The Sony Hi-MD recorder, particularly the MZ-RH1, is a marvel.
However, the Hi-MD format has an Achilles Heel: There is no way to
recover data from a corrupted Hi-MD disc. No tools or procedures
exists to help you when the disc can't be read.
The most common disc problem is caused by low power at the end of a
recording. The Hi-MD machine waits until recording is stopped to
write the table of contents (TOC) entry. This information tells the
Hi-MD where on the disc the recording is stored. When there isn't
enough power to write the TOC, the entire recording is lost.
A recorder that uses flash memory has problems when the battery power
runs low, too. The difference is that there are many effective,
inexpensive recovery tools to retrieve data from flash memory. When
these don't work, there are commercial services that specialize in
data recovery from flash memory.
So if you plan to use a Hi-MD recorder, keep close watch on the power
level of the battery.
I've heard from several individuals doing field work in South America
that the Hi-MD disc is proving to be more susceptible to contamination
from dirt than the old standard minidisc machines were. This makes
some sense, since the new disc packs 5 times more information than the
standard minidisc held onto the same size disc. The sites where data
is written are smaller, and the tracks are closer together. A little
dust could render the disc unreadable.
Flash memory, on the other hand, is not very sensitive to
contamination from dirt, mud or fresh water (salt water is a different
story).
Rob D. has a large number of Hi-MD recorders in use by his students.
Rob, what is the failure rate of Hi-MD discs in your classes?
--oryoki
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