HCenc: min/max GOP for DVD from a good source?

[florinandrei]

Let's assume I use a very high-quality 480i source - HD master footage, downscaled to 480i. The footage is from an AVCHD camcorder that usually operates hand-held, but may be on a tripod occasionally. Zooming and panning is some times under control, but may get pretty wild some other times. Some scenes have lots of motion, others are pretty static. The noise level is very low. Detail is very good. It's usually a mixture of dark and bright scenes.
So it's difficult footage from a content perspective (motion, light), but very good from a technical perspective (noise).

I use the "best" profile and the largest max bitrate that's safe for DVD.
The goal is to maximize the quality of the image on the DVD while staying compatible with any DVD player. I'm looking to encode most scenes at a max bitrate close to 9500 and an average bitrate 15%...40% lower than that. I wouldn't go so far as to push the bitrate up against the ceiling and make it effectively constant bitrate, as that may knock out some DVD players.

I don't want to make individual HC.ini files for each scene. I'm looking for some sort of "happy medium" that works well in most cases.

*MAXBITRATE 9500
*PROFILE best
*AUTOGOP 15
*CQ_MAXBITRATE 4.500
*AQ 1
*DC_PREC 10
*INTERLACED
*NOSCD
*MATRIX mpeg
*LUMGAIN 1
*PRIORITY normal
*WAIT 1

Any suggestions re: tweaking the GOP? Would the image quality benefit, in theory, from a longer GOP? A shorter one?

Any other suggestions for maxing out the quality? (I'm speaking strictly about HCenc settings, not about denoising in AviSynth and stuff like that, and the master is already very high quality)

[45tripp]

Any suggestions re: tweaking the GOP? Would the image quality benefit, in theory, from a longer GOP? A shorter one?

longer, in practice.
max standard ntsc gop size is 18. set it to that.


I'm looking to encode most scenes at a max bitrate close to 9500 and an average bitrate 15%...40% lower than that. I wouldn't go so far as to push the bitrate up against the ceiling and make it effectively constant bitrate, as that may knock out some DVD players.

why a cq encode?
if want to push out maximum quality within standard,
cbr is the best choice, and HC is not the right encoder for it.


Any other suggestions for maxing out the quality?

might as well max out aq to 4, increase lumgain to 2.
personally i never set dc higher than 8, and have scene change on.


tripp

[chickenmonger]

You may try changing the matrix from the default to a different one as suggested in another thread (http://forum.doom9.org/showthread.php?t=139359).

[florinandrei]

I'd rather not use CBR. There are too many flaky DVD players out there and I don't want to push them over the limits with a high-bitrate CBR. Maybe I'm too paranoid.

I don't need scene change, the scenes are already split into different files in the capture stage, and I'm processing each file separately.

I'll try this one and we'll see what happens:

*MAXBITRATE 9500
*ASPECT 16:9
*PROFILE best
*AUTOGOP 18
*CQ_MAXBITRATE 5.000
*AQ 4
*DC_PREC 10
*INTERLACED
*NOSCD
*MATRIX fox1
*LUMGAIN 2
*PRIORITY normal
*WAIT 1

[florinandrei]

I'll try this one and we'll see what happens:

*MAXBITRATE 9500
*ASPECT 16:9
*PROFILE best
*AUTOGOP 18
*CQ_MAXBITRATE 5.000
*AQ 4
*DC_PREC 10
*INTERLACED
*NOSCD
*MATRIX fox1
*LUMGAIN 2
*PRIORITY normal
*WAIT 1

Looks pretty good, but wow, it pushes the bitrate a lot to the ceiling. I'm not complaining, though. That's what I want actually.