What Is Bitrate ReDistribution? When Should It Be Used? [Archive]

TomBrooklyn

15th July 2007, 12:00

Hi jdobbs:

I read the FAQ before I posted. I didn't see it. I also searched for and found numerous threads about it before I posted. They discussed a lot of highly technical stuff I couldn't follow. Some users, like myself, might be able to use a simple explanation of what it is with a technical complexity equivilent perhaps to how to set a clock on a VCR.

jdobbs

15th July 2007, 14:41

That's just the problem. There is no simple explanation for Q. It is related to "quailty" but more accurately speaks to "quantization".

It is a way of determining roughly what the quality level of the output will be. More importantly, if you set the Q to a fixed level, with a fixed matrix, you can be reasonably sure the output for all segments will be of equal quality. So -- if you do an encode at a constant Q, the relative size of each segment can help you determine how the available space can be distributed across the segments in a way that will give consistent quality levels. If you have a high-action segment with a lot of demand -- sometimes a little more space can make the picture look a lot better. In redistribution, you may find a little extra bandwidth in one of the lower-demand segments that can be reallocated.

The important point is that you don't have to know what it is in order to use it. You just check the box.

TomBrooklyn

17th July 2007, 17:43

The important point is that you don't have to know what it is in order to use it. You just check the box.

Hi jd,
I think you meant "you don't have to know how it works to use it, " which I agree with. I do kind of have to know what it does (though not how it does it) to decide if I want to enable it.

I kind of figured it was something like what you said, as the name "Bitrate Distribution" is pretty self explanatory, but I don't like activating things without being pretty sure what it is.

I tried it and it seemed to override, negate, or modify the "Steal Space" function and redistribute bitrate across all the VTSs in an even manner or more even than it would have been with just Half D-1 and 50% Steal Space which is what I usually use for Extras. I wound up cutting down the bitrates on the Extras some more in Preview/Edit and reallocating the space back to the feature.

Could you comment on that or advise how Bitrate Redistribution works with/combines/overrides Steal Space and Half D-1?

Cheers.

zacoz

18th July 2007, 16:02

Sounds like you might have redist_all=1 set in the .ini file, which redistributes across all VTS's rather than just within the largest VTS. Hence you're moving bitrate back to the extras.

TomBrooklyn

20th July 2007, 01:24

Sounds like you might have redist_all=1 set in the .ini file, which redistributes across all VTS's rather than just within the largest VTS.
Hi,
Sounds like it, yes. How would I fix that? Where would I find the .ini file?

blutach

20th July 2007, 02:28

IN your DVD-RB Pro folder. It's called rebuilder.ini

Regards

TomBrooklyn

20th July 2007, 03:04

Hi, I found the file. I don't see a line for redist_all= though. Maybe because on my last project I took Redistribution off, but I'm not sure.

[Options]
Mode=5
OneClick=0
ReduceOpt=0
NoWarn=1
AdditionalOutput=1
LogFile=1
QuEncHQ=1
EncoderMinimized=1
RemoveDTS=1
HC_Quality=3
HC_Matrix=1
SkinVersion=12
AudioDub=1
QuEncodeType=0
iDCT=0
GOP=0
DCPrec=0
MainMatrix=Encoder Default
LowMatrix=Same as Main Feature
VLowMatrix=Same as Main Feature
ExtraMatrix=Same as Main Feature
ProCoder_Quality=4
DVD_Label=NO_SELECTION
DVD_Name=NO_SELECTION.ISO
MovieOnly=0
HalfD1=0
Convert_16_9=0
DisableInterlace=0
ConvertToYUY2=1
Skin=Rebuilder Default
HC_LUMGAIN=0
HalfExtras=0
Completed=1
[Paths]
QuEnc=C:\Program Files\DVD-RB PRO\Encoders\QuEnc\QuEnc.exe
ReJig=C:\Program Files\DVD-RB PRO\Encoders\ReJig\ReJig.exe
HC=C:\Program Files\DVD-RB PRO\Encoders\HC Encoder\HCbatch.EXE
FFMPEG=C:\Program Files\DVD-RB PRO\Encoders\FFMpeg\ffmpeg.exe
DECOMB=C:\Program Files\AviSynth 2.5\plugins\Decomb521.dll
NICAUDIO=C:\Program Files\AviSynth 2.5\plugins\nicaudio.dll
MPEG2DEC=C:\Program Files\DVD-RB PRO\DGDecode.dll
Working=C:\REBUILDER WORK PATH\
Output=D:\REBUILDER DESTINATION\
Source=D:\MASTERS_OF_HORROR_HOMECOMING\
[Audio]
Selected=
Remapping=
[Subpictures]
Selected=

Boulder

20th July 2007, 05:14

The option is also available in the GUI, update to the latest version.

TomBrooklyn

20th July 2007, 16:53

The option is also available in the GUI, update to the latest version.
Hi. OK.

I had 1.26.1. I went with 1.26.2

BTW, what is the MOBILE addition?

I not sure, but I might have gotten an error on upgrading...Run-time error '7': Out of memory. This popped up when I was upgrading, but it might have had something to do with Roxio, as when I "OK'd" on it, Roxio opened up.

jikchung

21st July 2007, 00:06

Your previous post about the MOBILE additions was already answered.

Here (http://forum.doom9.org/showthread.php?p=1023294#post1023294)

TomBrooklyn

21st July 2007, 14:59

Your previous post about the MOBILE additions was already answered. Here (http://forum.doom9.org/showthread.php?p=1023294#post1023294) Oh, I must have missed that notification. Thanks.

TomBrooklyn

26th July 2007, 09:44

The option is also available in the GUI, update to the latest version.
Hi. I've updated but I couldn't find any options for bitrate redistribution. Pray tell, where would that be?

Boulder

26th July 2007, 10:04

I'm at work now and I can't remember exactly, but I think the two options are under the Mode menu.

TomBrooklyn

26th July 2007, 10:09

Opps. I looked at RBPro on my other computer and it wasn't the latest version. I see an option for "Apply to all VTS's" in the latest version. I'll fiddle with that and see how it interacts with Save Space. Thanks.

mattstan

15th February 2008, 23:21

I've just read all the entries that mention bitrate redistribution in this forum's FAQ sticky, and this thread. There's one question that I think remains unanswered, unless it is answered in the bits I did not understand, I'm afraid some of it was over my head.

jdobbs wrote in this thread:
"...sometimes a little more space can make the picture look a lot better. In redistribution, you may find a little extra bandwidth in one of the lower-demand segments that can be reallocated."

Because of jdobbs comment above, it seems to me that I should enable bitrate redistribution and leave it enabled for all my encodes. The last time I looked into it there was a comment by jdobbs somewhere saying it was experimental and only advanced users should use it but that was several Pro versions back.

So my question is: For less advanced users like me, should I leave bitrate redistribution enabled for all my encodes? If not then is there a rule to follow as to when it will help? Finally what do I do with the 'Always use HC for redistribution pass', use it or not use it or when should I use it?

I use CCE SP with DVD-RB Pro (latest version, as of today's release, v.1.27.1).

Thanks a lot DVD-RBuilders. --I'm so impressed with the level of technical knowledge displayed in this forum, even if I don't always understand it.

blutach

16th February 2008, 00:21

If you're using CCE, it's a good idea to tick Use HC for redist pass.

I leave it on pretty much always now. Remember to tick Apply to all VTS if you are doing an episodic DVD where the eps are in different VTSs.

Regards

Video Dude

16th February 2008, 01:34

If you're using CCE, it's a good idea to tick Use HC for redist pass.

This recommendation is in a number of threads but I was wondering why. I would have thought to let the encoder being used for the movie do the redist pass since each encoder allocates bits differently. Is HC during redist pass more exact or effective?

Sharc

16th February 2008, 08:12

Unfortunately CCE may crash during the redistribution pass, under certain unpredictable conditions. It's a bug in CCE, and you will find discussions on that in the related threads. Nothing DVD-RB can do about it. CCE aborts silently, means there is no warning or error message whatsoever. But the result of the redistribution for the affected segment is crap (blocky).

HC handles the redistribution pass safely. Basically it is correct what you say that redistribution and encoding should preferably be done with the same program. Numerous tests have however indicated that HC, CCE and QuEnc produce very similar distribution profiles (see related threads / posts). hence the encoders are exchangeable for the purpose of redistribution. The bitrate allocation depends mainly on the degree of motion and picture details and brightness, and the various mpeg encoders behave very similar in this respect.

Moreover, the meaning of "accuracy" should not be overestimated in the context of redistribution. The essential is that a certain segment gets a higher or lower average bitrate compared to the standard linear reduction process. Whether this difference is say 10% or 11% is secondary. You won't notice any difference in viewing.

jdobbs

16th February 2008, 13:05

mattstan

16th February 2008, 13:42

I've personally only seen it happen on CCE SP2. I then ran the same source through CCE SP and it worked correctly. CCE Basic uses HC for REDISTRIBUTION anyhow -- because it has no single pass VBR capability.
and do you enable bitrate redistribution for your own personal encodes? Also just to make sure I've got it right do you recommend using bitrate redistribution for all/vast majority of encodes?

In fact I can't believe it's not occurred to me to ask you this before but... I would think that most users have their own standard settings which they use for most encodes (mine are: movie only, CCE SP 2 pass -3 if v. large source-, remove all but main audio out, remove all subtitles except English and/or forced subtitle stream). So jdobbs, for your own personal use of DVD-RB for DVD-5 compressions, do you have your own standard settings? If so, what are they? Or are you so far beyond this, that with any encode you examine source bitrates, material, etc., and work out custom settings best for that particular source? Either way what's your own technique for your personal encodes?

Finally from time-to-time people post screen caps of video frames done by different compression settings/encoders. I have various software which will take snapshots but none which will take me to an exact frame first, so that when capturing an image from the various encodes I can be sure I am capturing the same frame, I can get as close as 1 second but that could be 24-28 frames out! Have you guys got around this problem with a particular piece of software that allows capturing a specific frame?

Thanks again all.

Sharc

16th February 2008, 13:45

I had it with CCE SP 2.70.2.10 Trial. I was hoping that it may only happen with non-standard matrices, until I had a case where it failed with the CCE default matrix....
True, it happens in exceptional cases only, but it is very annoying if one discovers it on the finalized backup only.
Since a while I have been using HC for Redistribution AND encoding more and more (bias 30, Lumgain 2). The results are generally very good.

Video Dude

16th February 2008, 16:02

Thanks for the explanation Sharc.

jdobbs

16th February 2008, 18:50

and do you enable bitrate redistribution for your own personal encodes?I enable bitrate redistribution for all my encodes. While it only improves certain sources to any noticable level, it doesn't degrade any (as long as you use the default REDIST_LOW_THRESHOLD level), so I just leave it on.

My personal settings are almost all the defaults (which is why they are the defaults). Many of the features added to DVD-RB are there at the request of its users and they have various reasons for requesting them. I rarely use alternate matrices, for example.
Finally from time-to-time people post screen caps of video frames done by different compression settings/encoders.I don't find screen caps to be particularly useful. You never know whether the capture is from an I, P, or B frame and until you do it isn't useful to compare it to another frame. Also, you have to evaluate anything based upon how it is to be used. Movies aren't watched a frame at a time. It's like trying to evaluate a waterfall by looking at a single drop of water.

laserfan

16th February 2008, 19:00

...just to make sure I've got it right do you recommend using bitrate redistribution for all/vast majority of encodes?I use it exclusively, and I suspect most experienced RB'ers do as well.

In case this isn't obvious though, it DOES introduce extra time to the process.

mattstan

16th February 2008, 19:37

I enable bitrate redistribution for all my encodes. While it only improves certain sources to any noticable level, it doesn't degrade any (as long as you use the default REDIST_LOW_THRESHOLD level), so I just leave it on.
Ok thanks again. A problem though 'REDIST_LOW_THRESHOLD' is not in my REBUILDER.INI file at all. I'd guess that it isn't there because every time a new version of DVD-RB is released I install it with 'update' and don't allow my ini files to be over-ridden. Should I add 'REDIST_LOW_THRESHOLD' to my ini file manually in which case what should the exact line I add be?

I don't find screen caps to be particularly useful. You never know whether the capture is from an I, P, or B frame and until you do it isn't useful to compare it to another frame. Also, you have to evaluate anything based upon how it is to be used. Movies aren't watched a frame at a time. It's like trying to evaluate a waterfall by looking at a single drop of water.
Okay point taken, I didn't know there were more than one frame type in play. I wanted to use the frames to help visualize what's happening in a particular encode and use an image viewer to quickly switch between the same frame from 2 different encodes to get a visual reference of how the 2 encodes differ. --BTW nice waterfall metaphor :) except you would learn something about a waterfall from a single drop of water, and if you watched enough single drops (frames) you'd have some idea of what the waterfall looked like, sort of.

I'm pretty sure everyone in this forum would agree - I've never had a piece of software so comphresensively and rapidly supported by it's author before - thank you very much indeed for taking such as active role, you are, very definately, The Man.

Regards, etc.

blutach

17th February 2008, 00:38

In case this isn't obvious though, it DOES introduce extra time to the process.Many times, no. I've seen times when the redist will take a segment or 2 back to 100%, so you get an extraction not an encoding.

Regards

jdobbs

17th February 2008, 00:46

Should I add 'REDIST_LOW_THRESHOLD' to my ini file manually in which case what should the exact line I add be?No, don't add it. When it isn't there, the default is used. "Hidden" settings are hidden for a reason -- because it's normally best to not set them.

Wombler

17th February 2008, 11:20

Movies aren't watched a frame at a time. It's like trying to evaluate a waterfall by looking at a single drop of water.

That's a very good point.

It would be like trying to assess the playback quality of a standard cine film by taking one individual frame that exhibits motion blur and examining it in great detail.

In the digital arena (just like the cine film) quite frequently lack of detail apparent on individual frames isn't remotely noticeable when that video segment is actually played.

Wombler

mattstan

17th February 2008, 14:34

No, don't add it. When it isn't there, the default is used. "Hidden" settings are hidden for a reason -- because it's normally best to not set them.
Thanks jdobbs.

J-Wo

2nd March 2008, 02:43

Question about the bitrate redistribution feature and which quantization matrix is used. Let's say i have a main movie with 3 cells, and the average bitrate for my encode is 3000 kbps. I've selected the Med-Med (2800-3500) matrix for the main movie. After matrix redistribution, RB assigns the 1st cell 2000 kbps, the 2nd cell 3000 kbps, and the 3rd cell 4000 kbps. Will RB still use the Med-Med matrix for all three cells, or will it recognize that I've chosen different matrices under Options -> Advanced -> Quantization Matrices? For example, RB should assign the 1st cell the Low Bitrate Matrix and the 3rd cell the High Bitrate Matrix. I know this feature has been in RB Pro for a while now but I've only started to try it recently.

blutach

2nd March 2008, 04:37

J-Wo

2nd March 2008, 05:51

It will reassign the matrices to the ones you have selected in Options. You can check this out in your ECL file.

However, if you subsequently play with the segment editor and cross a "boundary", the matrices are not updated.

Thanks, I did go poking around in the ECL file and came to the same conclusion. Just wondering though, what do you mean by playing around with the segment editor? Is that the thing in the preview/edit tab?

blutach

2nd March 2008, 11:18

Yes.

Regards

J-Wo

3rd March 2008, 00:39

For fastest possible processing, you can run the redistribution pass without any filtering.

The above line I grabbed from the sticky FAQ. Just to confirm, there is no "automatic" setting to do this, right? i.e. if I normally use filters for my encodes, I cannot use one-click method with bitrate distribution but still have the OPV step done without filters. Am I correct?

chompy

18th March 2008, 22:07

It will reassign the matrices to the ones you have selected in Options. You can check this out in your ECL file.

However, if you subsequently play with the segment editor and cross a "boundary", the matrices are not updated.

Regards

Then, is it safe to manually change in REBUILDER.ECL the intra0 to intra7 and inter0 to inter7 values (to match the new matrix values) of every segment that has crossed a boundary? Or is it necessary to change other settings?