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Film grain synthesis? Oh man, I don't know how I feel about this one. Without viewing any comparisons, my first reaction is...why not just higher bitrate inst

Film grain synthesis? Oh man, I don't know how I feel about this one. Without viewing any comparisons, my first reaction is...why not just higher bitrate instead?

Ameo 4y ago
Film grain is similar to noise which by definition compresses extremely poorly. By actually modeling the way the film grain is produced, they can avoid sending what is essentially random data over the wire while still preserving the visual effect of the film grain itself. That way, the bitrate can be spent to encode the actual video data at a higher quality.
- simbas 4y ago
  you did a good job
pornel 4y ago
This can be said about every lossy compression technique. Why do quantization that throws away details, and not send higher bitrate instead? Why do edge prediction that can smudge things, and not send higher bitrate instead? Why do inter-frame prediction which can cause wobbly motion and not send higher bitrate instead? The answer always is that the technique allows better use of bandwidth, so you can have a better image without increasing bandwidth. Or if you're able to increase the bandwidth, you can have even better picture with the technique than without it (until the bandwidth is so high that you can send the video uncompressed, but that's not happening anytime soon for video on the web).
- babypuncher 4y ago
  Think of how much money Netflix saves by streaming movies to your TV at 5mbps instead of 10mbps. Serving a single user, the cost difference is negligible, but across 120 million users it probably saves them millions in bandwidth costs. I still buy blu-rays though so I am a firm believer in the "just throw more bits at it" solution.
  - ubercow13 4y ago
    That's a false dichtomy. At any bitrate Netflix chooses to stream at, this technique could improve perceived quality. Meanwhile blurays also use codecs with similar advanced reconstructive techniques - even with the higher bitrate they are essential to maintain a high perceived quality.
klodolph 4y ago
I like this quote from the article, > The correct answer to this question is that often the choice is not between the original film grain and the synthesized one. When video is transmitted over a channel with limited bandwidth, the choice is often between not having the film grain at all (or having the grain significantly distorted by compression) and having synthesized grain that looks subjectively similar to the original one. Film grain doesn’t compress well. If you buy a 1080p Blu-ray disk, you can get a bit rate of something like 40 Mbit/s. Go watch 1080p video on Netflix, and you’re going to get something closer to 5 Mbit/s. Yes, the codecs are different—yes, you can talk all you want about how everything is going to be fast when we all get 5G—but this is still the ground reality that most people are working with. The bit rate is more of a constraint you have to work within than a variable you can just tweak to get the results you want. By comparison, ProRes 422 has a target bit rate of 147 Mbit/s for 1920x1080@29.97.
- babypuncher 4y ago
  Blu-Ray came out 16 years ago and streaming services still haven't really caught up in image quality. Physical media still has some life left in it.
  - Wowfunhappy 4y ago
    Well, the 4K ones didn't come out 16 years ago. Would you take a 1080p BluRay over 4K Netflix stream? I'm legitimately curious. I feel like we sometimes prioritize higher resolutions over overall detail.
    - klodolph 4y ago
      I generally take a Blu-Ray 1080p over any streaming option. Note that plenty of movies, in the theater, were never done in 4K to begin with. 4K is great for selling TVs, but cinematographers and directors seem to be more lukewarm on using 4K. I think most movies are still done at 2K. Your UHD Blu-ray Disc might just be an upscale.
      - 4y ago

Film grain synthesis? Oh man, I don't know how I feel about this one. Without viewing any comparisons, my first reaction is...why not just higher bitrate instead?

Ameo 4y ago

Film grain is similar to noise which by definition compresses extremely poorly. By actually modeling the way the film grain is produced, they can avoid sending what is essentially random data over the wire while still preserving the visual effect of the film grain itself. That way, the bitrate can be spent to encode the actual video data at a higher quality.

simbas 4y ago
you did a good job

pornel 4y ago

This can be said about every lossy compression technique. Why do quantization that throws away details, and not send higher bitrate instead? Why do edge prediction that can smudge things, and not send higher bitrate instead? Why do inter-frame prediction which can cause wobbly motion and not send higher bitrate instead? The answer always is that the technique allows better use of bandwidth, so you can have a better image without increasing bandwidth. Or if you're able to increase the bandwidth, you can have even better picture with the technique than without it (until the bandwidth is so high that you can send the video uncompressed, but that's not happening anytime soon for video on the web).

babypuncher 4y ago
Think of how much money Netflix saves by streaming movies to your TV at 5mbps instead of 10mbps. Serving a single user, the cost difference is negligible, but across 120 million users it probably saves them millions in bandwidth costs. I still buy blu-rays though so I am a firm believer in the "just throw more bits at it" solution.
- ubercow13 4y ago
  That's a false dichtomy. At any bitrate Netflix chooses to stream at, this technique could improve perceived quality. Meanwhile blurays also use codecs with similar advanced reconstructive techniques - even with the higher bitrate they are essential to maintain a high perceived quality.

klodolph 4y ago

I like this quote from the article, > The correct answer to this question is that often the choice is not between the original film grain and the synthesized one. When video is transmitted over a channel with limited bandwidth, the choice is often between not having the film grain at all (or having the grain significantly distorted by compression) and having synthesized grain that looks subjectively similar to the original one. Film grain doesn’t compress well. If you buy a 1080p Blu-ray disk, you can get a bit rate of something like 40 Mbit/s. Go watch 1080p video on Netflix, and you’re going to get something closer to 5 Mbit/s. Yes, the codecs are different—yes, you can talk all you want about how everything is going to be fast when we all get 5G—but this is still the ground reality that most people are working with. The bit rate is more of a constraint you have to work within than a variable you can just tweak to get the results you want. By comparison, ProRes 422 has a target bit rate of 147 Mbit/s for 1920x1080@29.97.

babypuncher 4y ago
Blu-Ray came out 16 years ago and streaming services still haven't really caught up in image quality. Physical media still has some life left in it.
- Wowfunhappy 4y ago
  Well, the 4K ones didn't come out 16 years ago. Would you take a 1080p BluRay over 4K Netflix stream? I'm legitimately curious. I feel like we sometimes prioritize higher resolutions over overall detail.
  - klodolph 4y ago
    I generally take a Blu-Ray 1080p over any streaming option. Note that plenty of movies, in the theater, were never done in 4K to begin with. 4K is great for selling TVs, but cinematographers and directors seem to be more lukewarm on using 4K. I think most movies are still done at 2K. Your UHD Blu-ray Disc might just be an upscale.
    - 4y ago