What causes jagged edges?

[maestro]

What causes the jagged edges in the following stills? Is it something that can be avoided/fixed/covered up?

The scene was shot with an XL2 in 16:9. Is it simply a consequence of miniDV?

On the left side of the toaster

The side of his face

His shirt

Window and shirt


If anyone could shed some light on this for me I would appreciate it, thanks.

-Brandon

[Richard_G]

It's interlacing, you'll only see it when displaying the output on a computer monitor, it won't be there when you view it on a TV.

[edDV]

How did you cap it? Looks like a single field.

What are you trying to accomplish?
Is a still your goal?

[thecoalman]

Make sure when you encode the video you use lower field, http://www.videohelp.com/forum/viewt...631&highlight=

If you using the video for something other than TV playback try the frame mode, I'm pretty sure that has it but not %100 percent posittive. Used fram based instead of lower field.

[lordsmurf]

It looks de-interlaced.
If this is a still of an interlaced frame, it may just be image aliasing.

[edDV]

If a still is the goal there are hardware cards and software programs that do multi-frame interpolation for an optimal deinterlaced still.

[lordsmurf]

Or pick a frame with low movement.

[edDV]

that too

[vhelp]

My JVC GR-DVL820U cam does this too, when I shoot in frame mode.
(memory mode via firewire)

While the cam is shooting footage, its capturing 2 fields of 240 pixel
horizontally as fields, and then merges them into a full 720 x 480 frame
resolution.. Because of the mode your cam was in, during that project,
your cam was doing a unique de-interlace and the result is a fairly good
looking full (non-interlace) frame.
.
Horizontals are the enemy of such contraptions (aka, interlace origin)

This would indicate that yours is not a true full field progressive cam.
That also means my cam is not too. But then, I knew that 8)

If your cam *does* have a true full frame mode, then I would use it (if
your aim is for progressive content) - Progressive always encodes better
than interlace. Always. But, a good encoder can do a little bit of wonders
with interlace, if properly used under a skillful user.

There are ways around even this issue, if you shoot certain scenes at
a fixed focal length. The problem is, because you are not in control
(even though you may believe so, since you are behind the cam) this cannot
always happen.
.
The technique requires practice, but if your particular source is primed
for the project, then you can eleminate this, using the technique of fixed
focal length footaging. Your given scene(s) will have to be relavent to
this type of project. That's gonna be hard, because fixed focal length is not
constant. In other words, its dificult to do, and requires a bit more plannign.
Although there are situations where you can use it, it is most probably not
worth it in most projects.

I believe thecoalman has this cam. You might ask for some tips on how he
manages to get good footage out of this cam.

- vhelp 3379

[lordsmurf]

Progressive always encodes better
than interlace. Always.

Don't agree.

[takeshi]

Exactly. Progressive does not always encode better. It really depends on your final intended display. Progressive doesn't do a bit of good if you're going to view the results on an interlaced display. It can be useful if you properly work with progressive in post to simulate film but it takes a lot more than just shooting in progressive to accomplish this.

In any case, the stills taken from video footage are quite meaningless for two reasons. One, interlacing helps to smooth issues like this. Two, a field is displayed for 1/60 of a second and it really doesn't matter (remember, video has the added dimension of time as well).

If you're intending to shoot stills then you should really be using a digital still cam or using software to interpolate the missing lines. If you're intending to display your video on an interlaced TV then nitpicking individual fields is pretty pointless. If your target is a progressive display then you need to deinterlace your footage properly to deal with this.

[dipstick]

lordsmurf wrote:

vhelp wrote:
Progressive always encodes better
than interlace. Always.


Don't agree.

I do agree.
The only drawback is the camera movement has to held to a minimum. That means tripod and slow smooth pans. Also it looks much better in NTSC 30 fps than PAL 25 fps.

I've done many back to back comparisons with interlaced and frame mode recordings. No doubt, Frame Mode wins every time. Better image quality, more detail, not to mention better compression properties due to more information per frame.

[edDV]

An encoder can perform equally well from an interlaced or progressive source. It sees and manipulates all pixels in the image in either case.

That would be true for native progressive or native interlaced sources. If a native interlace source has been "deinterlaced" prior to encoding at the same raster size, the artifacts introduced through the deinterlacing process will negatively affect encoder performance.

[dipstick]

Yes, I was talking about Progressive source and not de-interlaced Interlaced source.

I agree de-interlacing an Interlaced source is a bad idea. The only exception would be for special effects like slow motion, where you take 30i and split it into seperate fields. Then using various filters, resize to make 60 fps, witch can then be slowed down to 30 fps for a smooth slow motion effect. Sure it's not perfect, but it does work pretty well.

[edDV]

There are reasons to deinterlace for some special effects or especially for high compression for low bandwidth transfer (e.g. webstream or low quality archive).