Re: [Bug-gnupod] SoundCheck/ReplayGain

[chris.com]

H. Langos wrote:

Hi Chris,

On Mon, May 25, 2009 at 11:06:45PM +0200, chris.com wrote:
  

I first fetch the RG-tag from the FLAC file and transform it to its  
SoundCheck equivalent
Then I transform the file with flac and lame to a music-only mp3 file  
(no tags).
Next I add (with id3v2) an iTunNORM comment field to the mp3 file and  
fill it with ten copies of the SoundCheck value (as seen on  
hydrogenaudio.org)
And finally I addsong the file to the iPod.
    

Could you send me a small sample mp3 from this stage in your process? 
Preferably something short and under creative commons license. (try
http://www.freesound.org/ if you need samples)
  

I will pm you two samples, one with ReplayGain -9 (i.e. SoundCheck 00001F07), the other with RG/SC +9 / 0000007D.
In iTunes you can hear the difference clearly

The CVS version will probably do the whole process for you. It will not 
generate an iTunNORM comment though, but use the replay_track_gain directly 
to generate the soundcheck attribute. It is however not widely tested yet.
  

I think the CVS version will do the whole thing but I'm running gnupod on a small NAS (nslu2) without floating point support
Which means that converting flac to mp3 takes a long time. Calculating ReplayGain however takes forever.
That's why I want to pass the flac ReplayGain directly as SoundCheck into the mp3 file
But I will take a look at the CVS version. Can you tell me where I can get it?

mktunes picks up the SoundCheck data correctly; I can see the value in
the iTunesDB file, but the iPod doesn't seem to see it, because the
volume doesn't get adjusted.
    

Are you sure that the soundcheck value is in the itunesDB?
Did you check the iTunesDB with hexdump or did you look at the 
GNUtunesDB.xml?
  

I checked a hexdump, The GNUtunesDB.xml file also contains the right value.

iTunes as well reads the SoundCheck value I added correctly because when  
I plug and unplug it with iTunes without changing anything,
iTunes recreates the iTunesBD file (with my own SoundCheck value) and  
now the volume gets adjusted correctly.
    

Maybe iTunes reads your iTunNORM comment and accepts some deviation that
gnupod does not? E.g. gunpod insists on finding a space in front of the
first hex number group in the iTunNORM comment.
  

Probably something like that. I tried copying the iTunNORM comment from an iTunes modified file into my mp3 file but to no avail.

cheers
-henrik