I have this old CCD image lying around that even older HDD and I'd
like to convert it to ISO:

$ ls -lh *.img
-rw-r--r-- 1 lucio lucio 607M Jan 28  2005 e.i.vol.16.img

$ time ccd2iso e.i.vol.16.img e.i.vol.16.iso

Unrecognized sector mode (0) at sector 0!

real	0m0,110s
user	0m0,003s
sys	0m0,005s

$ ls -lh *.iso
-rw-r--r-- 1 lucio lucio 0 Jan  6 15:03 e.i.vol.16.iso

ccd2iso output no errors, it took almost no time, but it also failed to convert the file.

I can provide you with the IMG file if needed.

Dear Maintainer,
this seems to be an upstream issue.
The ccd2iso author states in the README file [1],
"only single session image supported", maybe this image
was more complex than ccd2iso is prepared for.

There is also an upstream bug report [2], but
the project seems kind of inactive since a few years.

Kind regards,
Bernhard

[1] https://sources.debian.org/src/ccd2iso/0.3-7/README/#L54
[2] https://sourceforge.net/p/ccd2iso/bugs/8/

(Maybe a workaround could be to mount the ccd with cdemu [3], not packaged in Debian,
and take an iso image from the virtual drive.)
[3] https://cdemu.sourceforge.io/