### Frequently asked questions Q: What is the purpose of CDmage? A: It's a utility, which performs different tasks with a common CD image files on your harddrive. The most-wanted being: scanning, repairing and extracting. Q: What kind of image scanning does CDmage provide? A: It checks sectors against corruption. There are rules defined by ISO standards, which must be followed by each sector of the CD. Other programs can perform similar checks as well, namely well known BINChunker and Fireburner. CDmage displays all corrupted sectors along with a description of each error found. Q: Should I use CDmage for image scanning instead of BINChunker (Fireburner)? A: Yes, you should. There are known cases when CDmage found more errors than BINChunker. CDmage tests header, subheader and intermediate fields of M1/M2 sectors. These tests aren't performed by BINChunker. Errors found with such tests can be nasty and can cause more damage than others. Q: I heard that CDmage can repair image errors... A: You are right, but not all errors can be repaired. CDmage uses a similar mechanism for repair as CD writer/reader does. It uses Error Correction Code fields (ECCP&ECCQ) of the sectors. Q: How safe is repairing of corrupted sectors with CDmage? A: 100% safe if corruption isn't intentional. Repaired sector is exactly like it's original. Please note than not all image errors should be repaired. There are intentinal errors which are part of some copy protection schemes. Some CD ripping apps (CloneCD, BlindRead...) let you make working copy of your legally owned software. If copied software is copy protected, then it's image files can contain intentional corruptions. Repairing of them would cause a non-working copy when burned. Q: What's the "Severity" column in the error log? A: All errors found by CDmage can be one of three severities - low, medium, high. Severity level means whether CDmage will be able to repair the sector. Low - yes for sure. Medium - probably yes. High - no. Note that severity does not mean how much is sector currupted. Even very corrupted sectors can be repaired successfully. Level of severity is indicated also by color of an icon on the left side of the error log. Colours are: green=low severity, orange=medium, red=high. Q: Why can't some sectors be scanned? A: Not all sectors have fields which allow you to check them. It's not possible to check M1/2048 or Audio sectors. They don't contain any error detection/correction fields. Only few checks can be performed on the M2/F2 sectors. Repairing of such sectors is mostly unsuccessful since they don't contain any error repair information. Q: What's the "Content of sector" column in the error log? A: CDmage can locate which part of ISO9660 and/or Joliet file systems is contained in the data field of corrupted sectors. Just after a scan there's text "yet not identified" which means, that location tests weren't performed yet. Tests can be started by clicking the command in the "Action" menu or on the toolbar, Results are then displayed in this column. Q: How can I set the "sector numbers" option in the Extract dialog? A: This option applies to data tracks only. All data sectors with size 2352 have header field with sector number in it. This option allows you to set the sector number from which sector numbering will start. If the destination track will have the same position within image as source track leave the option set to "Use numbers of source track". Otherwise, advanced users can adjust this option accordingly. Q: What about the "If error found" option in the Extract dialog? A: This option is enabled only if the destination track for extraction of the Mode2 tracks is set to the Mode1 track or to the file based on the Mode1 track (VirtualCD or Virtual Drive file). Mode2 sector can be either Form1 (with data field 2048 bytes long) or Form2 (with data field 2324 bytes long). Mode1 sector has a data field 2048 bytes long, thus Mode1 and Mode2/Form1 sectors are fully "conversion compatible". Conversion from Mode2/Form2 to Mode1 sectors isn't possible without information loss. "If error found" option defines what to do when there's an attempt to convert Mode2/Form2 sectors into Mode1 sectors. Possible options are: 1. "Stop extraction" - extraction stops, partially extracted destination file isn't deleted if "Keep broken files" checkbox is on. 2. "Replace with empty sector" - extraction doesn't stop, data field of source sector is ignored, destination sector data field is filled with zeros. 3. "Ignore" - extraction doesn't stop, source sector is handled as Form1 sector i.e. first 2048 bytes of data field are used for destination sector. After extraction CDmage reports number of sectors "replaced" or "ignored" for options 2. and 3. Q: What are the possible file/folder flags? A: The possible flags are: D - item is the folder F - item is the file H - file/folder is hidden A - associated file (def. by ISO9660 standard) (rare) E - file has Extended Attribute Record (def. by ISO9660 standard) (rare) M - files with "multimedia" signature (AVSEQ??.DAT files of Video CD images as example) Q: How do I set "first audio track properties" when opening raw image? A: These settings apply to raw images with data tracks which are followed by audio tracks (mixed mode and possibly video cd). The pregap parameter adds silence of selected duration in front of first audio track. Some images (Blindread, CloneCD) already contain silence in the beginning of the first audio track, therefore the value should be set to 00:00:00. CDRWin images usually don't contain this silence, standard setting for most CDRWin images should be 2 seconds (00:02:00). If the exact value is known it should be entered here. The start adjustment affects mixed mode and video cd images which have data track(s) with sector size different than 2352 (m1/2048 or m2/2336). Such images are rare. It isn't possible to determine the exact startpoint of the first audio track of these images. First try to open the image with the start adjustment set to 0. Then if there's strange sound in the beginning of the first audio track reopen the image with slider shifted one position to the right and repeat until sound disappears. Similarly, if the first audio track starts later than it should, reopen image with the slider shifted one position to the left until the track starts ok. One slider position shifts the startpoint of the first audio track by about 2 seconds (1:72 or 147 sectors exactly). Q: I selected track for scanning, but I keep getting message "There are no tracks selected..." A: Tracks should be selected in the right panel, not in the left tree view... Q: Extracted single data tracks other than first within the image cannot by reopened by CDmage anymore. Why? A: CDmage tries to find filesystem in all data tracks, which are first within the sessions. If the filesystem isn't valid, CDmage refuses to open such image/track. Extracted tracks, which weren't as first (i.e. the first track of the first session) in their source image, don't have valid filesystem. They either don't have the filesystem at all (Video CD), or the filesystem is only partial and internal links point to nonexisting sectors (session 2 and above). Q: Two seconds precision when comparing files? Why is it there? A: Precision of the FAT filesystem is two seconds. If the file timestamp is set to some value, the real value can be shifted withing range of +/- two seconds. Comparing of such files would lead to the timestamp mismatch. Option allows to treat files with the timestamp difference less that two seconds as if they were exact same. More to come...

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