overshooting size? and ntsc question

[lnx227]

using divx 3.11 and gknot .21b, i keep getting over my filesize target (695) by maybe 25-30mb (going by the new guide). Never had this problem before (old guide/version .19). Any ideas on what settings i might be overlooking?

Another thing, i have an complete NTSC DVD, it's just under two hours i believe. Now, i can't seem to get a good compressability when tryign to shoot for one cd. Inverse telecine (when check) will cause an error when i start the encoding process... i think the errror is somewhat ignored as gknot is still trying to do something when i try to close it.

any ideas? thanks

[TheWEF]

use "force film" in dvd2avi.
post your complete *_gknot.log

wef.

[lnx227]

i may have deleted it.. but i will check later (it's on the other comp).

i was under the impression if dvd2avi didn't show any film percentage, i should not have force film on?

[jggimi]

I too, have found that when encoding a true NTSC source, where the original framerate is 29.97 -- e.g.: a video rather than film source -- the size estimation is *significantly* lower than the result. It may be something as simple as the higher framerate, or, it may be associated with interlaced 29.97 sources.

I seemed to get this same result with the Divx4 codec whenever I've used 29.97fps in the .d2v file. -- Happens when the dvd was a video rather than film transfer. And, for those sources, one shouldn't force film or otherwise try to undo the Telecine process; one was never performed.

(As a side note, I've found it helpful to temporarily change the start point when checking sources with dvd2avi ... on a lot of transfers, the frame rate during leaders at the start is NTSC 29.97, and drops down to 23.976 once the film source starts.)

I ended up using nearly a .30 bit/(pixel*frame) rate to fit 90 minute videos inside 700MB CDs. This size reduction was needed whether I selected "fast" or "smart" deinterlacing.

I don't want to sound like this is a complaint -- it's not, it's just the experience I've had. And, TheWEF was very clear that the estimates are just that -- estimates. GKnot has been a godsend.

Hey, WEF, did you know that your best and most helpful documentation on GKnot is not readily available inside GKNOT, or from the Guides link at doom9. They're hard to find, but I love them both:

http://doom9.net/gknot-divx3
http://doom9.net/gknot-divx4

Thanks for one terrific, useful, easy to install and easy to use tool!

[seoulsteve]

@inx227 --> all of the DVDs i have are NTSC at 29fps. i suggest that for ALL encodes you use "forced FILM".

there may be other was for an advanced user to get a good (or even crashless) encode out of using something other than "forced FILM", but it's a good idea for novice users to force the film into 24fps.

also, if you read the guides, going from 29 to 24 frames per second will up the quality of your encode a bit.

[jggimi]

Originally posted by seoulsteve
all of the DVDs i have are NTSC at 29fps. i suggest that for ALL encodes you use "forced FILM".

there may be other was for an advanced user to get a good (or even crashless) encode out of using something other than "forced FILM", but it's a good idea for novice users to force the film into 24fps.


Steve,

I believe that all of your DVD's are Telecine films. That is, they were all originally 24fps converted to NTSC 29.97fps to play as NTSC video.

A DVD transfer whose source was not film, therefore, should neither have "Forced FILM" in DVD2AVI, nor an Inverse Telecine -- "iVTC" filter added to the Virtual Dub or Nandub encoding.

"Forced FILM" in DVD2AVI should be used on all Telecined content that has non-Telecined leaders. Leaders like the "WB" logo, the "Miramax" logo, the "Dreamworks" logo. It can also safely be used on fully Telecined material.

If, on the other hand, you have content that consistantly shows "Interlaced" and "NTSC" rather than any FILM content in DVD2AVI, then you should not use "Forced FILM" unless you want problems. I don't know what type of problems you would get, cutting 20% of your frames -- I imagine audio synch would be one of them.

When all else fails, I trust theWEF's guides. He recommends Forced FILM only when the content beyond the leader has been Telecined. That's why he recommends using the Preview in DVD2AVI and checking the content.

[JayTray]

I have noticed if you add an audio file size to Gknot you must include the "audio" and video in the last pass. I was adding the audio info into Gordon Knot and encoding both passes with no audio. And then I would mux the two together in Nan Dub. I think this may be a bug with Gknot or maybe I am just crazy. But this has solved my file size problem. If you absolutely must encode the audio and video seperately (i.e. Encoding DivX 4.x with vbr MP3 audio) don't add an audio file size in Gordon Knot. Just choose no audio in the in the interlieve and audio header section. Then subtract your audio size from the desired file size and you should come out with the same size file as you entered (give or take a MB).

I hope this is what is causing your files to be too big. I know it sure solved mine. Good Luck!

[jggimi]

I have figured out, I think, why my size was incorrect. I needed to rtfm, again.

NTSC sources should have IVTC -- inverse telecine -- turned on and the framerate set to 23.976, per the guide. Missed that. I'll test it on my next NSTC encoding.

Am not sure about non-Telecined sources, though.

[jggimi]

ok. Vdub wouldn't run with iVTC filter, altered framerate in Gknot, and true video source.

However, a progressive source sizes properly, compared to interlaced. Not a big deal.