Originally posted by: corky-g
Sweeping aside all the good advice about speed affecting compatibility, the basic question is - does speed of recording/burning affect the sound quality in the final product? The answer is - no it does not. Quality is binary - it is a faithful repro of the original or it is nothing.
Actually that isn't true.... CD's use a few genius techniques to ensure that a few missed bits do not stop the CD playback having a problem. Some people have now heard of the EFM encoding used on CD's due to its importance in producing copies of protected discs, but few really understand why EFM encoding is used and the advantage it gives.
EFM encoding does actually provide a level of immunity to bits missing from the data stream. EFM meaning 'Eight-to-Fourteen-Modulation' replaces every possible 8-bit sequence with a 14-bit sequence instead. The main purpose of this is for laser tracking.... the laser would never be able to follow the disc track if this encoding wasn't used and a string of bits was all 0's, it relies on the fact that there is always a regular sequence of pits to follow.
In adding this redundancy, it also adds a small level of error correction in itself.... if 1 bit out of the 14 is wrong, as its decoded down to 8-bits, the decoder could have a pretty good
guess at what the correct bit sequence is, but remember its a guess. If it is a small error it will most likely get it right, but it could actually mean that it can gets it wrong also.
There is another error correction technique used on CD's which relies on the fact that different parts of each sound sample are not stored one after the other in order so that if one section is misread, it will not impact a whole sample. The error correction system also tries to combat this, but of course is not infallible.
The problem with writing at faster speeds is that the quality of the pits created on the CD becomes less 'sharp' (for want of a better way of putting it). The media has less time to be formed and is exposed to a shorter burst of laser light whilst rotating at a higher speed....... this is why some car CD players or other players cant read some discs. Of course, the quality of the media is important, but write speed is a critical factor.
So, as to answer the quote I've used:
There is a sound quality difference... find someone who has a good quality sound system that has good balance across the widest possible frequency range, good CD player and make a good variation of a CD burned on different media at different speeds and then see for yourself... you may be surprised at how much some things can vary whilst still being technically identical.
EDIT: Oh, as a side note, for those having problems with CDR's in their car systems, try using a CDR which uses a Gold reflection layer and a PhtaloCyanine (sorry if spelt wrong) dye layer. It may not suit everyone's players but I've found this to be the best on problem hardware
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