67 lines
4.8 KiB
Markdown
67 lines
4.8 KiB
Markdown
# What is dvdisaster?
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**dvdisaster** provides additional [ECC](https://en.m.wikipedia.org/wiki/Error_correction_code) protection for optical media. If a medium gets damaged, dvdisaster can recover it as long as the amount of damage is smaller than the amount of ECC data you added to protect it.
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It can loosely be compared to [.par2](https://en.m.wikipedia.org/wiki/Parchive) files, but the protection works at the *iso* level instead of working at the file level. This way, even if metadata from the optical medium filesystem is damaged, dvdisaster can still work flawlessly.
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Please refer to the [PDF manual](documentation/user-manual/manual.pdf) for more information.
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# Unofficial version
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The last upstream version by Carsten Gnörlich is dated 2017, and could be found on the [official](https://web.archive.org/web/20180428070843/http://dvdisaster.net/en/index.html) [website](https://web.archive.org/web/20180509154525/http://dvdisaster.org/en/index.html) which is [now](http://www.dvdisaster.net) [down](http://www.dvdisaster.org). The original source code [repository](https://sourceforge.net/projects/dvdisaster/files/dvdisaster) doesn't have it, but [Debian sources](https://sources.debian.org/src/dvdisaster/) does, thanks to the maintainer there.
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The original [README](README) has been left untouched in this repository.
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This version is built on top of the latest upstream version, with the following notable enhancements:
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- Most Debian patches have been applied, those specific to Debian have been omitted
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- Windows build supported again, it was dropped upstream a few versions back
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- A CLI-only version, not depending on gtk (`CLI_ONLY=1 ./configure && make clean && make -j4`)
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- Regression tests confirmed working on Linux64, Windows32 and Windows64, for normal and CLI-only builds
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- Added pre-defined sizes for BD-R Triple Layer (100GB), BD-R Quadruple Layer (128GB)
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## 3 available protection modes ("codecs")
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**RS01** creates error correction files which are stored separately from the image they belong to.
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The artefact is an **ecc** file, which must be stored on another media than the one we're protecting.
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**RS02** creates error correction data which is added to the medium to protect, we call this *augmenting* the image we're protecting. Damaged sectors in the error correction information reduce the data recovering capacity, but do not make recovery impossible - a second medium for keeping or protecting the error correction
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information is not required.
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**RS03** is a further development of RS01 and RS02. It can create both error correction files and
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augmented images, with the following added features:
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- RS03 can use multiple CPU cores and is therefore much faster than RS01/RS02 on modern hardware.
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- RS03 error correction files are - contrary to RS01, and to a lesser extent RS02 - robust against damage.
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- RS03 is more robust, but also more restrictive: The augmented image must completely fill the medium now while the size of augmented images can be freely chosen in RS02.
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The changes for parallel computation and higher robustness make RS03 a bit less space efficient,
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e.g. RS03 error correction data has slighly less error correction capacity than its RS01/RS02 counterparts on images with equal size.
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For more information please refer to the [CHANGELOG](CHANGELOG).
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# Rationale
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Even if the optical media era is sunsetting now, and has been for a few years, it's still of some value for off-site backups. In any case, we still have media in our hands that we want to be able to repair, should it be damaged, during the next years/decades. Repairing is actually pretty much the very reason of dvdisaster existence (as long as parity data has been added, of course).
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The idea of this unofficial version is to ensure dvdisaster doesn't get hard to find, use or compile, should upstream development never resume (we hope it does!).
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This is also why precompiled Windows binaries and a precompiled static CLI-only Linux version are available here.
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# Compiling
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See the [INSTALL](INSTALL) file. The [workflow file](.github/workflows/release.yml) that is used to automatically build binaries for each release can also help.
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# Screenshots
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### Scanning a damaged CD under Windows
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### Scanning a healthy BD-R (single layer) with Linux GUI
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### Creating an RS03 error correction file with Linux GUI
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### Verifying a BD-R image with Linux GUI
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