[Gtkpod-devel] Possible error in libgpod

[Nathan T. <na...@to...>]

Please CC me on any response - I am not signed up with this list.

I have found an odd issue with cover artwork not being shown on my ipod nan=
o. =20
At first, I thought it was an amarok issue, but after investigation, it=20
appears to be a libgpod issue.

When I add a song with artwork, the images do not appear.  Through comparin=
g=20
with files created by iTunes (and reading the docs on ipodlinux.org), I was=
=20
able to pinpoint the issue.  I am not sure if this is iPod Nano-specific, o=
r=20
if it applies to all artwork-capable iPods.

I added artwork using the "test-write-thumbnails" program in the tests=20
directory of libgpod.

Here is a sample portion of my ArtworkDB after adding the artwork to the iP=
od.=20
(specifically the mhii header)
00000140  6d 68 69 69 98 00 00 00  e0 01 00 00 02 00 00 00  |mhii..........=
=2E.|
00000150  40 00 00 00 00 00 00 00  a8 84 38 5c 2c fb 76 0c  |@.........8\,.=
v.|
00000160  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |..............=
=2E.|
00000170  00 00 00 00 a0 14 01 00  00 00 00 00 00 00 00 00  |..............=
=2E.|
00000180  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |..............=
=2E.|
00000190  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |..............=
=2E.|
000001a0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |..............=
=2E.|
000001b0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |..............=
=2E.|
000001c0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |..............=
=2E.|
000001d0  00 00 00 00 00 00 00 00  6d 68 6f 64 18 00 00 00  |........mhod..=
=2E.|

That is what libgpod wrote to the iPod.  It does not display an image on th=
e=20
iPod.  However, changing it to the following *does* work (the iPod recogniz=
es=20
the thumbnail):
00000140  6d 68 69 69 98 00 00 00  e0 01 00 00 02 00 00 00  |mhii..........=
=2E.|
00000150  40 00 00 00 a8 84 38 5c  2c fb 76 0c 00 00 00 00  |@.....8\,.v...=
=2E.|
00000160  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |..............=
=2E.|
00000170  a0 14 01 00 00 00 00 00  00 00 00 00 00 00 00 00  |..............=
=2E.|
00000180  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |..............=
=2E.|
00000190  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |..............=
=2E.|
000001a0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |..............=
=2E.|
000001b0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |..............=
=2E.|
000001c0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |..............=
=2E.|
000001d0  00 00 00 00 00 00 00 00  6d 68 6f 64 18 00 00 00  |........mhod..=
=2E.|

=46rom what I can tell in the code, it appears that the field "mhii->image_=
id"=20
is getting written as 64-bit, when it should only be written as 32-bit...so=
=20
in my case, the song_id field should begin at offset 0x154 instead of 0x158=
,=20
and the orig_img_size should begin at 0x170 instead of 0x174.  From what I=
=20
can tell in looking through the code, all seems to be correct - but I must =
be=20
missing something (I'm not the most experienced C programmer...)

Also - the "01" following the orig_img_size field should probably be a zero=
 -=20
it doesn't seem to hurt the iPod if it's a 1, but in reading the=20
documentation on ipodlinux.org, it should all be zero-padding.

I have been running these tests based off of an up-to-date CVS build (check=
ed=20
out at 9:00 pm MST on 2/17)

Again - thank you for your attention to this.  Let me know if you need any=
=20
more information.

=2DNathan Toone