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CD docter high speed vs slow speed. - 3/19/2003 6:38:22 PM   
rjw

 

Posts: 932
Joined: 8/18/2001
From: Netherlands
Status: offline
Okay a lot of you people think that high speed meassureing isn't accurate on most drives and slow speed is more accurate about disc qualtiy.
Well after some testing I have my doubts.

Now let me first explain what we are meassureing here.
We are meassureing here the read errors of a drive on a cd-r.

Now here comes the interresting point.
At low speeds we will see how the media performs in a drive at a low speed. (There will be less influence of side effects. Now at lower speeds the disc will behave more uniform with most recorders. )
This gives us some info of the burnquality.

Now on highspeed you test actually how it would perform normally in that drive. This includes side effects you normally have when reading a cd-r at that high speeds.
Now a good quality disc (I said not burn/dye quality but disc quality) should score prety much the same if your drive can handle the media still correctly at high speed. However some drives have clearly allready problems with the media at there top speeds.

However if the disc is mishapped(Curved,bad allined) or has bad tracking. You will find a lot of errors more.
Why because of the bad shape/tracking problems the drive cannot read it correct at the high speed.
Depending on the construction a drive will have less or more problems in this case.
So now if we know that our drive can read good media then we can also know if the disc was fabricated correct.
(You still have to verify that you drive can support correct reading of other media at highspeeds.)

Now what is the best option ?
Why a lot of people say low speed. I do not agree.
Check this I have some DST media that performs allmost as good as TY media on low speed on my Lite On 48246S. Now a lot of people will say this media is good. No it isn't since after trying to read the data back on some devices it is clear that a lot of drives cannot read it back correct.
First conclusion was CD Docter is useless.
a drive with 100% C2 accuracy could not detect the problems how could it be. Just for checking things I runned CD Docter a second time and since I didn't had much time I choose high speed.
Now the DST disc has C2 errors at the end. Now I checked it again on low speed and found the same excellent score.
Now I thought what if I lower the speeds on the other drives could I then read my files.
And yes I could read them on allmost all drives.

So what does this tell us.
To know the quality of a disc. You will first have to be shure that your drive can read cd-r's normally at a high speed.
(check with some quality media and some different drives )
Second step will be to meassure at both speeds.
So you know quite rough the data/burn quality and quite rough the construction quality.
On both tests a disc should perform good without big differences to say if it is a good disc.
In case you want to know of a disc is usefull in combination with your burner then only use highspeed.
Post #: 1
RE: CD docter high speed vs slow speed. - 3/20/2003 12:37:53 AM   
Dolphinius_Rex


Posts: 3310
Joined: 9/14/2002
From: Vancouver, B.C. Canada
Status: offline
I'm interested in knowing your opinion of my testing techniques that I use on my webpage?

I figure between Nero CD Speed at full speed and CD Doctor at low speed I've got my bases fairly well covered. If there are any C2 errors, they SHOULD appear in the Quality Check, and if files are unreadable, then Scan Disc will let me know....right?


_____________________________

Canada; Leading the world in being just north of the U.S.A.

(in reply to rjw)
Post #: 2
RE: CD docter high speed vs slow speed. - 3/20/2003 6:02:15 PM   
Matthew

 

Posts: 943
Joined: 1/2/2002
From: United Kingdom
Status: offline
It depends....

If Doctor is fussier at high speed, but does NOT show a raised error count on good media, then high speed is clearly the way to go - a faster and simultaneously more critical test.

CDspeed seems to vary - it can show yellow for a sector, on a CD that showed no C2 and acceptable C1 in Doctor.

The proviso to using CD doctor in FAST mode, is that it does manage to show an acceptably low error rate for CDs that are good.

One final note for CDspeed - with some drives, it seems you need to start and than abort a transfer rate test - and then start the quality check very quickly, in order to run that at high speed.

(in reply to rjw)
Post #: 3
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