"Spark" marks?

[Reading Bug]

I haven’t noticed this problem with DVDs, but I frequently buy specialty CDs online (primarily of limited edition film scores) and have lately received some discs with what I can best describe as “spark” marks – little specks on the recordable side of the CD that look as if a spark has fallen on it.

None of the CDs seem to have trouble during playback (haven't listened to them all yet), but I'm concerned if information could somehow be missing nonetheless. They're limited editions that may be very hard (or very expensive) to replace should something go wrong. Is there any reason to be concerned about such marks? What might cause them?

I tried taking a photo of one, but it’s simply too difficult due to its size and the reflectivity of the disc. Many thanks!

[admin]

I have to really control lighting, even with a makeshift studio setup and macro lenses, to get decent media shots. But even then .... that reflection. Hard to do.

Those are defects in the pressing material. I try to get an exchange, when it's from a store.

If exchange/replacement is not possible...

You would be wise to make backup copies of these discs, a 1:1 to Verbatim DVD+R DL media. Several methods will work, but I find the best one is AnyDVD + ISO Puzzle. (Or just ISO Puzzle if there is no "copy protection" present.)

DVD Decrypter often works, but it really depends on the aggressiveness, age and presence of CSS encryption. (NOTE: I don't support people who copy discs they don't own, but I also don't support shoddy products. Just another valid reason people need to be able to copy media.)

This assumes all your CDs / DVDs are pressed retail releases, not DVD-R/CD-R releases (official or unofficial). If these are recordables, then it's just shoddy media with dye layer errors. I see those, too -- especially from B-grade junk re-branded/overprinted in UK.

[Reading Bug]

It's a pressed, retail release. And I've already done one exchange due to scratching, having to ship it back to them as it's all online. It's this new, replacement disc that has the mark. Very frustrating.

Would it cause any information to be lost? Now or in the future? I'm going to listen to it again a little later...

Oh, and I've already made backup CD-Rs, plus it's ripped to my HD in uncompressed WAV (44.1 KHz, 16 bit, stereo). And those files are backed up on another HD. So I should be ok in that sense.

[admin]

In most cases, there were audible pops or visual glitches/skips in the discs, from all the ones I've seen in the past decade or two.

At very least, ECC kicks in. If you're lucky, the ECC can work around the issue, but not always.

I would copy it. See if ISO Puzzle reports any bad blocks. Be sure to set DVD Decrypter to not skip bad areas, make it error and halt on a bad sector.

You can also try to test the disc in standard testing software, like Nero DiscSpeed. Run a surface scan and a speed read test. That software is stickied here in the blank media forum.

[Reading Bug]

Thanks Admin. The company is actually going to send me another copy of the disc with my next order, so hopefully I'll be set. Thanks again.