UDF or ISO? Is one "better"?



Is one more ‘secure’ than the other. Does one have a larger overhead?

In the past few years, I’ve always choosen UDF, since I seemed to get more coasters using ISO on my old MSI 8x and LG 4160B burners.

Knowing what I do now, I blame Princo and Ritek media, and not updating the LG’s firmware (this was when I knew less about H/W flashing, and was the biggest cause of the problem)

But is there any more data redundancy in UDF? Because I did seem to get slightly better results with UDF.


Anyone? This is a great technical question.

In general, it seems like pressed CDs use ISO and pressed DVDs tend to use UDF. So I tend to follow that example when I record my own discs.

The other thing is that one came make a hybrid ISO/UDF disc. Would that offer any benefits (like having a backup of the file system if one version gets damaged)?


I personally think it’s a lame technical question.

Anyway, I always choose ISO/UDF bridge when possible.


I just signed on and was doing a search on which is better to burn to your hard drive, ISO or VOB.

Curious - why is it a lame question? CloneDVD gives me a choice or the two mentioned above, and I really would like to know the advantages of each.



UDF is THE Format for DVD.

That’s the point not to deal with ISO on DVDs.


I guess I’m learning again. So ISO does not work for DVD?

Or is ISO just not recommended for DVD? I know that I’ve ripped some directly to ISO and played them on my PC.


You’re talking about two different kind of “ISO” and that can be rather confusing.

The original question relates to the filesystem used on the DVD, which could e.g. be some kind of UDF (Universal Disc Format) or ISO 9660. It’s also possible to have multiple filesystems on the DVD each pointing to the same files - the ISO/UDF “bridge” that chef referred to.

The other type of ISO that you’re talking about, is the file type (or extension) that is commonly used to store an “image” of an entire CD or DVD disc. This type of “ISO” file can contain any type of filesystem or lack thereof that is present on the disc. Not all applications that can handle ISO images are capable of handling ISO image with strange or missing filesystems however.

An ISO 9660 filesystem will work just fine on a DVD if you want to use it for data, but if you want to have a DVD Video compliant disc, then the disc must contain a UDF version 1.02 filesystem.



Thanks for your reply. Very helpful!

I wonder why then, that CloneDVD has a setting that allows ripping a DVD to an ISO file. Here I somehow thought that by ripping the DVD to an ISO file with CloneDVD I could later burn the ISO image to a DVD 5.

Not a good idea?


The ISO file doesn’t have to contain an ISO 9660 filesystem, and in this case it would contain and UDF 1.02 filesystem (from the original disc), and later when burning the ISO file (containing not an ISO 9660 but an UDF 1.02 filesystem) to a DVD5 (DVD+/-R Single Layer 4.7 GB disc), your copy would contain the same filesystem as the original.

I re-iterate that the “ISO” file doesn’t have to contain an ISO 9660 filesystem, even though that’s probably where the name originated years ago.


What I am most interested in is the robustness of the filesystem. Does UDF (any version) offer more protection in terms of error correction or is error correction of optical media (DVD) independant from the filesystem/structure used?

I know that ISO 9660 does have a file size limit, for a single file, 4GB if I remember correctly. It also has filenaming restrictions unless extended options are chosen in a burning program to alter those restrictions.

So I think what the original poster is asking, and what I am interested in as well, is whether there is any difference in data integrity between the two file structures.


The PI/PO error correction on DVDs is independent of the filesystem used.

I’m not really sure if there is any difference in data integrity between ISO 9660 and UDF - which is why I haven’t tried to answer that question! :slight_smile:


Thank you again, DrageMester. This was very helpful indeed, and very much appreciated. :slight_smile:


Ah, sorry, I wasn’t aware that you meant image here with ISO…


Anyone know what the actual technical differences are between UDF and ISO?


Probably my fault, chef.

I didn’t know enough to ask the right question. Learning every day though!



Do stand-alone video players (MPEG4 compatible) support UDF ?


They would have to support UDF 1.02 on DVD Video discs, because that is the format you get on pressed discs.

Whether those MPEG4 (e.g. DivX) players support both UDF and ISO 9660 filesystems for DVDs with MPGEG4 files is not something I can answer, but I imagine that it’s very unlikely that they wouldn’t support UDF 1.02 for this purpose.


well… still… the question is not yet answered…

but, what i was thinking about…
does UDF have a better support when dealing with large amounts of files?? like… storing a multi-million pics library on one DVD… for some reason i feel that ISO 9660 is ANCIENT, so, in addition to not being able to support large filesizes, i don’t know if it might have a problem when trying to deal with a a blasting number of small files… and also, for further support in the future, i think that UDF is readable on all OS’s, and mainly on the newer ones in the case of versions beyond UDF 1.50, while our Ancient Iso brother might start showing some problems…

currently, i’m using ISO/UDF for my large-numbered files… just because i’m not yet sure of the differences between the two file systems… though i lean towards UDF…

any advice or explanation would REALLY REALLY be helpful :slight_smile:


UDF has slightly more overhead in how it saves the filenames, directory structures, etc. But, it has much better support for larger directory trees, larger filenames, and a larger character set to use for directory/file names. There is nothing in either that affects data integrity - that is handled a layer below the file system with the ECC in each sector.

As a small test, I created image files of the same dozen files “burned to a cd” using each of the available file systems. The sizes of the images (in bytes) came out as follows:
2,015,314 iso9660mode2.cif
2,089,938 JolietMode2.cif
2,261,458 udf.cif

ISO9660 stores the filenames in ASCII, no longer than 31 characters, and with no special characters.

Joliet stores the same ISO9660 driectory/file listings, but then completely duplicates the directory/file listing in Unicode allowing more than just english letters and special characters and allows for longer filenames.

UDF uses the same basic disk and volume layout, but uses a completely new and different layout in the directory listings allowing it to save information that relates to modern HDD file systems in order to save file ownership (uid, gid), access control lists, MAC times (instead of just a C time), and so on.


[B]taylormade[/B], thanks for your input and welcome to CDFreaks! :slight_smile: