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Old 21st June 2016, 23:28   #1  |  Link
3hj
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Help correcting de-interlacing problems, please.

Hello.

I have a VHS tape, recorded many years ago on a consumer VHS-C camera. What I have now is a second-generation dub on a VHS tape, made from the original VHS-C tape.

A while back, I borrowed a DVD recorder from someone, with the hopes of getting a digital copy of this video. The results were okay - not horrible, but I could only get MPEG-2 video from the device.

Wanting to get an uncompressed good quality capture of the tape, with the aim of doing post-processing to improve the image, I sent my tape in to a 'professional' capture facility and paid them to capture it for me. Why? Well, they advertised that they had professional S-VHS decks, external TBCs and were able to provide uncompressed video. The VHS has quite a few dropped frames and horizontal lines in certain parts, so this was an attractive option.

They didn't end up delivering uncompressed video - simply another MPEG-2 file - but that's besides the point. Their TBC noticeably helped the rough parts of the video. The problem, however, is that they badly deinterlaced the result.

Here is a detail (so that the de/interlace effects can be dramatically seen) from one of the frames of the DVD recorder capture I made:
Name:  01.jpg
Views: 113
Size:  45.6 KB

Compare that to the exact same frame from the capture I got from the production house:
Name:  02.jpg
Views: 114
Size:  37.8 KB

Notice how both fields seem to be blended together. This motion smearing effect appears throughout the video, and is horribly annoying. Their capture is better in a lot of other ways, though, so I'd like to be able to salvage it.

For comparison, here's the same frame again, from my DVD recorder capture, run through the Yadif filter, showing what a 'correct' deinterlace of that specific frame should achieve:
Name:  03.jpg
Views: 118
Size:  39.4 KB

So my question: is there any way to "re-interlace" this footage? As in, separate the blurred end product back into the original field order? Or, at least, fix this issue and end up with non-ugly deinterlaced footage? Ideally I'd like interlaced footage, but at this point I would be grateful for any kind of improvement!
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Old 22nd June 2016, 00:22   #2  |  Link
johnmeyer
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Your attachments have not yet been approved, but in general, if the transfer house delivered a deinterlaced version, you didn't get a professional transfer. You really want to deal with the original, interlaced video for as far down the chain as you can. You certainly never want someone else to do it for you: they usually screw it up, as you have found out.

The best thing would be to ask them to transfer it again and give you an interlaced version, and have them save it using either a lossless codec (best option), or at least something that will produce very minimal compression artifacting. I have always been a fan of Cineform, but I think people on this forum may have some better, more modern suggestions.

Finally, while you can indeed "re-interlace" footage using motion estimation, it will compound the loss that you've already experienced by allowing the transfer house to deinterlace. Remember that deinterlacing always degrades the result. There is no way around that. Once you have done it, for most situations, there is really no reason to turn it back into interlaced video. My recommendation is to always keep it interlaced, and then either let your TV or software player do its job of deinterlacing, or do it yourself using some really good software, but only after you've done everything else.

Of course if you have to re-size, you must deinterlace before you do that, so if you go that route, just keep it deinterlaced.

Last edited by johnmeyer; 22nd June 2016 at 00:25. Reason: Hit "save" instead of "preview" button, and I wasn't finished yet
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Old 22nd June 2016, 00:31   #3  |  Link
vivan
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Quote:
Originally Posted by johnmeyer View Post
Remember that deinterlacing always degrades the result. There is no way around that.
That really depends, for example QTGMC has lossless mode that keeps original fields and only interpolates missing ones. But of course result is worse than if you just allow it do to as it wants.
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Old 22nd June 2016, 00:56   #4  |  Link
johnmeyer
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Quote:
Originally Posted by vivan View Post
That really depends, for example QTGMC has lossless mode that keeps original fields and only interpolates missing ones. But of course result is worse than if you just allow it do to as it wants.
Yes, QTGMC is one of the best deinterlacers out there. My only point is that regardless of the algorithm, and regardless of how many fields are adjusted, the new fields are always going to be approximations of what they would be if the video had been 60p instead of 60i (or 50p/50i for PAL). There will be artifacts. How bad and how many is a function of the nature of your video, the deinterlacing tools chosen, and your skill in using them (there is no "set it, and forget it" setting when deinterlacing).

However, since I've made this point more than a few times before (in other threads), I won't go into it any further. I'll try to see if there is a way to salvage something, once the attachment's to the OP's #1 post are approved.
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Old 22nd June 2016, 04:35   #5  |  Link
manono
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I just approved the pics. Yes, they completely screwed it up. Even if you wanted them to deinterlace it, they used the worst possible one - a simple blend deinterlacer. I think you have a good case for demanding your money back and either having them do it over, correctly this time, or for taking your business elsewhere. I don't even know why those fools are still in business, except that the average person doesn't know enough to be able to tell they're incompetent. Since when is it common practice to deinterlace tape captures when digitizing them?
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Old 22nd June 2016, 04:58   #6  |  Link
johnmeyer
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I didn't realize that the attachments were all still photos. I find it impossible to tell anything about interlaced video by looking at a still photo of an entire frame. That said, manono is probably correct. I already made the same recommendation that you get the tape re-captured. You'd probably get a better transfer from Costco (I think they sub it out to Yes Video).
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