D2SROBA: sizing pass or transcode ?

[MorienteZ]

Hey guys,
first of all thanks to the authors and assistens of the brilliant tool D2SRoba.

I'm wondering after using D2SRoba for a while and doing some experimenting, if it would be more appropiate to aim for an oversized encode (cd) adjusting the Q-factor (e.g Q-factor=2) and have D2SRoba transcode the movie instead of (8/10% of all my cases) having an undersized encode (cd) which has to undergo a sizing pass taking much longer than transcoding.
How much quality is lost during a transcode?

Transcoding versus sizing pass? What's your opinion?
Time effeciency versus quality?

[tylo]

You may be best off with setting 'Adjust %' between 1.0 and 2.0 somewhere. This will give a higher amount of oversizes. Still, only by a few percent (0-5%). This small compression with e.g. Rejig should not be possible to spot visually, AFAIK.

Example:
1. Q=35, undersize 3% -> Sizing pass (+3% size)
2. Q=32, oversize 3% -> Transcode (-3% size)

(Q=33.5 would maybe be optimal, but impossible).

Alt1: The quality gain in the sizing pass is very small, maybe comparable to only one Q step, i.e. it ends with -> Q34.

Alt2: This starts out better (Q32), and the transcoding reduces it a little, maybe comparable to 2 Q steps at most (guessing). -> Q34.

Conclusion: The difference is insignificant, IMO, so find an Adjust % that oversizes in about 6/10 cases.

[Holomatrix]

Hi Tylo, what are the conditions again when your program desides whether to do a VBR sizing or Transcode pass on an oversized encode?
I did a movie and set 'Transcode if oversized' but it oppted to do the VBR pass. Does it VBR size pass when the D2Sroba calculated Q is higher than my conditional size set Q value? or visa versa?
Thanks

[tylo]

Hi Holomatrix. Yep, you're right. If determined Q is over the 'Q over' value, it will do a CCE VBR sizing pass. It is recomended to to use VBR sizing when Q is high because it may improve quality. If you still only want transcoding for resizing, set 'Q above' to a high number.