Finding two nearly indentical frames?

I have some VHS type recorded from TV I want to digitalize and convert to H.264. And some of my type have commercials recorded. What I want to is to cut out the commercials and merge the parts before the CM and after the CM seamlessly. I think maybe I need to find out the repeated frames before the CM and after the CM to do this? or I have another option? (OK, I posted in this AVIsynth section because I dont know where I should put it and I think this forum is frequented by the most advance user in the whole doom 9 forum...)

Hi, To cut commercials I use a manual method with Virtualdub. First, I select all the frames of the commercial and delete it. After, after brightening the video I delete, in a frame basis, those totally black. I never have found duped frames but, if any, I would have a second view of the video with virtualdub with the last of the frames I would retain and operating in the main session I would visually delete duped frames until I reach the frame marked in the second session. Another tech is delete a frame, move 1 frame before until the frame is duplicated. Then do the last delete. Good luck.

In my country, TV channel logo are always disabled at commercials. So, we can use some logo detector to detect and cut this frames.

Oh, sorry, maybe my english is too bad and I cant state my situation clearly. What I want to do is as follows: -------

you could grab the audio out and look for matching waveforms of the part you're wanting to check out. any methods based on checking one part of video against a test clip would be quite slow indeed, wheras looking at the corresponding audio waveforms can be quite a lot quicker. though either way you do it there's going to be a fair bit of manual work.

I just open it in vdub and scroll through the video holding shift so it only shows keyframes. Commercials always start with a keyframe (well, it's not required or anything, but it's a scenechange so it almost certainly does) and there's a couple in a row so you can generally see them even when scrolling at a decent speed.

You could use e.g. the helper script for finding the right trim-points for a seamless match.