A1: Progressive Vs. Interlaced dilemma
 

Guys, please help me here. I love this camera (A1) but it has too many modes and I can’t take a decision. Should I use it in 60i or 30F?

I’m a sucker for resolution and on my Sony 60” 1080P TV the 60i seem sharper to me. All the tests on the internet would prove that. On the other hand I get better results downconverting 30F to regular DVD than 60i (may be my technique but the interlaced fields are not blended as well as I wish).
True is that DVDs will eventually go away in my home since I’ll move to blue ray and I could probably keep everything in 60i for ever. The 30F is damn cool though and much better than my old 720P from JVC (HD1) I don’t mean the obviously better resolution and colors but also in terms of progressive artifacts the Canon is MUCH BETTER. They are almost absent.

With the JVC though I was an happy camper with 30P and since I didn’t have other choices I wasn’t making my life too complicated, now I have a dilemma every time I use the camera : 30F or 60i ?

I’m bugged by the loss of resolution in 30F (that may be is just in my head, please convince me otherwise)

I’m bugged by the interlace artifacts when I scale down to progressive DVD SD when in 60i (may be you do a better job then me setting your SW, I use Premier 1.5 btw)

Give me a suggestion so I stop with this and go for one mode only. Now I’ve 50% of my tapes in 30F and 50% in 60i can’t go on like this :-)

Thanks a lot

Gabriele

I like the look of 30F better. No interlace artifacts. The loss of resolution is insignificant for me.

There's no resolution loss in the horizontal, and only 10.6% loss in the vertical for 24F.

I prefer 60i for the smoother motion handling and reality look.

http://dvinfo.net/conf/showpost.php?...2&postcount=17

I like 30f over 60i and 24f. No resolution loss in 30f and no interlacing issues on down conversion.

I prefer the full frame mode (25F, since I live in PAL land).

Nevertheless interelace gives you one option that might be interesting and that I have used quite a lot in the past:
You can render films with DOUBLE FRAME RATE (60p in your case) which gives you unseen motion definition. I use Vegas for this (field interpolation) and the results look very convincing.

Hi Gabriele. If you shoot 60i, why not make 60i DVDs? This would help to avoid interlace artifacts because most TV monitors can handle interlaced video very well.

Richard

Hi Michael. Can you explain what you mean by "unseen motion definition". Sounds very interesting but I haven't come across this before.

Also, how do you use your final 50p output? Is it only for viewing on a computer or is there some DVD player that supports this?

Richard

Hi Michael I would also be interested in this
Are you Changing the project properties in Vegas to 50fps (double PAL) and then rendering in 50p?

Fergus and Richard, I change Vegas project properties to 50 fps (progressive), although this is not necessary. I simply render my 1080 50i projects with a 720 50p template (interpolating fields) and get 50 fps clips. These clips are only for my computer.

Sure, this is not native 50 fps - due to the interpolation of the fields there are subtle artifacts. But the motion definition (when panning, for example) is 50 fps and it looks stunning compared to the more "stuttering" 25 fps film look that we are so used to. 60 fps is even more stunning.

I think there will be the same resolution loss in the vertical for 30F as there is for 24F. I'm going to do the resolution test for 30F using the IMATEST MTF50 software and post the result later today.

I think that would be spectacular for motion handling. My JVC GR-HD1 had a 480p60 mode that would give a clue, lower resolution yes..., but incredible reality.

Yes!

I once watched a SHOWSCAN ride film (70 mm at 60 fps) in Las Vegas. Very impressive ... not the plot, but in terms of reality of motion. (I guess the technical term is "motion definition", or is it "motion resolution"?)

Michael I have tried this and it looks great - my only problem is that my PC struggles with 50p WMV files - I can only really go up to 720p. Does this method mean that its bob deinterlacing - ie loosing half the resoltion? If so is it necessary to go to 1080p? What format are you rendering to?

Cheers

Fergus, try to modify the default MainConcept-mpeg-template (HDV 720-25p) that comes with Vegas. Set frame rate to 50 fps (progressive) and increase the bitrate from 18.3 to about 40 Mbit/s.

For even better renders I modify the AVI CineForm template (HDV 720-25p Intermediate) that comes with Vegas.

I am sure the Vegas deinterlacing procedure is not BOB but something much more "intelligent", since the render - although it is "only" 720 - looses almost no definition/resolution compared to the native 1080.

By the way: I always use the Classic Media Player to play back the rendered 50p files.

30F does result in a small drop in the vertical resolution over 60i, just like 24F, about 10-12%.

http://dvinfo.net/conf/showpost.php?...0&postcount=39

Thanks Michael I'll give it a try when I get home.

Just wondered why 40mbs is necessary for 720-50p mpeg file? HDV is 25mbs - is it because effectively vegas is creating twice as many frames and you therefore need more bitrate to encode it as well as 50i at 25mbs? It seems a shame to increase the file size. I wonder what the effect would be of taking the 50p file into vegas and then rendering to wm9 25p? A more "progressive" looking encode?

Can MPC play back the cineform codec? I have a feeling my PC might be a touch underpowered (P4 2.8 1GB ram)

Do you think you would gain any resolution by going from 720 to 1080-50p?

VLC effectively does this process on the fly using the BOB deinterlace option (ie doubling to 50fps) - Linear seems even better but is very demanding!

Cheers
Fergus

Yes, I guess so, it's twice as much frames!
25 MBit/s does work, too, but my impression is that a little more blocking artifacts occur.


Yes, it can. But your CPU might be a little too slow. I use P4 3.4.


Yes, resolution would be still a little better.
But I simply didn't find out yet how to render to 1080 50p with the MainConcept/Cineform codecs. The codecs always crash in 1080 50p mode. If you find a solution - please tell me, since I am a resultion fan myself.

Yes, I use VLC myself to compare native 1080-50i (VLC linear deinterlacing on the fly) with rendered 720-50p (MPC). My impression is that rendered 720 50p looks better in terms of motion definition and almost as good in terms of resolution.

Thanks again Michael - the advice is much appreciated.
I love the look of linear in VLC but on my system it stutters a bit (hard to resist the temptation to go to a Core Duo!)

I'm interested to hear your views since I think that motion definition is very important to the overall impression of the footage - I will see if I have any joy going to 1080-50p mpeg2. You could always try WM9 advanced profile for 1080-50p which works fine for me (except my system struggles with that at high bitrate!)

As an aside I am having an issue with the contrast/brightness/levels of the footage imported into Vegas. I find that if I drag an m2t into vegas and do nothing the render (and preview) is always noticably brighter / washed out (even though the levels/brightness are set to 0.00) Have you experienced anything similar? I was thinking opf posting in the vegas forum as Im stuck as to why this is happening.

Cheers

Fergus, I never tried rendering to 1080 50p with WM9. Thanks for the proposal. I am going to test this.


Yes, I have, but only if I render to DIVX, XVID, WM9 etc. That's why I am a bit disappointed by these codecs.

Mostly I render to MainConcept HDV (.m2t) or to CineForm - both give me exactly the same contrast/brightness/levels like the native m2t. Even if I decrease the bitrates for .m2t renders to 10 Mbit/s, the levels keep unchanged, only blocking artifact increase. Please try rendering to .m2t or to CineForm and give me a short feedback how your resulting contrast/brightness/levels look.

Well I have tried the mpeg versus wm9 test and you are right - the brightness is only increased on the wm9 encodes - very frustrating!!!

the cineform encode played fine in MPC at 720p so thansk for the tip! Filesize is huge though even compared to mpeg2 at 40mbs. For the filesize I think wm9 at 720p is a good compromise at 50fps as 12.5mbs seems adequate for decent quality. Its just a shame the brightness/contrast gets messed up....

Sadly I also have the error in vegas if I try mpeg2 in 1080-50p :(

Thanks again for all advice
Fergus

PS do you have Vegas set to progressive or top field first in the project properties?

That's right. I only render to CineForm when I want extra high quality, or when the render is intermediate, that is part of another edit.

I leave it in "top field first" mode, although I am quite sure it does not make any difference when rendering to 50p - I think I tested this once. (Better double-check it!)

Pleased to hear that you're satisfied with the results, Fergus! And good to have verified my own findings.