What is "NetMD"?
Announced in mid-2001 and first introduced on the Sony MZ-N1 portable
recorder in December, NetMD is an extension to the Minidisc format
that allows direct transfers of compressed, ATRAC audio from a PC to
Minidisc via USB interface. Audio transfers can be conducted at rates
considerably faster than realtime (up to 64x for LP4 audio on certain units).
Why is it considered a "format extension"?
NetMD equipment requires complementary NetMD PC software for control
and data transfer functions to be conducted. By standardizing the
PC<->MD USB protocol, Sony assures
compatibility between NetMD equipment and NetMD software packages from
various manufacturers.
What NetMD software packages are there?
Commercial
Non-commercial
(Note that none of the non-commercial packages provide
high-speed downloading from a PC or Mac since the secure DRM aspects
of the NetMD USB protocol have not been cracked)
- Open/NMD Project (Open source community/Unix,
Linux and MacOS): In development; currently allows track
titling and renumbering via shell commands.
- Win
NetMD (Christian Klukas/Windows): In development, currently
allows analog, realtime uploading from NetMD equipment to PC. Windows GUI
and command line based versions available.
- Xmd
v0.1 (Open Source Community, Pete Bentley/MacOS X, Darwin,
FreeBSD, etc.): In development, currently only playback and titling functions are
present.
- M3U2Sburner (Paolo Sessa/Windows) M3U2SB automates
the download of mp3 files to NetMD, using the procedure suggested by Dino. It will also extract titles from
mp3 files and put them into the Simple Burner database so they don't
need to be inserted manually.
- SimplerMD (Clint
Mers/Windows) Similar to M3U2SB, SimplerMD automates the
Nero->SimpleBurner route, even handling more songs than can fit on
a single CD.
- GNetMD (Pete Ryland/Unix/Linux). A free suite of
tools for using NetMD on Unix and Unix-like systems. It currently
includes an xmms plugin and a GNOME2.0 GUI and a gnome-vfs layer is
currently in development.
What equipment supports NetMD?
So far:
What restrictions does NetMD impose on transfers?
- Protected Tracks Audio tracks downloaded to Minidisc by
OpenMG Jukebox and BeatJam are marked as "protected" and cannot be
deleted or divided by most Minidisc equipment; only a "check-in" with
NetMD PC software will delete the track. (This feature ironically
makes Minidisc portables with NetMD downloaded tracks as inflexibile
as solid-state MP3 players). Tracks downloaded with Simple Burner do
not have these restrictions however and behave like normally recorded
MD tracks.
- PC to MD Download Only Only audio downloads (PC->MD
transfers) are possible. Presumably for reasons of digital rights
management, audio uploading (MD->PC) is not possible. (If this
strikes you as oppressive, please consider sending polite email to netmdfeedback@am.sony.com; Sony staffers compile and
report customer email comments on NetMD uploading to Robert Ashcroft,
US VP of Portable Audio. We petitioned Sony on this topic last year, but have yet
to see any result).
- SP-mode Quality not Available Users can create SP, LP2
and LP4 mode tracks on Minidisc through OpenMG Jukebox downloads, but
audio imported into OpenMG Jukebox (from CD, MP3, etc. sources) is
converted and stored on the PC only in LP2 or LP4 format ATRAC3
files. So even when these files are downloaded onto the MD as SP mode
tracks, the tracks cannot exceed LP mode quality. NetMD downloads
through Simple Burner create only LP2 or LP4 mode tracks.
What is known about the information transferred over the USB link?
NetMD hacking is still in its infancy. So far, however:
Is there any way of transferring MP3s to MD without using OpenMG
Jukebox?
Dino Inglese, a Minidisc T-Station message board member offers
this tip for using Simple Burner to circumvent OpenMG Jukebox (see his
humorous original posting).
CAVEAT: You will need Nero, and Nero's Imagedrive feature, or
something similar that can create a virtual CD disc image and allow
you to mount it to your desktop.
Five easy steps to a clean and hassle free MP3->MD download
- Open Nero, select Audio CD from the presets and drag all the MP3's you want into it. Nero is far less picky about formats and sample rates. I found this method foolproof.
- Save or 'Burn' your CD to your hard drive (not your burner). Nero will give you a default filename of 'image.nrg'
- Use Nero's Imagedrive (bundled with Nero) to mount the
.nrg (CD-image) you just created. Lets say Drive 'F' for this example.
I am not an expert, but I found these first 3 steps took around 2
minutes or less for a regular size audio CD (i.e. burning and
converting about 10 MP3 tracks to an audio CD 'image' on my hard
drive). I have a 1GHz/PIII, so that helps with the MP3->PCM
conversion times. A faster machine would mean proportionately faster
MP3 conversion and image creation.
- Select your 'virtual F' CD drive in Simple Burner and burn it to Minidisc.
- When you are done, trash the large .nrg file sitting on your desktop.
If your machine is fairly fast then Simple Burner's
CD->ATRAC conversion is done in on-the-fly in RAM with the disk
hardly ticking over at all.
Advantages of this Method
- You are using reliable software.
- Checkin/checkout is avoided.
- Unlike OpenMG, files aren't left all over your hard drive.
- You can delete and re-arrange the downloaded tracks on your MD without having to resort to
connecting it back to your PC.
- It is faster and doesn't thrash your hard drive.
Wouldn't the transfers go even faster with USB 2.0?
Current
NetMD download speeds require less than 20% of USB 1.1's 12Mbps peak
bandwidth:
-
LP4 audio @ 32x download requires only
2.1Mbps (i.e. 66kbps*32)
- LP2 audio @ 16x is
2.1Mbps as well (i.e. 132kbps*16).
- SP mode audio at 1.6x is 2.25Mbps
(i.e. 1411.2kbps*1.6). (Observing this, perhaps driver or interface
problems that restrict NetMD USB transfers to roughly 2.5Mbps really
are limiting the speed of SP mode transfers! If so, the answer is yes, USB 2.0 would help, but
so would simply fixing whatever the USB 1.1 problem is).
What other NetMD FAQs are there?
