Copying CDs

[guiller]

Slow speed burning has more to do with playback compatibility compared to the brand of blank used (except for no-name stuff.) The slower you can burn, the more time the laser has over that particular spot on the disc to burn a more precise and deeper data pit.

A pit or no pit equates to the digital Ones and Zeros. Instead of almost nice round easily distinguishable data pits, the faster rotational speeds produce a smeared "teardrop" effect which will cause some decks to incorrectly identify the next space as a One instead of a Zero or just skip and poop out altogether. I have an old Pioneer burner that I keep around that will do 2x which I still use for audio compilations. My newer CD/DVD combos won't go below 4x and I've seen some that won't go below 8x-10x.

Perhaps I'm totally wrong on this, but I understand that pits and hills (differences in profile depth) are more a feature of commercially produced CDs. CD-Rs have a chemical layer that is flat in profile and changes color after being hit by the laser of the burner. They simulate the profile of hills and valleys by a sequence of obscure and clear spots on a flat surface, which causes a similar difference in the reflectivity of the laser of the reading machine. This is what I first read when CD-Rs came into the market and an explanation as to why some lasers could read them and some not, owing to a dependece in the light frequency of the reflection coefficient of the material in the CD-R.

All the best

 

[dmusgrave]

Ok here comes the IT geek out of me...

Technically a stamped CD has bumps and flats that are read as 0's and 1's. I'm not sure what the correct technical term for the bumps and flats are...

Bumps shine the light away from the optical sensor, flats reflect the laser directly into the optical sensor.

A non-burned CD-R is completely reflective. A CD burner "burns" the parts of the disc that would be bumps on a stamped CD, making them non-reflective and read as 0's. Non-burned portions of the CD remain reflective, shining the laser into the sensor, and are read as 1's.

 

[sleddogman]

Ok here comes the IT geek out of me...

Technically a stamped CD has bumps and flats that are read as 0's and 1's. I'm not sure what the correct technical term for the bumps and flats are...

Bumps shine the light away from the optical sensor, flats reflect the laser directly into the optical sensor.

A non-burned CD-R is completely reflective. A CD burner "burns" the parts of the disc that would be bumps on a stamped CD, making them non-reflective and read as 0's. Non-burned portions of the CD remain reflective, shining the laser into the sensor, and are read as 1's.

Ummm... kinda-sorta, but not quite.

The term Data Pits is a rather simplification of what really goes on and how a CD (orDVD) is actually read by the drive. Read this followed by this for the nitty gritty.

The CD fabrication machine uses a high-powered laser to etch the bump pattern into photoresist material coated onto a glass plate. Through an elaborate imprinting process, this pattern is pressed onto acrylic discs. The discs are then coated with aluminum (or another metal) to create the readable reflective surface. Finally, the disc is coated with a transparent plastic layer that protects the reflective metal from nicks, scratches and debris.

Meanwhile, here's a few electron microscope scans of a Mitsui and a Verbatim CDR burned at 2x and 4x that I had tucked away.
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[Windwalker]

Meanwhile, here's a few electron microscope scans of a Mitsui and a Verbatim CDR burned at 2x and 4x that I had tucked away.
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Thanks I now have wallpaper for my PC, that no one will know what the he!! it is

 

[whoaru99]

With CD blanks these days, one can hardly trust even a good brand name because they probably have different grades of media.

To be REALLY sure, one needs to read the media ID of the discs and compare it to a list of quality ratings for the actual manufacturer, not just who's name is on the package.