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About Strato V, Dolby Vision, and FEL

MikeKobb

Well-known member
◥ ◣ Kaleidescape, Inc.
🏆 1000+ Posts! 🏆
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Greetings all,

This is going to be a bit of a technical deep dive to address a topic that has come up in several threads here on the forum recently. People who are familiar with Dolby Vision as implemented on Blu-ray Disc players may have heard the terms “FEL” and “MEL”, and these terms are now being used here when talking about Strato V. However, as I’ll explain below, these terms really don’t apply to Strato V, so I’d like to clear up any confusion.

First, four quick bits of background that are going to be important.
  1. In YCbCr color space with the PQ curve and BT.2020 colorimetry, it takes 12-bits of precision such that the smallest possible change between adjacent pixels is imperceptible to a human.
  2. Consequently, the master files that are used to create both HDR10 and Dolby Vision content use 12 bits per color component.
  3. Video encoding and (especially) decoding hardware is designed to deal with 10-bit information, not 12-bit. This is where the “10” in HDR10 comes from. With 10-bit YCbCr color, the smallest possible change can be visible, which is why we sometimes see banding in large areas of similar color, like a blue sky.
  4. It would be really great to preserve the imperceptible steps from the 12-bit master, so one of the goals of Dolby Vision was to find a way (or ways) to effectively fit 12 bits of color information into 10 bits on the video decoder.
Okay, with that background, let’s talk about Dolby Vision and FEL. There are versions of Dolby Vision (called “profiles”) that are designed around the capabilities of different types of playback hardware. 4K Blu-ray Disc players use Profile 7. Profile 7 relies upon a second video decoding engine that’s required in 4K Blu-ray players by the format specification.

Because Profile 7 was designed for optical discs, and there was a desire to have the discs be backward-compatible with HDR10-only players, Profile 7 starts with an HDR10 “base layer” that can be played on any 4K player. The base layer is then augmented with an “enhancement layer” when played on a Dolby Vision-capable player. (Decoding that enhancement layer is the part that requires the second video decoding engine mentioned above.) The enhancement layer in Profile 7 contains two elements:
  • Dynamic per-scene metadata. Unlike HDR10’s static metadata that includes relatively crude information about the movie as a whole, Dolby Vision dynamic metadata has information for literally every shot in the film, and that metadata can be rich and extensive to allow the colorist to fine tune how each shot will be rendered to best represent the original intent.
  • (Optional) “Residual” color information that, when combined with the 10-bit HDR10 base layer, reproduces the additional color information present in the original 12-bit master image.
If a Profile 7 enhancement layer includes the residual color information, it’s called a “full enhancement layer” or FEL. If it only contains the dynamic metadata, it’s called a “minimum enhancement layer” or MEL. So that’s where those terms come from.

Some folks have said things like, “Strato V doesn’t have FEL,” or have likened Strato V’s Dolby Vision implementation to Profile 7 with MEL. But this statement is not correct, because Strato V is not a Profile 7 player.

Strato V is a Profile 5 player. There is no concept in Profile 5 of an enhancement layer, because the dynamic per-scene metadata and the extra color detail is present in the base layer. How? Profile 5 takes the same original 12-bit master image as used for Profile 7, but instead of splitting it into base and FEL enhancement layers, it converts it from YCbCr color format into ICtCp before encoding.

ICtCp is a color format that is specifically designed to represent color in a way that more closely matches how the human visual system perceives color. Basically, our visual system is more sensitive to changes in certain parts of the color/brightness spectrum, and less sensitive in others, and ICtCp takes advantage of this to make more efficient use of the bits available. With 10 bits of information, ICtCp color encoding produces an image with the same sort of imperceptible pixel-to-pixel changes that would require 12 bits to accomplish if using YCbCr. To emphasize: it’s a more efficient representation, tailor made to human perception.

By transforming the 12-bit YCbCr master image to ICtCp, Profile 5 is able to use the 10-bit video decoding engines present on current system-on-chip designs like the one used in Strato V, and it has no need for a second decoder, which these chips don’t have. Since HDMI doesn’t support ICtCp, Profile 5 players like Strato V convert the decoded ICtCp color back to 12-bit YCbCr during playback and send that 12-bit signal to the display.

The result is that Strato V’s Profile 5 playback is accomplishing the same thing as Profile 7 with FEL — it’s recovering the fidelity of the 12-bit YCbCr master image and delivering it alongside dynamic metadata. And, as a bonus, if connected to an HDR10 display, Strato V will convert that ICtCp image to an HDR10-compatible output that retains the 12-bit YCbCr. You do lose the dynamic metadata since that’s not supported by HDR10.

Obviously you can’t get something for nothing, and in this case the trade-off compared to Profile 7 is that Profile 5 does not have a backward-compatible HDR10 base layer that could work on something like Strato C. This is why there are different HDR10 and Dolby Vision downloads on the store. But by making that trade, Profile 5 is able to run on a single decoder and deliver the same benefits in terms of color fidelity that Profile 7 requires dual decoders to produce.

So, to sum up — saying “Strato V doesn’t have FEL” is not telling the full story. Both Profile 7 with FEL and Profile 5 as implemented on Strato V are doing the same thing: preserving the fidelity of the 12-bit master file. The results are not identical, because both approaches have lossy elements, but they are comparable.

I hope this helps to clarify matters.
 
I have no idea what I just read, but I'm glad there are people in the world who understand this stuff. There are things that can't be dumbed down enough for me to understand and we just found another one. However, thank you for your contribution to the subject as I'm sure many on here will find it extremely valuable!
 
Given that a lot of these topics came up within context of LLDV and processors, it'd be great if any of the video experts could do a brief follow up on this thread. Building upon the above information, would using a device like an HDFury, or a processor like a Lumagen or MadVR, provide any picture quality benefit to a Strato V and a (non-Dolby Vision) projector?
 
I would like to know if the HDR10 implementation of K is the same as Blu-ray players/ optical discs. Or if there is a different approach like DV.
 
Given that a lot of these topics came up within context of LLDV and processors, it'd be great if any of the video experts could do a brief follow up on this thread. Building upon the above information, would using a device like an HDFury, or a processor like a Lumagen or MadVR, provide any picture quality benefit to a Strato V and a (non-Dolby Vision) projector?
I think from what Kris Deering has said on the other forum there is no benefit in sending HDR as LLDV for the Lumagen to then tonemap over just sending HDR10.

I would be curious to know how the DV to HDR10 conversion happens in the Strato V though and if it’s worse to do that over just using the HDR10 download. I quickly tried comparing the DV version to the HDR10 version both going to my Lumagen without the LLDV hack so the Strato V was doing the DV to HDR10 conversion and they looked the same to me.
 
I have no idea what I just read, but I'm glad there are people in the world who understand this stuff. There are things that can't be dumbed down enough for me to understand and we just found another one. However, thank you for your contribution to the subject as I'm sure many on here will find it extremely valuable!
I took the liberty of asking ChatGTP to explain this, but using baseball terminology...

Welcome to the Game!

We’re stepping up to the plate to break down some complex plays happening in the world of video encoding, especially when it comes to Dolby Vision and how it relates to Strato V. Just like in baseball, we’ve got different players, strategies, and rules to navigate.

The Players and Their Roles​

  1. 12-Bit Master File: Think of this as our star player, the ace pitcher. This player has the highest level of skill and precision, allowing for the smoothest game possible (or in video terms, the best picture quality).
  2. 10-Bit Video Encoding: This is like our solid but less flashy infielder. While they can handle most plays, they can miss some subtle nuances that our ace pitcher might catch. This is why sometimes, in larger color areas (like a blue sky), we see “banding”—it’s like a player fumbling a ground ball.
  3. HDR10 and Dolby Vision: Picture these as two different game plans. HDR10 is a straightforward strategy that works well, but Dolby Vision is like a high-tech playbook that allows for more dynamic plays, using more information to improve the game (or picture).

The Plays​

  • Profile 7 (FEL): This is a double-header. It starts with a solid base hit (the HDR10 layer) that any player (or player setup) can use. Then, it pulls out the big guns with a “full enhancement layer” (FEL) for players equipped with special skills (like a Dolby Vision-capable player). This layer has detailed metadata that fine-tunes every pitch in the game, ensuring that each scene gets the best treatment possible.
  • Profile 5 (Strato V): Here’s where things get interesting. Strato V isn’t playing the same game as Profile 7. Instead, it’s like a pitcher who has a different throwing style. Instead of needing to rely on two separate throws (base and enhancement), it’s able to throw a single, powerful pitch that’s already been optimized. It uses a special technique called ICtCp, which allows for a more efficient representation of color—kind of like having a pitching strategy that maximizes every ounce of skill from the pitcher.

The Outcome​

Both strategies—Profile 7 with FEL and Strato V’s Profile 5—are aiming for the same goal: to keep the game (or video quality) as close to the original master as possible. They each have their own strengths and weaknesses, and while they don’t operate identically, they both deliver solid performances.

The Bottom Line​

So when someone says, “Strato V doesn’t have FEL,” it’s not quite telling the full story. Both strategies play hard and achieve impressive results, but they do so in their own unique ways. Whether you’re watching on a Profile 7 setup or the Strato V, you’re still getting a great game—just with different strategies on the field.
 
I took the liberty of asking ChatGTP to explain this, but using baseball terminology...

Welcome to the Game!

We’re stepping up to the plate to break down some complex plays happening in the world of video encoding, especially when it comes to Dolby Vision and how it relates to Strato V. Just like in baseball, we’ve got different players, strategies, and rules to navigate.

The Players and Their Roles​

  1. 12-Bit Master File: Think of this as our star player, the ace pitcher. This player has the highest level of skill and precision, allowing for the smoothest game possible (or in video terms, the best picture quality).
  2. 10-Bit Video Encoding: This is like our solid but less flashy infielder. While they can handle most plays, they can miss some subtle nuances that our ace pitcher might catch. This is why sometimes, in larger color areas (like a blue sky), we see “banding”—it’s like a player fumbling a ground ball.
  3. HDR10 and Dolby Vision: Picture these as two different game plans. HDR10 is a straightforward strategy that works well, but Dolby Vision is like a high-tech playbook that allows for more dynamic plays, using more information to improve the game (or picture).

The Plays​

  • Profile 7 (FEL): This is a double-header. It starts with a solid base hit (the HDR10 layer) that any player (or player setup) can use. Then, it pulls out the big guns with a “full enhancement layer” (FEL) for players equipped with special skills (like a Dolby Vision-capable player). This layer has detailed metadata that fine-tunes every pitch in the game, ensuring that each scene gets the best treatment possible.
  • Profile 5 (Strato V): Here’s where things get interesting. Strato V isn’t playing the same game as Profile 7. Instead, it’s like a pitcher who has a different throwing style. Instead of needing to rely on two separate throws (base and enhancement), it’s able to throw a single, powerful pitch that’s already been optimized. It uses a special technique called ICtCp, which allows for a more efficient representation of color—kind of like having a pitching strategy that maximizes every ounce of skill from the pitcher.

The Outcome​

Both strategies—Profile 7 with FEL and Strato V’s Profile 5—are aiming for the same goal: to keep the game (or video quality) as close to the original master as possible. They each have their own strengths and weaknesses, and while they don’t operate identically, they both deliver solid performances.

The Bottom Line​

So when someone says, “Strato V doesn’t have FEL,” it’s not quite telling the full story. Both strategies play hard and achieve impressive results, but they do so in their own unique ways. Whether you’re watching on a Profile 7 setup or the Strato V, you’re still getting a great game—just with different strategies on the field.

I've come to the right place, that's amazing.
 
I took the liberty of asking ChatGTP to explain this, but using baseball terminology...

Welcome to the Game!

We’re stepping up to the plate to break down some complex plays happening in the world of video encoding, especially when it comes to Dolby Vision and how it relates to Strato V. Just like in baseball, we’ve got different players, strategies, and rules to navigate.

The Players and Their Roles​

  1. 12-Bit Master File: Think of this as our star player, the ace pitcher. This player has the highest level of skill and precision, allowing for the smoothest game possible (or in video terms, the best picture quality).
  2. 10-Bit Video Encoding: This is like our solid but less flashy infielder. While they can handle most plays, they can miss some subtle nuances that our ace pitcher might catch. This is why sometimes, in larger color areas (like a blue sky), we see “banding”—it’s like a player fumbling a ground ball.
  3. HDR10 and Dolby Vision: Picture these as two different game plans. HDR10 is a straightforward strategy that works well, but Dolby Vision is like a high-tech playbook that allows for more dynamic plays, using more information to improve the game (or picture).

The Plays​

  • Profile 7 (FEL): This is a double-header. It starts with a solid base hit (the HDR10 layer) that any player (or player setup) can use. Then, it pulls out the big guns with a “full enhancement layer” (FEL) for players equipped with special skills (like a Dolby Vision-capable player). This layer has detailed metadata that fine-tunes every pitch in the game, ensuring that each scene gets the best treatment possible.
  • Profile 5 (Strato V): Here’s where things get interesting. Strato V isn’t playing the same game as Profile 7. Instead, it’s like a pitcher who has a different throwing style. Instead of needing to rely on two separate throws (base and enhancement), it’s able to throw a single, powerful pitch that’s already been optimized. It uses a special technique called ICtCp, which allows for a more efficient representation of color—kind of like having a pitching strategy that maximizes every ounce of skill from the pitcher.

The Outcome​

Both strategies—Profile 7 with FEL and Strato V’s Profile 5—are aiming for the same goal: to keep the game (or video quality) as close to the original master as possible. They each have their own strengths and weaknesses, and while they don’t operate identically, they both deliver solid performances.

The Bottom Line​

So when someone says, “Strato V doesn’t have FEL,” it’s not quite telling the full story. Both strategies play hard and achieve impressive results, but they do so in their own unique ways. Whether you’re watching on a Profile 7 setup or the Strato V, you’re still getting a great game—just with different strategies on the field.
So V is using a cheat code. 🤣
 
I've come to the right place, that's amazing.
I won't post any more for fear of derailing the thread, but it's rather hilarious getting ChatGTP to explain this in different ways. I've now run it a number of times asking it to explain using the plot and characters from different movies.
 
I took the liberty of asking ChatGTP to explain this, but using baseball terminology...

That.... is actually shockingly good.

The one thing the AI missed is that Profile 7 FEL is not just the detailed metadata, but also the "residual" color information to get back from 10 to 12 bits.

But wow. 🤯
 
Profile 5 players like Strato V convert the decoded ICtCp color back to 12-bit YCbCr during playback and send that 12-bit signal to the display.
So does this mean that it´s actually capable of sending a YCbCr 4:4:4 signal?
 
Which one yields "better" picture for a non-DV projector?

1. Strato V LLDV-> Lumagen LLDV -> PJ
2. Strao V HDR10 -> Lumagen -> PJ
 
I won't post any more for fear of derailing the thread, but it's rather hilarious getting ChatGTP to explain this in different ways. I've now run it a number of times asking it to explain using the plot and characters from different movies.
Now I desperately want to read how The Dude (from The Big Lebowski) would explain this to me. I might have to go make a ChatGPT account...
 
Now I desperately want to read how The Dude (from The Big Lebowski) would explain this to me. I might have to go make a ChatGPT account...
Your wish just came true

Imagine the Dude lounging with a White Russian, breaking down Dolby Vision profiles in his laid-back style:

"Okay, man, so here’s the deal. Dolby Vision is all about making the picture look real nice, right? Profile 5 is like when you're chillin' at home with your 4K TV and it’s got this dynamic metadata that adjusts the brightness and colors for each scene. It's pretty groovy—your colors pop, and the darks stay deep, man.

Now, Profile 7, that’s a step up. It’s like when you roll up to the bowling alley, and instead of just the regular lanes, you’ve got these ultra-premium lanes that can handle more HDR content and work with streaming services like Netflix and Disney+. So, it’s all about making sure you get the best visuals no matter what you’re watching.

In short, Profile 5 is solid for home viewing, but Profile 7 is like, 'Hey man, let’s take it to the next level!' Just enjoy the show, dude."
 
So does this mean that it´s actually capable of sending a YCbCr 4:4:4 signal?
The bit depth (12-bit) and the chroma subsampling (4:4:4) are actually not related in that way. The numbers in 4:4:4 don't refer to bits; they refer to pixels in a sampling grid and whether each individual pixel has its own chroma information or if the chroma is sampled across adjacent pixels.The 12-bit number refers to how much color resolution there is per color sample. So, for example, if you have one color sample that contains the color information for a cluster of 4 pixels, you may have 10 bits of data in that sample or 12 bits of data in that sample.

There are some useful diagrams here:

The AVC/HEVC/VVC decoders on the available Systems-on-Chip support 4:2:0 but not 4:2:2 or 4:4:4 chroma sampling, so Strato V will output 12-bit 4:2:0.
 
I think from what Kris Deering has said on the other forum there is no benefit in sending HDR as LLDV for the Lumagen to then tonemap over just sending HDR10.

He had a couple theoretical examples where LLDV could be a better experience...

There is the possibility that the DV encode provides a higher quality encode for the video processor to work with, but this is yet to be demonstrated with any actual content.

There are a few cases where the DV version on Kaleidescape has an Atmos track, while the HDR10 version is a lesser format, though this would be expected as a temporary advantage, and of course it's an audio-related improvement vs video.
 
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