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MD Data for Music

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Jason

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  • 1 month later...
Guest Anonymous

Why would you want your portable music player to accept data discs, so that you could use your portable as an external drive on your pc? The program still wont let you upload stuff off of the disc through the usb unless they change the program. :cry:

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MD Data v1 had the same capacity as a music MD - 140Mb. MD Data2 had the same capacity as an audio CD - 650Mb.

What if an MD recorder operated more like a portable MP3 player so that you could record uncompressed PCM audio or store many hours of audio in a compressed format such as MP3 (perhaps Sony could offer a software version of the ATRAC1 Type-R codec integrated into the software)?

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Actualy, LP2(132kbps+30 empty bytes for no-MDLP compatibility)x160mins=230.4Mb

Actually, LP2(132Kbps + 30B) * 160m ~= 1239 Mb

Why? Note that the 'b' in Mb is a little b not a capital b. Little b means bit and Big B means byte (8 bits = 1 byte). The calculations look a bit like this:

(132kbps * 1024 / 8 + 30B) * 160m * 60s = 162489600B

162489600B = 158681.25KB = 154.962158203125MB

Which then leaves a bit of room for the TOC smile.gif

I'm pretty sure that MD Data discs (the small ones) only hold 140MB, while an audio disc holds 160MB. Why? I have no idea.

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Let's keep it simple, ATRAC1 (SP) is 292kbps * 75 min = 1314Mb = 160.4MB. MD sectors are 2352 bytes each, carrying 2332 bytes of music per sector, so there are about 70433 sectors per disc. MD-Data sectors are still 2352 bytes each but only carry 2048 data bytes per sector, the rest is checksum/error correction headers. So 70433 sectors * 2K per sector gives 140.9MB. The discs are the same, it's just the way the data is formatted that changes. (But, all MDs have a CD-format read-only TOC that identifies what kind of disc it is. Audio MDs have a different tag on this track than Data MDs.)

When 80 minute audio MDs were introduced, no equivalent change was made for data MDs. If you have an MD-Data drive with hacked firmware, you can probably get a few extra megabytes onto an 80-minute MD. I haven't tried it myself, though I may do so, now that I think of it.

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Guys, I think we've kind of wandered away from the original intent of this topic, which was using MD Data disks for music storage.

Personally, I think it wouldn't hurt Sony much at all to bring out a new type of computer-capable MD system that would use MD Data2 disks. I think the extra storage capacity would definitely give it an edge over the solid-state MP3 players, at least (the HDD-based ones are in a class of their own, I have to say). 650Mb for a few dollars compared to $200 for 128Mb of CompactFlash? I know which one I'd choose.

The only problem is that there's already an established infrastructure based on MD Music disks and it would make it somewhat difficult to not only get people to change over but also to get new people to buy the system. That and Sony recently brought out a glut of new MD recorders, so it's not likely that any major change to the system will come about anytime soon.

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Just like with the MDLP format, Sony can and should make MDData2 enabled portables that can also play current MD Music disks. That way, no one trashed their existing collection and would attract buyers otherwise looking for a bulky, hard-drive based player. Small body and high capacity AND removable media would make the ultimate portable music system.:!:

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Just like with the MDLP format, Sony can and should make MDData2 enabled portables that can also play current MD Music disks.  That way, no one trashed their existing collection and would attract buyers otherwise looking for a bulky, hard-drive based player.

I think Jason's onto something here. Backwards compatibility would be a very important feature for MD Data2 recorders, especially with long-term MD owners who may have large collections of MD Music recordings.

However, I don't think that MD Data2 is likely to be used in a commercial unit anytime soon because, as I said before, Sony have just introduced a whole new range of NetMD models and now is not the time to introduce a new format.

There's also the issue of cost. The higher-density disks would require more precise and accurate hardware (650Mb onto a physical space 1/4 the size of a CD is pretty dense), which would cost more. It's likely that Sony MD Data2 units of comparable size to current models would be prohibitively expensive (then again, so were the original MD units, but there you go). A high price probably wouldn't do any good to Sony's chances of successfully promoting the units.

Personally, I would think that Sony could benefit greatly from using MD Data2 in the future somewhere along the line. The increased capacity (and hopefully not too large an increase in size) would make MD units more competitive with MP3 players.

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  • 1 month later...

It seems to me that a unit that would play MP3s recorded to MD, and MD themselves would be a hot item. It could also be used to carry data, like many MP3 players. The media is cheaper than the current memory cards. Size of the decoder isn't an issue, MP3 players are quite small. CD manufacturers have made the leap, why not MD?

I understand that ATRAC is a compression method too, but wouldn't MP3 give like quality for less disc space?

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Bit for bit, MP3 is inferior to ATRAC. I can agree with Sony's policy not to record MP3 directly to MD, it'd be a waste of space to get something listenable.

Tiny (keychain, etc.) USB/Firewire hard drives are all the rage these days. Sony has totally missed an opportunity to invent/own a market here, and now it's too late.

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  • 2 months later...
  • 2 weeks later...
Guest Anonymous

Actually, LP2(132Kbps + 30B) * 160m ~= 1239 Mb

Why? Note that the 'b' in Mb is a little b not a capital b. Little b means bit and Big B means byte (8 bits = 1 byte). The calculations look a bit like this:

(132kbps * 1024 / 8 + 30B) * 160m * 60s = 162489600B

162489600B = 158681.25KB = 154.962158203125MB

Which then leaves a bit of room for the TOC smile.gif

I'm pretty sure that MD Data discs (the small ones) only hold 140MB, while an audio disc holds 160MB. Why? I have no idea.

I think apart from THe ATRAC Lossy compression it also usess lossless compression that compresses bit like a zip file.

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  • 4 weeks later...

I think apart from THe ATRAC Lossy compression it also usess lossless compression that compresses bit like a zip file.

AFAIK (and you can feel free to correct me, if I'm wrong), MD Data didn't use any type of native compression scheme. It'd simply take too long to compress and recompress every single file that comes through.

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  • 1 month later...

Audio and data MDs have the exact same disc format. There is a status bit on the read-only TOC that tells what kind of disc it is; this is the only difference. The disc sectors are 2352 bytes. In data mode, 2048 bytes are used for data and the remaining 304 bytes are used for checksums/ECC bits. In audio mode only 12 bytes are used for checksum/overhead. This is why calculating the capacity gives you two different results for data vs audio.

In data mode the system acts like any other SCSI hard drive, there is no compression performed unless the host operating system adds it itself.

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