1 Reply Latest reply: Jan 30, 2013 11:28 PM by Guy Burns
Guy Burns Level 2 Level 2 (345 points)

My problem was originally the subject of another post (https://discussions.apple.com/message/20968737#20968737), but I thought I should bring it to the iTunes forum, instead of the general OSX forum. If there is a more specialised sound forum on another site that would be more suitable, please let me know.

 

I have been given about 100 CDs by Jessie Vonk, wife of Hans Vonk who was the conductor of the Saint Louis Symphony Orchestra until his death. She wants me to transfer them to another format. The collection, Hans' personal collection, consists of professional recordings of the orchestra, burnt in-house to CD. Most of them remain unpublished, but a few were broadcast on National Public Radio. About a third of the CDs have serious problems, and most of the others are proving difficult to read.

 

Apart from the problems with the CDs themselves, it amazed me that my three optical readers differ significantly in their ability to read burnt disks that are degraded. All three readers handle good CDs and DVDs okay – but sus burnt CDs are another matter.

 

And myself, I also have a problem: I thought digital was digital, but it appears not to be so with audio CDs. Depending on the drive, the drives appear to be internally interpolating for missing data before the computer sees the data (I'm guessing here), and such interpolation introduces a sort of analogue component to what should be truely digital. Sometimes the interpolation is so extreme the recording turns into garbage.

 

Initial impressions of my three drives (further tests to come):

 

  • Internal Intel iMac drive (mod 2011). Next to useless for faulty CDs. The poorest performer of the three. It gives up early than the other two drives, and sometimes cannot read a disk that the other drives can at least recognise.

 

  • Brand new Samsung SE-506, external, USB, Blu-ray drive. Can read disks that the iMac drive cannot, but it has the serious problem that it thinks it can read disks correctly when in fact it can't do so accurately. I have had several examples where the Finder reports no errors when reading Aiff files straight from the Samsung, but when played, all sorts of audio errors can be clearly heard. The drive must be interpolating for missing data, and the Finder is not aware of that, as no errors are reported during the rip.

 

  • Pioneer DV-109 (about 6 years old), external via Firewire. By far the best of the three drives for reading faulty disks. In conjunction with Max, it can read badly corrupted CDs that the other drives just give up on or make a hash of.

 

Here's one example. I've just tried copying a 53 minute performance of Berlioz's Symphonie Fantastique, recorded in 1999 and burnt sometime before 2004 (when Hans died). The disk does not appear to be severely scratched, though it does have small scratches here and there, so I can only assume the problem is in the burning.

 

All rips below are into m4a format.

 

1. Pioneer drive, ripping by Max, the read took about 6 hours. Via Max > Preferences, I enabled full Paranoia and ten retries. Such a long read time suggests Max had to read most of the data ten times at x1 speeds, and even then most of the data, I assume, was faulty. But it got there, though the recording has a constant, light crackling in the background. File info is reported by the Finder as 227.6 MB, 53.45 duration. Next test is to reduce the retries to something like three, instead of ten.

 

2. Pioneer drive, ripping by iTunes, the read took a few minutes. File info is reported by the Finder as 11 MB, 2.48 duration, with no indication at any time that there was any fault. The audio sounds similar to the Max rip, above, but stops at 2.48.

 

3. Samsung drive, ripping by iTunes, the read took a couple of minutes. I ended up with a full length recording that sounds like a detuned FM radio station – constant clipping and hissing, but not any crackling. File info is reported by the Finder as 275.7 MB, 53.45 duration.

 

4. iMac drive, ripping by iTunes, the read took about a minute. No indication that the rip was not complete or that any faults were encountered. The 15-second audio has more severe crackling than the Pioneer (Max) rip, #1 above, but the sound is not as bad as from the Samsung (iTunes) rip, #3 above. File info is reported by the Finder as 1.2 MB, 0.15 duration.

 

Interesting results. iTunes does not report faulty rips. A 53-minute recording can appear to be successfully ripped even though you end up with only 15 seconds of faulty sound. And it seems that these modern slim-line drives, internal or external, have serious problems when they try to read faulty disks. I've tested three: the internal iMac drive, the Samsung, and a Panasonic UJ141 that was purchased new before Christmas but since returned because of its poor performance. None give results anywhere near as good as the Pioneer.

 

Are slim-lines known to have lesser performance than their fuller-bodied brothers?

 

I'm just about to buy the latest Pioneer, a BDR 208, to put through its paces. Here's hoping it performs as well as, if not better, than its ancestor, the DV-109 (http://www.pioneer.eu/eur/products/archive/DVR-109/page.html).

 

If anyone has any comments, please respond. After I complete my testing, and with some input from readers of this thread, I will turn my findings into an interactive PDF, with sound files, so that other people having problems with copying faulty CDs won't have to spend as much time and money as I have in trying to achieve acceptable results.