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AV1@Scale: Film Grain Synthesis, The Awakening
161–170 of 230 posts
Re: AV1@Scale: Film Grain Synthesis, The Awakening
#162Film grain needs to die. Its time is past. Sepia photographs and running 16 FPS silent film at 24 FPS are already dead. Next, film grain. Eastman Business Park in Rochester has been demolished. Also, please stop putting dust and scratches on YouTube videos. Thank you.
But why does filmgrain need to die?
Re: AV1@Scale: Film Grain Synthesis, The Awakening
#163Earlier quoted context omitted.
For an example, watch Shogun. Director apparently thought that most of the screen being out of focus was a positive. Quite distracting.
I've noticed this in a few things the last few years. The top and bottom of the shot are out of focus and it is super distracting to me. Maybe it is meant to draw the eye to the middle of the frame.
Yup, notice that as well. A blurry vignette. Needle sharp in the center, but objects that are the same distance are blurry at the edges of the frame. At first I thought they use vintage lenses, but it's probably done in post.
I sometimes do something similar on photos, where I darken the edges a bit.
Re: AV1@Scale: Film Grain Synthesis, The Awakening
#164Earlier quoted context omitted.
People often assume noise is normal and IID but it usually isn't. It's s fine approximation but isn't the same thing, which is what the parent is discussing. Here's an example that might help you intuit why this is true. Let's suppose you have a digital camera and walk towards a radiation source and then away. Each radioactive particle that hits the CCD causes it to over saturate, creating visible noise in the image.…
I think this is geared towards film grain noise, which is independent from movement?
It's the same thing. Yes, not related to the movement of the camera, but I thought that would be easier to build your intuition about silver particles being deposited onto film. You make in batches, right?
The point is that just because things are random doesn't mean there aren't biases.
To get much more accurate, it helps to understand what randomness actually is. It is a measurement of uncertainty. A measurement of the unknown. This is even true for quantum processes that are truly random. That means we can't know. But just because we can't know doesn't mean it's completely unknown, right? We have different types of distributions and different parameters in those distributions. That's what we're trying to build intuition about
Re: AV1@Scale: Film Grain Synthesis, The Awakening
#165This fails to acknowledge that synthesized noise can lack the detail and information in the original noise . When you watch a high-quality encode that includes the actual noise, there is a startling increase in resolution from seeing a still to seeing the video. The noise is effectively dancing over a signal, and at 24 fps the signal is still perfectly clear behind it. Whereas if you lossily encode a still that disca…
The noise does not contain a signal, does not dance over it, and is not detail. It is purely random fluctuations that are added to a signal. If you have a few static frames and average them, you improve SNR by retaining the unchanged signal and having the purely random noise cancel itself out. Retaining noise itself is not useful. I suspect the effect you might be seeing is either just an aesthetic preference for the…
Denoising generally removes signal too. Removing noise and reconstituting similar noise to maintain the apparent qualities of an input can help compression, but you are also cutting out true details (typically fine detail).
The effect GP is pointing out is how denoisers damage detail, which is true. This detail can persist over multiple frames, which is why many denoisers include a temporal comparison component to mitigate the damage, but you still lose detail.
Re: AV1@Scale: Film Grain Synthesis, The Awakening
#166Earlier quoted context omitted.
The noise does not contain a signal, does not dance over it, and is not detail. It is purely random fluctuations that are added to a signal. If you have a few static frames and average them, you improve SNR by retaining the unchanged signal and having the purely random noise cancel itself out. Retaining noise itself is not useful. I suspect the effect you might be seeing is either just an aesthetic preference for the…
Denoising generally removes signal too. Removing noise and reconstituting similar noise to maintain the apparent qualities of an input can help compression, but you are also cutting out true details (typically fine detail). The effect GP is pointing out is how denoisers damage detail, which is true. This detail can persist over multiple frames, which is why many denoisers include a temporal comparison component to mi…
Definitely, but that's a result of compressing (with any algorithm) past a bitrate that would allow detail to be retained with high frequency details including noise being the first to go, not the result of noise having signal as was stated and more importantly unrelated to film grain synthesis which is about adding something new on the output side.
Re: AV1@Scale: Film Grain Synthesis, The Awakening
#167Earlier quoted context omitted.
Right, the current implementation is bad. In theory though, I don't see any reason why client-side grain that looks identical to the real thing shouldn't be achievable, with massive bandwidth savings in the process. It won't be, like, pixel-for-pixel identical, but that was why I said no director is placing individual grain specks anyway.
If the original is an actual production shot on film, the film grain is naturally part of it. Removing it never looks good. If it is something shot on a digital camera and had grain added in post, then you can go back to before the grain was added and then do it client side without degradation. But you can never have identical when it originated on film. That's like saying you can take someone's freckles away and put…
Sorry, I am talking about the case where grain was added in post. You originally said, and I quoted:
> If a director/producer wants film grain added to their digital content, that's where it should be done in post.
To me, this philosophy seems like a patent waste of bandwidth.
Re: AV1@Scale: Film Grain Synthesis, The Awakening
#168Earlier quoted context omitted.
Uncompressed 4k video is ~5Gbps (3840 * 2160 * 3 * 24 * 8). A 2-hour movie clocks in at about 4.3TB. (3840 * 2160 * 3 * 24 * 60 * 60 * 2) All that is 24fps. That's without audio, which I assume you also want to be uncompressed.
TBF even as bloated as 48/24 FLAC is it's a rounding error at that point.
But FLAC is compressed. Don't forget 13 channels. Only the best! Probably 192 khz.
Re: AV1@Scale: Film Grain Synthesis, The Awakening
#169This fails to acknowledge that synthesized noise can lack the detail and information in the original noise . When you watch a high-quality encode that includes the actual noise, there is a startling increase in resolution from seeing a still to seeing the video. The noise is effectively dancing over a signal, and at 24 fps the signal is still perfectly clear behind it. Whereas if you lossily encode a still that disca…
The noise does not contain a signal, does not dance over it, and is not detail. It is purely random fluctuations that are added to a signal. If you have a few static frames and average them, you improve SNR by retaining the unchanged signal and having the purely random noise cancel itself out. Retaining noise itself is not useful. I suspect the effect you might be seeing is either just an aesthetic preference for the…
> If you have a few static frames and average them, you improve SNR by retaining the unchanged signal and having the purely random noise cancel itself out.
That's exactly the point of GP though. Even though each individual frame might be almost indistinguishable from random noise you can still extract patterns over time. This is also the case if you don't average the frames in software but let the viewer's brain do it. If you just remove all "noise" from each frame and then add random noise back those patterns will be lost.
In practice you won't have static frames but also movement so recovering the signal from the noise becomes a lot more complicated.
Re: AV1@Scale: Film Grain Synthesis, The Awakening
#170Earlier quoted context omitted.
These days, when we see noise/grain in an end product it has likely been added in post-production. So, ideally, studios would provide distributors with a noiseless source plus grain synthesis parameters. Bonus: many viewers would welcome an option to turn it off.
> provide distributors with a noiseless source plus grain synthesis parameters. What parameters would that be? Make it look like Eastman Ektachrome High-Speed Daylight Film 7251 400D? For years, people have taken film negative onto telecines and created content of grain to be used as overlays. For years, colorists have come up with ways of simulating the color of specific film stocks by using reference film with test…
GPs point is that those streaming platforms will remove the grain anyway and that process loses information compared to working with the original.