Suggestion: Let CCE allocate bitrate?

[bobwillis]

Hi all,

I've been comparing DVD2DVD encodes with those from DVD-RB in main-movie only mode (using the same CCE encoder settings). With some films, it is evident that DVD2DVD produces better quality (less blocks) than DVD-RB.

The main reason for this (to my thinking) is that because DVD2DVD presents the whole film to CCE in one segment, CCE is able to make a more informed decision about how best to allocate bitrate throughout the film.

I understand that DVD-RB currently encodes the movie in several segments and DVD-RB tells CCE what the average bitrate is for each segment. I was wondering, is it possible to modify DVD-RB (just for main movie only mode) so that the main-movie is presented to CCE in one segment, thus CCE could distribute the specified average bitrate as it sees fit. This would lead to a more constant picture quality.

Regards,
Bob

[jikchung]

This is a topic that has been covered numerous times here. Try a search and read those threads.

[jptheripper]

not only has it been discussed, but i believe you are mistaken

"This would lead to a more constant picture quality." is an urban myth so to speak, and has been shown to be inaccurate

if you can show a dvd2dvd and dvd-rebuilder movie only encode frame grab comparison where there is blocking in the rb and not the d2d.. then it may carry more weight.

[bobwillis]

Jpripper,

I am able to show on my display several frames where D2D produces less blocking. The problem with using the segmented average source bitrate to determine the segmented average target encode bitrate is that IF too little bitrate is used for a complex source chapter, then the backup will suffer the same consequence (worsening quality). Likewise if the original encode uses too high a bitrate (for the complexity of the source), then the resultant encode will also have excessive bitrate (this is a waste).

It makes sense for the tool actually doing the encode to actually determine what bitrate is allocated throughout the film. It can make the most informed decision if presented with the whole source.

After once again explaining the validity of my argument (hopefully with greater success this time), I will politely restate my original question - is it possible to modify DVD-RB to work in this manner? If so, is this a planned additional feature?

Regards,
Bob

[jdobbs]

And I'm able to show through hundreds of tests that the quantization levels of the individual frames are virtually identical when doing it the way DVD-RB does it compared to doing it against the entire film.

I'm so tired of this argument... not because you've brought it up bobwillis -- but because I've had to explain it so many times. It truly is based upon mathmatics.

[jdobbs]

@bobwillis

Hope you don't think I'm being rude... that's not what was intended. :cool:

[jptheripper]

i will politely restate as well

the "It makes sense for the tool actually doing the encode to actually determine what bitrate is allocated throughout the film. It can make the most informed decision if presented with the whole source." sentence is where you have made a misperception

the tool that is encoding already made that decision, it was made by the studio during their encode.

jdobbs duplicates this and recenters for smaller disk size.

So what you are asking for has already been done and is unnecessary to duplicate

[bobwillis]

Hi Jerry,

I didn't realise this subject had been brought up so many times on this forum. As you probably know, I have mainly been involved in beta-testing DVD2DVD for the last couple of years and I haven't kept a keen eye on the DVD-RB forum side of things. I had hoped that this would be a not too taxing modification, that I would personally find useful (just for main movie mode), I won't lose sleep if it doesn't happen.

Many thanks for your software,
Bob

[jdobbs]

One of the problems you run into (there are a few more) is that you couldn't use CCE Basic and get an accurate recreation of the original... CCE Basic has no ability to force I-Frames at chapter points...