capturing and preserving interlaced content - some questions

[Bobbo01]

Hi all,

I am trying to capture source material from old tapes from several sources (Hi8, Digital8, VHS-C and VHS). I would like to convert the material to a digital format and then discard the tapes. I will not discard the tapes until I can validate that I have captured them digitally and have preserved the quality of that source tape.

I, like most others, have struggled to deal with getting interlaced content on my progressive monitor and LCD TV. I don't like deinterlacing because in all cases, it removes quality from the source material. I'm all about retaining 100% quality.

The AVI plays with interlaced lines on my progressive monitor (to be expected), so I am unable to validate whether or not the captured AVI is on-par with the source material.

http://www.sendspace.com/file/cf1qh3
This link will allow you to download two files: A source AVI and and an MPG that was converted from that AVI which will be my DVD output eventually.



When I convert the AVI into an MPEG-2 file and play it back on my Sony Bravia TV, I get much better results (the interlacing is gone), but I still know that the source material looks slightly smoother. I'm worried that the converted MPEG-2 file may have actually become deinterlaced and I am not even realizing it. I convert with CCE 2.7 and the only options I really change are:

"output to top field first" - check this box
"offset line = 1" - default is 0

Without these two options set as they are, the resulting content will display unwanted interlaced lines on my Sony Bravia TV.



So ultimately, I have two questions. I'm hoping someone can download the attached zip file and analyze my files. It's not too big - only 41 MB.

1. Is my source avi preserving the full quality of the original source tape? --- I can assure you that the original tape plays back very smooth on a television set.

2. 2. Is my converted MPEG-2 file, which is displaying properly on my Sony Bravia TV, playing with interlace, or has it been deinterlaced during the conversion process?

Thank you very much!
Bob

[jagabo]

Your source AVI is interlaced, bottom field first, compressed with a DV codec. Any decent media player on a computer should deinterlace it on the fly. The MPG file is still interlaced but it has been converted to top field first by shifting the frame up one scan line (which is what you expect from the CCE settings you used). Other than that missing top scan line and MPEG compression artifacts you aren't missing anything. The bitrate on the MPG file is a bit high if you're going to make a DVD.

The source does have overly hot brights. But that's typical of D8/DV camcorders. The MPG file has retained those over bright areas. It would be better if you pulled the gain down a bit to bring them into conformance.

[Bobbo01]

Your source AVI is interlaced, bottom field first, compressed with a DV codec. Any decent media player on a computer should deinterlace it on the fly. The MPG file is still interlaced but it has been converted to top field first by shifting the frame up one scan line (which is what you expect from the CCE settings you used). Other than that missing top scan line and MPEG compression artifacts you aren't missing anything. The bitrate on the MPG file is a bit high if you're going to make a DVD.

The source does have overly hot brights. But that's typical of D8/DV camcorders. The MPG file has retained those over bright areas. It would be better if you pulled the gain down a bit to bring them into conformance.

Thanks for your response jagabo!

I have a question though - if I deinterlace the material with a 'decent media player', won't I be reducing the quality? My goal is to find a way to view the original source material (preserved in AVI) so that I can ensure that it parallels the source material before I discard that. Currently, I can't view an AVI in any way without interlace artifacts displaying.

Thanks
Bob

[jagabo]

I have a question though - if I deinterlace the material with a 'decent media player', won't I be reducing the quality?

For playback on a progressive screen you need to deinterlace. Otherwise you'll see comb artifacts. Even on an interlaced CRT TV you see only one field at a time so the video is being deinterlaced.

[Bobbo01]

I have a question though - if I deinterlace the material with a 'decent media player', won't I be reducing the quality?

For playback on a progressive screen you need to deinterlace. Otherwise you'll see comb artifacts. Even on an interlaced CRT TV you see only one field at a time so the video is being deinterlaced.

I guess I'm not fully understanding how interlacing works...
Is there any way to view digital interlaced content in its originality? Or do I need to purchase a legacy tube television?

[jagabo]

Each frame of interlaced video contains two half pictures, called fields. Each half picture is contained in every other scan line of the image, one in all the even numbered scan lines, one in all the odd numbered scan lines. They are intended to be viewed separately and sequentially. So a 30 frame per second interlaced video should be viewed at 60 fields per second. In a true interlaced video (like you have) each half picture comes from a different point in time.

Software can simulate what an interlaced CRT TV would do. The closest is a simple bob (each field is displayed separately, with the missing lines of the other field interpolated from the current field). You can get better image quality with a smart bob (in portions of the image with no motion both fields are displayed, in areas of motion the missing field is interpolated, or the software analyzes motions in the scene an may use data from the other fields to fill in).

[Bobbo01]

Thanks jagabo - this is good information.

So there is no software on the market that offers "true interlaced playback emulation"? Is this a limitation of the actual physical monitor itself? What if I connected a tube television to my computer?

From what your describing, it sounds like everything that's available attempts to mold the two fields together (somehow) to make it play on a progressive system.

So all broadcast television that is of interlaced source is being deinterlaced "somehow" by the television I am watching - is that correct?

[jagabo]

So all broadcast television that is of interlaced source is being deinterlaced "somehow" by the television I am watching - is that correct?

Yes. On a CRT it's a natural result of the way the CRT works. The electron beam scans one field at a time. The beam is usually about 2 scan lines thick so the missing scanlines of the other field aren't black. By the time one field is being drawn the previous field has faded away.

So there is no software on the market that offers "true interlaced playback emulation"?

Software that performs a simple bob is very close to what you see on a CRT (aside from other issues like LCD lag, color gamut, etc.).

What if I connected a tube television to my computer?

Some people do that. You have to convince your graphics card to put out an interlaced TV compatible signal.

From what your describing, it sounds like everything that's available attempts to mold the two fields together (somehow) to make it play on a progressive system.

The advanced bob techniques deliver a better picture (when they're working right) than an interlaced TV.

[Bobbo01]

The MPG file is still interlaced but it has been converted to top field first by shifting the frame up one scan line (which is what you expect from the CCE settings you used.)

Can you explain to me in more detail of why shifting / offsetting this line by 1 has fixed the "combing" effect I am seeing if I do not apply this?

[jagabo]

The MPG file is still interlaced but it has been converted to top field first by shifting the frame up one scan line (which is what you expect from the CCE settings you used.)

Can you explain to me in more detail of why shifting / offsetting this line by 1 has fixed the "combing" effect I am seeing if I do not apply this?

It does not "fix" the combing effect. It simply reverses the field order. What was the top field becomes the bottom field, and what was the bottom field becomes the top field. So now they should be displayed in the opposite order. Originally the bottom field was displayed first, then the top field. Now the top field should be displayed first, then the bottom.

Both TFF and BFF are valid and DVD compliant. The field order must be properly specified in the encoded video so the player knows which field to display first.

[Bobbo01]

Well the combing effect vanishes when I encode with the offset on. Without it, interlace combing elements are present. I guess I just don't understand why swapping the fields would eliminate it it (or at least appear to eliminate from the way I see it). Honestly, it looks like a very smooth, fluid, lifelike shot.

Also, do you know how to achieve the equivalent of the "offset = 1" and "top field first" in TMPGENC? I would like to use that encoder, but I have not figured out how to convert a file that looks the same as a CCE converted file.

Thanks
Bob

[jagabo]

If you those CCE to the exactly opposite, "output to top field first" - unchecked, and "offset line = 0", the video should also play properly. Any other combination will result in a problem.

In TMPGEnc Plus (I've only used that very old version) all you have to do is make sure it recognizes the source is interlaced and BFF. If it misidentifies the source, override it. Make sure it's set to encode interlaced. It should then encode interlaced BFF and that should play properly.

I seem to recall that some old versions of VLC only played TFF MPG files properly. Maybe that's your problem?

[Bobbo01]

Thanks for your help today. I will investigate other programs to play back AVI files and do some further research on BOB deinterlacing.

I am fairly confident that, even though I can't play them back, the AVI files are retaining the quality. I guess I will have to test it out on an analog system to really prove that though.

Do you have any more advice on the AVI to MPG conversion you could share with me? You already mentioned turning down the brightness a bit. If you can think of any more ways that the resulting MPG file can be improved, let me know.

Thanks again!
Bob

[jagabo]

The clip you posted looked like it was from a D8 tape. That recording was fine except for the blown out brights (but there's nothing you can do about that, that's whats stored on the tape). Capturing from analog sources like Hi8 or VHS you can get slightly better quality using lossless codecs instead of DV. If your capture device doesn't have a line time base corrector you really should get one for the best quality caps.

Check the black and white levels with a histogram or waveform monitor. Capture with the right levels using the capture devices proc amp. That will give better results than adjusting the levels later. Avoid noise and sharpening filters in the capture device. There are much better software filters for that. Especially if you're willing to learn AviSynth.

[_Al_]

I, like most others, have struggled to deal with getting interlaced content on my progressive monitor and LCD TV. I don't like deinterlacing because in all cases, it removes quality from the source material. I'm all about retaining 100% quality.

I have a question though - if I deinterlace the material with a 'decent media player', won't I be reducing the quality? My goal is to find a way to view the original source material (preserved in AVI) so that I can ensure that it parallels the source material before I discard that. Currently, I can't view an AVI in any way without interlace artifacts displaying.

This Avisynth is difficult to learn but then the door is open, to follow last input.
There is all kind of tablets, smart phones out there today, that will cost a few buck soon and you can feed them with your video. Not sure what direction is going to take on an account of viewing interlace video. I'd make an executive decision and make my SD interlace video turn into progressive one. 60p, not 30p , that would not be enough. Sure, you can back up that interlace avi an make 60p progressive on top of that, basically what you are decided to do anyway perhaps but you encode mpeg2 instead of mp4.

H.264 is much better compression (within mp4 container). And it is ready to view anywhere.I tested this one 60p.mp4 on some cheap android tablet (4.0.4) I have here and it plays flawlessly:
http://files.videohelp.com/u/198160/60p_main_3.0_CRF.20.mp4
used QTGMC within Avisynth to generate 60p from 30i and x264 encoder, notice the size it is half the size of yours mpeg2

Just to give you heads up, don't want you to be disappointed when people around you take out those gadgets out later on, or even now and will complain that that mpeg2 is large or picture squashed, players in it might not respect NTSC aspect ratio.

[jagabo]

Something to keep in mind: QTGMC is a great smart bob deinterlacer. Better than any TV or Blu-ray player available now. But in the future devices will get better at deinterlacing -- maybe even better than QTGMC. If you deinterlace now you will be forever locking in that quality of deinterlacing. But if you leave your video interlaced future deinterlacers will continue to improve the display of your interlaced videos. Use QTGMC to make videos for watching now. Archive your original interlaced video files.

h.264 (x264 in particular) supports interlaced encoding. Some devices may not handle it though. And those that do won't give as good quality as QTGMC now. If you want to try it, here's an interlaced x264 sample MKV of your video.

[sanlyn]

Just to give you heads up, don't want you to be disappointed when people around you take out those gadgets out later on, or even now and will complain that that mpeg2 is large or picture squashed, players in it might not respect NTSC aspect ratio.

Really? NTSC supports 4:3 and 16:9. There are players that don't support 4:3 and 16:9?

[jagabo]

There are players that don't support AR flags in MKV or MP4 files.

[_Al_]

Really? NTSC supports 4:3 and 16:9. There are players that don't support 4:3 and 16:9?

Software players in tablets might not, in phones, that's what I meant. I let NTSC go years back, not coming back.
I do not want to hijack this thread though, just a heads up for OP. He is all about quality, but that mpeg2 was terrible for example, I think it should be let sound here that there is H.264 and modern devices. No disrespect for what was said here.

[sanlyn]

That's a mighty narrow point of view. No NTSC for olde AL? No TV? Don't watch any movie made more than 15 minutes ago?
That's a shame. Wish I could afford to throw away all my entertainment every month or so and replace it.

[_Al_]

Why are some of you, long time contributors for videohelp, bitter like this. Is it necessary? I do not take anything from you, just heads up for op. Can you respect that without this disrespect crap? We are talking about home made video here not some beloved broadcast.

[sanlyn]

Disrespect? Sorry you took it that way. Mmm, yeah, I re-read my post and it does look that way, even to me! Then, I apologize. However....if I had to depend on a tablet to watch video, and it's a tablet that you say won't play my favorite MPEG's, then it would be the tablet that hits the trash bin. Meanwhile, I personally in 2012 spent $3000 for HD recording, processing, etc., but the old cable box and the 3 old NTSC DVD recorders are still pumping away, dozens of classic movies a month (some of them get stuffed into the new PC and come out 4 flicks on a BD platter). And still building the PC for my HD PVR. So, I don't think I'm that far behind, myself. But I don't readily ditch good-running gear for age issues. Especially when those $500, $600, and $700 good ol' boys from 2004-2005 gave me 17 classic flicks with good PQ + audio while I was away for Christmas, and they look pretty good on the $1800 NTSC player that's still going from 2002 (they look nice on last year's $900 BD job, too).....I guess if I had spent $35 on a Coby player and $90 on Sansui DVD-VHS combos back then, and had spent the last 10 years going thru 4 more short-lived copies of each, they would all be in the trash and I'd be saying good riddance.
But mine still work, and so does the new stuff. So I use both, old and new. I think that's what I was saying.

[_Al_]

I do not use tablet to watch my movies exclusively, btw, it will play mpeg2 from DVD too, but with no aspect ratio, did not try maximum bitrate but I guessit can handle much higher than DVD bitrate because it handles H.264, there might be app that fixes aspect ratio (player) did not need to look for it , the point was that he can do it differently, interlace troubles him so there is a fix. I'd let him decide, he will make DVD's anyway as it usually comes to that. He might even doesn't realize that he can bring that 60p to CRT, some media player in between will just pass correct analog to the TV.

I do not watch TV at all, do not record TV at all, I can watch football , mostly only hockey or tune up Me-TV for good old shows Twilight Zone etc. Using Netflix or whatever streaming it is available, documentaries, movies you cannot tune up in TV, or order disc if I wanna check out movie. Different approach.

[sanlyn]

I'm with ya, _Al_, we're not that far apart. Most TV is godawful lunacy. It burns me up paying for 140 channels and using only a handful.

So I didn't miss your point. At 2-AM my auto-pilot word mastery starts blowing fuses. Ye olde SD DVD's will obviously not be here forever (so, too, with h264) -- so, for archiving the O.P. would take note of your cautions. Fortunately if one keeps up with forums like this one finds workarounds to keep the old goodies runnin'. But we're heavily into movies in our home, and a good old a/v component gets to be a member of the family. We do get rid of plain old junk, but discarding precision gear is just not in me I guess.

[Bobbo01]

Thanks all-

Jagabo - I will definitely save the source files in interlace - I like your idea of waiting around for deinterlace technology to improve.

_AL_ - I am all about quality. Also, I don't mind so much about the 4:3 display on hand-held devices. Everyone who will view these tapes understands that it was filmed back in the late 90s, when 4:30 display was the standard for home video.