problem using decomb

[KF]

I was trying to convert an Indian film. DVD2AVI says it's NTSC interlaced 29.97. I loaded an avs script using mpeg2dec into virtualdub and say that there were blended frames. I used the last legacy decomb and avisynth 2.07 with telecide and decimate with cycle=5. I used cce 2.50 sp and did the pulldown at the end. On the whole I was happy with the finished product, however, I have noticed that every few seconds there is a frame missing, the movement skips. The audio is all in sync. I suppose I could put up with it on this instance but I wouldn't like all my encodes to be like this. Any help for the future will be much appreciated.

[manono]

Hi-

You should always check the frames before encoding, particularly if DVD2AVI shows it to be interlaced, or 100% NTSC. So make your .d2v with No Field Operation and make an .avs script with this:

Telecide(Post=False) #No decimate.

Open it in VDub and find a place with movement/action. You're looking for duplicate frames. If you see one every 5 frames, then it can be IVTC'd. If you see none, then you have to leave it at 29.97fps and either deinterlace or encode it as interlaced in CCE. Although I've never seen this with Indian films, if it's been mastered from a PAL source, there's a chance you'll see duplicates every 6 frames, in which case your final script will become:

Telecide(Guide=3).Decimate(6) #I don't know if you can run Pulldown on that, though.

If you see the duplicates every 5 frames, and still got the periodic skipped frames, then you might try:

Telecide(Guide=1).Decimate(5)

or some of the other tricks you can find in the DecombHelp file.

[KF]

Thanks, I shall try your first suggestion to locate the duplicates. Just to let you know, I did try the guide=1 and cycle=5 but was getting blended frames coming through.

[manono]

Hi-

Have you checked if the blends are already in the fields? To check, knock off the Telecide-Decimate and add SeparateFields() to the script. If they're still there, then there's nothing Decomb or anything else can do about it (unless you start fooling around with the SelectEvery command, and even then there are no guarantees).

If the fields don't come already blended, and you don't like the blended deinterlacing, then you might try:

Telecide(Guide=1,Blend=False).Decimate(5)

but that's liable to make it even jumpier. Personally, I'll take the blends anyday. The chances are good that you just have a badly telecined movie, and nothing's going to make it look perfect. Another thing you can try if your resolution is low enough, and the fields aren't blended is:

SeparateFields().SelectEven().Decimate(5).#No Telecide

No interlacing, and no blends. And even if the fields are blended, that'll eliminate many of them. But it has other possible bad side effects including shimmering. I do that sometimes with especially bad sources.