Nero 7.5 changing .IFO files

[geohei]

Hi.
DVD
I encoded some video DVDs using Adobe Encore DVD. I used Nero 7.5 to burn the DVDs. However, after burning the DVDs, I compared (byte/byte compare software) all files (.IFO, .VOB, ...) and noticed that the .IFO files were apparently changed by Nero somehow.

Is this normal?
What's the purpose?

Thanks,

[redwudz]

Normal, no. But not unusual for Nero. It tends to re-encode when it shouldn't at times. If you have a DVD compliant VIDEO_TS folder, try burning it instead with ImgBurn. Use 'Build' mode. No re-encoding, ever. Or you may be able to turn off the re-encoding in Nero. Or it's possible that they weren't DVD compliant.

[geohei]

No, it's not about reencoduing the DVD! It's the .IFO/.BUP file (data structures, NO VIDEO!), This file is small and contains DVD administrative data. Hence my surprise that Nero touches these files.

The .VOB files files remain untouched!

Thanks,

[geohei]

... for info ...

In some other forum, I found out that it is probably due to the fact, that nero tries to redefine the layer break of this DL DVD.

[jman98]

Nero compresses the IFO and BUPs to be in the same block wherever possible. I can speculate as to why they might do that, but I don't know the real reason. The problem with this is that IFO and BUP files are supposed to be in different blocks so that if the IFO block goes bad in the future, the BUP can be read and the DVD will play. If they are in the same block and that block goes bad, the disc isn't playable because the BUP won't work. The chance of that one block containing both the IFO and BUP info going bad is low, but it could happen. BUPs exist to provide a backup in case the IFO is bad and it's stupid to squeeze them together like Nero does and provide a single point of failure.

Yes, Nero may also try to re-define the layer break. Because of that and the BUP/IFO nonsense I talked about, I now only use ImgBurn for burning.
I use PgcEdit to create ISOs and burn with ImgBurn. The reason I use PgcEdit is that it's the only way I can be sure that my ISOs separate the BUPs and IFOs with 32k gaps. The method is described here:
http://www.digital-digest.com/~blutach/pgcedit_guide/burning_with_pgcedit/burning_with...pgcedit_v2.htm

[navi310]

One should never use Nero to burn Double Layer DVDs. 8)

Imgburn all the way.

P.S.
What version of Encore are you using? Why don't you let it burn the DVD?

[geohei]

ImgBurn also has a Layer Break" option ("Calculate Optimal" or "User Specified"). Somehow all DL video burn programs insist to manipulate the layer break.

- Why is that?
- Which burn software do you recommend for DL DVD burns (video)?

Thanks,

[VegasBud]

geohei,

If you're referring to dual layer, tests that jinjin_jp did (see here) indicate that nero adds padding inside the IFO file(s), instead of between files (as ImgBurn and PgcEdit do), to obtain a valid layer break. That would, of course, change the size of the IFO(s).

If you're talking about single layer, and only the IFO(s) changed size, I don't have any idea what nero is doing, or why nero is doing it.

To answer your latest questions:

All dual layer disks must have a layer break defined, and there are rules as to where the layer break can be. The reason "all DL video burn programs insist to manipulate the layer break" is so the layer break adheres to the rules. The probability is that any potential layer break location will need to have padding added to kind of "slide" that point into the right location.

Some software (like nero) take the layer break selection out of your control, and set the layer break using an algorithm. That's certainly easier, but very unlikely to consistently produce the best layer break. ImgBurn not only lets you control where the layer break is located, but lets you preview the video at that point, to help you choose the best place. Consequently, to get optimum results, ImgBurn is the best program to use for burning dvd-video to dual layer (or single layer, for that matter).

[geohei]

Thanks a lot for the explanations.

Why is ImgBurn the best choice? Because it lets the user choose where the layer break should be, or is the burn quality better (somehow)?

Thanks,

[VegasBud]

For selecting a layer break, there is no better program than ImgBurn. The burn quality is as good as the burner/media allows, which is all you can ask of any burning software. It's not an exaggeration to say that ImgBurn combined with Verbatim +RDL media is the only way I (and many others) would recommend to burn dual layer dvd-video (or just data disks).

By the way, ImgBurn is just as good for burning single layer media.

[steptoe]

I don't touch Nero anymore for any DVD videos I need burning, been using DVD Decrypter and now IMGBurn, it produces better burns, produces more compatable burns and more importantly doesn't mess with anything it shouldn't be, unlike Nero that decides it knows best and screws up

I've proved this when I used to use Nero, by what happened :

Previous Nero burnt DVDs played fine, bought another DVD player different brand, previous DVDs if they played at all skipped and stuttered so much to be unplayable, most of them the other player wouldn't even recognise there was a disc in the player. Put it back in the 1st standalone player with no problems .....

Tried DVD Decrypter as it was then (now use IMGBurn, same author but does burn and nothing else), everything that previously refused to play now played perfectly 100%, so had to re-burn those DVDs that refused to work in the 2nd standalone player, every single one of them now played perfectly in both standalone players, so have not touched Nero since as its a known 'feature' that it can and does change the IFO's


I even used the exact same media, same speed, same method, same spindle. The only thing I changed was the burning software, so my results do prove that DVD burning software is NOT all the same


Give IMGBurn a try, it can't do any harm, its 100% free and it does exactly what it says without being massivly overbloated and containing things that you may never or hardly use just to make it more appealing



No, I don't hate Nero I still use Nero 8 for audio CDs and data burning which its perfectly good at, from my personal experiences and quite a few others that have had 'issues' its not that great at burning DVDs, which is why a lot of people still use Nero 6 as at least that was stable



This explains what might be going on :

There can be gaps on a DVD. The most notable ones are those used to ensure that no ECC block contains any portion of an IFO file and its associated BUP file. Since ECC blocks are 16 sectors long (32K), the easiest way to accomplish this is to ensure that there are 16 sectors between the end of the IFO and the start of the BUP. With VIDEO_TS.VOB or VTS_xx_0.VOB files less that 32K (or absent) this means using a gap



Burning programs handle this in one of three ways, two of which are correct.

· They can honour the authoring program's layout and place the data on the disk according to the pointers in the IFO files

· They can make their own layout decisions and alter the pointers accordingly

· They (notably Nero, at least in several past versions) pack the data as closely as possible and ignore the pointers

The upshot of this is, to use ISO images to maximize the chance of a "good burn". Burners and burning programs don't examine the data or the layout of an ISO image, they just burn it

Why is this needed?

If an IFO is unreadable (e.g. a CRC error in a sector), the player looks for the BUP, which is stored on the disk right after the VOBs for the titleset. Now suppose the VOBs for that titleset are small and the data is packed in. There is a chance that the BUP occupies exactly the same bad block that the IFO did, making the BUP useless and the disk, dead in the water

Essentially, the basic problem is that without the proper spacing, a single CRC error that would normally only affect one of the two files will affect both, rendering both useless. If proper spacing exists, it would take at least two CRC errors (one affecting each) to render both the IFO and BUP useless

It’s important that one failed sector does not ruin both the IFO and the BUP, making the DVD into yet another coaster


Also, this link should give an idea why the correct layer breaks are important when burning a DL media

http://www.mediachance.com/dvdlab/Helppro/layerbreak.htm

[GeorgeW]

Yes, Nero may also try to re-define the layer break. Because of that and the BUP/IFO nonsense I talked about, I now only use ImgBurn for burning.
I use PgcEdit to create ISOs and burn with ImgBurn. The reason I use PgcEdit is that it's the only way I can be sure that my ISOs separate the BUPs and IFOs with 32k gaps. The method is described here:
http://www.digital-digest.com/~blutach/pgcedit_guide/burning_with_pgcedit/burning_with...pgcedit_v2.htm

That's also an option within IMGBURN -- so you could just use IMGBURN to do the image creation (or build directly to disc).

Regards,
George

[jman98]

steptoe - Excellent post! I was far too lazy to provide such information, but hats off to you for doing so.