What is the best way to IVTC an NTSC TV Capture?

[sidawg]

I'm trying to build my own archive of DivX encoded TV shows but have just realized that I've been encoding from an NTSC source when I should've been encoding from FILM (to squeeze out a better bitrate for the file size). How can I get the original NTSC MPEG2 capture into a 23.976 project file with DVD2AVI so I can encode it with gknot?

Here is what I've been doing:
1) Capture TV Show into MPEG2 with my Radeon AIW 8500DV
2) Edit out commercials with MPEG-VCR and resave as MPEG2
3) Load MPEG2 file into DVD2AVI.

After previewing the file in DVD2AVI, the video stats show the following:

Aspect Ratio = 4:3
Frame Rate = 29.970
Video Type = NTSC
Frame Type = Interlaced


Then I make sure of the following settings in the toolbar under Video:

Field Operation = None
Color Space = YUV


Then save the project to make a .d2v file and a .mpa audio file generates aswell.

4) Encode the .mpa audio file with gknot to .mp3
5) Load the .d2v file into gknot.
I target a size of 100MB (for 1/2 hour shows), resize to 320x240, and click the Save & Encode button. Then I select Neutral Bicubic and start encoding into DivX5.

So basically... can I do either of the following 3 things:
A) Just click "Force Film" in DVD2AVI and get 23.976 fps .d2v project (even though the stats say it's in NTSC)?
B) Just select "Inverse Telecine" from the window where I choose neutral bicubic (after pressing Save & Encode the first time in gknot)?
C) Just click the checkbox labelled "IVTC in avs -> correct frame count" on the final Encoding Control Panel in gknot?

I've read lots of guides telling me to use TMPGEnc to induce IVTC but is there an easier way? I'm having trouble using TMPGEnc and I'd like as much of an automated approach as possible to doing this.

[manono]

Hi-

A. No, not if it says NTSC.
B. Yes.
C. Yes also. You have to do them both.

All this presumes it's been telecined in the first place. I don't capture, so I don't know what those files look like. How can you tell if it's been telecined? Go back to the DVD2AVI Tutorial jggimi pointed you to before. It explains it in 3 different places, I believe. Hint-if telecined, there will be 3 progressive frames followed by 2 interlaced frames, in every 5 frame cycle.

[sidawg]

Thanks for the help manono! My source files are definitely telecined so your IVTC instructions worked great! How great?... well here is an example:

Before I was encoding my files at 29.970fps (captured as NTSC from an analog cable signal). I'd target these encodes at 85MB per half hour episode (which works out to be around 20 min running times after editing out all the commercials). At the time, I was achieving around .180 bits/pixel quality which produced some artifacts but was acceptable to me.

NOW after IVTCing my encodes, I am achieving considerable gains in quality while being able to reduce my target filesize. I'm getting around .210 bits/pixel at 75MB filesize encodes (that's around a 14% gain in quality) and artifacts have been reduced considerably!

For anyone reading this post and wants to learn more about IVTC, you can find it here (http://www.doom9.org/ivtc-tut.htm).

[manono]

You're welcome, and thanks for reporting back. I'm glad it's working out for you.

If you were still encoding for the same file size, it would be a 25% gain in quality. Plus, the encodes look better anyway, because you no longer have the deinterlacing artifacts. If you had been blending the fields, you don't have the blurriness anymore.

Look at it this way; when you're encoding at 29.97fps, you're encoding 25% more frames than when you IVTC and encode at 23.976fps. That's a big quality hit when encoding for the same file size. Eh? :)

[sidawg]

LOL it sure does... eh! :)