dvdisaster Version 0.72 | To the Internet version

Contents

News
Overview
Howtos
· | The big picture
· | Scanning media for errors
· | Putting error correction data on a separate file
· | Putting error correction data on the medium
· | Recovering media images
· | Getting information about images and error correction data
· | Testing image compatibility
| - | with error correction files
| - | when augmenting images with error correction data
· | Dialogs and buttons
Download
Questions and Answers
Bug reporting

### Testing compatibility between error correction files and ISO images

Motivation: You want to write data to a medium and create an error correction file for it. In order to save time you do the following:

1. You create an ISO image using your CD/DVD/BD writing software.
2. You write the image to a medium.
3. You create the error correction file from the same image.

Possible incompatibility: The writing software creates a medium which does not exactly match the image. This might prevent the error correction from recovering the medium contents when it becomes defective.

How to test compatibility:

Please note that some steps are only sketched out here; follow the links to the respective sections to find detailed instructions and examples.

|  | Create an ISO image of the data you want to write on the medium. If you need help on creating ISO images please refer to the example of creating ISO images.

|  |  | Write the medium and create the error correction file. Use the just created image to write the medium. Then perform these basic settings and create an error correction file from the image.

|  |  | Create a second image from the written medium. Use these settings and read the medium as described in creating an image for making an error correction file. However you can stop the walk-through when the reading is finished as we do not need to create the error correction file again.

|  | Enter the name of the second ISO image which you have just read from the medium. Please note that the following test is useless when working with the image which was initially created using the CD/DVD/BD authoring software.

|  | Enter the name of the error correction file in case it is not already present from the previous actions.

|  | Start the evaluation by clicking on the "Verify" button.

|  | Look at the verification results. If you get the green messages "Good image." and "Good error correction file." your authoring software and dvdisaster are compatible. You can continue creating the error correction files directly from the ISO images produced by the authoring software.

Possible error causes and remedy:

Typical problem: wrong image size. The verification may find out that the image is larger as expected. Typically the difference is 150 or 300 sectors for CD media and 1-15 sectors for DVD/BD media. These might simply be zero padding sectors appended by the writing software. To find out if this really is the case do the following:
Screen shot: Wrong image size.

|  | Start a recovery process.

|  | Confirm the dialog. A dialog will appear asking you if it is okay to remove the superflous sectors from the image. Answer "OK".

|  | Stop the recovery process, as after truncating the image there is nothing more to do.

|  | Start the verification again by clicking on the "Verify" button.

|  | Consider the new results. If you now get the green messages "Good image." and "Good error correction file." your problem is purely cosmetic: The writing software has indeed added zero padding sectors while writing the medium.

If the problem persists after carrying out the above steps do not assume that dvdisaster and the writing software are compatible. The created error correction files will probably be unusable.

Use the following method for creating the error correction files instead:

Alternative method avoiding incompatibilities:

1. First write the data to the medium.
2. Use dvdisaster to create an ISO image from the written medium.
3. Use this image to create the error correction file.

This method takes more time due to the additional reading process, but it also has the advantage of testing the newly created medium for readability.

Old documentation (V0.70)

Copyright 2004-2009 Carsten Gnörlich. Verbatim copying and distribution of this entire article is permitted in any medium, provided this notice is preserved.