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AV1@Scale: Film Grain Synthesis, The Awakening

netflixtechblog.com

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Re: AV1@Scale: Film Grain Synthesis, The Awakening

#131

Post by LocalH »

supertrope wrote: post #75
UltraSane wrote: post #52

Earlier quoted context omitted.

Film grain and 24fps are both examples of people being far too attached to the technical limitations of film.

23.976 fps has been put on a pedestal as the "correct" look. Just look at the reaction to The Hobbit. However it does provide some objective advantages. 60 fps requires more lighting. Adding more lights means more electric setup and heat for actors in heavy makeup and costume. In post production that's more frames to edit.

23.976fps is only "correct" when telecining to a 59.94Hz format. 24fps round is the "correct" format in terms of actual filmmaking. I don't know of many films specifically shot at 23.976fps.

Re: AV1@Scale: Film Grain Synthesis, The Awakening

#132

Post by kevinsync »

Ok, very cool. But I want Netflix to explain it related to Seinfeld, which at 10-12 feet looks fine, but up close looks insane. Blocky MJPEG + grain filter??

It's not like we're on Pentium II processors anymore -- I can filter just about anything with ShaderGlass [0] on a shitty computer (and some of the CRT shaders like crt-hyllian-curvature are brilliant, especially on old shows like NewsRadio that only exist on DVD) .. and I'm shocked that Netflix doesn't just have this built into their Apple TV app or whatever. I'm shocked PLEX doesn't have it! (that I know of)

I made a comment on a different post about imagining a world where local AI/LLM/whatever does some favorable processing for you, by you, on your device, of web content, to enhance your experience. I really believe media (streamers all the way down to open source devs) need to begin to incorporate whatever's out there that reduces friction and increases joy. It's all out there already! The heavy lifting has been done! Just make Family Matters look like how it looked when I was locking in on a Friday night for TGIF LOL

[0] https://github.com/mausimus/ShaderGlass

Re: AV1@Scale: Film Grain Synthesis, The Awakening

#133

Post by wyager »

zoky wrote: post #121
kderbe wrote: post #107

Earlier quoted context omitted.

Grain is independent frame-to-frame. It doesn't move with the objects in the scene (unless the video's already been encoded strangely). So long as the synthesized noise doesn't have an obvious temporal pattern, comparing stills should be fine. Regarding aesthetics, I don't think AV1 synthesized grain takes into account the size of the grains in the source video, so chunky grain from an old film source, with its big s…

> Grain is independent frame-to-frame. It doesn't move with the objects in the scene (unless the video's already been encoded strangely) That might seem like a reasonable assumption, but in practice it’s not really the case. Due to nonlinear response curves, adding noise to a bright part of an image has far less effect than a darker part. If the image is completely blown out the grain may not be discernible at all. S…

It sounds like the "scaling function" mentioned in the article may be intended to account for the nonlinear interaction of the noise.

Re: AV1@Scale: Film Grain Synthesis, The Awakening

#134

Post by adgjlsfhk1 »

magicalhippo wrote: post #126
kderbe wrote: post #118

Earlier quoted context omitted.

Your first link doesn't seem to be about introducing noise, but removing it by averaging the value of multiple captures. The second is to mask quantizer-correlated noise in audio, which I'd compare to spatial masking of banding artifacts in video. Noise is reduced to make the frame more compressible. This reduces the resolution of the original only because it inevitably removes some of the signal that can't be differ…

Here's[1] a more concrete source, which summarizes dithering in analog to digital converters as follows: With no dither, each analog input voltage is assigned one and only one code. Thus, there is no difference in the output for voltages located on the same ‘‘step’’ of the ADC’s ‘‘staircase’’ transfer curve. With dither, each analog input voltage is assigned a probability distribution for being in one of several digi…

One thing worth noting is that this extra detail from dithering can be recovered when denoising by storing the image to higher precision. This is a lot of the reason 10 bit AV1 is so popular. It turns out that by adding extra bits of image, you end up with an image that is easier to compress accurately since the encoder has lower error from quantization.

Re: AV1@Scale: Film Grain Synthesis, The Awakening

#135

Post by Mr_Minderbinder »

eviks wrote: post #21

> Picture this: you’re watching a classic film, and the subtle dance of film grain adds a layer of authenticity and nostalgia to every scene It just adds visual noise that obscures details of the authentic scene, and nothing prevents nostalgia from being tied to many of the more prominent visual cues like old actors or your own old memories from when you watched it first... > contributing to [film's] realism But ther…

> But there is no grain in reality, so it does the opposite

The author did not do a particularly good job of selling the merits of film grain. I am not sure what he meant by that but I will say that it does increase the perceived sharpness of the image as well as perceived detail, even if it is just an illusion. The cinematographer Steve Yedlin describes it as giving the viewer’s eyes something to “latch” onto.

Re: AV1@Scale: Film Grain Synthesis, The Awakening

#136

Post by Mr_Minderbinder »

plorkyeran wrote: post #123
kibwen wrote: post #46

Earlier quoted context omitted.

Documentaries might care about accurately representing reality. For every other cinematic genre, "authenticity" is not an inherent goal. If film grain is part of the director's vision, then that's just as valid as a choice to have dramatic non-diagetic music playing in the background of a scene (which is highly inauthentic, but also highly effective at evoking emotion, which is the point of art).

I don't see how that is supposed to be relevant to the article's claim that grain adds authenticity and realism. Someone claiming that non-diegetic music adds to authenticity would also be weird.

I think what the author meant is that film grain is part of the authentic visual aesthetic of cinema produced using celluloid materials. A de-noised image is therefore inauthentic as that is contrary to the appearance of the original projected image or source/master elements.

Re: AV1@Scale: Film Grain Synthesis, The Awakening

#137

Post by cma »

crazygringo wrote: post #96

This 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…

You could do an ai or compressed sensing upscale first, with multiple frames helping, have that be the base video sent, and then regranularize that.

Re: AV1@Scale: Film Grain Synthesis, The Awakening

#138

Post by notpushkin »

godelski wrote: post #130
kderbe wrote: post #107

Earlier quoted context omitted.

Grain is independent frame-to-frame. It doesn't move with the objects in the scene (unless the video's already been encoded strangely). So long as the synthesized noise doesn't have an obvious temporal pattern, comparing stills should be fine. Regarding aesthetics, I don't think AV1 synthesized grain takes into account the size of the grains in the source video, so chunky grain from an old film source, with its big s…

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?

Re: AV1@Scale: Film Grain Synthesis, The Awakening

#139

Post by jebarker »

Animats wrote: post #110

Film 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.

Fake film grain maybe, but saying all film grain needs to die is like saying oil painting brush strokes need to die.
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