Re: [Bug-gnupod] Patch to support ReplayGain / mp3gain

[Richard van den Berg]

Hi Henrik,

On Mon, April 20, 2009 17:47, H. Langos wrote:
> I hope the iPod does take care of clipping issues. (Or aren't there any?)

In theory there could be clipping, but for 99% of the current pop music
releases the volume will be lowered. And even for those (older) releases
where the volume will be increased, peaks will rarely go beyond full
scale. Only for music with a wide dynamic range such as classical clipping
could become a real issue.

> Ever encountered any problems there?

Nope. I did see some clipping warnings while running mp3gain, but I never
heard any issues. At home I use SqueezeCenter which I expect to implement
the solution explained here:
http://replaygain.hydrogenaudio.org/player_clipping.html
I've only been using the iPod for about a week, but didn't hear any
problems so far.

> Nice summary there. You could add that link to the documentation of
> _parse_ReplayGain(). :-)

Yes, I will. Giving credit is the least I can do for stealing the code. :-)

> But if you were only after the iTunNORM syntax,
> you might have saved yourself some google time...
[snip]
>            http://www.id3.org/iTunes_Normalization_settings

Actually, I did stumble upon the slimdevices.com page that information was
taken from. From there it only took a few minutes to find the flac2mp3
perl code. Only after I turned it into a full ReplayGain to SoundCheck
script I found out that writing the iTunNORM tags does not help with
iTunes 8. You need to write to the iTunesDB. Googling some more for the
iTunesDB binary format I found gtkpod which says it had adapted it's C
code from gnupod. :-)

Cheers,

Richard