definitive guide to deinterlacing mpeg-2 --> XviD anyone?

[graysky]

I've googled around and tried a few guides... can someone recommend a *good* guide that shows the correct method to deinterlace an mpeg-2 stream (capped w/ my pvr-250) when encoding to xvid?

[guns1inger]

AutoGK does a pretty good job and will encode for you.

The following is from a basic script provided elsewhere by Manono

LoadPlugin("C:\Path\To\DGDecode.dll")
LoadPlugin("C:\Path\To\LeakKernelDeint.dll")
MPEG2Source("C:\Path\To\Video.d2v") #or AVISource if an AVI
AssumeTFF()#if TFF, Assume BFF() if BFF
LeakKernelBob(Order=1)#if TFF, Order=0 if BFF

The original script continues on to perform processing on the deinterlaced stream, then separates it back out to fields - something you don't need.

I am not saying this is the best method, however it is certainly worth a try.

[graysky]

Interesting, do you have a link to the original source? Also, how does one account for the differences 30 fps --> 24 fps imparts on the audio stream? I would think this would produce A/V sync errors?

[jagabo]

how does one account for the differences 30 fps --> 24 fps imparts on the audio stream? I would think this would produce A/V sync errors?

That is an inverse telecine rather than a deinterlace. It has no effect on the running time. Think of it like this:

Take a stack of 30 playing cards. Flip them over at 30 cards per second. It takes exactly 1 second to flip them all over. Now throw away 6 cards, you have only 24 cards left. Flip them over at 24 cards per second. Once again it takes exactly 1 second to flip them all.

[graysky]

Cool... thank makes sense. Problem is with the method. It simply doesn't work The resulting video looks horribly scrambled.

The source video is an mpeg-2 stream captured via an PVR-250 from an analog cable NTSC feed. The goal is to encode to an xvid avi file. My understanding is that I need to either inverse telecine or deinterlace prior to encoding. ...so am I interested in inverse telecine or deinterlacing? Also, can you point me to a good guide to do so?

Thanks.

[manono]

Why don't you upload a small (10-15 seconds with motion/movement) section of this video for us to have a look. Then one or another of us can tell you what you have, and how to treat it. Or take guns1inger's advice from the first response and let AutoGK handle it.

The best guide on how to tell what your source is like and how to IVTC and/or deinterlace, is one I was involved in writing several years ago. The methods/software/filters have changed considerably since then, but the basics are still sound:

http://www.doom9.org/ivtc-tut.htm

[graysky]

It appears that the framerate option in vdmod works when set to:

Source rate adjustment: No Change
Inverse telecine (3:2 pulldown removal): Reconstruct from fields - adaptive

That at least gives me an avi that's ~24 fps. If you believe the math for Qf, encoding fewer fps allows you to use less bitrate for a given Qf.

Qf = bitrate/(v. res x h. res x fps) x 1000

Therefore, the lower that fps term is at a given bitrate, the greater Qf will be... thoughts?

[jagabo]

Think of it like this: If you display a JPG picture for one hour you have a one frame per hour video. If your JPEG file is ~150 KBytes (reasonable for a 720x480 image) that's about 1 Mbit per hour. That works out to about 0.28 Kbits per second.

By the way, VirtualDub's automatic IVTC isn't very good. Better than nothing but you can do much better with AVISynth filters.

[edDV]

Cool... thank makes sense. Problem is with the method. It simply doesn't work The resulting video looks horribly scrambled.

You are missing something here. 24 fps film is telecined to 29.97 fps (59.97 field per second) video so that it can be displayed with smoother motion and less flicker. Movie theaters don't display 24 fps either. They use a gate to repeat frames at 48 or 72 fps to reduce flicker.

The reason you are reducing frame rate to 24fps (23.976 to be more precise) is for transmission efficiency. It is the job of the hardware or software player to process 24fps for display. A DVD player will re-telecine to 29.97 fps or if in progressive mode, repeat frames in 3 then 2 order to get 59.94 fps playback.

Computer software players will convert 24 fps to your display card's refresh rate.

[graysky]

MeGUI is the answer to my problems.. thanks to all who replied.