cool new product: prtbl Cd player that plays MP3s

[bongo]

MPTrip Discman
$115

Now you can record the MP3 files to a 650 megabyte CD-R or CD-RW and play them directly on our MP3 player. Each CD-R or CD-RW can hold more or less 160 songs, which can be arranged in different directories in the order that you want. Of course it plays regular audio cds.
http://www.easybuy2000.com/store/pro...3_discman.html


No, I am not selling it but am thinking about buying it. There is a FAQ page link on the above page I added which has some interesting factoids, but the but the one that really caught my eye (in a negative way) was this:

"1b.)Burn the CD-R/CD-RW at 1 or 2x (speeds) .If you burn them at 4x it will NOT work"


From a strictly technical point of view, what possible difference can the speed of the burn make on a CD rom reading, I mean once it is burned, IT IS BURNED....right?

So how can they say it won't read a disk burned at 8x, but will at 2x?? curious

thanks





[This message has been edited by bongo (edited 19 July 2000).]

[thecurse]

i talked to my friend who lives in hk and there are currently a few different portable cd based mp3 players avaible. my complaint about the first generation ones are the lack of displaying the song name. i will hold out for a while and just keep using my test machien at work as my mp3 player.

[spoogenet]

Although you would maybe think that there isn't a difference between burning at 1, 2, 4, or 8X, there is. Most people recommend burning audio discs at 1X, although I almost always burn at 4X and haven't had a problem yet.

Backing up PS discs, though, must be done at 1X. Even 2X almost always fails.

The reason they probably say that is that if you burn at 4X, you are obviously more likely to have errors. If their error correction algorithms aren't that great or fast, then you'll have problems reading the 4X.

Just a couple thoughts/comments.

b

[bongo]

wow, I did not know that. I burn all my audio disks at 8x, and my crappy little $50 philips prtble CDplayer reads them all.

hmmm...
thnks

[xortam]

Big difference in the error correction for audio versus data, such as MP3.

[Technoid]

Somehowe i think it has to do with the quality of the Burner, disc's and the reader!

The burning speedlimits of the varius burners is not set at X because the burner cant burn faster but because thats the fastest it can burn without errors.

Probably every burner can write at its reported read speed but thge result would be a coaster (destroed disc).

Some cheaper 4x burners was obviusly "overspeeded" 2x burners because only 1 of 10 disc's burned at 4x was readable!

Same goes for cheap cd readers to!

------------------
INTEL PIII550 MSI 6163
G400Mill 32MB SGRAM + RRG
SBlive
256 MB RAM CAS2
43GB HDD Space!(Actual 40GB) (13+30 Quantum drives)
Pioneer 104S DVD 10x CD 40x SLOT IN
SONY CRX140E 8/4/32 CDRW

[adamhamilton]

> Backing up PS discs, though, must be done at 1X. Even 2X almost always fails.

Not true, I've written hundreds of PS CDs at
2x (the max my poor old writer can do) with no problems.

I think it just depends upon the writer and quality of CD-R.

[spoogenet]

Not true, I've written hundreds of PS CDs at
2x (the max my poor old writer can do) with no problems.

Ok, maybe it doesn't HAVE to be done at 2X, but you are certainly the exception to the standard. 1X is basically the rule for most everybody.

BTW, what burner/CD-R are you using? Because I know plenty people with good burners and discs that are limited to 1X for PS discs.

b

[xortam]

I don't know what the term PS is so you'll have to explain that one to me.

The principal problem that occurred with burning audio CDs is that of buffer underuns. It used to be that only SCSI burners were able to reliably write more than a 1x rate. In recent years, IDE burners have improved considerably and are able to burn at higher rates.

Pardon for the long post, but I'm pasting in an excellent article on CD errors. It will explain the difference in audio versus data error correction techniques and why the Discman probably can't cope with the higher error rates found on greater than 2x burners ...

Compact Disc Errors

by Bob Starrett http://www.cdpage.com

All compact discs have errors on them. Some of them have a lot of
errors. Even with the errors, however, you can still read a CD
accurately. Why? Because CDs use Error Detection Code and Error
Correction Code (EDC/ECC) to correct these errors as the CD is played
(audio) or accessed (data).

Two categories of errors occur on compact discs: logical errors and
physical errors. Logical errors are errors in the structure of the user
data and control data on the disc. Physical errors are actual
microscopic physical artifacts on the disc produced during the
production or recording process, or defects introduced after production,
like scratches or foreign materials on the surface of the disc.

Whenever we talk about disc quality, we are talking about the
interaction of the disc with the mechanism that it is being played on.
The performance or error rate of a CD can only be measured by reading
the disc; therefore, the performance of a particular disc is a
combination of the disc and the mechanism used to read it. Disc errors
are not absolute; they are a reflection of how well the disc works with
the drive it is being accessed on.

Audio CDs use an error correction code called Cross Interleaved Reed
Solomon Code or CIRC. An audio CD does not need as much error correction
as a data CD-ROM because an incorrect bit in an audio stream will not be
heard, while an incorrect bit in a computer program could crash the
program (or the computer). When an audio CD player encounters an error
that it cannot correct, it just skips 1/75th of a second, and you are
unlikely to hear any difference. Many errors. however, will make the
audio sound bad. These errors can be caused by scratches or dirt on the
disc, or can be a result of a poorly manufactured or recorded disc.

A CD-ROM disc uses additional error detection and correction code on top
of CIRC. This code is called Error Detection Code/Error Correction Code
(EDC/ECC). When a CD-ROM drive has trouble reading a sector correctly
(and it knows this because the EDC tells it so), the ECC can usually
correct that error by calculating the correct value of what is being
read. It does this by using other data on the disc that exists for the
specific purpose of correcting errors.

CIRC applies two levels of error correction, called known C1 and C2. C1
corrects small, random errors. C2 corrects large errors and burst
errors. Six "E" errors arise from these two levels of correction: E11,
E21, E31, E12, E22, and E32.

E11, E21 and E31 errors occur at the first stage of error correction,
C1. An E11 error means that one bad byte was corrected at the C1 level,
E21 means two bad bytes were corrected there, and E31 means that three
or more errors were corrected at C1. The first number in an "E" error is
always references the number of errors and the second number always
references the decoder level, in this case, C1, or Level 1.

In Level 2 or C2 of error correction, E12 means that one bad byte was
corrected at decoder level C2, E22 means two bad bytes corrected and E32
means that three or more bad bytes were passed to the Level 2 correction
but were not corrected. E32 errors are uncorrectable, and are not
acceptable on a CD-ROM disc. An uncorrectable error in a computer
program can cause the program to crash, and if a disc containing such
errors is used as a master for factory replication, the equipment at the
mastering facility will abort when it sees the uncorrectable error. The
mastering must then be redone, resulting in additional costs and delays
in the replication job.

Compact discs are composed of pits and lands that a CD-ROM drive or CD
audio player reads and interprets to retrieve data or play audio. Many
people believe, incorrectly, that the pits and lands represent the 1s
and 0s that are ultimately interpreted as data or music. In reality, it
is the transition between a pit and a land that represents a 0 or a 1.
Pits have different lengths and an ideal shape. Variations in the shape
of the pits and variation in the lengths of the pits can cause physical
errors.

Variations in the lengths and shapes of the pits on a CD are called pit
length deviation and pit geometry, respectively. Pit length deviation
means what it says. A pits on a CD needs to be one of nine different
lengths. These are referred to as "T" lengths and are T3, T4, T5, T6,
T7, T8, T9, T10 and T11. When a pit is not of the specified length for
its class, errors can occur on the disc. For example, a T3 pit that is a
little too long may be interpreted by the read laser as a T4 pit. This,
of course throws everything off and causes errors. Likewise, a T11 pit
that is too short might be interpreted as a T10 pit, again causing
errors on the disc.

Pit geometry generally refers to the shape of a pit, not its length. If
you think of a pit as a small mesa, there is an ideal slope that should
exist at each end of the pit. If this slope is out of specification, you
have poor pit geometry and this, too, can cause errors on a disc.

When you hear about disc errors, you usually hear about Block Error
Rate, or BLER. BLER measures how many errors occur in a given time
period while the disc is playing, usually an average over a ten-second
time span. Some of the factors that can contribute to an unacceptable
BLER are jitter, dropout, eccentricity, birefringence, reflectivity, and
poor push-pull tracking. Numerous other factors also can cause the
physical errors that make a disc perform poorly, or become unreadable
altogether.

...sometimes, when you think about it late at night, you wonder that the
whole thing works at all!

[uberlad]

I actually have one of these little beauties, and it plays my mp3's fine despite the fact that they were recorded at 6X.


There is nothing better than having more music on one CD than battery life in your music player 8-) (and a power adapter at your desk)

Uberlad



------------------
-------------------------
8 out of 10 women say they would feel no qualms about hitting a man.
5 out of 10 referred to me by name.

[Jorden]

Better yet, the other MP3 player for your stereo. I heard it on the radio last week, and don't remember the name of the thing, but it's a stationary MP3 player, that plays audio CDs as well, and it can be upgraded with a harddrive, so you can store up to 28 hours of MP3s in the player.

Already sounds like Sky Radio, but then without the advertisements every 15 minutes

Jord.