Alpha (developer) versions
Help us testing! We have some new functions under development and
would like them to be tested by more people before making the next official release:
You are invited to test these features as described below. Please
report both
positive and negative results so that we can get a better
picture of how the new functions are working. Thanks in advance!
A word of caution: The alpha versions might lock up the drive and/or the
operating system and require you to reboot. They might contain other bugs
and should not be used to process media containing important data.
If in doubt, please continue using the stable version 0.70
and wait for the release of version 0.72.
Downloads
The alpha versions use the same package format as the regular releases.
dvdisaster-0.71 (devel23) | 06-May-2007 |
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Added support for C2 scanning of CD media.
Andrei Grecu submitted improved versions of the RAW recovery heuristics.
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dvdisaster-0.71 (devel22) | 22-Apr-2007 |
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Igor Gorbounov started the Russian translation of on-screen texts.
Added selection of 20h/21h raw reading modes to enable defective sector
reading on more drives. Fixed some inefficiencies during raw sector recovery.
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dvdisaster-0.71 (devel21) | 15-Apr-2007 |
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Andrei Grecu provided an algorithm for recovering defective CD sectors
from multiple incomplete RAW reading attempts.
Sergey Svishchev helped porting dvdisaster to NetBSD.
Other features include: a selectable number of reading attempts, verification
of CD sectors using the raw L-EC and EDC data, and a redesigned preferences dialog.
RS02 checksum handling has been improved in the adaptive reading strategy.
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How to report your results
Please report your results by sending an email to
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Your report should contain a simple description of your results in textual form.
If you are experiencing difficulties with your BD/HD DVD drive, please activate
the log file feature in the preferences dialog (cf. the screen shot), perform a
scanning or reading action and include the log file in your mail.
In case of inconsistent output, a screen shot might also be useful.
Do not forget to include information about your
operating system version and your drive model.
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Please note that dvdisaster will only work with the (re-)writeable varieties
of media, so seeing it reject DVD-ROM, BD-ROM and HD DVD-ROM is not an
error.
Testing topic: BD/HD DVD media compatibility
dvdisaster contains support for BD and HD DVD drives based on the MMC5 specs.
Since both formats are very new and evolving, there might be issues with
certain drives and operating systems. Please try the following for testing
the drive compatibility:
- Create a reference error correction file.
- Read the image with dvdisaster.
- Verify the image using the reference error correction file.
1. Creating the reference error correction file
Please follow the instructions at the end of this page.
2. Reading BD/HD DVD images
Make sure that you have deleted the reference image and that you are using the
following settings. Note that the preferences dialog changed between previous versions
and dvdisaster 0.71 (devel-23):
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In the "Image" preferences tab, only "ISO/UDF" and the linear reading strategy
should be selected.
No other features should be marked here. |
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The settings in the "Drive", "Read attempts" and "Files" tabs should be left off
or at their defaults as shown in the screen shots. |
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Click on the "Read" button to create the BD/HD DVD image.
Please watch the marked areas in the dvdisaster
window (the example to the left is for a DVD+RW)
for plausible values:
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- The medium label should be printed correctly.
- The medium type must be properly recognized.
BD media should come out as either BD-R or BD-RE; possible values for
HD DVD are HD DVD-R and HD DVD-RAM.
- The number of sectors must be correct. If you are not sure how to verify the number
of sectors, this can also be done later in the verification step.
- The manufacturer ID should have a meaningful reading, although some media seem
not to have one.
- The reading speed curve should match the drive specs.
3. Verifying BD/HD DVD images against the reference error correction file
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When the image has been read,
select the reference error correction file (cf. [1] in the screen shot)
and press the "Verify" button.
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This will check the image for completeness (e.g. that the correct number of sectors
has been read) and that its contents are intact. If everything goes well,
you will see the messages "Good image" and "Good error correction file" as shown in
the screen shot above. All output lines should be printed in black (the actual values
shown will differ from the screen shot). Red values indicate problems with the image.
Testing topic: CD/DVD media on BD/HD DVD drives
Some BD/HD DVD drives might be downward compatible with CD and DVD media.
It is interesting to see if they behave like normal CD/DVD drives,
so it would be nice to have the above tests repeated for such media.
Please note that no manufacturer identification will be shown for CD media,
and that there are many different DVD types: DVD-R, DVD+R, DVD-RW, DVD+RW, DVD-RAM,
and their two-layer versions. Do not assume that a drive working with one type will
also handle the others well ;-)
Testing topic: Raw sector reading and verification on CD media
dvdisaster can verify the integrity of CD sectors by reading them in raw mode
and evaluating the MSF (sector number), EDC checksum, and L-EC error correction
vectors contained in the raw data.
This feature helps to work around drives which become unreliable when pushed to the
limits of their built-in error correction. It should be supported on all drives
and operating systems,
but in order to make sure please perform the following tests:
- Create a reference error correction file from a CD.
- Read the CD image with dvdisaster in raw mode.
- Verify the image using the reference error correction file.
1. Creating the reference error correction file for a CD.
Please follow the instructions at the end of this page.
2. Reading CD images in raw mode.
Make sure that you have deleted the reference image and that you are using the
following settings.:
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In the "Image" preferences tab, only "ISO/UDF" and the linear reading strategy
should be selected.
No other features should be marked here
and the settings in the "Drive" and "Files" tabs should be
left at their defaults. |
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Activate raw reading in the "Read attempts" preferences tab by checking the respective box.
Leave the other values at their defaults as shown in the screen shot.
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Click on the "Read" button to read the CD image in raw mode.
3. Verifying the CD image against the reference error correction file.
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When the image has been read,
select the reference error correction file (cf. [1] in the screen shot)
and press the "Verify" button.
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This will verify that raw reading created the same image as normal reading.
If everything went well, you will see the messages "Good image"
and "Good error correction file" as shown in
the screen shot above. All output lines should be printed in black (the actual values
shown will differ from the screen shot). Red values indicate problems with the image.
Testing topic: Reading of defective sectors from CD media
Andrei Grecu provided an algorithm for recovering defective CD sectors
from multiple incomplete RAW reading attempts.
This algorithm needs a CD/DVD drive which can return partial and/or uncorrected
data from bad sectors. Since multiple reading attempts may yield different parts
of a defective sector, retrying hard enough may eventually give enough information
to reconstruct the original sector.
However only a minority of drives do actually support the required reading mode.
Even worse, requesting the transfer of defective data after a read error seems
to catch some firmware and operating system programmers at a surprise.
If they did not provide for this case,
your drive and/or operating system may crash and require you to reboot.
So be careful trying these tests:
- Checking whether your drive can transfer data from defective sectors.
- Trying to actually recover defective sectors.
1. Checking whether your drive can transfer data from defective sectors.
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Make sure that only "ISO/UDF" and the linear reading strategy
are selected in the "Image" tab. The "Files" tab should have
default settings as shown in the screen shot. |
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In the "Drive" tab, set the "Raw reading mode" to 20h.
Setting "Reread defective sectors" to 1 times is recommended
as it might speed up reading on some drives.
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Use these settings in the "Read attempts" tab.
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Insert a good CD medium into your drive and perform a scan or read operation.
You can abort the operation after a few sectors have been read. Then click on
"View log" to the lower right of the dvdisaster window.
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Locate the line beginning with "Using READ CD" in the log window (see the red/green
markings in the screen shot).
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If this line says only "Using READ CD, RAW reading" then this particular drive does not
transfer data from defective sectors. For this drive, the following test can be skipped
(Note for Linux users: Newer kernels require you to be root for this test to succeed).
However if you get a message like "Using READ CD, RAW reading, Mode page 1 ERP = 20h",
your drive claims to be able to transfer raw data from damaged sectors (some drives
report a value different from 20h; this is okay). Try the following to see
if we can really get more data from the drive:
2. Trying to actually recover defective sectors.
Now comes the tricky part; you need a CD medium which contains some real defective
sectors. Good testing candidates are media with discolored outer areas, or worn out
CD-RW media which contain read errors right after being rewritten. Media containing
read errors from scratches should be avoided as these are typically not recoverable
by the raw reader.
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Activate logging and log file creation as shown in the preferences window to the left.
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Keep the "View log" window open and start a scanning or reading operation.
When the drive approaches an unreadable area, keep a close look at the logged output.
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This is a log file excerpt from reading a damaged medium. Watch for messages similar
to the highlighted ones.
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If you see one or more of the following messages, your drive and operating system
are capable of transferring data from defective sectors:
- "Raw Reader: Sector accumulated for analysis."
- "Recovered in raw reader by iterative L-EC."
- "Recovered in raw reader by plausible sector search."
- "Recovered in raw reader by heuristic L-EC."
What to do if raw reading seems not to work:
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Return to the preferences "Drive" tab and set the "Raw reading mode" to 21h.
Some drives appear to need this mode for raw reading. Repeat step 2.
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If neither 20h nor 21h work,
there might be several reasons why raw data can not be read:
- The medium might be damaged beyond the drive's reading capabilities.
Try another defective medium.
- The drive simply lied about its capabilities.
Try another drive.
- Your operating system may have a faulty CD-ROM driver / SCSI layer.
Try the same drive under a different operating system. Under Linux, try another
kernel. The early 2.6.x kernels seem to work better than the current ones.
If raw sector recovery works for you, you will typically be able to recover about
10% to 20% of defective sectors that would otherwise be unreadable. It is however
unlikely that you will be able to recover a damaged medium by using raw sector
recovery alone, so you are strongly advised to continue protecting
your media by using error correction data.
Creation of reference data
The above tests require you to create a reference error correction file.
This is done in two steps:
Step 1a) Create a reference image from CD and DVD media
To create reference images from CD or DVD media, please use
- a known good version of dvdisaster, e.g. Version 0.70.4,
- a known good CD or DVD drive, NOT a BD or HD DVD drive,
- media which are free from any defects and do not contain RS02 error correction data.
Please make sure that the following settings are made in the preferences dialogue
(for dvdisaster 0.70.4):
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ISO/UDF must be selected for image size determination.
No other features should be marked in this preferences tab. |
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The linear reading strategy must be selected.
No other features should be marked in this preferences tab. |
Read the image using these settings and proceed with step 2.
Step 1b) Create a reference image from BD or HD DVD media
Please use the recording software which came bundled with the drive to
create an .iso image from the BD or HD DVD medium. The medium must
- be one of the writeable varieties (e.g. -R/-RW);
BD-ROM or HD DVD-ROM wlll not work;
- be free of defects and not contain RS02 error correction data.
Make sure to create an .iso image; proprietary formats like .nrg will not work.
Also remember that creating BD/HD DVD images need a lot of hard disk space,
so store them on a suitable partition ;-)
Step 2) Create the reference ecc file from the image
Now create a RS01 error correction file from the reference image with the following
settings:
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We use the smallest possible redundancy since the tests depend only on
the checksum capability of the error correction file.
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Please give the error correction file a
distinctive name (e.g. cd.ecc, dvd-r.ecc, etc.)
and keep it for the tests described above.
The reference image can be deleted now.
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