Rate Control Curve Compression ...

[Sagittaire]

1) I want perfect curve compression control with qcomp.
2) I want perfect control on I->P ratio quant and P->B ratio quant

Anyway with max quality (QPRD, AQ and certainely other), I haven't perfect control on rate control.

What are setting with max quality to reactive qcomp and type frame ratio command?

[Dark Shikari]

QPRD and AQ are unrelated to ratecontrol; are you thinking of mbtree?

Beyond that I don't understand anything in your post.

[Sagittaire]

Well in fact I make complete test for BluRay Rate Control Encoding. I make actualy encoding at 24 Mbps (max at 40 Mbps and cpb at 30000 kbit). I use dithering for source and source have low compressibility.

- I want see how work VBV with x264 in difficult area (cpb saturation)
- I want perfet linear quality (1.00 for ipratio and pbratio) because dithering produce noise flicking with high ratio.
- I want see if qcomp tweak can help for really complex area and compare encoding with different curve compression between real CBR and real VBR interval (qcomp in [0.00 -> 1.00]). Anyway qcomp and even type frame ratio seem inactive in my test.

desactive mbtree don't desactive QPRD and AQ?
desactive mbtree reactive qcomp?

[Dark Shikari]

mbtree has no relation to QPRD and AQ.

Yes mbtree vs. qcomp (the algorithm, not the option) is what --no-mbtree controls.

[AnonCrow]

- I want perfet linear quality (1.00 for ipratio and pbratio)
Perfect linear quality , or constant quantizer ?
If the latter, no VBV settings would be possible.

You'd just encode with the qp value that produces ~24Mbps (find the approx. value needed with a 2-pass encode),
and hope the video doesn't have bitrate peaks beyond 40Mbps
(analyze the finished video with something http://forum.doom9.org/showthread.php?t=143162 ).

Encoding with CRF and no-psy (or just tune psnr) and the VBV options would probably be somewhat
closer to what you want but would look inferior to a CRF encode with just the VBV options.

[Sagittaire]

Perfect linear quality , or constant quantizer ?
If the latter, no VBV settings would be possible.


It's possible for local area: encoder simply encode at higher local average but anyway really constant local quantizer for complex area.

Codec with good VBV must make that, else at cpb saturation, RC will encode all type frame at exactly same size (for BR it's 208 ko/frames and that produce extreme flicking). In this case the VBV quality is the most important parameters even if the codec is extremely efficient codec. In this particular case poor efficiency codec with good VBV will produce better quality than good efficiency codec with poor VBV.

[Sagittaire]

mbtree has no relation to QPRD and AQ.

Yes mbtree vs. qcomp (the algorithm, not the option) is what --no-mbtree controls.

Yes, I have good control now for qcomp and ratio with --no-mbtree.

mbtree produce really better quality?