The sound group (1/86th second) constitutes the finest resolution at which the audio stream can be edited. Older consumer grade MD decks have an edit positioning accuracy of approx. 60 msec (5 sound groups) but many modern machines allow edit positioning in units of a single sound group (11.6ms).
In they talk about the bit allocation algorithm, and how it in general allocates more bits than are available, so they have a method for subtracting an offset from the allocations in order fit within their bit budget for a sound frame.
In the zero or simple input case, there can be unused bits in some frames, but since there is an unvarying (i.e. fixed) relationship between 11.6 ms of audio and a 424 byte "sound group" on the disc, the system is not flexible enough to actually take up less disc space when it doesn't need it.
Recordable MD's are similar, but a pre-groove replaces the pits and valleys and an MO coating replaces the aluminum one. When recording, a laser is focused from one side of the disc onto the pre-groove and heats a spot on the MO recording layer to its Curie point while a magnetic field from a head in contact with the other side of the disc aligns magnetic domains within (read: magnetizes) the heated spot on the MO layer (the N/S orientation corresponding to 0s and 1s in the data). During playback the MD machine focuses the laser on the pre-groove again, but at lower power, and the data is read back by measuring changes in polarization of light reflected from the previously magnetized regions (the Faraday effect).
In order to playback both pre-recorded and recordable media, all MD units have a dual function optical assembly which can, depending upon the disc type, detect changes in either reflectivity or polarization.
In terms of audio quality, pre-recorded MDs are in theory no different than recordable MDs, although, as always, audio quality depends upon which version of ATRAC the discs are encoded with. Some users have noticed certain pre-recorded MDs that sound worse than a homemade copy of the same CD with a modern MD recorder. It's likely that the ATRAC encoders used for prerecorded MDs are improved over time just as they are in the consumer units.
Finally, recordable MDs have an extra hole in their case, which is sensed by a microswitch within the MD unit that connects to the REFLECT pin of the microprocessor. It tells the MD player's microprocessor whether signal reflectivity is high (for pre-recorded) or low (for recordable).
Presented here are the results of a small experiment I conducted to compare the raw block error rate of various brands.
The service manual for the Sony MDS-503 Minidisc Deck tells , and from there how to display the BLER (raw block error rate [per second]) as it reads the disk. Using this feature I compared the block error rates of TDK, Idemitsu, Maxell, Panasonic, Sony and Keep blanks.
In he says: "The CD specification allows for discs to have up to 220 raw errors per second. Every one of these errors is (almost always) perfectly corrected by the CIRC scheme for a net error rate of zero."
I have reason to believe that 220 is the threshold for MD as well, since MD uses [modified] CD logic for encoding data on the disc, and since 220 is actually one of the error thresholds used for setting the MDS-503 focus bias.
The un-surprising result: No discs had anywhere near an BLER of 220.
The procedure is to use "continuous recording" in diagnostic mode to make a test disk, then look at the error rate while reading back from the disk.
The table below shows the average and maximum BLERs for each brand. "In", "mid", and "out" refer to the three areas on the disc which are tested by default, they begin at cluster 40, 300, and 700 respectively.
Some discs had been recorded on previously in normal audio recording ("non-continuous") mode. The BLER of these areas was typically 20-50, and always higher than the areas made with "continuous-recording" in diagnostic mode.
The Sony disc was the only surprise, perhaps it had a weak/bad spot. In any case, it was still well within the presumed threshold for CIRC.
I am not sure if comparative quality judgements can be made from these results since the tests were done on three short (approx. 10 second) intervals of each disc. I think the main conclusion is that all the discs are well within the threshold of "identical" from a post error correction point of view.
The other consideration is longevity, and I quote two paragraphs from the excellent book by John Watkinson The Art of Digital Audio where he is discussing the magnetic layer of a Magneto-Optical disc:
Magnetic layers with practical Curie temperatures are made from proprietary alloys of iron, cobalt, platinum, terbium, gadolinium and various other rare earths. These are all highly susceptible to corrosion in air and are also incompatible with the plastics used for moulded substrates. The magnetic layer must be protected by sandwiching it between layers of material which require to be impervious to corrosive ions but which must be optically transmissive. Thus only dielectrics such as silicon dioxide or alumnium nitride can be used.
The master is developed and electroplated as normal in order to make stampers. The stampers make pre-grooved disks which are then coated by vacuum deposition with the MO layer, sandwiched between dielectric layers. The MO layer can be made less susceptible to corrosion if it is smooth and homogeneous. Layers which contain voids, asperities or residual gases from the coating process present a larger surface area for attack. The life of an MO disk is affected more by the manufacturing process than by the precise composition of the alloy.So, perhaps, more expensive discs might last longer (rather than have a lower initial error rate). I don't know the real situation though, maybe all the manufacturers have excellent quality control.
There are two potential problems with fragmentation: interruption of music due to excessive seeking, and loss of free space.
Concerning interruption of music, fragmentation alone will not cause a problem. A typical MD player can buffer 10 seconds of music and read the disc at 150 Kbytes/sec. (roughly the 1x CD data rate) which is over 4 times the MD audio rate. You will only have problems if it takes the player more time over any 10 second period to access and read segments of music than it does to play them.
My simple tests with the '503 showed that it could not keep up with an arbitrarily long string of 2 second segments located at alternate ends of the disc (on a 74' MD), but that it could with 4 second segments. Assuming a full stroke seek takes about 2.3 seconds (measured by listening to the unit seek) and 3 seconds of music can be read in about 0.7 seconds, it would seem that the smallest segments a player could keep up with on a continual basis would be about 3 seconds long if they were located at worst case locations on the disc, and would cause the player to be constantly seeking and reading. You would need to have a string of segments this size or smaller, for at least 10 seconds duration, at opposite ends of the disc, to cause a problem.
This simply cannot happen through fragmentation alone since all free list segments are at least 12 seconds long (see below). A worst case seeking condition that caused intermittent muting could still be created if 3 second or shorter segments from opposite ends of the disk were catenated together, but free list segments are allocated in sorted order (see FAQ section on ), so that unless you are trying to create such a pattern, you are rather unlikely to make one in the normal course of editing.
The free space problem is caused by unused segments of disc space less than 12 seconds long that are not available for reuse. My simple tests showed that whenever the MDS-503 could coalesce space it did, so that lost space is only a problem when many small unused segments less than 12 seconds long are scattered throughout the disc, not adjacent to any existing free space. It is possible that in a normal editing operation of deleting dead space between tracks, up to 12 seconds per track could be lost, and on a disc with 25 tracks that would be 5 minutes lost to fragmentation. Though this does not seem troublesome, one real problem may occur in a sound effects application where all the tracks are tiny (< 12s), since if you were to delete every other track, nothing could be coalesced and there would be no change in the amount of free space.
Though the degree of fragmentation depends upon your recording and editing patterns, I cannot see it causing problems in any but extreme circumstances. It should also be noted that all fragmentation is eliminated when an "Erase All" operation is performed. This restores the disc to a single TOC entry containing all the free space.
However, Arnaud Devilder (MPO MD disc sales manager) says: "I have to say that these products are only MARKETING. Avoid using them, we saw in our test labs that these products are very bad for your hardware."
A very high durability of the [magnetic head] contact cycle can be achieved, e.g., more than a million passes.Taking the worse case scenario, an MD machine left in record-pause mode at the lead in (i.e. innermost) area of the disc [diameter: 32mm] and running at the highest linear velocity (1.4m/sec) would spin at [1.4/(.0323.14159) 60] = 836 rpm. At this speed, 1 million revolutions [passes] would take approx. 20 hours. So, record-pause for several hours is okay. A day or two is probably not.
Here's a tip when recording a CD unattended: put the CD player in repeat-all, this will cause the MD player to record to the end and stop (rather than go into record-pause). You can easily delete the extra tracks later.
A found that subjects did not find a difference between ATRAC processed music and its original, but could readily spot the difference when a special test signal was used for the comparison.
However, one significant difference with DAT is that differences with the original increase in each subsequent copy generation, even when recording digitally. Each time the MD is played, a full 16-bit data stream is regenerated from the compressed data. Each time it records, the input data stream is recompressed. See ATRAC below.
Both are data compression algorithms, used to store the information content from a stream of 16-bit samples in fewer bits. The purpose of compression is to reduce the rate at which the disk has to deliver or record bits, and to reduce the total number of bits stored. There are many compression algorithms. The ones used for computer data (for example in archiving programs) are lossless; the result of decompression is identical to the input.
PASC and ATRAC are both "lossy" algorithms. In order to get greater compression, they do not attempt to preserve every bit of the original data, but rather only the acoustically "important" bits. Considerable cleverness goes into finding the sounds masked by properties of the human auditory system, ones that you would not hear even if they were reproduced. By all accounts the two schemes do amazing well, considering they operate in real time.
See the for further technical details.
44100 samples/sec (incoming single channel rate)
/ 512 samples/soundgroup (giving 86.133 soundgroups/sec/channel)
2 channels (giving 172.266 stereo soundgroups/sec)
212 bytes/soundgroup (giving 36.5K stereo bytes/sec)
8 bits/byte (giving stereo bits/sec)
= 292162.5 bits/sec.
has a system offering 18:1 compression, pitched as something of an alternative to MP3.
The next question then becomes, why not copy the compressed data directly, thereby avoiding the asymmetry of compression and decompression? Unfortunately, consumer grade MD machines do not provide access to their compressed data, nor do they provide a way of directly recording compressed data, even if it were available. The S/PDIF digital interconnect only carries data in the linear (PCM) format. Professional machines however (such as the with direct ATRAC I/O) do allow exact bit for bit MD copies to be made.
Every component of the chain from the DAC to the eardrum is important to good sound reproduction. All elements other than the compression algorithm must be held constant before A: B comparisons are made, for example.
The decoder (playback) side of ATRAC has a fixed structure, and though ATRAC chips are all generally expected to decode with nearly the same quality, increases in digital signal processing accuracy may allow slight audio quality improvements (if those improvements have not already been made to modern ATRAC chips).
Since the ATRAC encoder plays the largest role in how an MD sounds, the implication for making digital copies between two MD units is to use the older unit for playback and the newer one for recording. When making analog copies, the relative quality of the A/D and D/A converters must be born in mind.
In general, all ATRAC versions are fully compatible with each other. However, if you play or record something with 1.0 the result will be rather poor no matter from which version the source came from or goes to. If you take a higher version the result is generally be good enough, when you use ATRAC 3.5 for either playing or recording it gets even a bit better. For portables and car-players with 3.0, the weakest link is the A/D converter.
The practical result: buy a 3.5 or better for 'home use', record there, and you get better quality in your 3.0 portable or car-player.
Translated by Felix Gers.
The ATRAC encoder removes information from the audio material in order to store it on the MD (5: 1 compression with loss). To make better MD recordings from CD, connect the MD recorder to the CD player via a digital connection (if possible). Thus, the ADC (poor in the first generation machines) cannot affect the sound quality. Otherwise, when recording via the analog input, make sure to adjust the manual recording level on the MD machine so that the meter peaks just above -12 dB (on the Sony MZ-1, never enable the AGC for CD recording).
One advantage of analog recordings is that MD recorders flag them "SCMS-penultimate", meaning that a digital copy can be made of them. One disadvantage of analog recordings is that track marks will be laid down based upon the recorder's detection of silences in the analog source (depending upon recorder settings and capabilities); this is less reliable than using the digital indications of track changes available in an S/PDIF (digital) signal from CD players.
Regarding the 'R30: A user connected a 303 to the R30 using a POC (optical) cable and compared the two meters. The result: Just consider the top bar to be 'digital over' and try to adjust your level in such a way that the second bar doesn't light up too often when recording from an analogue source (even less when recording live). That should do it. Compared to the MZ-1 the R30 meter is not very useful.
Crutchfield's is devoted to analog vs. digital recording to Minidisc.
See also the .
Regarding the occurrence of outright bit errors due to a marginal cable: S/PDIF contains only parity information, there is no error correction capability. If the errors are bad enough to cause bits to arrive with incorrect values, the likely result is that the digital audio receiver will not be able to lock on to the signal.
A goes into further detail about S/PDIF, and has some comments about why jitter is not a problem even in equipment without buffers. Another goes into great detail about S/PDIF, even giving schematics for AES/EBU <-> S/PDIF conversion. Finally, Digital Domain has written a very in digital audio systems.
A cheaper route, if you're willing to do a little electronics work, is to follow .
What follows is a discussion of audio digital interfaces. These interfaces come in 2 classes, optical and electrical.
The optical format has two connector types: the small, squarish "TOS-link" connector and the optical miniplug, which has the same connector dimensions as a normal (electrical) mini-plug. You can buy optical cables with any combination of these two [male] connectors at the ends. TOS-link is usually limited to maximum cable lengths of 10 to 15 meters. The Sony part numbers for the optical cables are as follows: miniplug/miniplug: POC152HG, miniplug/TOS-link: POC151HG, TOS-link/TOS-link: POC-15HG. These cables can be ordered from Sony Parts (see below).
There are two electrical formats. [the following excerpted from the DAT-link manual]
SPDIF: (Sony/Philips Digital InterFace): This is the interconnect that is most often used on consumer DAT machines. The connectors are standard RCA phono connectors. This type of connector may also be lableled "IEC Type II" or simply "Digital I/O". Standard analog phono cables can usually be used for the digital data, however some cables that are designed for analog may not be able to carry the high rates needed for the digital data, especially over long distances. Many high-end audio stores carry special digital phono cables that solve this problem. [The pro-audio FAQ says not to use audio cables, but that video cables will work].
AES/EBU: This type of cabling is most often found on professional equipment. It uses three-pin XLR connectors. Cables designed for analog applications work fine for AES/EBU connections as well. However, note that shielded cables (most cables are shielded) must be used, otherwise unacceptable levels of radio or TV interference may be generated. This type of cabling is the preferred choice for long distance runs between digital audio equipment.
It is important to realize that there are subtle differences in the control information that is sent along with the audio data on these different connectors. The two main formats of this information can be broadly categorized into Consumer and Professional. For most applications, if you are using the SPDIF or fiber-optic connections, the consumer format applies. For AES/EBU connections, the professional format applies. Some DAT machines will not operate at all unless the correct format is used.
A conventional 16/20/... bit DAC uses resistive dividers to add a value proportional to the bit significance of each bit to its output voltage. As more bits are added to the DACs resolution, the more significant bits' accuracy must be improved to at least the value of the least significant bit, or there is no point in increasing the resolution. It is quite difficult to make a resistive divider network with the required accuracy.
With a 1 bit DAC, the output voltage is produced by pulse width modulating a single fixed voltage. The accuracy is determined by the stability of the clock that times the width of the pulses - it is not difficult to very accurately time duty cycles using a clocked counter. All that is needed to increase the resolution of a 1 bit DAC is a faster clock and a counter with more binary digits. -Colin Burchall
There are two classes of DACs. One-bit DACs and multi-bit DACs. A 20 bit DAC is (theoretically) better than a 16 or a 8 bit DAC. You can't compare them with one-bit DACs because they use another principle to convert from digital to analog. Multi-bit DACs always convert different values for the same time period. One-bit DACs convert the same value with different periods of time.
Multi-bit DAC: Fixed time period, varying voltage/current.
One-bit DAC: Fixed voltage/current, varying time period. -Ralf Kuchenhart
Modern Sony portables (MZ-R900/700/500 and later) have an improvement to their skip resistance called "G-Protection", Sony describes it as follows:
For the first time in MiniDisc players/recorders, Sony offers Skip-Free G-Protection technology. Now you can jog with it, blade with it, board with it and enjoy other favorite activities while listening to uninterrupted, skip-free music. The G-Protection technology recovers laser position 10 times faster than previous designs! So it can withstand the impact of actual jogging: 8G impacts at 3 times per second.
Eliminates or reduces skipping during many active uses.
The provides a good basis for understanding how this feature works. ATRAC (and other transform audio coders) store audio in the frequency domain. The samples are stored as floating point numbers, with an exponent and a mantissa. The so-called Scale Factor is the exponent, which is stored in 6 bits, giving 64 (2^6) possible values and yielding final sample values in the range of -120dB to +6dB. Each Scale Factor step is 2dB. During an SF Edit operation, each soundgroup is read in from disc, the Scale Factors within it are incremented or decremented by a certain amount, and it is written out again. It's a much cheaper operation computationally than decoding to the full waveform, scaling it, and then recoding it.
Scale Factor Edit does have a limitation: If you use Scale Factor Edit to decrease volume to the point that some Scale Factors in the signal become zero, the information in those samples is lost and cannot be restored by a subsequent Scale Factor Edit operation to increase volume. Likewise, if Scale Factor Edit is used to increase volume beyond the point at which some Scale Factors in the signal attain the maximum possible Scale Factor value, previously distinct Scale Factor values will begin to "max out" at the highest value and the signal's fidelity and dynamic range will decrease unrecoverably. Due to this limitation, SF edit operations that taper track endpoints to or from zero volume cannot be reversed.
MD drives certainly buffer during recording, otherwise MDs could not make recordings over discontiguous free blocks on the disc due to the dead time during interblock seeking. The bigger problem is, what happens when the recorder is jarred and the hot laser skids across already recorded material? One of the brochures for the professional MD units mentioned that they had a special circuit to cut the laser power when any shock occurred, thereby avoiding overwriting [much] already written material. On the normal consumer portables, you could probably lose some material when a shock occurs during recording. In any case, they're able to recover and get back on track.
Modern Sony MD decks also have a hidden super UNDO function. A user describes how to on modern Sony MD decks.
If you have an older machine without an ``UNDO'' function, there are two approaches. If you've got an MDS-302, 303, S35, or S37, try this first:
This machine doesn't have a specific undo function, but it can be made to forget about the edits in a simple manner, without having to open the unit. When you have deleted a track by accident for example, you just unplug the unit. Make sure that the unit isn't playing or recording before you unplug it (press the Stop button first). Now wait for about 30 secs for the power supply capacitors to discharge. Press the AMS knob, and while holding it, plug the unit back in. If you're lucky the recorder will enter in Test Mode (it always did this correctly in my case). Now you can simply press the Eject button to remove the minidisc without the new TOC being written to disc! The reason that you must enter Test Mode is because when you just plug the unit back in, it still remembers that the TOC isn't written yet. The moment you plug it back in the new TOC is written to the disc and you have lost the deleted track forever! After you have removed the disc press the Repeat button to leave Test Mode. You have to unplug the unit and plug it back in to enter the normal user mode.
-Steven Scholte ()
The following is a method that will work for all machines, but it requires more work:
I'm sure everyone who has a Minidisc deck has done this. You're editing down a disc, splitting blank spots away from other tracks, then deleting the blank spots - and all of a sudden, your quick fingers just deleted the track, rather than the space. This is usually followed immediately with loud obscenities. :) I hear that some of the new units have an "undelete" feature, but my MDS-302 does not have one.
I did this once (twice actually, within a half hour) while editing down a disc on which I had made a one-time live recording of a choral performance, that could not be re-recorded. Desparate, I remembered that the MD unit only wrote the TOC (Table of Contents) to the disc when the disc was ejected. When you do edits, it's actually only changing pointers in memory, which are then all written at once to the disc when it's ejected.
With this in mind, I unplugged the unit while it was still turned on. I removed the case, and examined the drive mechanism. There is a large gear at the back, and I found that by turning it by hand, it worked the eject mechanism, and the disc was slowly ejected as I turned it. Once I had the disc in my hand, I plugged the unit back in.
I figured it would be confused, so I took a blank MD, slid the write-protect tab open so that it wouldn't write to it, then plugged it into my recorder. Once it figured out that it had a new, fresh disc, I then ejected it and re-inserted the original disc with the live recording on it.
As I had hoped, the disc had been restored, and all the edits I had made (including the one wiping out an entire track) had been forgotten.
Now, whenever I do any editing, I periodically eject and re-insert the disc (just to write the edits to disc). This way, if I DO mess up and have to go through the manual eject sequence again, I won't lose ALL of my edits.
-Scott MacLean ()
The MDS-501 can me made to "forget" about editing simply by unplugging it. Even if you turn it back on and eject the same disc (without removing it the hard way) your edits will be lost.
For the MZ-R30 portable, this will work:
The MZ-R30 writes the TOC-Area after pressing the Stop-button or, if batteries are in use, after disconnecting the AC power adapter. After deleting anything, the R30 begins playing the succeeding piece automatically. As long as the R30 is playing, the TOC-Area is not written. To Undo a delete, take away all power sources while the R30 is playing; the TOC-Area will be the same as before the deletion took place. But note, if you use the AC power adapter and LIP-12 or LR6 AA in the supplied battery case, you must first remove all batteries before disconnecting the power adapter, otherwise the TOC-Area will be written right after disconnecting the power adaptor.
SCMS stands for "Serial Copy Management System" and is the way copies of digital music are regulated in the consumer market. In essence, it prevents more than one generation of digital copying. It is implemented through information that is added to the stream of data that contains the music when one makes a digital copy (a "clone"). When making an analog copy only the music is transferred so there is no SCMS, and copying is totally unrestricted. Decks considered "professional" -- usually more expensive and with pro features, such as balanced XLR input/output -- are exempt from needing SCMS. Different manufacturers' pro decks behave differently: some allow one to set the SCMS code how one wishes, some only if the pro i/o is used, and some ignore it completely.SCMS Bit Definitions: Bits Meaning Explanation ---- ------------ ---------------------------- 00 Permitted No restrictions at all 11 Restricted Allow 1 generation 10 Prohibited Do not allow copies SCMS Operation on consumer decks: Source Recorded on copy -------------- -------------------------------- Analog input 11 CD 10 Digital, 00 11 or 00 (depending on model) Digital, 11 10 Digital, 10 Will not record Dubbing MD to MD with SCMS: Play Deck Connection Record Deck SCMS Problem? -------------- ------------- -------------- -------------- Consumer MD Digital Pro MD No Pro MD Digital Consumer MD No Pro MD Digital Pro MD No Consumer MD Digital Consumer MD Yes any MD Analog any MD No
SCMS does not limit the number of times you can copy a certain CD or MD. For instance, you can make 20 copies of a CD - you just can't copy any of the 20 copies.
It is ironic that if SCMS is to prevent unauthorized duplication of copyrighted information it has the above loopholes that a professional ripoff artist can easily use. And it is unfortunate that supposedly legitimate users, such as musicians recording their own music on cheaper, consumer decks, are restricted in the number of generations they can copy their music. [jfw/rg]
You can also try here:
Gallery of Consumer Electronics
663 N Michigan Ave
Chicago IL 60611
(312) 943-0817 (fax)
Tracy Outlet Center
1005 Pescadero Ave., Ste. 183
Tracy, CA 95376
You can also get Sony service manual and parts/accessories at:
Sony Electronics Inc.
National Parts Center
8281 N.W. 107th Terrace
Kansas City, Missouri 64153
phone: 800-488-7669 (parts)
816-891-7550 ext 33 (publications/manuals)
In Europe, you can order Original Sony Parts here:
Gehado Electronic Service GMBH
germany, Tel: +49-231-937-000-21,22,23...28
Schaltungsdienst Heinz Lange
Zehrensdorfer strasse 11
Germany, Tel: +49-30-72-38-13
In the US, Tritronics carries Service Manuals and parts for Aiwa, Sony, Sharp, JVC, Panasonic, Denon and others:
1306 Continental Drive
Abingdon, MD 21009
Telephone: 800 638 3328
Sony Electronics Inc.
Factory Service Center
Sony Service Center
390 University Avenue
Westwood, MA 02090
Phone: +1 800 282 2848
Fax: +1 617 329 1345
Sony also has a National Direct Response Center at 800-222-7669, representatives there can help you troubleshoot problems with Sony equipment.
Try one of these for Sharp equipment (or call 1-800-BE-SHARP and use your touch tone phone to find an authorized service representative near you):Video Electronics & Parts
212 243 0786
In the UK, Sharp (and other maker's?) parts can be ordered from:
(A Dixons subsidiary): 0870 9090444.
Or here for direct factory service:
Sharp Engineering SEK
Kitaku, Higashi Tabata
Enclose a note describing the problem in simple and clear English.
I did find the Napa Valley "Cassette Crate 12", a single-shelf crate that (obviously) holds 12 cassettes, and it clearly would hold about twice that number of MDs in their little sleeves. So presumably the 2-shelf model that I got might be called "Cassette Crate 24". And any other brand would be just as good.
If it helps, the Napa Valley outfit is:
Napa Valley Box Co. Inc.
11995 El Camino Real
San Diego, CA 92130
I am using a plastic rack that is actually meant for DAT-tapes. You know the type that c-cassettes used in the history. You can hang the rack on the wall and attach several of them together... Two MDs fit into a space for one DAT. It might not be very nice looking furniture in the living room, but for example in a studio it is actually quite handy as when You hang the racks so that You can store the disks horizontally you can also easily read the labels... -Janne Auvinen Turku, Finland()
DAT cases work the best for storage. I bought mine in San Fran for under . It will hold a total of 80 MD's. It is heavily padded and comes with a durable shoulder strap and casing. -
Thomas Halasz () reports that the hard plastic box that comes with Ferrero Roche Chocolates (Italy) is the perfect size for holding 25 MDs, sans jackets. The box is transparent with an articulated lid. The chocolate is good too.
Other users report: ``I just stick my MD's Sans case in a plastic 3X5 index card box. It holds 25, fits like a glove, and cost .'' and ``Here's a really cool MD storage idea (at least I think so); the wood crates that hold three bottles of wine with sliding wooden covers and wooden dividers. Fits perfectly, one box holds lots of MD's. Just watch out for slivers.''
Yet another simple suggestion: Just glue a stack of MD cases together. ()
You can also check the MD page for suppliers of cases.
Here are some pointers for printing labels for the Minidiscs themselves using the blank stickers that come with each MD blank disc:
These are the dimensions needed to print on the labels that come with Memorex Minidiscs using Microsoft Word. The dimensions are:
Top Margin: 0.57"
Side Margin: 0.91"
Label height: 1.91"
Label width: 1.4"
Number across: 1
Number down: 1
From the Labels dialog, click the "Options" button and then the "New Label" button and you will see a window with entry boxes for the above data along with a text box where you can enter a name for this type of label. (I used "Memorex Minidisc".) Click the "OK" button and the label data will be saved for future use.
Note that the actual dimensions of the label are slightly different than these (probably because Word and my printer don't exactly agree on how long 1" really is...) but these are what I found to work after some trial and error. Note also that this is for the main label only - also on the same sheet are 3 skinny labels that aren't printed to (but are accounted for in the side margin). If your printer will feed such a small sheet (which mine, surprisingly, did) then you're all set. If it won't, then you can tape the sheet to the top, right corner of a regular piece of paper and feed that through.
-Ross Miller ()
Though ATRAC2 was never incorporated into an exported Sony product, the Sony states "a second format, called ATRAC Data, is used by Sony in a digital music distribution system offered via the SkyPerfecTV satellite service in Japan". This "ATRAC Data" is most likely ATRAC2, however Sony's makes no mention of "ATRAC Data", and certainly any audio stored on a Minidisc would have to conform to existing ATRAC standards for Minidisc.
ATRAC3 (as described briefly by and in more detail by a (PDF)) appears quite similar to ATRAC2 in structure. The only difference is that ATRAC3 again uses the original ATRAC's QMF (Quadrature Mirror Filters) for band splitting, whereas ATRAC2 used PQF (Polyphase Quadrature Filters). Given the popularity of MP3, and the fact that there was no existing ATRAC2 format to be incompatible with, it seems plausible that marketing arguments, as much as anything else, convinced Sony to rename their high compression codec ATRAC3.
Sony has measured ATRAC3plus fidelity at 64kbps and found its (mech. .) Sony's current PC software produces ATRAC3plus output at user selectable bitrates of 132, 105, 66, 64 and 48 kbps. AV Watch Japan has done a bit of and comparison with ATRAC3 (mech. .) ATRAC3plus is described briefly on (local ).
The non-LP machine's display of the track name is also likely to show the characters "LP:" at the beginning of the title. These characters are put there by MDLP recorders in their factory default setting (this feature, called "LPstamp", can be disabled). MDLP machines will also strip off the initial "LP:" (if LPstamp is enabled) when displaying LP track names.
After loading you can listen to the following audio snippet of "Sichia". The example was intentionally chosen from difficult material, in order to highlight the audio quality differences at various bitrates.
Getting the PC version of RealProducer to encode at these rates is a bit tricky, since the PC GUI is neither convenient nor obvious. Here are the steps:
It initially displays a "New Session" dialog box, asking for the name of the .wav file you wish to convert, and the name of the target ".rm" file you wish to create; browse to these or fill them in.
Here, the bitrate is selected in an indirect fashion through the "Target Audience" checkbox. This checkbox is intended for you to specify the sort of network bandwidth your audience will have. What it does is select ATRAC3 bitrate of the file you will encode.
This leads you to the Target Audience Settings dialog:
in which you can set your preferred ATRAC3 bitrate for each of the possible network speeds. However, with the "basic" version of the program, you are not allowed to change anything in this dialog box. It is only useful for selecting different target audiences and then seeing what ATRAC3 bitrate each corresponds to. When encoding Stereo Music, the correspondences are as follows (we include here the "Sichia" clip mentioned above, encoded at each bitrate for comparison):
(ATRAC3 Block Diagram)
In DWDD, the recording medium is actually a 3 layer sandwich consisting of (from top to bottom) the displacement (aka readout) layer, the switching layer, and the memory layer. When the switching layer is heated to its Curie temperature (which is below the Curie temperatures of the memory and readout layers), it allows a small magnetic domain in the memory layer to appear larger than it really is in the readout layer.
The Magnetic Super Resolution technique was first discovered by Sony, and Sony that references 4 Canon patents. See for further information.
[Magneto-optical systems like Minidisc that use Magnetic Field Modulation are able to record domains smaller than the laser spot because they actually create crescent shaped regions that are magnetized as the recording layer cools below its Curie temperature. The size of these regions is determined by the switching rate of the signal sent to the magnetic head. See Sony's ].
Several changes were responsible for the increase in capacity:
Note: (1)As stated in Sony literature
The first generation ATRAC was a far cry from the quality of Type-R DSP for ATRAC introduced in 1998, and in fact it was probably similar in quality to MP3 at 128kbps. This view is supported by conducted on Sony's behalf by and . Both reports showed a near equivalency of ATRAC3plus at 64kbps with MP3 at 128kbps:From ITS Test Report, showing near equivalency of
If indeed ATRAC3plus at 64kbps is equivalent to MP3 at 128kbps this is good news for two reasons: 1) 1GB blanks will be able to hold 34 hours of audio equivalent to [email protected] and 2) ATRAC3plus at 256kbps should be quite good, and quite likely better than original ATRAC at 292kbps.
(Japanese) has this diagram (click to enlarge):
Unless you have however, the only route onto or off of a Minidisc is through realtime recording and playback (except for the ). And NetMD or not, you can't get at the compressed audio directly from a computer. This is the biggest functional difference between MD and computer connected MP3 players and CD-R burners.
Seriously: one must weigh this question for themselves. There are tons of happy MD and CD campers out there, just consider the usage patterns that are likely to be convenient for you and whether MD or CD fits them better.
See also the .
As for direct transfers from Minidisc to PC, such a capability would be great! (And a asking them to add it.) Unfortunately Minidisc was designed with a so-called "audio/data firewall" that prevents the ATRAC audio data on MDs from being accessed directly by computer. This was done to comply with Recording Industry concerns over music piracy. (The fact that Sony has introduced the [a portable MP3/audio CD player that is fully USB connectable for seamless audio/data transport to/from PC] is an irony due to the CD's grandfathered status as a computer peripheral that appeared before the Home Recording Rights Act [a law that impedes consumer bit for bit copying of audio content, see ]).
One year after Minidisc appeared, Sony announced MD Data -- it consisted of a slightly modified Minidisc blank and the , an MD data drive with SCSI interface. This permitted users to use MDs as a computer data storage format. Unfortunately, due to the requirement for a firewall, MD Data drives cannot read or write ATRAC data on Audio MDs.
Despite the built-in firewall, one company does sell a system for direct computer access to ATRAC audio data. By modifying the firmware in Sony's original MDH-10 data drive, EDL in Britain has been able to create the , a PC package allowing direct computer based transfer of ATRAC from MD to PC, with ATRAC to .wav file conversion done on the PC. The system is intended for audio professionals (radio stations, etc), and carries a price tag (US00) to match.
Yes, the Hi-MD format allows you to use your Hi-MD recorder as 1GB external USB drive. Prior to Hi-MD, [std-MD] audio MDs were not capable of holding computer data. A now-obsolete branch of std-Minidisc, called MD Data, was capable of holding 140MB of data per disc (functioning much like a Zip or floppy disk, but using Minidisc technology). MD Data discs were not compatible with std-MD audio discs. You can read about the old MD Data units in the .
that recorded images to an MD. What is the difference between that technology and the technology used to record images to a CD-R?The MD and the 3-inch CD-Rs used in the Sony CD1000 are completely different. MD: magneto-optical recording on cartridge enclosed 64mm disc. CD-R: dye based (i.e. optical) recording on an unenclosed 300mm or 80mm (3-inch) disc. The two formats are completely incompatible.
?Hardly. There would be multiple problems trying to play a bare MD in a CD player:
The MD and mini-CD track pitch and optical parameters (spot size) are the same however.
If it's a USB to digital (e.g. TOSlink) PC-Link it will not work on those rare MD recorders (e.g. MZ-R5ST) that have only microphone or analog audio inputs.
Copying Status: Public Domain. However, no liability is accepted for the correctness and safety any procedures or advice given here. This FAQ is distributed in the hope that it will be useful. Also, please include a notice that this file can be found at in any copies that you post.
As always, I would be much obliged for any updates and corrections from Sony Engineering. -