For example, when a surface in the video like a wall (which should look pretty static) is grainy and that grain continually moves/dances around during playback (despite looking ok when paused). Temporal is particularly good for videos with what I like to call “dancing dots” or “dancing pixels”. So if you’re looking at a face where the skin color seems pixellated and seems to be moving around like crazy, it should even this out. So by looking at multiple frames, the denoiser should have a good idea as to what’s supposed to be there, and what sticks out (and should be denoised).Īnother (still not accurate) way of thinking about it is that it averages out the pixels between frames. At the same time, if there’s actually *supposed* to be a white dot on that black surface, it’ll be there across all the frames. It works very well for noise/grain that’s very evident while the video is actually playing (grain that you might not notice when paused but is evident during playback).Ī simple way of thinking of it (not necessarily accurate, mind you) is that if you have say… a black surface during playback and a white “dot” shows up in 1 frame (then disappears again), this is something the denoiser is going to notice – when you’re looking at multiple frames, it stands out as something that shouldn’t be there. This is for the “temporal” part of the denoiser, which means it works across frames. To give you and idea as to the function of the last 2 values (_:_: lt:ct)… A thin strand of hair, a freckle, a drop of rain, and a piece of film grain can all look pretty similar to the de-noiser. You have to keep in mind that the higher the values are, the more detail you will lose in the image. On the other hand, if noise/grain are very evident with the video paused, LS/CS have a good chance of cleaning it up. The denoiser is essentially going to find all the bits of outstanding detail and blur/blend them – sure, it’ll probably get the noise/grain but it’ll grab detail from other areas in the process. If that’s the case (if it looks pretty good), high values for LS/CS probably aren’t going to do you much good. With the video paused, it might be tough to see the noise/grain. Pause your noisy video source (presumably a DVD – open it up in the player). So if you watch a video and pause it, the frame you’re looking at is essentially an example of what the denoiser looks at. These first 2 values affect the denoising when looking at a single frame (“spacial”). We’ll look at the first 2 values first ( ls:cs:_:_): The format for the denoiser in Handbrake is actually ls : cs : lt : ct Before you go entering something like 10:10:10:10 into the custom field though, it might be helpful to know what each value actually means. You can use those as starting points for some experimentation. If you’re ready to delve into the custom settings and are here simply to find out how, here are the details for each of the built-in presets to get you started: The bad news is that the custom settings aren’t well documented. The good news is that handbrake includes a denoiser. Not as big a problem if you’re fine with good quality settings and the huge file sizes necessary to store the grain/noise, but a massive problem the rest of the time – grain becomes small ugly blocks, and the rest of the image suffers. As far as the encoder can tell, it’s extra “detail” that it should try hard to keep – and it takes a sick amount of bitrate to try and do it. In any case, noise/grain is the bane of small x264 encodes. If you went with an average bitrate instead, your file size was probably fine, but it may have looked so bad that you wondered if maybe you forgot to enter a digit. If you used constant quality and went with higher RF values, you probably ended up with a larger-than-expected file that looked ugly anyway. If you’ve ever tried ripping a DVD with noisy source material to small (low-bitrate) files in Handbrake, you probably realized quickly that you just opened up a big bag of hurt. Hopefully you guys find it to be a little more helpful. So I put together a new write-up with a video and pictures which you can click here to visit. Update: I kinda felt like a jerk for telling everyone “oh, just do all these tests” to see various settings in action further down.
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