Can't set ECC redundancy % when inlaid in image

[larb0b]

Currently, you're unable to set the ECC redundancy percentage when using RS03 in image mode. In image mode, dvdisaster seems to default to 200% redundancy which is unable to be changed. It'd be useful to be able to change this in image mode for when you're just creating an image you're not going to write immediately (or are preparing an image for other types of media).

[Mo1sture]

I ran into this issue, but I don't think this is a bug but a matter of user error. I'm using the multi-disc ecc scheme where disk 1's ecc data is stored on disk 2, disk 2 ecc is stored on disk 3, etc. Disk 4 is my 'ECC disk' (this specific storage set has its needs met by disks 1-3), storing a second copy of the ecc data for disks 1 and 2, and the ecc data for disk 3. Total size of the 3 ecc files? ~18GiB.

When I plopped my ~24GiB (size of a single layer bluray) image containing the ~18GiB of files into dvdisaster, it generated me a ~48gb iso augmented with ecc data.

When I created an ISO image that was ~18GiB (size of the files inside the iso) and put that into dvdisaster, it appended ~4.9GiB of ecc data into the image resulting in a ~23.5Gib iso image to burn.

You need to leave the space in your ISO image for the augmented ECC data, otherwise dvdisaster assumes you're using the next bigger media option. This part is a bit of an assumption as I'm only feeding dvdisaster encrypted ISO files, but this program only functions on the disk/iso level. It can't see and utilize the 'free space' within your ISO since it doesn't function on the level of the filesystem contained within.

[speed47]

This is expected for the RS03 codec. The way it works, is that there is an hardcoded number of allowed ISO sizes for RS03, that correspond to each known media (CD-R, DVD-R, BD-R with 1/2/3/4 layers, with or without DM).

So indeed when augmenting the ISO file, dvdisaster will fill it up with RS03 data up to the next known media size.

This permits to have a higher resilience of RS03 with respect to RS02 or RS01: there is no RS03 metadata on a known location that would need to be present and readable on the disc so that dvdisaster can use it. The needed metadata is split into several pieces (called "roots"), and their exact location on the disc is inferred from the media size (which is fixed and known), and only a small number of these "roots" need to be non-damaged for RS03 to work. So RS03 is giving you more resilience at the cost of the ability to customize the ISO size out of the few predefined known media sizes.

[speed47]

As says @Mo1sture , dvdisaster works on the ISO level, so it doesn't see or understands "free space" within your ISO file (at the file level). If you want to add parity as files (maybe in addition to augmenting the ISO file with dvdisaster data), you want to have a look to parity files, such as the par2 format.

If you need to customize the resulting ISO size out of the predefined existing media sizes, you can use RS02. That's perfectly fine and that's why codecs can be chosen. It's not "less good" than RS03 if it fits your usecase.

[speed47]