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Looper's Delight
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I make audio cd-r's in a philips dual-deck job, and a denon cd recorder......problems? sometimes I forget to finalize them....
but seriously.
I've made countless dozens of cd-r's of our albums in an HP drive and in a memorex drive on the pc, 1.7GHz, w98, using cd-architect, and in a ricoh drive on an i-mac using toast/jam/os9.
I'm estimating that I've had maybe 1/200 coaster ratio, and it's largely irrespective of stock used. cd players that won't read a cd-r successfully will probably already be concealing errors on "pressed" cds aswell; cd-r's are a little harder to read for sure, because they're basically scorch-marks instead of dents doing the reflecting, but they were intended to run in the same drives and if they don't, it's usually the drive. if the media is faulty, the problem will be apparent in any drive, in my experience, including the one that burned it.
you'll tend not to get variations in the reflectivity of the scorches across one disc or even one batch of media, unless there's something badly wrong with your burner
I have a korg d1600 multitrack, with their recommended yamahaha 4416 drive fitted. it burns at 4x and fucks up nearly every time, using unbranded 80 minute media that works perfectly at 12x in the memorex. dunno. the errors are usually about 15' in, so I'm guessing some sort of sympathetic vibrational effect. after that, they play fine out to 80 minutes.
if the error's always in the same place, it's the media or the burner. if the skips are in a different place (and it may be hard to tell for sure) then it's the player.
when I get a new load of blank stock, I burn a load of /data/ (jpegs or whatever) onto one or two of them and verify it. large files are good, because they depend on a greater number of 0's and 1's for their overall integrity.
I don't know the details of the crc/checksum algorithms, but I'm assuming that the order of magnitude of error tolerance is going to be the same for any sort of 0's and 1's one might stuff onto them. even if you pay $2 apiece for blanks (and in london, they can be had a lot cheaper than that), you can still afford to make three copies and lock one in a dark place.
as for mass-production (i.e. upwards of 10) for sale on websites/at gigs and so forth, I have some experience here too..... we've had one or two coasters slip the net (as it were...) but not many. the secret is to do a session and check 1st, 5th, 9th &c&c, and check again if you change source files, reboot the pc or switch to a different brand of stock.
better yet- pay someone else to take the risk. lots of companies have set up shop that will bang out 10 or 1000 cd-r's for you, on maintained duplicators and using trusted stock. the extra cost is minimal and they'll do all sorts of other stuff like proper on-body printing &c. relatively small businesses like this can't afford to make mistakes, so they tend to be quite thorough in researching the best burners, burn-speed and (of course) the stock itself. upwards of 3-400, though, it becomes reasonable to do a glass-master/pressing.
as for the 80 minute cd in a regular player- I've had exactly the same problem in my ancient marantz (now totally retired) and a top-of-the-range quad unit, with /pressed/ cd's exceeding the original morita-san-wants-a-whole-symphony-on-this-damn-thing spec.
(philips were going to make the thing 14 bit, 60 minutes and 5", until the patron saint of walkthings intervened).
the issue is jitter/error correction of same. towards the outer edge of the disc, it's harder to extract 0's and 1's as accurately as in the centre, even though the rotation slows down, mainly because there's more vertical play in the mechanism and it throws the focus of the beam. I used to combat this effect in a non-jog-proof portable by tilting it, and you may find the same thing helps with larger machines, inconvenience aside.
if only it was just a laser.... I don't know why exactly, but I'm sure it's out there somewhere on "how stuff works".... but there's a little plastic lens glued on top of the laser diode. aswell as the diode itself aging and dimming, the plastic lens crazes and goes cloudy just like any other transparent plastic. also, the pickup device will get less sensitive. bearings and slides in the mechanism will wear and get play in them. the main rotor bearing, just like on a turntable or tape deck, will start to wobble. best thing the manufacturer can do is put a load of ram in there and hope that the checksums are within limits. otherwise the box has to start inventing audio..... and the same checks apply to writers- they're all readers too.
80 minute discs are outside of the original spec but are tolerated/allowed because modern players have more ram and can have a few goes at reading each bit. it won't help much if the bit isn't there to start with, and my experiences with the 80min discs I'm using at the moment would suggest that the HP, ricoh and memorex drives are fine with it, at up to 12x, but the yamahaha just can't get all the way to the edge without the odd wobble, even at 4x.
just my 2 cent's worth.
duncan/r.m.i.
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