Tip of the day: enabling closed GOP's in MPEG.now

[Flying dutchman]

Chapters yes (by means of importing a text file with the marker positions), menus no.

[bitz4brainz]

Eureka! I think I have made some serious headway on the problem, and it has to do with the open/closed GOP issue.

To backtrack a little: I am trying to transfer some out of print films from laserdisc to DVD. I capture with a DV camcorder (passthough), encode in TMPGenc, and author in MF2 (also the ES 1.2 demo, which has similar problems). For certain films I want the best possible quality so I'm splitting the movie across two DVD+Rs, one hour each. My encodes look great in PowerDVD -- while they are still plain MPEGs. But when I authored these same files into DVD with MF2, they stuttered badly in PowerDVD on the same computer. Oddly, there was no problem when authored in Roxio's little DVD Builder.

I took a clip (the Tie vs X-wing battle scene from Star Wars) and systematically tried various encoding settings. This site has been enormously helpful in understanding the settings:

http://dvd-hq.info/Compression.html

Among other things, I found that the stuttering got worse with higher bitrates. At 8Mb CBR it was horrible, but at 5Mb (VBR) the stuttering virtually went away. And there was something I had noticed earlier: At their worst, the stutters happened about twice a sec. I was then using a GOP size of 15 frames (1/2 sec). Coincidence? Probably not, and that's why I should have focused on the GOPs much sooner.

In my latest tests I used 8Mbs and varied other settings. By now I had eliminated B-frames, and my GOPs were 5 frames: IPPPP. That actually made the stuttering less often but more random (vs twice a sec.)

But I think the key issue goes back to what the good Doctor was talking about at the top of this thread. Closed vs open GOPs. He was talking about the fact that some authoring packages prefer *closed* GOPs, but the MPEG.now encoder Ulead is using produces open GOPs. He showed how to switch to closed GOPs.

Well, I think that MF2 and its big brother WS do not like closed GOPs, and that was what TMPGenc was producing for me by default. When I encoded last night at 8Mb/sec OPEN GOP, the stuttering virtually disappeared! (Still a very occasional blip.)

I still have a lot of work to do before I can be 100% satisfied, but I really think this was the biggest problem: Ulead MF2 can't handle high bitrates with closed GOPs.

Other notes: I have been IVTC'ing the film and trimming / reformatting for 16:9. I keep the soundtrack uncompressed PCM.

[Elie]

Thanks Doc for the tip!

In DVDWS's ini file, where would you insert the advance=1 in order to get the advanced menues?

Thanks again.
Elie

[Dr Mordrid]

You insert it thusly;

[VIODRIVER]
Advance=1

Dr. Mordrid

[crow8k3a]

I'm using the advanced features to produce SVCD mpeg2's, but i really don't notice any difference in quality from just selecting svcd from the menu like i did before, any ideas?

when i change a setting, and re-render the video, it does it in a couple seconds like its not changing anything from the previous render.

[Fred H]

Tried ifoedit095 but it produced a WinXP error shooting down Nero or InstantCD/DVD (mayby: "mia culpa"?) I demuxed with TMPGEnc.
I don't know why. MF did the same job much better. It was only a short test video I made, to experiment with my new NEC ND-1300A burner.

Fred H

[Jerry Jones]

Remember "Mr. XVCD?"

Ross McClennan?

I don't agree with everything Ross has written in the past.

But I noticed with great interest recently that he now admits on his Web site that the MainConcept encoder is delivering better results than TMPGEnc.

McLennan writes this about the MainConcept encoder:

"It’s extremely good and faster off the timeline than anything I have used in the past."

"In my tests it beat the Avisynth/Cinemacraft encoder version 2.5 (CCE25) combination for speed in DVD encoding by as much as 47% (depending on what is being encoded) and it is capable of providing similar quality at those speeds if you tweak it a bit."

"Goodbye, LSX and TMPGEnc, you have been blown away in the speed race at the same quality with this offering."

http://geocities.com/faussie01au/index.html

Doc, thanks for the tips about the video encoder quality slider settings.

Jerry Jones

http://www.jonesgroup.net

[crow8k3a]

if u could post your settings for mpeg stuff such as vcd xvcd svcd and dvd and how to get mspro w/ mainconcept to output those good mpegs, cause mine sure doesn't.