Re: [Bug-gnupod] SoundCheck/ReplayGain

[H. Langos]

Hi Chris,

On Thu, May 28, 2009 at 10:11:18PM +0200, chris.com wrote:
> Thanks Henrik for the time spent on this problem
>
> H. Langos wrote:
>> Hi chris,
>>
>> On Tue, May 26, 2009 at 11:33:53PM +0200, chris.com wrote:
>> some html... please reconfigure your email client... :-)
>>   
> I'm sorry but I don't see any html and I don"t know how to change what.  
> I hope this does it.

Yeap. Nothing better than text/plain :-)

>
> I didn't look into the files but the are all different at each step.
> My iTunes is 8.1.1.10

Thank you very much for that data! 

I didn't look deeply into the iTunesDB because it is not read by the
shuffle. (see http://banshee-project.org/~gburt/itunesdb.html chapter about
iTunesSD. You'll have to scroll down because the links are broken)

As I expected, the only difference between the iTunesSD.gnupod and
iTunesSD.iTunes are the volume fields.
I took a "hexdump -C" of them and compared the hexdump outputs:

$ diff -U5  iTunesSD.iTunes.hex iTunesSD.gnupod.hex                             
                           
--- iTunesSD.iTunes.hex 2009-05-28 23:04:59.000000000 +0200
+++ iTunesSD.gnupod.hex 2009-05-28 23:04:59.000000000 +0200
@@ -1,29 +1,29 @@
 00000000  00 00 03 01 08 00 00 00  12 00 00 00 00 00 00 00  |................|
 00000010  00 00 00 02 2e 5a a5 01  00 00 00 00 00 00 00 00  |.....Z..........|
-00000020  00 00 00 00 00 00 00 00  00 00 ff ff f7 00 00 01  |................|
+00000020  00 00 00 00 00 00 00 00  00 00 00 00 64 00 00 01  |............d...|
 00000030  00 02 00 2f 00 69 00 50  00 6f 00 64 00 5f 00 43  |.../.i.P.o.d._.C|
 00000040  00 6f 00 6e 00 74 00 72  00 6f 00 6c 00 2f 00 4d  |.o.n.t.r.o.l./.M|
 00000050  00 75 00 73 00 69 00 63  00 2f 00 46 00 30 00 37  |.u.s.i.c./.F.0.7|
 00000060  00 2f 00 67 00 30 00 5f  00 66 00 61 00 6e 00 66  |./.g.0._.f.a.n.f|
 00000070  00 61 00 72 00 65 00 6d  00 39 00 2e 00 6d 00 70  |.a.r.e.m.9...m.p|
 00000080  00 33 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |.3..............|
 00000090  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
 *
 00000230  00 00 00 00 00 00 00 00  00 00 00 00 00 01 00 00  |................|
 00000240  00 02 2e 5a a5 01 00 00  00 00 00 00 00 00 00 00  |...Z............|
-00000250  00 00 00 00 00 00 00 00  ff ff fb 00 00 01 00 02  |................|
+00000250  00 00 00 00 00 00 00 00  00 00 64 00 00 01 00 02  |..........d.....|
 00000260  00 2f 00 69 00 50 00 6f  00 64 00 5f 00 43 00 6f  |./.i.P.o.d._.C.o|
 00000270  00 6e 00 74 00 72 00 6f  00 6c 00 2f 00 4d 00 75  |.n.t.r.o.l./.M.u|
 00000280  00 73 00 69 00 63 00 2f  00 46 00 31 00 38 00 2f  |.s.i.c./.F.1.8./|
 00000290  00 67 00 30 00 5f 00 66  00 61 00 6e 00 66 00 61  |.g.0._.f.a.n.f.a|
 000002a0  00 72 00 65 00 30 00 30  00 2e 00 6d 00 70 00 33  |.r.e.0.0...m.p.3|
 000002b0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
 *
 00000460  00 00 00 00 00 00 00 00  00 00 00 01 00 00 00 02  |................|
 00000470  2e 5a a5 01 00 00 00 00  00 00 00 00 00 00 00 00  |.Z..............|
-00000480  00 00 00 00 00 00 00 00  09 00 00 01 00 02 00 2f  |.............../|
+00000480  00 00 00 00 00 00 00 00  64 00 00 01 00 02 00 2f  |........d....../|
 00000490  00 69 00 50 00 6f 00 64  00 5f 00 43 00 6f 00 6e  |.i.P.o.d._.C.o.n|
 000004a0  00 74 00 72 00 6f 00 6c  00 2f 00 4d 00 75 00 73  |.t.r.o.l./.M.u.s|
 000004b0  00 69 00 63 00 2f 00 46  00 31 00 32 00 2f 00 67  |.i.c./.F.1.2./.g|
 000004c0  00 30 00 5f 00 66 00 61  00 6e 00 66 00 61 00 72  |.0._.f.a.n.f.a.r|
 000004d0  00 65 00 70 00 39 00 2e  00 6d 00 70 00 33 00 00  |.e.p.9...m.p.3..|


As you see the gnupod file allways contains 00 00 64 in the volume 
field while the iTunes generated field contains:
ff ff f7 for the -9dB file,
ff ff fb for the 0 file (are you sure it is realy 0? soundcheck 3E8 or none at 
all?),
00 00 09 for the +9dB

Unfortunately this is not the format documented in 
http://banshee-project.org/~gburt/itunesdb.html so we'll have to
investigate a little further.

Are you sure that the manual volume adjustment in iTunes was +/-0% for all
files?

It would be great if you could send me some more examples with +6dB and -6dB
and maybe +3dB and -3dB.

BTW: The differences between iTunesSD.iTunes and iTunesSDbis.iTunes are only 
in the paths. Everything else is identical.

If you want to make sure that the shuffle realy only needs the
data in the iTunesSD file, you can wipe the ipod, add those files 
with gnupod_addsong, and either modify the GNUtunesDB.xml and 
change the "volume" attribute, before running mktunes, 
or you can use a hexeditor on the iTunesSD file after running mktunes.

cheers
-henrik