Progressive or interlaced?

V

valdi99

Active member
Please clarify me that, as I am getting lost with GH2, AVCHD and its wrapers... I shoot wildlife, so I care a lot about smoothness of the movements. Quite often very fast movements, like flapping wings of small birds or trembling leafs on a tree and so on. I have been always told that interlacing is better over progressive, as the impression of the watcher is as the footage would have been smoother. Now we have GH2 and in PAL frame rates (i live in a PAL land) the 1080i/50fps is "interlaced", but output from the sensor is progressive. So how is it really interlaced? Is it only a flag cheating computers? Or rather AVCHD requirements..? Only odd/even lines are taken from the sensor at 50fps?

Anyway, what would be better for image quality and smoothness - 720p/50fps or 1080i/50fps? Or maybe native 24p? I can't agree with 24p... I do not care as much about resolution (or the size of image) as I DO care about smoothness! Let it be butter smooth, with ability to make a good looking sloMo. And also: better to shoot at 1/50sec. or follow the 180 degree rule and shoot 1/100sec?
 
Isn't all interlaced from progressive? I thought it was just an encoding thing. I can't imagine a sensor scanning only odd lines and then even lines. But hey, I'm probably wrong, lol.

Anyway, I think you should shoot at 1080i50. Although, reportedly the GH2 resolves almost as much resolution in 720p as it does in 1080i, so I guess it depends on the delivery. If it's going on the net, then 720p50 would be a better choice. If blu-ray or TV viewing, 1080i50 might be the way to go. Obviously the way to make your choice is just to try them out. :) Shoot a few test clips on the different modes, and have a look at which you prefer. The motion between 1080i and 720p should be exactly the same, but the encoder might like 720p more which may result in less streaks/artifacts (if there was any anyway), and maybe cleaner looking footage.

For the shutter I'd stick to the 180 rule, as you'll get more detail in the picture during motion, which is def. a plus for wildlife. A shutter of 50 has an interesting milky-smooth look to it, but it's likely to demand too much attention and after a while of watching it might get a little irritating.
 
Matthew P said:
I can't imagine a sensor scanning only odd lines and then even lines. But hey, I'm probably wrong, lol.
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I am not sure if is it a sensor or software (most probably both) but actually - I don't care. AFAIK progressive means that all lines represent one moment in time. At 25fps (in PAL land) every frame is taken 40ms after the preceding one. In interlaced mode even and odd lines are taken in 20ms interval and that makes a BIG difference to me.

Therefore I would rather think that 50i is better than 50p (despite of that GH2 don't provide real 50i), as the reality is "sampled" more often (20ms vs 40ms), so the better smoothness on 50i.
 
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Well, if you don't care then either 1080i50 or 720p50 will do for you, as I said. :) Both will look pretty much the same; try it out and make your own judgment. Just avoid 24p, as that is extremely juddery in comparison.

Just take into account delivery format, which I mentioned in my previous post.
 
valdi99 said:
Bigger would be better, but I have no idea how 1080i50 is made on GH2.
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Well, you've already said that you don't care. :) So don't bother musing about it. It's lovely and smooth like normal interlaced video, which is all you need to know.
 
Hi,
I'm lvining also in PAL land and did read (some time ago) a nice article about the differences GH1 vs. GH2 (didn't test it - but sounded plausible).

The GH2 makes 50 frames per second and drops the odd and later the even lines - so here you get a perfect 50i picture as it should be (looking forward to see a hack that just captures what the sensor allready get's).
On the GH1 (when the article was right) you capure 25p and it just get's stored as 50i.
 
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