Quantcast Output both progressive and interlaced? - digitalFAQ Forum
  #1  
05-15-2017, 05:47 AM
koberulz koberulz is offline
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What's the best/most efficient way to get a progressive output file while retaining the interlaced info?

My end goal is primarily web use, I suspect, but there may also be need to have footage on DVD or in broadcasts. So it makes sense to go through the reinterlacing after QTGMC when restoring, ending up with a DVD-compliant 25fps file.

It also seems like a massive waste to branch off after QTGMC and do everything twice - once for interlaced, once for progressive. Further, I'm not sure if the progressive file also needs to be 25fps.
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  #2  
05-15-2017, 09:17 AM
msgohan msgohan is offline
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By default, QTGMC does not retain the original source fields. It massages the original lines to fit better with its invented lines. There is a lossless mode you can enable, which means that something along the lines of QTGMC().SeparateFields().SelectEvery(4,0,3) would return the original, unaltered interlaced video. But the quality of the progressive file will likely worsen as a result.

Quote:
Originally Posted by koberulz View Post
It also seems like a massive waste to branch off after QTGMC and do everything twice - once for interlaced, once for progressive.
I guess what you're saying here is that one or more of your filters require progressive input.

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Further, I'm not sure if the progressive file also needs to be 25fps.
If you don't keep the deinterlaced file 50fps, you're screwed.
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  #3  
05-15-2017, 11:50 AM
koberulz koberulz is offline
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Quote:
I guess what you're saying here is that one or more of your filters require progressive input.
Yes.

Quote:
If you don't keep the deinterlaced file 50fps, you're screwed.
In what sense?
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05-15-2017, 03:50 PM
sanlyn sanlyn is offline
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Quote:
Originally Posted by koberulz View Post
What's the best/most efficient way to get a progressive output file while retaining the interlaced info?

My end goal is primarily web use, I suspect, but there may also be need to have footage on DVD or in broadcasts. So it makes sense to go through the reinterlacing after QTGMC when restoring, ending up with a DVD-compliant 25fps file.

It also seems like a massive waste to branch off after QTGMC and do everything twice - once for interlaced, once for progressive. Further, I'm not sure if the progressive file also needs to be 25fps.
You don't have to repeat the entire process. Keep the filtered, progressive copy. Re-interlace for DVD and broadcast. What you do with the 50fps version remains the question. For web use you'd need progressive media. Not al websites accept 50fps. The only choice there, as msgohan has alluded, is to discard alternate frames. That's not a good choice for action video -- it destroys 50% of the temporal resolution, giving jerky plaback during fast action and camera pans. Some websites (not all) will accept standard definition 50fps. The only usual distribition/disc format for 50fps PAL is 1280x720 BluRay/AVCHD, but you need fairly decent masters for getting SD into that format, and Adobe wouldn't be the upscaler of choice.

Or do you refer to the HD material you already have? If it's 1080i/25 it could be downscaled pretty well with Avisynth to 720p/50. 1080p/50 is not valid for BluRay and many players will choke on it..
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05-15-2017, 04:51 PM
koberulz koberulz is offline
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At present I'm reinterlacing, importing to Premiere, doing a final color correction, then editing out junk (timeouts, that sort of thing), adding chapter points, and exporting - to MPG via AME and/or frameserving out to MeGUI to create a progressive MP4.

I'm referring to the same VHS tapes my other threads are about.
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05-15-2017, 09:13 PM
msgohan msgohan is offline
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Quote:
Originally Posted by koberulz View Post
In what sense?
If you deinterlace to 25fps, how would you ever reinterlace that from 25p to 25i?
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05-16-2017, 12:10 AM
koberulz koberulz is offline
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I wouldn't. I'd either branch off from the 50p file into a 25i file and a 25p file, or just create a 25i file and then turn that into a 25p file.
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05-16-2017, 07:09 AM
sanlyn sanlyn is offline
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If you deinterlace 25i you have 50p. You can deinterlace 25i to 25p by either dropping alternate frames or blending fields. So how are you getting 25p by deinterlacing 25i?
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05-16-2017, 07:12 AM
koberulz koberulz is offline
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Code:
interp=nnedi2(field=1)
yadifmod(order=1, field=-1, mode=0, edeint=interp)
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05-16-2017, 08:48 AM
sanlyn sanlyn is offline
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In other words you're discarding the bottom field and keeping only 50% horizontal resolution. Why didn't you just say so?

Last edited by sanlyn; 05-16-2017 at 09:28 AM.
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05-16-2017, 09:31 AM
koberulz koberulz is offline
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You mean vertical?

I've had that script sitting on my drive as a simple deinterlacer for ages, found it on VH IIRC. If there's a better way, I'm all ears.
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05-16-2017, 09:37 AM
sanlyn sanlyn is offline
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Horizontal resolution -- i.e, temporal resolution. Uneven horizontal motion. Not for pans and action video, I'd say. That's what msgohan referred to earlier.
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05-16-2017, 10:21 AM
koberulz koberulz is offline
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So what's the best way to do things?
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  #14  
05-16-2017, 10:33 AM
sanlyn sanlyn is offline
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Dropping fields or frames is better than blending, by far. If you want 25i to 25p, dropping fields is your only choice. Will probably work for UTube or the web, where quality is low and most viewers are clueless anyway and will watch anything.
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05-16-2017, 11:01 AM
koberulz koberulz is offline
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Is there a better way if I work from the 50p version, or no?
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05-16-2017, 12:18 PM
sanlyn sanlyn is offline
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You have a 25i interlaced original.
If you deinterlace normally you'll have 50p. If you deinterlace same-rate, dropping fields, you'll have 25p at 50% temporal resolution. If you want that for the internet, you have to rescale to 640x480 or it will play at 720x576 (5:4 aspect ratio) instead of 4:3.

If you take 25i, deinterlace to 50p full frame rate, then drop alternate frames (SelectEven or SelectOdd) you'll have 25p at 50% temporal resolution. If you want that for the internet, you have to rescale to 640x480 or it will play at 720x576 (5:4 aspect ratio) instead of 4:3.

Or take 25i, deinterlace to 50p, keep all fields and frames and have all your resolution -- but it will be 50fps and you'll have to rescale to 640x480p for the 'net, considering that some sites will accept 50p and some won't. It won't work for normal broadcast unless you take 25p at 720x576 and encode it as interlaced. The encoder will apply an interlace flag to the progressive content. When it plays it will still have some judder on horizontal motion because of the discarded fields or frames, but a player will see it as interlaced. That might work for broadcast, but for the 'net you'll have to live with 640x480 @25p with reduced resolution or find a site that accepts 640x480 @50p.

The hard way is to try for BluRay or AVCHD. Deinterlace to 50p, rescale to 960x720p, add black borders of 160 black pixels to each side, and have 1280x720p at full motion resolution for BluRay or AVCHD which is 16:9 with a 4:3 upscaled image inside the frame. It will be a little blurry due to the upscale for SD-VHS. I would suggest that you upscale with Avisynth, not Adobe.

Actually PAL motion looks smoother when interlaced -- that's what people say, anyway.
[EDIT] Or for your own personal use with external players and TV, deinterlace to 50p and encode it as mp4 progressed with a 4:3 display aspect ratio.

Last edited by sanlyn; 05-16-2017 at 12:29 PM.
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05-16-2017, 12:40 PM
koberulz koberulz is offline
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Quote:
Originally Posted by sanlyn View Post
If you want that for the internet, you have to rescale to 640x480 or it will play at 720x576 (5:4 aspect ratio) instead of 4:3.
Treating the pixels as square?

Quote:
Deinterlace to 50p, rescale to 960x720p, add black borders of 160 black pixels to each side, and have 1280x720p at full motion resolution for BluRay or AVCHD which is 16:9 with a 4:3 upscaled image inside the frame. It will be a little blurry due to the upscale for SD-VHS. I would suggest that you upscale with Avisynth, not Adobe.
The issue here, though, is that I reinterlace to go into Premiere...I'd then be redeinterlacing out of Premiere...

If I drop the 50p file into Premiere instead, I need to spit it out, reinterlace, and bring it back in in order to get something for DVD. Unless I try and convert it from 50p to 25i within Premiere, but I'm fairly sure you'd reach through the screen and slap me if I tried that.
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05-16-2017, 01:12 PM
sanlyn sanlyn is offline
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You have the most convoluited wokflow I've ever seen.

Why don't you:
Deinterlace and denoise with Avisynth/VirtualDub. Save as lossless Lagarith or huffyuv 50p. Import into Adobe for color correction, save as lossless Lagarith or Avisynth. Use the second 50p file for all the other work. Yes, you end up with two 50p files, which is the price you pay for insisting on Adobe for whatever reason. The last 50p is a cleaned up, color corrected 50p that you can reinterlace for DVD, or discard alternate frames and resize for the net, or do whatever else you want.
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05-16-2017, 01:24 PM
koberulz koberulz is offline
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I've actually moved to completely uncompressed files coming into Premiere...I was using Ut but there was a really obvious drop in quality. Not sure if that would be true of Lagarith but I'm also trying to stay Mac-compatible from the earliest possible point in the process.

Color correction in Premiere is vastly easier, and I'm not familiar with any other software that will do the edits I need to get from the tape to the final footage (removing commercials, censoring audio, overlaying a score graphic, adding chapters, etc) and create a DVD-compliant MPG (with GOPs where I want chapter markers).
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  #20  
05-16-2017, 01:45 PM
sanlyn sanlyn is offline
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Quote:
Originally Posted by koberulz View Post
I've actually moved to completely uncompressed files coming into Premiere...I was using Ut but there was a really obvious drop in quality.
There's no quality loss with lossless codecs, so I have no idea what you mean. What's wrong with doing your edits on a 50p video in Adobe and outputting the edits as 50p? Take that 50p edited Adobe output:

Code:
### for DVD
AviSource(whatever file)
AssumeTFF()
SeparateFields().SelectEvery(4,0,3).Weave()
Code:
### for square-pixel 25p/mp4/internet
AviSource(whatever file)
Select Even()  # or SelectOdd
Spline36Resize(640,480)
For 720x576/50p/mp4/4:3. do nothing. Encode it as 4:3 DAR progressive.

But since no suggestion seems appropriate to your workflow, I wouldn't know what else to say.
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