From Winston@21:1/5 to All on Mon Nov 9 21:57:36 2020
I have an image of a damaged DVD+R that has a number of video recordings
on it. They were recorded with a TV DVD recorder, not a computer, so
the file structure should be pretty much consecutive sectors and
consecutive videos, apart from whatever the file system requires.
Unfortunately, many of the unrecovered sectors are low numbered ones,
and the image file doesn't seem to be mountable (or even recognized as ISO9660).
One approach I haven't ruled out is to have the DVD recorder format a
blank disc and copy that to the start of the damaged DVD image. I don't
know enough about video recording to DVD+R discs to know whether doing
that would leave things in a useful state. DVD recorders generally
record programs of not-initially-known-for-sure length, but maybe they
skip over some sectors when they start recording and only fill them in
when the recording has finished and the length is known.
In any case, the alternative I'm interested in at the moment is whether
there's something like fsck that can scan through the image and extract
the videos, similar to the way fsck finds unlinked files and puts them
in /lost+found/? I'm not seeing a /sbin/fsck_iso9660, so it looks like
fsck itself doesn't repair iso9660.
If there isn't such a program already, I'm guessing it wouldn't be all
that hard to write one that searches for file header blocks, if I knew
how to identify file header blocks.