On Fri, Feb 25, 2005 at 10:58:11PM +0100, Vegard Lundby Rekaa wrote:
> > Hi Vegard,
> >
> > what exactly are you comparing with md5sum? I ran into similar problems
> > when having an Iso image. When comparing the original Iso with the burnt
> > CD, I got read/write errors, IIRC. The way around was to mount the CD,
> > do a
> >
> > mount -o loop image.iso /mnt/loop
> >
> > and then do something like:
> >
> > cd /mnt/loop/
> > find ./ -type f | sort | xargs -n 1 md5sum > ~/iso.md5sum
> > cd /cdrom/
> > find ./ -type f | sort | xargs -n 1 md5sum > ~/cdrom.md5sum
> > diff ~/iso.md5sum ~/cdrom.md5sum
> >
> > Hth,
> > --
> > Andreas Rippl -- GPG messages preferred
> > Key-ID: 0x81073379
> >
> Thanks for the reply Andreas.
>
> I'm using the command 'md5sum /dev/cdrw' & 'md5sum image.iso', to visually
> compare the outputs. This have worked once before, do not know how.
>
> The method you mentioned gave no errormessages, and the final result was:
>
> hjem:/mnt/loop# diff ~/iso.md5sum ~/cdrom.md5sum
> hjem:/mnt/loop#
>
> Assuming this means the md5sum's are equal. Does this mean that the CD
> burned is burned correctly, and the command 'md5sum /dev/cdrw' is not
> working well?
>
> But still, the CD's I burn differ from the original. If I burn a
> divx-movie, parts of the burned movie has big errors wich the original
> does not have.
>
> Where is a good place to start looking for reasons for the error?
>
> Best regards Vegard
>
Hi Vegard,
it's been a bit since I had these problems, but I remember that they
mainly occurred because of lead-in/-out. From somewhere on the web I
pulled the one-liner
'dd if=/dev/cdrom | head -c `stat --format=%s ISO_image` | md5sum'
though I never really used it. My reasoning with the initial procedure
is however: if it mounts and each single file has the same md5 sum as
the original in the ISO, the CD is good. You have read each readable bit
on the CD for the verification. I consider this a pragmatic approach
which has worked for me so far.
Regarding the errors in the movie, what command did you use to burn the
CD? And does a verification between the loop-mounted ISO and the mounted
CD show the metnioned errors? Otherwise I have no clues for that
problem...
Regards,
--
Andreas Rippl -- GPG messages preferred
Key-ID: 0x81073379
Attachment:
signature.asc
Description: Digital signature