[vorbis-dev] ogg file header?

[Bob Kojima]

>
>There's quite a lot you have to do to handle all the cases. For the
>most common case, you just have to fix up one or two pages, but it's
>not really worth implementing that case seperately (I found out, I tried
>it). It's best to just implement everything (i.e. the most complex case),
>and use that all the time.
>
>See vorbiscomment (vorbis-tools/vorbiscomment/vcedit.c) for details on
>exactly how to do this (in C. Translations to other languages should
>be straightforward). This actually does _more_ than required (though not
>much more) in order to fix up some streams which old/broken encoders
>produced. I can explain any particularly confusing bits of the code
>if you need.
>

i have looked at vcedit.c and the following document: 
http://www.xiph.org/ogg/vorbis/doc/framing.html  these helped quite a bit.

a few questions though:

i notice that when ever you make a new ogg file with oggdrop it sets 
page_segments to 0x11.  does this suggesting that in the worst case no one 
is going to add comments that are longer that 17 * 255 so you always set 
page_segments to 0x11?  this must be the minimum expected because the 
document says that the max is 255 * 255.  is the 'complex case'  when 
comments get > 17 * 255?

can some one point me to the code were the page checksum is computed?  i 
understand how to do checksums, but i would like to look at some code to 
see exactly which bytes are being used to compute the checksum.  right now 
i'm using byte 80 (where 'OggS' begins) to the 0x01 stop byte at the end of 
the comments right before the 0x05 vorbis.  these must be the wrong bytes 
cause my checksum is not correct.

thank you,

bob

¤º°`°º¤ø,¸¸,ø¤º°`°º¤ø¤º°`°º¤ø,¸¸,ø¤º°`°º¤øø¤º°`°º¤

Bob Kojima
ko at fial.com
http://www.bong69.com
http://www.vw-pix.com

Fial Incorporated
4343 S.W. Corbett Ave.
Portland, OR  97201
503.227.7083
http://www.fial.com

--- >8 ----
List archives:  http://www.xiph.org/archives/
Ogg project homepage: http://www.xiph.org/ogg/
To unsubscribe from this list, send a message to 'vorbis-dev-request at xiph.org'
containing only the word 'unsubscribe' in the body.  No subject is needed.
Unsubscribe messages sent to the list will be ignored/filtered.