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pits are no longer at rectangular shape at high speed

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pits are no longer at rectangular shape at high speed

Postby jtan on Tue Jun 03, 2003 11:44 pm

is it true that the pits your cd-writer make on cd-r is no longer rectangular in shape when you write them in high speed?
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Postby CDRecorder on Wed Jun 04, 2003 12:45 am

Interesting... I don't know if this is true, but I didn't know that they were supposed to be rectangular in the first place.
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Postby Halc on Wed Jun 04, 2003 1:16 am

jtan,

can you be more specific? What do you mean by 'rectangular'?

It is true that at a higher writing speed the offset from land to pit is spread to a longer area (i.e. the transition is not as fast). Do you mean this or some other effect?

regards,
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Postby jtan on Wed Jun 04, 2003 2:00 am

isn't it that ideally, it should be of sharp edges...


Image

see the picture, the above is when it's written in slow speed, below is when it's written in high speed. that's what i'm told... i don't know how true it is..
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Postby ryus on Wed Jun 04, 2003 2:12 am

Its probably true that when writing at higher speeds the pits are not as sharp. But since optical drives read read digital data, in binary, as long as the drive can distinguish between a '1' or a '0', land or a pit, then the decoding of the data will be fine.
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Postby jtan on Wed Jun 04, 2003 5:15 am

i wonder if the pits not being sharp is the reason why C1/C2 errors happen?
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Postby rdgrimes on Wed Jun 04, 2003 9:04 am

It's the edge of the pit that's important, not the "shape". Sharp, clean edges are what makes it readable.
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Postby jtan on Wed Jun 04, 2003 2:50 pm

now i wonder... does the speed of the burn affects the sharpness of the pits?
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Postby Halc on Thu Jun 05, 2003 3:14 am

jtan,

yes, speed of the burn affects the transition from land to pit (the steepness of the edge).

Yes, it is conceivable that really bad transition can cause bit-level errors. However before that, they contribute to the jitter on the signal being read.

regards,
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Postby jtan on Thu Jun 05, 2003 8:38 am

that makes it confusing to me... burning slowly make the steepness of the pit better, but how come on some cases, burning faster do produce a lesser C1/C2 errors!
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Postby Halc on Thu Jun 05, 2003 11:38 am

jtan,

can you show me an example of where burning faster produces less C1/C2 errors than burning slower?

I'm now assuming that you are only comparing real hardware supported burning speeds.

It is possible to make worse burns by burning at a lower speed that the hardware does not support natively, hence it gets simulated by the burning software.

regards,
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Postby CDRecorder on Fri Jun 06, 2003 2:50 am

Check out this thread.
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Postby jtan on Fri Jun 06, 2003 5:10 am

Halc wrote:jtan,

can you show me an example of where burning faster produces less C1/C2 errors than burning slower?

I'm now assuming that you are only comparing real hardware supported burning speeds.

It is possible to make worse burns by burning at a lower speed that the hardware does not support natively, hence it gets simulated by the burning software.

regards,
halc


how do we know whether it's natively supported or not?

i doubt it's indicated...
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Postby Halc on Fri Jun 06, 2003 6:43 am

You can read the hardware specs or you can test with a Nero tool to find out the speeds supported. Some burnign programs indicate real hardware supported burning speeds from simulated ones.
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