Noise comparison: 35/4:2:0 vs. 180/4:2:2

[Gints Klimanis]

Piotr, thank you for posting the images. I'm using an image viewer that allows me to toggle between the two images, so it would be good to see the same frame from the EX1 and Nano. This is sometimes not easy to confirm with little or no motion, so consider swinging a stick in the frame somewhere. This would also provide an example for noise due to motion.

In your examples, I concur there is less EX1 noise on constant color areas such as the painted house, but there is also less detail and more "mosquito noise". In both the shadows (boards above door, wood fence on right) and the midtones (roof in sun), the Nano 100 MBPs shows a real increase in detail and less mosquito noise on the high contrast edges such as the top and bottom of the fence.

I would like to see the scene with your 220+ i-frame-only encoding and 140+ MBs LongGOP. 100 MBps may not be enough to see sufficient increases in detail for you to see value in the Nanoflash.

[Luben Izov]

Hello Piotr,
I understand the dilemma you are in regarding equipment malfunctioning.
Regarding last posted pictures, they are too milky and I couldn't see it properly. Piotr, is there any way, that you could clear your PP to Sony Camera PMW-EX1 default settings and shot, record and record to NF at 35 MBPS just as the camera records at the same rate. Do that with the NF on all possible settings of BitRate at the same light and object and we could talk about it after-words. The thread is very informative but it seems not clear, at least for me simply because the settings on your camera are not the default settings.
Just an idea...
Luben
Cheers

[Bob Grant]

Originally Posted by Piotr Wozniacki

Comments please, Bob :)

Because as Alister puts it:

"The very act of compressing a signal will reduce the appearance of noise as part of the compression process is to discard some picture information, so noise often gets "smoothed out".".

And I'm prone to agree with his statement, so more compression by EX1's own encoder -> less noise from SxS than from the nanoFlash at high bit rates (less compression).

Only conclusion I can draw from my very limited tests is that the noise *level* as recorded by the EX1 and as fed out the HD-SDI port is roughly (+/-20%) the same. As I said I lack easy access to the expensive test equipment to make a more detailed and accurate test.

Alisters comments are entirely true from my past experience and my understanding of how mpeg-2 works. Encoding very noisy VHS and grainy 8mm film to mpeg-2 really shows this up. Under extreme stress the encoder will simply only encode the noise pattern at the I frames. Most of my clients thought it looked better than the original, years after that experience I still don't know if I should laugh or cry.

As to your more general issue I cannot understand why you are using underexposed images. Of course better recording systems will preserve more detail and more detail is more noise. More detail also means more line twitter, you are quite likely pushing very close to the Nyquist limit as well.This is video science 101 stuff. If you want to test if the NF or something else in your signal chain is *adding* noise then record the in camera test patterns. They should have no noise to start with.

As an interesting aside the same complaint has been levelled at the ProRes codec. We have a KiPro and I'd wager good money I'd get the same outcome as you're getting recording to that.

[Peter Moretti]

Regarding ProRes, except for 4:4:4:4, which looks utterly amazing, FWICT, the ten bit ProRes codecs seem to underperform compared to the competition. Don't want to start a war here, LOL.

Piotr,

I think you bring up an interesting point that other people here w/ nano's could easily test. Namely, "Does Long-GOP add more noise than I-Frame only?"

From what you've said, this behavior is w/ the Long-GOP codec only, not the I-Frame (both similar and higher bit rate), correct?

[Piotr Wozniacki]

Originally Posted by Gints Klimanis

Piotr, thank you for posting the images. I'm using an image viewer that allows me to toggle between the two images, so it would be good to see the same frame from the EX1 and Nano. This is sometimes not easy to confirm with little or no motion, so consider swinging a stick in the frame somewhere. This would also provide an example for noise due to motion.

In your examples, I concur there is less EX1 noise on constant color areas such as the painted house, but there is also less detail and more "mosquito noise". In both the shadows (boards above door, wood fence on right) and the midtones (roof in sun), the Nano 100 MBPs shows a real increase in detail and less mosquito noise on the high contrast edges such as the top and bottom of the fence.

I would like to see the scene with your 220+ i-frame-only encoding and 140+ MBs LongGOP. 100 MBps may not be enough to see sufficient increases in detail for you to see value in the Nanoflash.

Gints,

Thanks for your comments. I don't think there is need for me to further tests, and post pictures here. I agree with your observations of the phenomena in both scene versions - the problem is that in order to see the nanoFlash format virtues, one needs to zoom into the pictures (or view them on a really large display). The excessive gran, on the other hand, can be seen without magnification, and on even a computer monitor. What's worse, in case of moving video it's shimmering, thus being even more annoying - and that's at just 100 Mbps! At 180 Mbps l-GoP, it's even worse.

[Piotr Wozniacki]

Originally Posted by Luben Izov

Hello Piotr,
I understand the dilemma you are in regarding equipment malfunctioning.
Regarding last posted pictures, they are too milky and I couldn't see it properly. Piotr, is there any way, that you could clear your PP to Sony Camera PMW-EX1 default settings and shot, record and record to NF at 35 MBPS just as the camera records at the same rate. Do that with the NF on all possible settings of BitRate at the same light and object and we could talk about it after-words. The thread is very informative but it seems not clear, at least for me simply because the settings on your camera are not the default settings.
Just an idea...
Luben
Cheers

Luben,

I have replaced the 2 pictures with the same 2, but taken after converting from sRGB to cRGB in Vegas - something I forgot to do originally, which caused the pics to look "milky".

I don't think there is a need for even more comparisons - if anything, I'd expect other users to confirm or deny my findings, so that I can be sure all my hardware is OK.

[Piotr Wozniacki]

Originally Posted by Peter Moretti

Regarding ProRes, except for 4:4:4:4, which looks utterly amazing, FWICT, the ten bit ProRes codecs seem to underperform compared to the competition. Don't want to start a war here, LOL.

Piotr,

I think you bring up an interesting point that other people here w/ nano's could easily test. Namely, "Does Long-GOP add more noise than I-Frame only?"

From what you've said, this behavior is w/ the Long-GOP codec only, not the I-Frame (both similar and higher bit rate), correct?

Yes Peter - for some reason, the I-Frame only picture looks cleaner.

[Piotr Wozniacki]

Originally Posted by Bob Grant

Only conclusion I can draw from my very limited tests is that the noise *level* as recorded by the EX1 and as fed out the HD-SDI port is roughly (+/-20%) the same. As I said I lack easy access to the expensive test equipment to make a more detailed and accurate test..

Well - they cannot be the same, if the theory (which I also believe in) that the 35 Mbps EX1 codes smooths out the noise is true (unless your wide +/-20% margin accounts for that).

Originally Posted by Bob Grant

As to your more general issue I cannot understand why you are using underexposed images. Of course better recording systems will preserve more detail and more detail is more noise.

All true - but EX series cameras tend to be particularly noisy in underexposed or just shaded, uniform color areas, and in real life you cannot avoid them - especially in run and gun shooting style. This is why I deliberately chose such areas to test for noise...

Well, I have more or less come to terms with the conclusion that all this is normal. However, in order to easy my mind that none of my hardware components is malfunctioning, I'd be grateful if somebody just confirmed or denied my tests with his own ones. The other way would be of course to try my EX1 with another nanoFlash, and my nanoFlash with another EX1 - but I don't have such opportunity at the moment.

Thanks, Bob.

[Gints Klimanis]

Originally Posted by Piotr Wozniacki

the problem is that in order to see the nanoFlash format virtues, one needs to zoom into the pictures (or view them on a really large display). The excessive gran, on the other hand, can be seen without magnification, and on even a computer monitor.

Piotr, while I agree that the noise can be seen, I see very similar noise in the video on a computer monitor for both SxS and Nano 100+ MBps. There is an obvious difference in the (macro) blocking noise in many scenes that I've shot, particularly flowing water, and it's more obvious in the video than in the frame grabs.

While I did present some samples zoomed in by 2x or 4x, it was easy enough to see the difference between the 35 MB SxS and 140 MB Nano in static unzoomed frames when switching between the two. If you compare the exact same frames, you'll see the difference as well.

[Piotr Wozniacki]

Gints,

I guess you're right - in the same nanoFlash 100 Mbps L-GoP testing session I posted grabs from yesterday, I can find frames where the virtues (less macroblocking, better color resolution) are equally easy to see in the nano clips played back on my 50" plasma without any magnification, as the increased noise is....

In the examples attached below, one can see more noise on dark, uniform color (as ususally), areas - like the green waste bin, or the brown wood elements on the left. At the same time, however, there are many improvements in the 100 Mbps nanofile that can be see easily as well - like the black writing on the orange label of the basket, and in many more areas...

So I guess 100 Mbps can even be used in run&gun; the higher bitrates of the Long-GoP format, however, should be reserved to controlled lighting / camera setting only (at least, with the EX-series cameras).

[Peter Moretti]

Originally Posted by Piotr Wozniacki

Gints,

Thanks for your comments. I don't think there is need for me to further tests, and post pictures here. I agree with your observations of the phenomena in both scene versions - the problem is that in order to see the nanoFlash format virtues, one needs to zoom into the pictures (or view them on a really large display). The excessive gran, on the other hand, can be seen without magnification, and on even a computer monitor. What's worse, in case of moving video it's shimmering, thus being even more annoying - and that's at just 100 Mbps! At 180 Mbps l-GoP, it's even worse.

Okay, but I was able to easily get the nano picture to look as smooth as the native EX-1 picture by simply adding a very light blur in post. Also, in post you can apply a matte to "de-noise" only those parts of the image you feel need correction. The EX1 smooths everything.

[Piotr Wozniacki]

Peter, almost everything is possible in post...However, that's not the point of this thread.

:)

[Piotr Wozniacki]

Buried within my clips, I have just come across something I didn't even intentionally record, but this raises my doubts again:(

In another thread on this forum (http://www.dvinfo.net/forum/converge...s-100mbps.html), it has been stressed how great the 100 Mbps Long-GoP is with motion, when compared to native EX1. I don't know how Jim Arthurs' samples were prepared, but I'm posting comparison of a single frame with a lot of motion blur. Please don't pay attention to the content - I know it's rubbish; I didn't shoot it carefully - just randomly moving the camera between two proper shots. Also, these are enlarged crops again. Nevertheless, it's the difference between native EX1 (left) and nanoFlash at 100 Mbps Long-GoP (right) that matters.

The nano clip is so pixelated it almost looks like falling apart!

Please comment.

[Adam Stanislav]

I'm starting to think there is something wrong with your nano! You should probably send to it CD for them to fix it.

[Piotr Wozniacki]

Originally Posted by Adam Stanislav

I'm starting to think there is something wrong with your nano! You should probably send to it CD for them to fix it.

Several posts above, Dan stated:

"I currently see no reason to suspect that your nanoFlash is malfunctioning."

I really don't know what to think now!