This post is rather long, but it will be very interesting to those who are seeking to know more about weak sectors - this will also raise quite a few questions Hereâs my lab workâŚ
With my previous tests on max.iso (for those who donât know itâs a file with weak sectors, see max.iso thread) one of my test result had been wrong. I have noticed that my test result of trying to record the max.iso file as an audio CD wasnât accurate and inconclusive.
Let me tell you what my test involved:
Preparations
I took the max.iso and made it into a multiple of 2352 bytes by appending bytes of zeroes to the end (did a bit of simple maths to calculate how much to add). Then I made a cue sheet:
FILE âZ:\MAX.ISOâ BINARY
TRACK 01 AUDIO
INDEX 01 00:00:00
Okay, I canât use this with CloneCD to burn it - because it doesânt accept cue sheets. I used Daemon Tools to mount the cue sheet & CD image and used CloneCD to get a CloneCD image of it (also verified the main binary files just be careful) and lastly burnt it to a CDRW at 4x writing with CloneCD.
Hardware/Software used
For writing: Plextor IDE 8432T, firmware 1.09 (latest)
For reading: Toshiba DVD SD-1502, firmware 1816 (latest)
CloneCD v4.0.1.3
Daemon Tools v3.10
WinHex (for padding of zeroes and comparison of files)
What was wrong with the test?
There were 3 problems:
-
My Plextor IDE 8432T drive (or the software - Iâm not sure exactly what is the cause) doesnât write the first few sectors of the image on to the CD. So I get a copy that had always been truncated at the start
-
Strange, but my Toshiba DVD could not read the last few sectors of the copy.
-
Also, with CloneCD v4.0.1.3 it some how resulted in a copy that was modified - I noticed this when I tested with a CDROM image with no weak sectors and using the same technique. Settings I used for writing: AWS off, Donât Repair Subs off, 8x writing.
Please, I donât wish to get into trouble with Olli, so lets not jump to any conclusions on CloneCD until we speak to him - anyway itâs not the issue here. The newest CloneCD probably has this fixed already - Iâm not sure.
The problems I described are conclusive because I have tried it 5 times over just to make sure.
A change of test strategy
Any way, I decided to change my test strategyâŚ
I used the same technique of padding the image, but this time I added a further 2 seconds of sectors to the front of the padded max.iso image and also a further 2 seconds of sectors at the end.
This time, I used Golden Hawkâs CDRWIN 3.8G to burn the cue sheet and image to the CDRW again at 4x, CDRWINâs raw mode: off.
Results
I read the CDRW with CDRWIN and Toshiba DVD and then I cut out the paddings of zeroes so that I could compare it with the original.
Finally, the result, the comparison gave 3 differences. But then I thought about it and suggested maybe those were because of jitter. So I re-read it - this time the comparison gave 0 differences!!! I tried 4 times and all gave 0 differences!!!
Now, Iâm getting somewhere (my eye brow raised - this is strange). I would expected differences. This raises the facts:
The writing of weak sectors are perfectly writable and the data are all intact and readable when you are writing an audio CD.
I further my testsâŚ
I did the same tests on the posted SD2 images (see âEFM Testing Images Mirrorâ thread) that I found in this forum and also the famous generated non writable weak.iso image posted by blackcheck (see âAlmost correct EFM recordingâ thread).
All of those resulted in 0 differences in comparisons to the original I started with.
So what is going on here?
It looks like the problem is not EFM encoding problem. Also, donât tell me bullshit - interpolation cannot help here!! You do the maths - it wonât give you those bytes!!
To me, it looks like the writer when it is fed with those weak sectors is probably truncating some bytes and so results in data CDs that has sectors different from the original - in most cases unreadable sectors - because of missing sync or header.