Minidisc
Introduction
I've been using Minidisc (MD) for several years now, starting out with an
Aiwa AM-F70.
It's a nice unit with all metal case, a backlit display and wired remote
with full display. I have an inexpensive CD changer with an optical output,
and using the programming features I have been able to put together some
compilation discs that are nice to listen to while working, reading or exercising.
I've also been able to make some interesting environmental recordings with
a homemade binarual mic. As nice as it is, it only records in SP, so a stereo
recording is only good for 74 or 80 minutes, depending on the type of disc.
Its battery life is rather short unless I use the external battery case with
3 AAs, and recording only works at 1x speed, so transferring songs takes
a while.
NetMD
NetMD was the next step
up in features & functionality from the basic Mindisc. It provides
LP2/LP4 encoding for up
to 5 hours of music on an 80 minute disc, and USB downloading from a PC.
I picked up Sony's
MZ-N505 for ~$150 and have been quite impressed. The only downside
is that its software only works within Windows.
OpenNMD was a community-based
project that attempted to build a set of open-source tools to access the
NetMD devices. Although there was some initial success in documenting the USB
command protocols, the DRM and encryption issues were never overcome and the
project ground to a halt. You can still find remnants here and there on the
web.
Hi-MD
Hi-MD is Sony's latest
upgrade to Minidisc technology. It provides new media with 1GB of
storage, higher density storage on original media (300kB), new encoding with
arguably better fidelity, and both download and upload via USB. In addition,
Hi-MD recorders appear as standard USB-Storage devices, allowing arbitrary
data read/write on the minidisc. In late 2004 I bought a
Sony MZ-NHF800
and have been very happy with it. It runs for 30+ hours on a single AA NiMH
battery, and with Hi-LP encoding I can get 35+ hours of music on a single 1GB
disc.
Audio data is still wrapped in complex DRM however, and the only way to
read and write it is via Sony's SonicStage application which runs only under
Microsoft Windows. Despite this, you can see the encrypted audio data sitting
in a directory on the disc, and it is possible to read it. I've documented
some of the details of the data format in several text files, along with a
simple C program which will parse the Hi-MD track data:
himd_info.tgz
Please let me know if you find this useful, or if you have corrections/additions
to make.
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Last Updated
:2005-08-06
Comments to:
Eric Brombaugh