Can adding noise help with the output rendering?

Wed Feb 27, 2019 9:31 pm

Hi Eric,

I came across this video a while back, and saw the discussion about 'YouTube Crunching the video'.

Would adding noise/dither help?.

Could a module specifically designed to do that job be of any use! Just wondering and putting this thought on the forum!

https://www.youtube.com/watch?v=rWAp7E6OLok
Studio-dbfx
 
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Re: Can adding noise help with the output rendering?

Wed Feb 27, 2019 9:49 pm

Thanks for the thought, but noise always makes compression worse ;).
Eric
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Re: Can adding noise help with the output rendering?

Wed Feb 27, 2019 11:17 pm

Ah! Okay :)

I did do a quick experiment, adding a little 'Bad TV' noise. It did improve the the pixelation when played back on my Laptop. Most probably experiment some more, rendering out a normal movie and another with noise, then combining the two.
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Studio-dbfx
 
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Re: Can adding noise help with the output rendering?

Thu Feb 28, 2019 12:29 am

Playing the videos on your laptop isn't the issue. You should be able to get perfect videos exported directly from Magic, whether or not they have noise. This is because you can use high-quality codecs and/or increase the bitrate however much you want.

The issue is what happens after uploading to YouTube. YouTube has fixed bitrates which cannot be adjusted by the user, so adding noise to videos means adding more information, particularly high-frequency information, to compress in the same fixed amount of bandwidth. This just makes the problem worse. Make sense?

From Wikipedia (https://en.wikipedia.org/wiki/Data_compression#Inter-frame_coding): "In areas of video with more motion, the compression must encode more data to keep up with the larger number of pixels that are changing. Commonly during explosions, flames, flocks of animals, and in some panning shots, the high-frequency detail leads to quality decreases..."

The key thing to understand is that *nothing* will improve this problem except increasing the bitrate, but as I said, you can't increase YouTube's bitrate. They set it at their HQ, and you'll just have to wait until they feel the world is ready for higher bitrates. It could be years from now.
Eric
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Re: Can adding noise help with the output rendering?

Thu Feb 28, 2019 5:53 pm

Noise won't help with compression, but it will help with local rendering in realtime for some cases.

When working in print, if there are gradients that have only a small difference between the values of the start and end colours, it's customary to add a little noise to avoid banding. Given that so many realtime effects are essentially warped gradients, adding a little noise as a final step can reduce banding artifacts in visualizations.

I've always loved this, that intentional errors can perceptually improve other aliasing errors. :-)
artnik
 
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Re: Can adding noise help with the output rendering?

Thu Feb 28, 2019 8:14 pm

Hi Eric,

I do get clear videos exporting from Magic! :). But depending what image/content I put in Magic, then apply some affects the banding colour separation will occur. It's not the fault of Magic! it's a GREAT piece of software! I'm getting some excellent results from the presets I'm creating! I get your point and artnik's about compression and bitrate. I had similar problems uploading to YouTube when using Particle Illusions SE. The animated graphics would look fine on the PC, but look terrible on YouTube unless you had it on HD.
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Re: Can adding noise help with the output rendering?

Fri Mar 01, 2019 3:40 pm

Part of the problem is also that video compression algorithms are better with "natural" imagery and tend to do poorly with "synthetic" images. It's how they were designed: to take advantage that in a moving image the eye won't notice simplification in areas where the natural textures have a lot of similarity from area to area.
Also, the algorithms do best when there isn't full frame motion, where all the available bandwidth is going to only changing part of the screen.

Visualization software, such as Magic, which uses highly synthetic images and where typically every pixel changes on every frame, is literally just about the worst case scenario for clean video compression. The only thing I can think of that's worse is a screen full of random static. i.e. noise. :-)
artnik
 
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Re: Can adding noise help with the output rendering?

Fri Mar 01, 2019 4:13 pm

Okay artnik! I get your point, adding noise doesn't help!

Here are some examples from Particle Illusion! Some look okay, whilst others don't. Not my video BTW


https://www.youtube.com/watch?v=DXwWZKkPxPM
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