Re: Resizing HD to SD 720 or 1080
 

Hi Adam

Quite correct.. the wrapper doesn't make it an interlaced file at all..it's progressive all the way so importing it into Vegas, one would leave Project Properties de-interlace box at none..which I tend to leave at default!

If I do shoot at 1080 50i I usually use VAAST's Upshift to transcode down to HDV (MPEG2) and then also tell Upshift to make the output file progressive so I always have progressive files in my project media. The end result from Upshift certainly seems to give a pretty sharp and pristine image but I have no idea what method NewBlue use (they make the software) to de-interlace. I wonder if V10 would de-interlace better than Upshift but I'm always in a quandry whether to use interpolate or blend...it's mainly weddings so there isn't really any high motion involved ... the help says use "blend" for high motion...do they consider high motion someone walking or more a Nascar race????

Yes, I know I should be shooting progressive but in PAL we only have 25P not 30P so you tend to get motion problems on frames unless you drop to 720 and use a double frame rate...with weddings I don't take the chance so they get done interlaced!!

Chris

Re: Resizing HD to SD 720 or 1080
 

Yes Adam...
That's the problem. Some people actually DO deinterlace PsF footage.
Some softwares interperate PsF footage as interlaced, and process as such..

Re: Resizing HD to SD 720 or 1080
 

I see what you mean now. And I agree, deinterlacing PsF is a no-no.

Re: Resizing HD to SD 720 or 1080
 

Typically blend fields is only used when high motion is combined with a fast shutter. Even in these situations many people would prefer the stop-action strobing-effect caused by interpolate fields to the blurry double-exposures caused by blend fields. To deinterlace a wedding recorded at 50i with a shutter speed of 1/50 second, I would use interpolate fields.

Re: Resizing HD to SD 720 or 1080
 

You basically would have to de-interlace before rescaling because in interlaced material the fields are incomplete images, they're missing every other line and regular rescaling algorithms can not cope with that (they assume an image with a homogeneous pattern of pixels).

From what I gather from the help, Blend fields would combine the lines of the two fields while interpolate drops one field then interpolates the missing lines in the remaining field. For 'PSF' material blend should be used. For rescaling PsF you'd de-interlace using blending.

Re: Resizing HD to SD 720 or 1080
 

Frans...

As far as the frame is concerned, it is considered progressive, regardless of what the sensors or internal mechanisms of the camera output...Deinterlacing the PsF frame should be avoided, since it is, in essence, a fully displayed frame, and not a frame consisting of two separate fields..

Re: Resizing HD to SD 720 or 1080
 

Afaik PsF is in interlaced format, each frame is split in two fields each with half of the lines missing. At least that is what I always believed interlace means.

From Wikipedia, the article Progressive segmented frame states
For an optimal resizing of such a frame, the software (or other equipment) will have to combine the two segments or fields (whichever word you prefer), into one frame before resizing. The recombination is the same operation as de-interlacing, although given the progressive origin of the segmented (or interlaced) frame that operation is pretty straightforward.

Re: Resizing HD to SD 720 or 1080
 

Actually, "blend" is what you should NOT use if you have a lot of motion, because it'll be blending two fields, and in those two fields, moving objects will be far apart. This will require a lot of blurring, and you're almost certainly going to be seeing quite a bit of ghosting.

"Interpolate" is better because it works with single fields. It may end up having slightly lower resolution, but the other kinds of artifacts will be far less.

Re: Resizing HD to SD 720 or 1080
 

Many thanks guys

That's a neat summary and I can really see the sense in de-interlacing with interpolate as a wedding is fairly slow moving.

I was transcoding with Upshift as mentioned and looking at the final SD DVD you can pick up ghosting here and there occasionally so I guess Upshift uses the blend method. What seems strange is you have 3 de-interlace options... "copy from input", "progressive", and "interpolate"

To me the 2nd and 3rd options both deinterlace!! but it seems one uses blend. The next batch I'll skip using Upshift and just transcode the clips to CanopusHQ and use Vegas to do the interlacing!!

Chris

Re: Resizing HD to SD 720 or 1080
 

Hi

I found 1080/50p looks even worse resized to DVD than starting with 1080i, it was a shock.

The main problem seems too be there is too much detail, when you start with 1080i and de-interlace and bob up to 50p, in the process you are approximating the image and essentially this removes detail. When it resizes down to 576i, the interlaced lines smudge up against each other and jaggies are less of a problem, and on de-interlacing the interlaced lines merge and knit together better. With 1080/50p straight down 576i those interlace lines sharply meet each other and you get jagged lines and it looks rough.

I think this is why 1080->720->576 is consider better looking, the extra resizing is helping remove detail.

I found better methods using AVISynth and a script, this works great on 1080i without having to de-interlace it, and does a good job with 1080p.

If you can, 1080p to 576p looks fantastic, like a good commercial film transfer if your footage can withstand being 25p.

I have tried resizing from 1080/50p to 576p at 50fps and it looks great, so you think just take odd lines from one frame and even lines from the other to get 50i and it should look equally great but interlaced, wrong, it looks horrendous, just too much detail in each interlaced frame.

Regards

Phil

Re: Resizing HD to SD 720 or 1080
 

Taking the "odd lines from one frame and even lines from the other" is not a good way to weave 50p into 50i. The usual method is

1. average line 1 and line 2 of frame 1 to obtain line 1 of field 1,
2. average line 2 and line 3 of frame 2 to obtain line 1 of field 2,
3. average line 3 and line 4 of frame 1 to obtain line 2 of field 1,
4. average line 4 and line 5 of frame 2 to obtain line 2 of field 2,
5. average line 5 and line 6 of frame 1 to obtain line 3 of field 1,
6. average line 6 and line 7 of frame 2 to obtain line 3 of field 2,
7. and so on

which has the advantage of being simple without introducing unacceptable aliasing or interline twitter.

What either Vegas or DVD Architect actually do to weave 50p to 50i is beyond me; however, there are reports that DVD Architect is better at such conversions than Vegas.

http://www.dvinfo.net/forum/what-hap...itect-5-a.html