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Would it be better for Replay Gain to be off by default?

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Julian67:
Currently a new default RockBox install is configured to have  "Track Gain If Shuffling" on.  This setting might more clearly be described as "Album Gain On Unless Shuffling".  I noticed several threads recently where people people encounter odd and apparently inexplicable issues with sound quality.  It's really hard to know what they mean without an audio sample, but it occured to me that the default in RockBox is not, as one might assume, to play back at the user set volume.  There is every chance that the level is being either raised or attenuated and the user does not even realise this and in fact may have checked the playback settings and even be confident that they have not enabled RG.  The attenuation is not such a big deal but the raising might be because the default is for no pre-amp adjustment and no clipping prevention so the potential is there to raise the level to undesirable levels and even induce clipping.

It seems that the default of RG Album Gain on with pre-amp 0 and no clipping prevention all presupposes that the user has very few, if any, albums with high positive album gain values and I began to wonder if that supposition was realistic so I examined my music collection:

I just looked at two parts of my collection, firstly Classical (includes Baroque, Early etc) and secondly Pop (includes any modern popular genre like Rock or Garage or Indie etc).

Of the 208 "Pop" albums only 5 have positive album gain and three of those are below 1 dB.  The highest is +3.35 dB.

Of the 819 "Classical" albums 518 have a positive album gain value(!) and of those 149 have an album_gain of +4 dB or higher.  There is one over 14 dB!  The albums with the higher values tend to be of single or duet stringed instruments, or choral works.

So I'm suggesting that the assumptions that led to RockBox's default RG settings might benefit from another look as they may cause problems for anyone who has a lot of unamplified or acoustic or vocal/choral music in their collection.  Btw this is not a complaint as it's no issue for me because quite a long time ago I Read The Fine Manual and discovered that just because I had never switched on RG didn't mean it was off!  But a typical new or uninformed user is not someone who has read the manual, and perhaps has never even heard of Replay Gain, and there is a chance that their music will play back with distortion and even severe clipping.

saratoga:

--- Quote from: Julian67 on October 05, 2012, 01:52:01 PM ---The attenuation is not such a big deal but the raising might be because the default is for no pre-amp adjustment and no clipping prevention so the potential is there to raise the level to undesirable levels and even induce clipping.
--- End quote ---

The replaygain reference level is so low this will basically never matter. 

AlexP:
I personally don't care one way or another, but would another solution be to turn on clipping prevention?

Julian67:

--- Quote from: saratoga ---
The replaygain reference level is so low this will basically never matter.  


--- End quote ---

I can offer an example that I believe demonstrates otherwise:

First the mediainfo:


--- Code: ---General
Complete name                            : 06 - Dulces exuviæ.ogg
Format                                   : OGG
File size                                : 6.77 MiB
Duration                                 : 4mn 50s
Overall bit rate mode                    : Variable
Overall bit rate                         : 195 Kbps
Album replay gain                        : 5.57 dB
Album replay gain peak                   : 0.982951
Album                                    : Spanish songs & vihuela solos
Track name                               : Dulces exuviæ
Track name/Position                      : 6
Performer                                : Catherine King & Jacob Heringman
Composer                                 : Alonso Mudarra
Genre                                    : Renaissance
Recorded date                            : 1997-01-01
CATEGORY                                 : classical
CDID                                     : b9104520

Audio
ID                                       : 602039608 (0x23E26538)
Format                                   : Vorbis
Format settings, Floor                   : 1
Duration                                 : 4mn 50s
Bit rate mode                            : Variable
Bit rate                                 : 224 Kbps
Channel(s)                               : 2 channels
Sampling rate                            : 44.1 KHz
Compression mode                         : Lossy
Replay gain                              : 4.46 dB
Replay gain peak                         : 0.764122
Stream size                              : 7.75 MiB
Writing library                          : libVorbis (Everywhere) (20100325 (Everywhere))

--- End code ---

This is ripped from my own CD to flac and subsequently encoded to Ogg Vorbis and the Replay Gain values being calculated by vorbisgain in album mode (vorbisgain -a <album_directory>)

The file: http://www.filefactory.com/file/3oy3lhxu2f59/n/06_-_Dulces_exuvi_ogg

Listen to it from 2m 0s to 2m 4s with RG album mode, no pre-amp, no clipping prevention.  Then listen with RG disabled.  There simply is no way to not notice the very unpleasant distortion even when played back with Rockbox volume level set to -20 dB.


--- Quote from: AlexP ---I personally don't care one way or another, but would another solution be to turn on clipping prevention?

--- End quote ---

Yes, I think that would be a sane default configuration for Rockbox (probably more acceptable for some people than my original suggestion to switch it off by default) and suspect it might eliminate some of these apparently inexplicable "I tried Rockbox and it sounds bad" posts from new users.

saratoga:
I should say almost never.  I've never seen this on music I use, but its certainly possible.  If you want, submit a patch. 

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