know, it's not that different, just wanted to a reason why since I didn't know what would cause this.

Any chance to analyze them in the playlist like Foobar? I don't even use the Media Library.

Last edited by WhichOne; 23rd December 2009 at 00:31.
WhichOne is offline   Reply With Quote
Old 23rd December 2009, 03:48   #4
Benski
Ben Allison
Former Winamp Developer
 
Benski's Avatar
 
Join Date: Jan 2005
Location: Brooklyn, NY
Posts: 1,057
Since Replay Gain values are calculated with floating point, it's easy to have small errors that add up over the whole file. The x86 FPU has 80bit precision, but every time you (or the compiler) spills a register onto the stack, it gets truncated to 32 or 64 bits. Subtle implementation differences can add up to measurable (but mostly insignificant) differences. Also, because the gain value is chosen out of a list of loud 'windows' of the track (think histogram), it's possible that the next loudest window was 0.13 dB higher (and not that the calculation process has 0.13 dB of error difference)

Anyway as J_Darnley said, the values are way below human perception. And it's tough to say which one is more accurate.

The track peak differences are just due to the display rounding. The values are identical.
Benski is offline   Reply With Quote
Old 24th December 2009, 02:09   #5
WhichOne
Junior Member
 
Join Date: Dec 2009
Posts: 9
Oh, I realized you could analyze via the playlist window to. That "send to" menu must have been blocked out my by mind since I never used it before.

I think I'll stick with Winamp's RG since even though they aren't different, I'd rather not have rounding lol. But I do wish Winamp would have the "Scan as Tracks/Album/Album by Folder" and quiet mode of foobar someday.
WhichOne is offline   Reply With Quote
Old 24th December 2009, 04:10   #6
DJ Egg
Techorator
Winamp & SHOUTcast Team
 
Join Date: Jun 2000
Posts: 35,821
Quote:
Originally posted by WhichOne
But I do wish Winamp would have the "Scan as Tracks/Album/Album by Folder" and quiet mode of foobar someday.
Winamp -> Prefs (Ctrl+P) -> Plugins -> Media Library -> Replay Gain Analyzer -> config
DJ Egg is offline   Reply With Quote
Reply
Go Back   Winamp & Shoutcast Forums > Winamp > Winamp Discussion

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump