Slower read speeds compared to fast

vbimport

#1

When trying to clone protected cd's it can sometimes be better to read the source (original) cd at the lowest speed possible.

Though i want to know why this is.

On normal cd's :

How do you gain more errors just because you used a higher speed ? Are we talking physics here or is there some timing process in the internal of the cd-reader that cannot keep up with some errors ?

If it can't read them , some error check routine has to take place and they just start reading that sector AGAIN. (Same as harddisk of floppy method). The usual error control would be : Try to read it again. So it doesn't really matter whether you use 1 speed or 72 speed to read a cd-rom. The retries get more and more perhaps of the psychical aspect (cd stretches , gets warm , etc)

On protected cd's (deviation of red/yellow book) :

Still.. how do you gain more errors ? The errors are there of course , it's part of the protection scheme , but why would a higher speed get you more errors. Next to the physical aspect there are fixed errors. But these fixed errors are known. It of course depends of the protection method , but the errors are known and thus the place of the errors can be known.
So in this case you could get to read it at 72 speed and just skip the "imprinted" error sectors and still have the same data you used to have.

Tricky thing of course is you can't possibly know on forehand if an error is imprinted (fixed (intended) error) or some dust particle (accidental error). But this could be done by perhaps reading the source cd several times , store all these images seperately and bit by bit compare the various images. The accidental errors may wander around the image of the cd but the fixed errors would stay in place. But you still could read the source cd continously on 72 speed. No need to set in on 1 speed.


#2

The only sensible thing I can come up with is the fact that the data is less likely to be read accurately at high speed as the reflected laser beam may not be correctly registered by the pick up lens. This would make hardware error correction more likey to occur, and it is possible that the error correction could make a mistake.

This is fine when the application ‘controlling’ the drive recognises the bit stream as garbage and instructs the CD to be read again. However a replicator program would not know that this bit sream is still in error and thus records the corrected, but still wrong, data.

Make any sense to you?
:confused:


#3

i read somewhere that the laserbeam is switched on and off…when you read/write at high speeds there is not enough time for switching and reading at the same time.
So there will be some data loss

When you write at high speeds the above will lead also to difference in the pits that are burned. The laser is not able to restore as fast to burn nice pits with a constant quality


#4

Orinoco , Based on that point of view it would mean that CloneCD tries to make up for the inferior hardware used inside the cd reader and writer.

Based on the standard reading process (Atapi , MMC 3 or what’s it called) all hardware should be compliant of that process, instead of making hardware that is semi-compliant and CloneCD tries to make it more compliant.

The software companies who use copy protection schemes do not make it a mandatory requirement that you use Aspi layers on some other method of reading their cd. Just the standard Atapi/MMC reading , that hasn’t been changed since the time of MS-DOS. (Correct me if i’m wrong here).

CloneCD uses its own internal processes to read and write a cd , but still your cloned copy should be readable by the standard reading processes. Wether or not it simulates / adds / enhances / skips / replicates errors on the source cd (to write an exact copy) that were on that source cd either by purpose or by accident.

CloneCD states that it makes a replica of what it reads. So say that you have a 700MB data CD-ROM that has 7 errors. 3 on purpose , 4 by accident. The cloned copy will have that same 7 errors , all 7 there on purpose (because it read 7 errors it will replicate those same 7 errors).

To reduce the amount of accidental errors it would of course be better to read it at the lowest speed (giving the correction process more time). BUT … when i use a source at 72 speed i should still be able to use it. Have never seen a source cd with the requirement of a maximum reading speed.

Concluded on this , this could mean that you also don’t need to read it at 1 speed as well to make the most-perfect copy of the cd. If the source cd has no maximum limits in reading why should you do that to make an image of it ?

There is of course the fact that the materials used in the target cd-recordable has not the same reflective percentage and physical aspects as your nice silver stamped source cd. So THAT could give you more and more errors. But that’s a quality thing.


#5

Originally posted by damiandimitri
i read somewhere that the laserbeam is switched on and off…when you read/write at high speeds there is not enough time for switching and reading at the same time.
So there will be some data loss

Well , that’s a really really crappy correction/reading method then. Re-reading that sector would give the appropriate result. Just apply some wait-state for the process.


When you write at high speeds the above will lead also to difference in the pits that are burned. The laser is not able to restore as fast to burn nice pits with a constant quality

But is that because of the physical aspects of the used media or is it a flaw of the hardware technology in your writer ?


#6

???

i said i read it somewhere…just sharing what i hear/know…
if i remember correctly it is explained in some help file of somew cd burn software.
It is not a theory of myself

i always read my music with max 4 speed
and i read my data with max 6.
Most of the time i read them slower.

Never have problems.


#7

I know i know :slight_smile:

Wasn’t trying to insult you so if it looked that way , i’m sorry. I was just trying to keep the think-tank active :slight_smile:

The thing is that if that is the case by reading a cd , sure you’d agree that the reading and control process then is very very crappy.
I mean , why even bother to read it at 72 speed if the laser keeps flashing on and off while still reading data… and thus have enormous failures. All failures which could have been prevented by just re-reading it or just waiting till the laser is active again. (which would make a 72 speed reader a 50 speed reader in practice because of all the re-reads.) BUT the errors wouldn’t be more.

Plus if the laser can’t restore that fast in the writing process … why doesn’t it wait with writing till its fully restored ? Am i thinking too simple here or does the MMC directives or something make this impossible ? We have buffer underrun protection in almost any writer now , do we need some laser restoration procection as well , so that if the laser can’t restore that fast… it waits ? :slight_smile:


#8

it is ok…i have a hard skull

perhaps that info is from the days the laser were not that good

they must be much better right now…with the high speeds and things like smart x or smart burn etc.

i must agree with you…but why are there so many posts of problems with errors on cd’s that are burned on high speeds…

is it the media??..they are produced in high amounts right now…and often that results in bad quality

I have the same questions that you have. What is the use of a high speed burner when it gives troubles. Does it have to re-read the data so often (to correct failures) that it is better to buy a slower one?? To be honest i think my old 6 speed gave me better quality burns then the newer drives i have.


#9

Well , there’s of course the marketing issue (" Look at us , we’re cool, we can ship a 72 speed reader/writer !"). I believe the standards (Red Book , etc) give little information about the quality of products. It’s a certain fact that when companies use copy protections nowadays , that those chosen protections deviate a lot of the standards.

It’s a matter of time before the companies bring out cd’s that can only be read by your cd reader on a certain speed , with certain drivers on a certain platform ( Cactus Data Shield does this a little already ).

Nevertheless if it’s just a technology upgrade (bigger , better , faster) , i’m to think that the hardware companies really stretch the regulations as far as possible. Because there are error corrections , they can sell their 48x writer as a 48x writer. That it hardly does 48x at all is no matter. Compare it with analogue modems in the old days. You could have 56k on that thing ! Sure . theoretically.

So , if the technology has been upgraded on the speed issues , why isn’t it upgraded in the correction process ? Why does a 48x writer make more errors than a 12x would. In accordance of the standard , it does not make sense on technology level , only on mechanical and physics level. Yet still the normal original source cd’s work flawlessly usually on any reader , no matter what speed it is. After i write it on a cd-r(w) the quality is greatly reduced , giving more errors and error corrections. So i still don’t get it why i should read the original source cd on 1 speed instead of 72 speed.


#10

i do not know what i can add more to your thread

we can only say to people that 32 speed or above (or even 24) is enough if you want quality.

The funny thing is that there are 48 speed writers but there is no media.

Other strange thing is that there are 32 speed certified media. I gues certified means that they passed some quality tests.
But when you scan them with for example with the smart burn media tester from LITE-ON it is advised to write them at 24.

WHY?? it says certified media. Or is LITE_ON telling us that you can burn at 32 speed when you are lucky.


#11

Have backed up many games for several years now and have always read and wrote at max speed. The only trouble I have encountered is with bad media which could be solved by writing slower or by using better media and there by writing at max speed.
I would bet on bad media as the culprit most of the time.


#12

Well from posts I’ve seen and from personal experience I can say that when reading a protected data disc with CloneCD it can happen that a drive picks up errors that aren’t supposed to be there. Why? Not completely sure but when I read my GTA3 disc 2 at full speed my Lite-On will pick up errors at the end of the disc. When I re-read it at a safe 4x then there are no errors. Weird? Yes perhaps but because of the active Fast Error Skip settings the sectors that might not be as good (reflective) as other sectors are seen as errors. I don’t know the technical background but I do know it just happens. I’ve read many reports on users getting a non working back-up because they used a too high read speed. When they lowered their read speed the back-up worked… Therefore I would always recommend to read protected data discs at a lower speed. Better to be safe than sorry!


#13

i had a funny error message in one of the beta’s of clonecd v4.
When i try to read at high speeds with my Tosh m1612, clonecd wasnt able to read the sub-channels’.
Only when i went back to 6 speed max the error was gone.
Olli couldn’t explain it