720p60 to SD DVD workflow

GrahamH

GrahamH

Well-known member
I've been shooting 720P60 this past week, and was surprised at what a poor job the encoders I have access to (AME, Procoder and TMPGEnc) did in converting the raw clips to 720x480 mpeg2 for DVD authoring.

So I fooled around with some preprocessing options this afternoon. I tried: 1) conversion to interlaced 60i; 2) frame-blending to 30P; and 3) frame-dropping to 30P.

Of these, frame-dropping footage shot with a 1/60 shutter worked the best for me. If anyone's interested, the avisynth script I ended up with was simply ...

Avisource("Cineform720p60.avi")
SelectEvery(2,1)
LanczosResize(720,480)

... followed by encoding as progressive 16:9 in TMPGEnc Xpress.

I'm interested to hear, though, how other folks have been handling this?
 
That's the best way to turn 720p60 into (720x)480p30. You can also decimate frames and use Lanczos resizing in VirtualDub. None of the major NLEs, that I'm aware of, does very good resizing. Tools like AVISynth and VirtualDub are worth their weight in gold (but they are free!).
 
How do you do that conversion? - every encoder and preprocessing method I tried produced either stairstepping or line jitter.
 
By line jitter you mean interline twitter? You really cannot get away from twitter with interlaced video, it is just more noticeable in SD. You can filter vertical details out, but the video will be softer. I cannot wait for the time when interlaced video becomes history.
 
Cranky's right, interlaced sucks, but it's the only way to keep the temporal resolution & smoothness if you're stuck with DVD-video format

If you have a 60p source and want a 60i DVD

AVISource("whatversource.avi")
LanczosResize(720,480)
AssumeTFF()
SeparateFields()
SelectEvery(4,0,3)
Weave()

I would recommend using HCEnc or CCE for this
 
Yup that script is what I used, with various levels of vertical blur experimented with. To me the interlace effects are too dire unless you give away all the sharpness - I'll be sticking with 30P.
 
GrahamH said:
PDR, what would you recommend for 1080i60 to 480i60?
Click to expand...

As you are probably already aware, most NLE's don't do interlaced resizing correctly. The proper way is to bob deinterlace , resize frames , reinterlace.

The problems with most programs is they use a poor resize algorithm and poor deinterlace algorithm resulting in jaggy artifacts and soft image

This is what I usually use, but it's slower from the higher quality deinterlacer

Code: 
AssumeTFF() 
interp=NNEDI2(field=3) 
YadifMod(order=1, mode=1, edeint=interp) 
Spline36Resize(720,480) 
AssumeTFF()
SeparateFields() 
SelectEvery(4,0,3) 
Weave()

But if you're plagued by interline twitter, and going to apply blur for DVD anyway, I wouldn't bother with a slower high quality deinterlacer, and stick with a faster one like yadif in bob mode [replace lines 2 & 3 with yadif(mode=1,order=1) ]. Many of the deinterlace jaggy artifact remenants from yadif (or lower quality deinterlacers) are less visible when resized to SD resolution anyway.

Another option you can experiment with is to use a softer resizer. Try a bilinear resize instead of lanczos or spline36 (the latter 2 are noticably sharper and crisper). This may seem bad practice to soften your image, but the limitation here is interlacing , DVD video, and twitter

Also, note that some DVD players and HDTV apply different post processing (like vertical blur or line doubling) to interlaced material. So what may look fine on 1 set of equipment, might not on another.
 
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Vimeo I believe turrns everything into P24. Sorry for all the questions, PDR, but any recommendation for a good P60-to-P24 workflow?
 
GrahamH said:
Vimeo I believe turrns everything into P24. Sorry for all the questions, PDR, but any recommendation for a good P60-to-P24 workflow?
Click to expand...

Don't they accept 30p ? Just use SelectEven() or SelectOdd()

24p from 60p isn't ideal , because you have to resample frames (because not evenly divisible).

So you can either decimate frames , decimate+blend frames, or generate in-between frames. None of them are ideal, the first 2 approaches have problems with jerky playback or blurriness, the last has problems with motion artifacts is very CPU heavy (i.e slow) but gives the smoothest results and usually the better in terms of overall quality

In avisynth you could use mflowfps or mvflowfps (part of mvtools and mvtools2) , or if you have After Effects, pixel motion. These basically calculate motion vectors and generate the in-between frames

The documentation in mvtools2 gives you examples, and how to tweak it higher quality (slower) or lower quality (faster)
e.g. of a slower method

Code: 
AVISource("video.avi") 
super = MSuper(pel=2)
backward_vec = MAnalyse(super, overlap=4, isb = true, search=3)
forward_vec = MAnalyse(super, overlap=4, isb = false, search=3)
MFlowFps(super, backward_vec, forward_vec, num=24000, den=1001)
 
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Vimeo originally converted everything to P24 - I guess that may not still be the case. I'll check. I uploaded some 60P converted to 30P last night and the result seemed to end up with a suspiciously 24P-like stutter to it. Or else the connection was spotty. Thanks for the suggestions.
 
Cranky said:
If you want to keep the "live" motion, then interlacing to 60i is the only option.
Click to expand...

No, 60p has the exact same motion characteristics and "live" appearance as 60i. It's about motion samples per second, not whether it's interlaced or progressive.
 
David Jimerson said:
No, 60p has the exact same motion characteristics and "live" appearance as 60i. It's about motion samples per second, not whether it's interlaced or progressive.
Click to expand...

But 60i is the only option to keep that temporal resolution for standard DVD-video, that's what cranky meant
 
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