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silasqwerty

Not all sectors being read on CD-R

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Hello! I noticed that not all the sectors at the end of a CD-R are being read, I noticed this when verifying disc images made by different programs such as Alcohol 120%. A screenshot and explanation of what seems to be happening here: https://github.com/claunia/DiscImageChef/wiki/Bugs-in-other-dumping-software This only seems to happen with CD-R discs, and I've tested it on two completely separate drives and computers. EDIT: Log is of dumping a disc, I can provide one for verifying a disc too if you need it.

Log:

I 17:12:22 ImgBurn Version 2.5.8.0 started!
I 17:12:22 Microsoft Windows 8 Core x64 Edition (6.2, Build 9200)
I 17:12:22 Total Physical Memory: 8,339,872 KiB  -  Available: 2,544,580 KiB
I 17:12:22 Initialising SPTI...
I 17:12:22 Searching for SCSI / ATAPI devices...
I 17:12:22 -> Drive 1 - Info: Memorex MRX-650LE v7 1.00 (I:) (USB 2.0)
I 17:12:22 -> Drive 2 - Info: ELBY CLONEDRIVE 1.4 (D:) (SCSI)
I 17:12:22 Found 1 DVD±RW/RAM and 1 BD-ROM/HD DVD-ROM!
I 17:12:44 Operation Started!
I 17:12:44 Source Device: [0:0:0] Memorex MRX-650LE v7 1.00 (I:) (USB)
I 17:12:44 Source Media Type: CD-R (Disc ID: 97m26s60f, CMC Magnetics Corp.)
I 17:12:44 Source Media Supported Read Speeds: 10x, 16x, 20x, 24x
I 17:12:44 Source Media Supported Write Speeds: 10x
I 17:12:44 Source Media Sectors: 93,122
I 17:12:44 Source Media Size: 190,713,856 bytes
I 17:12:44 Source Media Volume Identifier: MDL_360_INSTALL_
I 17:12:44 Source Media File System(s): ISO9660, Joliet
I 17:12:44 Read Speed (Data/Audio): MAX / 8x
I 17:12:44 Destination File: C:\Users\silas\Documents\Alcohol 120%\MDL_360_INSTALL_.ISO
I 17:12:44 Destination Free Space: 49,702,039,552 Bytes (48,537,148.00 KiB) (47,399.56 MiB) (46.29 GiB)
I 17:12:44 Destination File System: NTFS
I 17:12:44 File Splitting: Auto
I 17:13:00 Read Speed - Effective: 24x
I 17:13:04 Reading Session 1 of 1... (1 Track, LBA: 0 - 93123)
I 17:13:04 Reading Track 1 of 1... (MODE1/2048, LBA: 0 - 93123)
I 17:14:42 Exporting Graph Data...
I 17:14:42 Graph Data File: C:\Users\silas\AppData\Roaming\ImgBurn\Graph Data Files\Memorex_MRX-650LE_v7_1.00_TUESDAY-DECEMBER-25-2018_5-12_PM_97m26s60f.ibg
I 17:14:43 Export Successfully Completed!
I 17:14:43 Operation Successfully Completed! - Duration: 00:01:57
I 17:14:43 Average Read Rate: 1,591 KiB/s (9.2x) - Maximum Read Rate: 2,332 KiB/s (13.5x)

 

Edited by silasqwerty

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I don't understand the problem.  Are you saying the reading of discs is not complete?  That the images ImgBurn and Alcohol 120% make are not complete reads of the data on the discs?  As for their being CD-R's, the only thing that would probably matter here is that not all sectors are read because not all sectors are in use.  e.g. only the sectors actually burned on the CD-R would be read.

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I'm sorry that I wasn't clear, it seems that ImgBurn isn't reading all of the sectors on CD-R discs,  and that I noticed this because ImgBurn said that disc images made by other programs have more sectors than it sees on the disc. Someone who knows a lot more about this than me wrote this: "The problem comes because ImgBurn uses the SCSI READ CAPACITY command to decide the size of compact discs. DiscImageChef instead reads and interprets the Table of Contents, that describes the disc start and end. While that command should indicate the same size as the TOC interpretation, seems to not be so in some conditions (drive firmware bug?)." https://github.com/claunia/DiscImageChef/wiki/Bugs-in-other-dumping-software

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I don't really see a problem.  While there may be a difference between the 2 programs, ImgBurn has never failed to make an exact copy of a CD-R contents I read with it and burned it.

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Well it seems to me that ImgBurn isn't reading the last two sectors on the disc, I don't think it's particularly important information per se, but it's enough to make it inconsistent between the programs. And there is a problem somewhere since the programs are disagreeing about what the disc image should be, but I do admit it's not a particularly big problem. For all I know, it may be an issue with the other programs. Also, it looks like it's only a problem with some drives, I've only tried two so it might only affect a small number of them.

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Actually, I think your log shows it is creating the image correctly.

>> I 17:12:44 Source Media Sectors: 93,122

^^ That's from the disc capacity and is basically there for cosmetic reasons.

I 17:13:04 Reading Track 1 of 1... (MODE1/2048, LBA: 0 - 93123)

^^ That's from the TOC (or Track Information, one of the two). It's 2 sectors larger and therefore should be correct... if that's what you're saying?

ImgBurn doesn't use the disc capacity when making the image. It does however, like to tell you about potential issues when it notices that something isn't right.

Copy and paste the disc info text from the box on the right when you're in Read mode please as it'll quickly tell us where the problem is coming from. Firmware bugs are more common than you'd think.

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Alright, here you go! Also then if I understand you correctly, that warning "Session x, Track x is smaller on the disc than it is in the image file." is based on a number that isn't always correct? Would it be better to change that warning to only happen if the number of sectors according to the TOC is different, and not if there's difference in the more cosmetic number?

Memorex MRX-650LE v7 1.00 (USB)
Current Profile: CD-R

Disc Information:
Status: Incomplete
State of Last Session: Empty
Erasable: No
Sessions: 2
Sectors: 93,122
Size: 190,713,856 bytes
Time: 20:43:47 (MM:SS:FF)
Free Sectors: 255,323
Free Space: 522,901,504 bytes
Free Time: 56:46:23 (MM:SS:FF)
Next Writable Address: 104524
MID: 97m26s60f (CMC Magnetics Corp.)
Supported Read Speeds: 10x, 16x, 20x, 24x

File System Information:
Sectors: 93,124
Size: 190,717,952 bytes
Time: 20:43:49 (MM:SS:FF)

TOC Information:
Session 1... (LBA: 0 / 00:02:00)
-> Track 01  (Mode 1, LBA: 0 / 00:02:00)
-> LeadOut  (LBA: 93124 / 20:43:49)

Track Information:
Session 1...
-> Track 01 (LTSA: 0, LTS: 93122, LRA: 0)

ATIP Information:
Disc ID: 97m26s60f
Manufacturer: CMC Magnetics Corp.
Start Time of LeadIn: 97m26s60f
Last Possible Start Time of LeadOut: 79m59s74f

 

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That's not quite what I said. I said that specific line in the log was based on the 'Disc Capacity'. The values in the warning message are based on TOC information and Track Information. You can't just use 'Disc Capacity' when reading a disc unless it's single session/track.... and ImgBurn isn't just designed to read those, hence it never uses the 'Disc Capacity' value to decided on how much to read.

The problem is, either number (Track Info, TOC Info) could be incorrect and you can't 100% rely on either of them.... which is why the warning exists.

Your 'Track Information' and 'Disc Information' (Disc Capacity) would both suggest that Track 1 (as it's the only one on the disc) is 93122 sectors in length, but the TOC has other ideas and thinks it's 93124. That's common when dealing with discs recorded with the TAO method.

So... if there's a difference between what your drive is reporting via the two methods, the program warns you about it. This is not a bug in the program (as the thing you linked me to would suggest), it's there for a reason.

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Alright! Thank you for clearing up the confusion and being so patient with me! I'm still pretty new to this so I appreciate you taking the time to explain it. The last thing I'll ask about is when ImgBurn dumps the disc, the image it makes verifies without issue while all the other images I've tested give me that warning. That's another reason I thought it was a bug with ImgBurn. What do you think about that?

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Well, it depends on a few factors.

ImgBurn attempts to read those last 2 sectors before deciding if they should really be part of the image. If they're unreadable, it won't include them.

Sometimes it'll add stuff to the CUE file too, so it knows a bit more about the image and can adjust what it responds with accordingly.

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