Undocumented Redistribution settings

[DRP535]

First post here, so please be gentle. I have looked at the other threads about bitrate redistribution in here but they get very technical very quickly and they lost me. I'm using DVD-RB PRO v1.26.1 and notice there are a couple of undocumented options under the MODE menu pertaining to bitrate redistribution. I guess my question is a pretty simple one really. Is this a good thing? Will it improve the quality of my 9->5 conversions?

Also, is this a different thing to the documented but hidden setting "redist_all=1"?

As it stands right now, I'm doing an encode with Half-D1 for extras checked, Enable bitrate redistribution checked & I have the hidden setting "redist_all=1" in the INI file as well. I also have the following two lines in the INI as well (just as a test to see if my DVD player has a shit with either of them or not)

TargetSectors=2267500
CCEAQM=1

I'm using CCE SP2 v1.00.00.15 as the encoder.

Thanks

[jdobbs]

Remove the "redist_all=1" or set it to "redist_all=0" in the INI. If you are setting extras to Half-D1, it's obvious you are trying to apply less bitrate to them. The "redist_all" function sets a common quality level across the entire DVD -- meaning you will be probably applying more bits the to extras.

The real purpose of "redist_all" is for series discs (where you have multiple VTSs that may contain feature content). If you turn it off the redistribution will occur only within the feature VTS.

[Rippraff]

And don't blame RB if your output is oversized, because this valueTargetSectors=2267500
is quite too high.

Cu Rippraff

[jdobbs]

Good point.

If DVD-RB sizes perfectly to the target specified in your INI, you will end up with an image that is 4.39GB -- too big to fit on a DVD-5.

[DRP535]

Remove the "redist_all=1" or set it to "redist_all=0" in the INI. If you are setting extras to Half-D1, it's obvious you are trying to apply less bitrate to them. The "redist_all" function sets a common quality level across the entire DVD -- meaning you will be probably applying more bits the to extras.

The real purpose of "redist_all" is for series discs (where you have multiple VTSs that may contain feature content). If you turn it off the redistribution will occur only within the feature VTS.
Okay, thanks for that. I understand what "redist_all=1" is doing now. Is there a difference between this setting in the INI file and the check option under Mode in the menu settings of the GUI? If so, then what is that difference? I've looked in the program documentation for something about it to read but I can't find it.

[DRP535]

Good point.

If DVD-RB sizes perfectly to the target specified in your INI, you will end up with an image that is 4.39GB -- too big to fit on a DVD-5.
Yep, understood. I have been getting consistently sized images of ~4439 - 4441MB which is a bit undersized for the 4488MB capacity DVD-R I'm using. I was just reading the documentation and came across the hidden settings, saw this one and thought I'd try it out as a bit of a test to see if I could close the gap a bit between the sizes I have been getting and the capacity of a DVD-R.

I'm prepared for it not to work and for me to end up with an oversized image. I'm new to tweaking the settings and I'm just playing with things at the moment to learn more about it.

[chainring]

Okay, thanks for that. I understand what "redist_all=1" is doing now. Is there a difference between this setting in the INI file and the check option under Mode in the menu settings of the GUI? If so, then what is that difference? I've looked in the program documentation for something about it to read but I can't find it.

"redist_all=0" is just the Mode > "Enable Bitrate Redistribution" check mark. When checked, but without "redist_all=1" in REBUILDER.INI, the redistribution mode will only work its magic on the largest VTS, typically the feature. It will leave all other VTS's alone.

[DRP535]

Okay thanks, I get it. The menu option is just for the largest VTS and the hidden option is for the special case of episodic discs where you want it applied to all VTS.

Is this bitrate redistribution a good thing in general? Obviously I don't understand the full-on technicalities of what it's doing (and neither do I particularly want to I suspect because I think it will get very technical in a real hurry), but I'd like to know if it's generally a good thing to have happening from a picture quality perspective?

It sounds to me like it's a good thing, which is why I checked it, but if it's a good thing then why isn't it enabled by default? Are there some good reasons why you wouldn't want bitrate redistribution performed? I guess I'm basically asking for the pros and cons. Anybody?

[jdobbs]

On the next release I've added an option that allows you to set/reset "redist_all" from the menu also -- I found myself changing it a lot...

[Sharc]

Is this bitrate redistribution a good thing in general?
It sounds to me like it's a good thing, which is why I checked it, but if it's a good thing then why isn't it enabled by default?
My experience tells me that it is good and safe to go for redistribution.
Still - the method is relatively new and still lacks the broad experience. Moreover, as may be concluded from the various posts, most tests were done with CCE or HC only. It is therefore reasonable to keep at this stage the redistribution as an option and off per default, also in view of the fact that DVD-RB produces excellent backups with the proven standard method anyway.
As you are on CCE I think you can feel safe to have the redistribution enabled - and expect to get at least same or better picture qualtiy. The only disadvantage is the little extra time required for the redistribution pass, IMHO.
Anyway, any feedback on the experience is welcome.

[canuckerfan]

does this new method apply to multiple pass encodings for CCE?

[jdobbs]

Yes. Take a look under the FAQ sticky in this forum and you'll find a little background.

[jdobbs]

It sounds to me like it's a good thing, which is why I checked it, but if it's a good thing then why isn't it enabled by default? It's still unproven and needs more testing.

[Sharc]

@canuckerfan
It does the redistribution pass first and then continues as usual with the number of passes you selected. 2 passes are normally sufficient. I only do 3 passes if I set CCEAQM=1, however I wouldn't even recommend to set CCEAQM=1 with redistribution because it jeopardizes the Q / matrix principle in a way.

[DRP535]

And don't blame RB if your output is oversized, because this value
is quite too high.

Cu Rippraff
You're quite right about this. Just for the record, with this setting enabled, my image size came out at 4,500.1MB. A little basic maths and I'm now trying again with a TargetSectors=2260500 value instead to see if that gets me closer to filling the disc while still remaining burnable.

[canuckerfan]

hmm... quite interesting. I'm going to dig through the big thread and see if I can use this method for manual CCE encodes since I don't use RB too often. thanks.

and I am correct that this method is adapted for CBR sources, but won't harm VBR sources?

[~bT~]

^ u cant do it manually mate. even if u can, it wont work properly AFAIK.

[Boulder]

You can do it, remember that I've done that for some years now..

This post gives you the short description: http://forum.doom9.org/showthread.php?p=956059#post956059 . You just need to use the spreadsheet in a slightly different way. One cell means one video when you do manual work, and you also need to subtract the audio bitrate from the final calculated avg bitrate. The 4375MB for available space is what I've used, it'll fill the DVD close to the maximum.

[~bT~]

^ cheers! did not know that.

[jdobbs]

Just for the record, with this setting enabled, my image size came out at 4,500.1MB. Which would be 4.39GB -- exactly as predicted.

Output_Size = Target_Sectors * 2048 * 1.015

But as I've said before, pushing to the edge is typically not a good thing to do. Even good discs are much more likely to fail on the outer edges. Also, encoders are not exact and if you set a target value that gets you to the edge -- you will occasionally oversize. It can waste a lot of time reencoding for an improvement in picture quality (a few megabytes) that is not measurable.

[DRP535]

Mr Dobbs, could you please explain to a numpty where the 1.015 in the equation comes in?

As a starting point to work out a TargetSectors value I took the capacity in bytes of a DVD+R(W) and divided that by 2048 being 2KB/sector to come up with

4 700 372 992 / 2048 = 2 295 104 which ended up being way too large as I found out. The amount I was out was this factor of 1.015. Where does it come from?

[jdobbs]

It's posted somewhere in this forum -- actually probably several times.

the 1.015 adjusts for the overhead required to encapsulate the MPEG stream into the VOB (DVD) format.

[DRP535]

Thank you very much. As an aside, here's something that took me by surprise. You know I was playing around with the TargetSectors value? Well, using a value of 2267500 gave me an image size of 4,500.1MB. Then I removed the redist_all=1 setting from the INI and reduced the TargetSectors value to 2260500 and what happened surprised me. I got an image size that was bigger!! It actually came out to 4,513.2MB. So quite considerably bigger in fact.

I just thought this was interesting and worth posting the result here for comment. Of course the sources were absolutely identical and all settings were identical except for those mentioned above.