• Full Index
• Complete FAQ
• Disk Topics
• Audio Topics
• Minidisc Specific Topics
• Miscellaneous Topics
• MDLP (``Long-Play'') Mode Topics
• NetMD Topics
  1. What is "NetMD"?
  2. Why is it considered a "format extension"?
  3. What NetMD software packages are there?
  4. What equipment supports NetMD?
  5. What restrictions does NetMD impose on transfers?
  6. What is known about the information transferred over the USB link?
  7. Is there any way of transferring MP3s to MD without using OpenMG Jukebox?
  8. Wouldn't the transfers go even faster with USB 2.0?
  9. What other NetMD FAQs are there?
• Hi-MD Topics
• Beginner Topics

1. 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).

2. 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.

3. What NetMD software packages are there?

   Commercial
   • RealOne w/NetMD Plugin (RealAudio/Windows only): RealAudio has announced a NetMD plug-in for their MP3/streaming media player software. The plugin can be downloaded from within the free version of the RealOne application (download) by following these instructions:

     (Version 2)

     • On the View menu, click Devices.
     • Under Devices double-click Add A New Device
     • On the pop up Preferences Window, under Deivces click Add A New Device.
     • RealOne connects to its mothership server and lists all applicable portable device plug-ins.
     • Click the "Sony Music Devices" check-box. It then asks you to "Click the Install button", do this.
     • When RealOne player completes the download and installation, click "OK" to restart it.

     (Older Version)

     • On the Tools menu, click Check for Update.
     • In the AutoUpdate window, click Devices.
     • Select Sony Music Devices Plug-in and click Install.
     • When installation is complete, click OK to restart RealOne Player

     Sony also has instructions for downloading and using RealOne Player.

   • Sony Software

     • Sonic Stage (Sony/Windows only): Supercedes OpenMG Jukebox (see below) as principal Sony tool for downloading audio to NetMD devices. Ships with 2003 portables (MZ-NE410, ... MZ-N10).

     • OpenMG Jukebox 2.2 (Sony/Windows only): This is the primary tool Sony provides with their NetMD equipment. Also supplied with Sony's solid-state music players (MemoryStick and Network Walkman), it allows downloading of compressed audio to the NetMD unit, as well as titling and track renumbering. OpenMG Jukebox supports the SDMI concept of track "check-out", wherein at most 3 copies can be downloaded to Minidisc before a "check-in" is required (the check-in operation deletes the downloaded audio track from the Minidisc).

     • Simple Burner (Sony/Windows only): This software is shipped with Sony's US NetMD units (download) and simplifies the downloading of tracks from PC-mounted audio CDs to Minidisc. The SDMI check-in/check-out restriction is absent in this software and downloaded tracks may subsquently be deleted from the Minidisc. Unfortunately, Simple Burner does not support SP mode downloads.

   • Beat Jam (JustSystem Inc./Windows only): Supplied with Panasonic's NetMD equipment (mech trans of BeatJam announcement).

   • Muria (Kenwood/Windows Only): Supplied with Kenwood's MDX-J9 NetMD boombox.

   • InterJuke (JVC/Windows Only): Supplied with the JVC SS-NT1MD mini-compo system.

   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.

4. What equipment supports NetMD?

   So far:
   • Sony's MZ-N1, MZ-N707, MZ-N505, MDS-NT1, MZ-S1, LAM-Z1, CMT-C7NT.
   • Sharp's IM-MT880.
   • Panasonic's SC-SV1, SJ-MR250.
   • Kenwood's MDX-J9.

5. 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 [email protected]; 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.

6. What is known about the information transferred over the USB link?

   NetMD hacking is still in its infancy. So far, however:

   • Known elements of the protocol: The Open/NMD project is documenting the protocol as it progresses.

   • Further Protocol Documentation: The FreeMD documentation sheet has low level details of (known) NetMD USB transactions.

   • Encrypted PCM transfers for SP mode tracks: Judging from the careful experiments of Lance Birch, it appears that when NetMD downloading is being used for creating Minidisc SP mode tracks, the OpenMG software decompresses the [always LP2 or LP4 mode] PC file to standard 16bit, 44.1kHz PCM audio, encrypts it, and downloads that. The fact that PCM is being used for recording SP mode tracks is heartening since it indicates that NetMD downloads could retain SP mode audio quality, given the right PC software. Though current NetMD recorders reportedly offer only 1.6x speed downloading for SP mode tracks, USB 1.1's 12Mbps bandwidth would allow downloads at up to 8x realtime. Certainly the technology in Sony's MXD-D40 4x speed CD->MD dubbing deck could be directly applied for this purpose.

     The PCM is encrypted in transit because Sony is trying to prevent unauthorized access to "locked" ATRAC3 audio that may have been purchased from online music distributors; failing to encrypt the PCM data would allow hackers an easy way of making off with an "open" copy of the song.

   • Unadulterated OpenMG file data transfers for LP2/LP4 mode tracks : Birch's experiments reveal that the audio data transferred over the USB link (sent in blocks of 4096 bytes) is nearly identical to the original contents of the OpenMG music files on the PC. Marc Britten comments "the data transferred is not 100% identical, approx every 3 1/2 blocks an 8 byte block of data is inserted (we think this is a key) and the 8 bytes of OMG data that appeared just before that key is repeated."

7. 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

   1. 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.
   2. Save or 'Burn' your CD to your hard drive (not your burner). Nero will give you a default filename of 'image.nrg'
   3. 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.

   4. Select your 'virtual F' CD drive in Simple Burner and burn it to Minidisc.
   5. 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.

8. 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).

9. What other NetMD FAQs are there?

   • Minidisco
   • PlanetMG (general OpenMG FAQ) Sony Singapore
   • Sony ("Ask Sony" interactive FAQ)
   • NetMD commentary at IGN for Men.

• The Sony Europe MD FAQ liberally borrowed from this document, but nonetheless provides a good summary of the more complete document below.
• MinidiscForum.de has authored a German language Hi-MD FAQ.

Return to the MiniDisc Community Page.

Return to the Minidisc Community Page