cbr or vbr...not a quality question

[travis morgan]

hope this makes sense...do stand-alone dvd players "prefer" a constant-bitrate or a variable-bitrate? which one would be less problematic for a dvd player? or is it an issue for the dvd player at all?

[NearlyCritical]

I don't know if standalone DVD players 'prefer' CBR or VBR, but I can say that I have never had any issues with my PAL standalone using CBR for SVCD.

[AbuNidal]

"In terms of video and audio quality, SVCD is in between VCD 2.0 and DVD, using a 2x CD drive to support variable bitrate (VBR) MPEG-2 video up to 2.6 Mbps [...]"

quoted from http://www.uwasa.fi/~f76998/video/svcd/overview/

Do I need to mention that using VBR can significantly reduce your filesize / increase your video quality?

Check out http://www.vcdhelp.com/ to see if your DVD-Player has SVCD-support

[kdiddy]

To Answer your question: NO

as long as you dont exceed the max your player can read, you should not have a problem with either CBR or VBR. Aand to correct the afore mention statement, VBR does not SIGNIFICANTLY reduce filsize, but it does allow for better allocation of bits which does significantly improve overall quality over CBR.

[Antonio S.]

kdiddy said...

Aand to correct the afore mention statement, VBR does not SIGNIFICANTLY reduce filsize,...

This is not true. VBR SIFNIFICANTLY reduce filsize. It does it for 30-50 percent of file reduction. For example,CBR @ 2.6 Mbps allows 37 min of movie in a 650 MB cd. Using the same rate using CQ VBR may allow almost 60 min.

Antonio S.

[kdiddy]

Man dont start this dumbshit of yours again...

A) Either learn to spell first or learn to proofread!

B) Again, it will NOT SIGNIFICANTLY reduce filesize, not even close to 30-50%, it will ONLY allow better allocation of bits period which improves quality. That is why there isnt a single bitrate calculator has an option for VBR or CBR, show me one that has an option for this???? It only has bitrate period. In theory, a file at CBR of 1150 and one at multipass avg. 1150 VBR will have the same exact filesize because it's specified bitrate is the same. In reality, they will be different because not 1 single software encoder can actually encode VBR and sometimes CBR at specified rate. Sometimes if you specify 1150, you might get 1138, that is the fault of the ENCODER, NOT of VBR vs. CBR. The more passes you do, the more accurate the encoder is a maintaining the avg. bitrate. A 30-50% difference in filesize translates into either a 30-50% reduction in TIME or BITRATE which are the controlling factors in filesize. In order to get 50% more of video into the same space than CBR, your avg VBR will have to be 50% less, which means less quality, or your time of video will have to be 50% less, PERIOD, simple math.

C) "Using the same rate using CQ VBR may allow almost 60 min." Again here you go comparing apples to oranges. TMPG's CQ-VBR setting has NO bearing at to this comparision. With this setting, you can only set your max & min ranges. Which leaves the encoder to decide what your avg bitrate will be, which means you can not accurately predict the bitrate nor filesize. Thus you can not compare filesize of CBR.

[Kedirekin]

I see your argument kdiddy, but I think it is specious. The reduction of the average bitrate below CBR bitrate does not necessarily result in a reduction in quality.

I would argue that VBR 1200/1800/2400 is very close in quality to CBR 2400. So, for arguably equal quality, you get a file that is 25% smaller (or 3 CDRs instead of 4). I agree with Antonio S here.

Similarly, CQ VBR *can* result in smaller file size for a given quality. True, the file size is unpredictable, but that doesn't invalidate the argument.

PS. the only mispellings I see in Antonio's post are in his (verbatim) quote from your post - Aand [sic] and filsize [sic].

[kdiddy]

"VBR SIFNIFICANTLY reduce filsize."

You dont see the misspellings here??

"The reduction of the average bitrate below CBR bitrate does not necessarily result in a reduction in quality.would argue that VBR 1200/1800/2400 is very close in quality to CBR 2400. So, for arguably equal quality, you get a file that is 25% smaller (or 3 CDRs instead of 4). "

Depending on the movie, this could be true. But again here, this is not a 50% reduction in bitrate is it?? In order to get 50% more of the movie, then your average would have to be 1200, not 1800...and I find hard press to believe that a VBR clip of 0/1200/2400 would provide better quality than CBR at 2400.

"Similarly, CQ VBR *can* result in smaller file size for a given quality. True, the file size is unpredictable, but that doesn't invalidate the argument."

Yes it does, the debate is over VBR vs. CBR at SAME SPECIFIED bitrate. You can't bring CQ-VBR into this because you can not specify bitrate and thus cant gaunrateee an even playing field. So mike this clear finally:
Multipass VBR at 0/1200/2400 VS. CBR at 1200 will produce approximately equal video filesizes...ie maybe 795 MB vs. 790 MB, 795 MB vs. 400 MB. A VBR in this example will NOT produce a filesize 30-50% smaller than the CBR file. The VBR file will have better overall perceptual quality than the CBR file.

[waldok]

Kdiddy, this time you lose a "d" and become Kiddy for bothering with tiny spelling mistakes.

Guys, what about stopping this kind of "I am right", "No it's me", "No you"re wrong", "Learn to spell", blablabla

Obviously both Antonio and Kdiddy are right here, VBR sure allocates bits more efficiently than CBR (that's what it is meant for) and THUS will generally produce a smaller file, but the size decrease ratio depends a lot on the contents of the movie.

No need to argue, I am right (I was born right). Who doesn't say like me is wrong. This makes my life so much simpler :D

Waldok:cool:

[Kedirekin]

I completely agree Waldok. This is a pointless argument, because it's semantics. Who decides what's significant? Who decides what equal quality is.

On the other hand, it's sometimes fun to argue. Besides, I disagree with the vehemence of kdiddy's argument. And his jumping down Antonio S' throat for misspellings was totally uncalled for considering the (more severe and noticeable) misspellings in his. It'd have been funny, except that his post was so mean spirited.

PS. I've had VBR 2498/1500/300 that to me are indistinguishable from CBR 2498. It's definately dependent on the movie and the person viewing it, but still, that's a 40% reduction in file size - seems pretty significant to me.

[Mozart]

Originally posted by waldok
No need to argue, I am right (I was born right). Who doesn't say like me is wrong. This makes my life so much simpler :D


hummm... George W. Bush's quote?;)

[kdiddy]

"No need to argue, I am right (I was born right). Who doesn't say like me is wrong. This makes my life so much simpler "

you feel better now?

"except that his post was so mean spirited."

Mean spirited my ass, it amazes me the thin skin of which people exhibit on forums on the net. To get offended by what someone you don't know says about you is, for lack of a better word, "pussiness".

"PS. I've had VBR 2498/1500/300 that to me are indistinguishable from CBR 2498. It's definately dependent on the movie and the person viewing it, but still, that's a 40% reduction in file size - seems pretty significant to me."

Again, were that the example, I would agree; however, since that again is NOT the issue at hand, there is no need to bring it up. The issue for me was that of AVERAGE VBR vs CBR of same bitrate.

But now that this has strayed o' so far from the original post, which again the answer is simply, No.

[travis morgan]

i only asked if stand-alone dvd players had a preference when it came to bitrate...variable or constant? from what i have read...it doesn't have a preference.

but i would like to address the "significant reduction in size" arguement.

example 1: kdiddy
average vbr=2000 max=2500 min=0
cbr=2000

no significant reduction in size.

example 2: antonio
average vbr=500 max=2500 min=0
cbr=2000

significant reduction in size.

note...what "significant" is to one is not necessarily to another.

i think this is what was trying to be conveyed in the postings.

[Antonio S.]

to travis morgan:

As I post before...

kdiddy said...

Aand to correct the afore mention statement, VBR does not SIGNIFICANTLY reduce filsize,...

This is not true and will never be... "Variable bit rate" (VBR) allows better allocation of bit rate and this will reduce SIGNIFICANTLY file size. This is one of the biggest assets of VBR.
As an Electrical Engineer, I prove things at the field, first studying the theory and then experimenting (in this case encoding). The only thing that I am doing here is posting my results.
If people like Kdiddy likes it or not, is his problem, and this only prove how unprofessional and childish a person can be. I am not going to debate him with pussy talk, or personalism. I am just going to post what I discover...
As an Engineer I can tell you that rules and theories are changed with experimentation, and not all theories are 100 percent true....

Antonio S.

PD- My first language is not English. Sorry for the mistakes. If someone prefer that I post in Espanish language, I can do it also.

[kdiddy]

"As an Electrical Engineer, I prove things at the field, first studying the theory and then experimenting (in this case encoding). The only thing that I am doing here is posting my results. "

No one ask or cares what your resume is truly. And as Ive asked you before on topics, prove it, put ya money where your mouth is. I will open up FTP space you and everyone to see, and you encode a video clip of say 30 mins, post to my FTP space, and prove to me where that clip at the same specified birate at CBR & average VBR cuases the VBR filesize %50 less than the CBR file. just email me and I will give you the FTP info.

[waldok]

Mozart, what about closing this one while it's time ? ;)

Travis, sorry for not answering your initial post and contributing to push things away from your initial question. From what I've noticed, DVD players (mine at least) don't really care about CBR or VBR. For the moment, any type of SVCD plays fine (except damn interlaced issue I mentioned in other posts :)
As long as your MPEG2 settings remain in the 'SVCD range' and standard, there should be no problem (some players also deal very well with non standard' svcds).

Kdiddy, I intended no offense, so, well, sorry for your poor sense of humor. A little bit more practice would help, maybe ? :D

Waldok. :cool:

[Mozart]

Originally posted by waldok
Mozart, what about closing this one while it's time ? ;)



I'm sorry. I don't have any moderator power outside DVD2SVCD forums. Only ScooterMyth (the moderator of this forum), super moderators and administrators can do this here.

btw: what is your opinion about these new smilies?:devil: :angry: :sly: :scared: :stupid:

[waldok]

Yep, they look great ! (Especially the one with the sign!)
I also may use :angry: from time to time

Waldok :cool:
:stupid:

he he he...

[travis morgan]

waldok,

i think i got my questioned answered.

i do have to admit i have enjoyed the debate here too. :)

[Doom9]

I just have a final remark before closing time.

actually.. both parties are right and wrong at the same time.

Consider the following simple example: We have a clip that contains 5 minutes of still parts and 5 minutes of action. Let's encode that at bitrate X in CBR mode one time. Then, you try to substract delta from each frame in the low motion part and add delta to each frame in the action part. Then you refine that process taking into account how well you will notice a certain frame and the complexity of the frames. In the end what you'll have will have the same size but have the bits distributed over the frames differently and more efficiently. Hence.. you get a better looking movie at the same size.

Now consider a different case: you take the same clip and encode it at a lower cbr rate (say Y), then you do the same bitrate distribution refinement process. In the end the file will look better than the cbr movie. However, if you compare our vbr file with average bitrate to the file with cbr bitrate X then the former is not necessarily worse.. it may even be better depending on how good the refinement process has been done and how big the the difference between X and Y is. Let's assume that we chose Y in a way that will permit the vbr clip to have the same visual quality as the bitrate X CBR clip.. so the bitrate Y vbr clip will be smaller but look the same.

So we have these 2 cases.. same size and better quality, and lower size but same quality. I still recall the discussions when nandub came out.. some people were expecting to put much longer movie on a single CD at the same quality as before, and others expected better quality at the same length. Both is possible depending on how you do it and in the end I don't know which fraction did win the argument.. I think neither did.. some are using it to create smaller files, and some to create better looking movies.. it's just a matter of preference.