[Vorbis-dev] Cover art

[Ian Malone]

2009/3/27 ogg.k.ogg.k at googlemail.com <ogg.k.ogg.k at googlemail.com>:
>> serialno -1295842600: granulepos 0 on page with no completed packets, must
>> be -1
> [...]
>> granulepos 0 errors are probably due to the comment packet not being
>> split up correctly (the pages carrying fragments before the end should
>> be granulepos -1), but I don't have a page pulling tool handy to
>
> oggz chop might fix that one.
>

oggzchop didn't, but running through vorbiscomment did (and the
encoded image seems to be preserved).

The "size parsing error" actually occurs in oggz's reading of the mode
section from the end of the decode setup packet and has nothing to do
with the cover art.  Packetno 2 ends like this:

    0996: 00010100 00010110 00011000 00011010 00011100 00011110  ......
    099c: 00100000 00100010 00100100 00000000 00000000 00000000   "$...
    09a2: 00000000 00000000 00000000 00000000 00000000 00000000  ......
    09a8: 00000000 00000000 00000000 00000100                     ....

It looks like the preceding mapping section ends with a sufficiently
long string of zeros that oggz_auto.c gets frustrated in attempting to
read back and until it finds non-zeros in the 32bits that would be the
window and transform blocks. This is liboggz-0.9.8, I see the warning
has been #ifdef-ed out in SVN; the size value is still used to read
mode blocks in.

-- 
imalone