The product does what it says: it resurfaced the disc by applying fine radial scratches to the surface which players are supposed to have no problems with.
I used it on a CD of mine that has some scratches that caused my mp3 encoder to have problems, and I wasn’t about to purchase another CD just to get it to my computer properly, so I figured I would try one of these. Now the CD player, like windows media player or dBPoweramp or the Windows CD Player works fine, as does my portable, but when I tried to encode it as an mp3 the songs were quite chirpy.
Any ideas why? And if this is what happens with mp3s, should I avoid using it on pure data discs like games or backups etc? AFAI have ever K radial scratches are ignored by players, but if that’s the case, why the appearance of more chirps in the encoding process?
I may be talking straight out of my arse here, but I think that it is to do with the error-correction, which might be able to cope with the damaged CD to the extent that it plays OK, but when the pits and lands are read and represented digitally, the errors are not corrected in such a subtle way.
Not that I don’t appreciate the comment, Mangetout, but it still seems unclear to me as the product is marketed to repair games, which implies data-integrity. So why the chirps?
honestly, it does probably have something to with with the error correction. error correction on a computer is much different thatn that of a stand alone player. on top of that, audio cds are written differently than data cds. i understand it is all data, but the formats are a bit different. here is an example: audio cds were put on the market with a certain type of copy protection scheme. the discs were basically normal audio cds with a whole crap load of errors. your regular stand alone cd player doesnt care and wants to play them. your computer on the other hand says there are too many errors and gives up.
so, i do think it has to do with the error correction, but there are some solutions. your could copy the files onto your computer first as a wav and with error correction turned off or use a program that performs “raw read.” this will copy all of the data as is with errors and all.
Another solution may be to make a normal audio cd copy from your scratched cd and then make the mp3s from the copy.
in the end just understand that the error correction is a strange thing. sometimes it helps(fixes errors) and sometimes it hurts(can’t read disc at all)
I’m going to disagree with the error correction thing. IIRC, audio CDs actually have much poorer error correction than data CDs. An 80 minute CD-R can only hold 700MB of data, but 80 minutes of audio takes up over 800MB (80 * 60 * 44100 * 2 * 2 / 1048576) - data CDs have a lot of overhead for error correction. Audio CDs rely on the player’s ability to interpolate missing data to fill in tiny scratches.
Do you hear the chirping when you play the ripped WAV file, or only after encoding it to an MP3?
I guess I wasn’t really disagreeing after all. It’s possible, as other posters have said, that the CD player is interpolating or muting the scratched parts, but the computer is reading garbage instead.
You might be able to create a decent MP3 by running a lowpass filter (around 30 KHz perhaps) on the WAV file before encoding it.
Actually, I’ve managed to simply record the wav file in real time as it is being played, and then convert that to mp3. It worked fine, of course, but is very tedious, and didn’t address the issues of whether or not this thing was safe for data CDs. I just finished reading an article about making CDs and there is some very robust error checking done on CDs, to the point where they can be detected and corrected for.
That is a good question, I didn’t rip to WAV at all, but I’d be surprised if the result wasn’t the same. If audio CDs don’t really use error correction in their encoding, or at least not the point that data CDs do, then it would make sense that the mp3s would chirp but a data CD would be read fine since it could be corrected.