Nex 5N - Compressed vs Uncompressed Video Example

Started Nov 28, 2011 | Discussions thread
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paulcurtis
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Nex 5N - Compressed vs Uncompressed Video Example
Nov 28, 2011

I mentioned in another thread that i would upload an example.

EDIT: Okay the jpeg compression from the drp gallery has destroyed the differences between the images. I will have to see if i can find another way of hosting the image: any ideas?

I did a test, comparing the compressed AVC video (highest settings) with recording the uncompressed HDMI output to uncompressed video (via a Blackmagic Shuttle onto SSD).

You can see that the compression does (obviously) make a difference. This scene wasn't being whip panned nor does it have a lot of motion in. So i wasn't attempting to 'break' the compression either.

You can see that the uncompressed has a lot more detail, you can see some colour aliasing on the sat dish, which is hidden by compression munge on the other example.

If you look at colour channels you can see the effects of the 4:2:0 sampling as well.

What is more interesting is that on the compressed version you can see some dark blue horizontal lines on some bricks to the right. This is very odd, it's a very digital artefact and the uncompressed version does not have this. This looks like a compression mistake.

These are small crops blown up 200% (nearest neighbour) for display. They are a little soft, focus was on the bricks in the back but through a CV 28 lens which is a little soft due to the coatings. However the uncompressed very would sharpen up quite nicely.

The same shot with my canon dSLR would have looked like moire city.

So the NEX5N is actually a capable video performer. But as per my other thread, the HDMI out overlays stupid graphics that can't be turned off. So it's not useable yet. What great potential for such a tiny cam.

hope this is of interest to some

cheers
paul

Sony Alpha NEX-5N
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