An African Union mission has recommended that child's military share power with the civilian president as one of three options towards restoring constitutional order following last month's killing of President Idris Derby. A military council led by Derby's son, Muhammad Idris Derby, seized power in April after his father was killed while visiting troops opposing a rebel insurgency. The African Union, which could suspend child over the military takeover, sent a fact finding mission to develop strategies for return to constitutional order and democratic governance. In a report, the mission recommended that AU's Security Council could support the military transition as it stands while appointing a special envoy to ensure the military kept their promise to organize elections within 18 months. And don't forget to hit the notification button so you get notified about fresh news updates.


We explain gluten sensitivity This is Tina. During the last few months, she has problems with her stomach. It hurts and she's bloating very often Since last week she also developed a headache, which makes her tired all the time Tina is getting worried. She has to see a doctor Tina's doctor asks about her eating habits and the symptoms of her disease. The doctor thinks that Tina has problems with gluten First he makes a test to rule out wheat allergies and celiac disease. Now he is sure it's gluten sensitivity Gluten is a protein found in wheat, barley and rye. When a person is gluten-sensitive and tolerant this protein causes a reaction Just as with Tina Researchers are still looking for biomarkers that would diagnose this disease. Right now, there is no specific test But gluten sensitivity is diagnosed if the symptoms improve after staying on a gluten-free diet Unfortunately, the only treatment for gluten sensitivity is following a gluten-free diet This means no more pasta for Tina. This new diet excludes all wheat, barley, rye and cross contaminated oats Since we don't know what causes a bad reaction to gluten yet, the only way to stop the symptoms is to stay away from gluten altogether But don't worry. There are a lot of products in the market that are gluten-free even pasta, bread and cereals And by the way eating gluten-free products is a form of precaution Doesn't influence whether or not you will develop a gluten sensitivity


At Audiology Associates of Prestonsburg, you can live your life the way you want and find the freedom of better hearing. You'll experience patient care that is specific to you with exceptional follow-up care that ensures your hearing and balance needs are being met. Audiology Associates at 1428 Northlake Drive in Prestonsburg. Letcher County Tourism will be holding their annual Turkey Trot 10K and Gobble Wobble 5K on Saturday, November 19th at the Raven Rock Golf Course in Jenkins, Kentucky. Yeah, so the Turkey Trot 10K and the Gobble Wobble 5K are an annual race that we have every year and it's a fundraiser. We had a lot of people last year. I'd say close to half the people last year for these races were not from Eastern Kentucky. We had people from North Carolina, Pennsylvania, Tennessee, Virginia, West Virginia that came and did this race and it got a pretty, pretty, pretty wide net. Proceeds for the event will be going towards a great cause. This year, all the proceeds that we make for this fundraiser is going to help flood relief victims all over Eastern Kentucky and specifically Letcher County. As of this point, we've almost raised as much money this year as we did all of last year. Pre-registration is available online for $20 and guarantees a free t-shirt. Registration Day of is $25 and begins at 8.30 a.m. For more information or to register, you can visit the Letcher County Tourism Facebook page. For Mountain Top News, I'm Kelsey Dean.


Welcome to Toffey TV. It is the Everton News Daily on the day Everton sacked another manager. Frank Lampard has left his post. There was a non-announcement at 3 o'clock. As I am recording this, Everton still have not announced it. That might have changed by the time this video actually comes out. It seems like the press were briefed around 3 o'clock with all major outlets releasing the news that Frank Lampard had been sacked. As I said, we are still waiting for official confirmation from the club. That may come once, listening all the eyes, a daughter and all the tees are crossed, but it is out there. Ultimately, if you have sacked the manager, just tell everybody because those fans have been waiting on this decision. Again, a nept failure from the football club again to communicate with its own fan base. Obviously, the sacking came after Everton's 2-0 defeat on Saturday to West Ham United. They know their poor, poor result with Everton looking like they couldn't fight their way out of a wet paper bag. Some people liked Frank Lampard, but let's be honest, his record was absolutely atrocious as the manager of Everton Football Club. Probably the worst record of any Everton manager of all time. That's something that Frank Lampard will have to hold for a very long time. Hopefully, it is a very, very long time that he holds that record. Now, it will all be down to, all the talk will be down to who replaces him. The early favourites are Michelle O Bielsa and Sean Daish. Bielsa apparently has been spoken to by Farhad Meshiri, but it's not clear whether that would have the full weight of the board behind it in Kevin Fellwell. The club now apparently are taking a more collegiate approach to making decisions. Farhad Meshiri set himself after the game on Saturday that wasn't his decision to sack Frank Lampard. So, it must be a board or Kevin Fellwell's decision and therefore, I imagine that will go into replacing him as well. It did come out last night that Sean Daish was not on the list to succeed Frank Lampard, but he is definitely one of the bookies favourites to come in. It does make sense when you put everything together trying to keep Evan in the Premier League, but we'll have to wait and see. Wayne Rooney has apparently been contacted by the club to see how interested he is. The same happened 12 months ago. He was in a job then, he's in a job now. Again, how much would he look at the situation and think I can do something with that? And that will obviously play a big role at a big part where that Evan would bring him in. Obviously last year, probably a lot easier, he was only in Derby. This time, he's over in America at DC United and if they were going to give him the job, then maybe if they'd just offered him a job, he would take it, but obviously going through the whole interview process while he's over there and he's managing a club in MLS that I still am pre-season would seem to be a little bit maybe too far. Well, after waiting to see, all these names are going to come out in the next few days. It doesn't matter what name you throw out to fans in general. Most fans can't agree on who they want and don't really know who they want themselves. It's a situation we were in last year till the club themselves. We've got it basically down to two names and we were basically put into a situation of Sophie's choice where neither candidate were great and we ended up with Frank Lampard and we might be in that situation again, but well after waiting to see and there's going to be a lot of fallout and there's going to be a lot of chat and there's got to be a lot of things said I imagine in the next few days about the situation. We hear daily on today that Abdelhaid the Corate fallen out with Frank Lampard after the dressing room burst up after the Southampton game and that's why he was not involved on Saturday. This is a player again who probably wanted to leave Evan for a while and has not been allowed to. Michael Keane is in the same boat as well. He was not part of the squad. He's another player who wants to leave Evan and he's not been allowed to leave Evan and these situations were starting to grow and the Gordon today has been linked with a move to Chelsea and Newcastle United. He didn't come off the bench on Saturday and there is talk that he didn't even want to travel to West Ham on Saturday either because of the situation, because of everything that's gone on. It's become quite clear on Anthony Gordon's front that he does or he's certainly interested in opportunities elsewhere and why wouldn't you? He's a young lad and he clearly thinks he's got the talent and to prove himself at the top level even though he hasn't proved it quite at Evan. So there's so much, there's going to be so much fallout from this. Apparently Frank Lampard himself is really, really disappointed with the situation. You can understand why he's so appointed. He hasn't really been given the money or the tools certainly so far this window either. Ironically Dan's humour is set to come in. He was looking like he was going to be confirmed today. That might happen tomorrow now with even talk that he said he wouldn't sign until he knew who was on the list to be the next manager. I don't know why that would matter considering he's not going to be staying at Evan. It would seem after this season and it is just alone. It's just another crazy situation at Evan which is a making of their own. The situation we saw the scenes on Saturday, fans made their feelings known once again with the banners and nothing I don't think is ever going to change at this club until things are changed at the top of this club. So that doesn't seem like it's going to happen soon and we're going to have to continue with this situation and see if we can bring someone in who can get in a couple of signings in the last week or so of the transfer window and start picking up points. Luckily for Evan they haven't got a game on Saturday the place obviously are slow week on Saturday. You know easy game. So they've got a few days maybe to get this situation sorted out but once again Evan will find themselves without a manager in January looking towards the transfer window closing and it's just a joke. It really is a joke. Everything that people have said about the club and the board they prove on a daily basis. They can't even come out and say they've got this situation under control because they haven't even put out an official statement about the situation. So there you go. Let us know your thoughts in the comments. Make sure to give this video, like and subscribe if you haven't already. Earlier on today we were live straight after the news was announced and Alan Stubbs, ex-Everton captain Alan Stubbs joined us in the studio. Make sure you check that video out. It's on YouTube as we speak. We'll be live tomorrow from half one with more reaction and speculation about what is going to happen with the Evan managerial situation and you never know. By then they might have confirmed Frank Longpart. There's no longer the Evan manager. There you go. Thanks for watching. If you want more great content as well make sure to check out Toffy TV premiere. The link is in the description and it will be on the screen in a moment. See you later.


It's a pleasure to be here. I'll be discussing scattering amplitudes and my actual title will be the connection with inter-gubility. The sort of overarching question is, is how do massless particles interact? And the context in which I will be discussing this question is in flat space. And I will be considering this from the viewpoint of a perspective picture. So when we start from tree level and add loops and so on, a lot of ideas have been developed from this viewpoint because there's a huge program of people making precision calculation for LHC physics. So we benefit a lot from this extensive study. Massless particles, so most particles in the world are massive, but describing them as massless is relevant when you describe the sort of long range interaction, which for example in QCD means that distance much longer than inverse masses and also of course look at distance much smaller than 1 over lambda QCD when we apply, yeah. So there's a wide range of energy scales in QCD where the approximation particles are massless is a good approximation for maybe not for the top part but finding particles. So they're very interesting to study and these are the ones I will study in these lectures. But I will discuss the general case, non-super symmetric, but a lot of progress recently has occurred. Yeah, one distance smaller than lambda QCD. Oh, sorry. Thank you. Yeah, so the masses of the like quartz, yes. Thank you. Sorry, what's this equation? Yeah, yeah, this is short distance compared to mass and confinement. Okay, so there'll be a very interesting connection in a special case of N-quals-4, Super Youngness, very special theory where at least in the planar limit there's a connection with integrable system. So we'll be using this general theory that has been developed for practical calculations in QCD and so on to address to discuss how we see integrability arise in this setup, in this special theory. And at the same point, at the same time using integrability, I think the long-term goal of this program is that we learn how to calculate much more efficiently. Again, okay. Will that be okay? I will try to stick to that point. Sorry. Okay, so to start in perspiration theory we'll start beginning at three level and it will be very important, very useful to understand three level thoroughly. We'll be using a lot of simplification that occurs in three plus one space-time dimensions. So when we discuss massless particle for momenta, you can write as a, you can take the, you can construct the vial operator from it, which is a two by two matrix, which is of this type, P zero plus PZ, P zero minus PZ, PX plus I, PY, this is basically P slash for vial fermion. And that two by two matrix is the property that if P square is massless, then the depth of P alpha dot is equal to zero, and P alpha alpha dot can be written as a product to spinners. Again? Many small levels. Okay. So the important equation is that P alpha alpha dot is equal to a product of two spinners. And yeah, these spinners are the solution of the vial equation. This, yeah, so this is factorization in four dimension, which is very useful to simplify notation. So we're looking at the S matrix of one shell particle. The first case is one particle goes to one particle. That's just the identity, there's nothing to say. The next case is three point, three particle amplitude. And if you try to have three on-shell particles interact in four dimensions, one, two, three, the on-shell condition imposed at all moment are zero. And since P three is P one plus P two, it's imposed at P one dot P two is equal to zero. Here, these lambdas, all environments can be written in terms of these lambdas here. And P one dot P two is equal to what people write like this, where one two is equal to the anti-symmetric symbol of lambda one alpha and the two beta. So if you anti-symmetrize those two things, you make a Lorentz invariant product of the spinners. You have the similar Lorentz invariant product of the bar spinners. And all Lorentz invariant products can be written in terms of these invariants. And for the three point amplitude, this is equal to zero, which should use that at least one of them has to vanish. So there are two cases, which I would draw first like this. That's when, well, if the case when one two is equal to zero, one can show that one three and two three are equal to zero also. So there's a case where our angle brackets vanish. And that means that the lambda one is proportional to lambda two, it's proportional to, all the lambdas are proportional. And there's another vertex in the theory in which they are, in which the lambda two are proportional to each other. So there are the two basic vertices. Normally, you might say that if you have a three point vertex in Minkowski space, the normal conclusion, if you think about the real momenta, is that all the momenta have to be coordinated with each other. Here we're doing something slightly more general. If we allow the momenta to be complex, then these and these are independent cases. And now in Minkowski signature, you will have both of them simultaneously. But as we'll see later, it's very, you will get a lot of information if we distinguish those two cases. So what are these vertices? Let's consider Yang-Mills theory, for example. So in Yang-Mills theory, the external states are labeled by polarization, which can be gluonous two-elicity polarization, plus or minus. Yes. OK, yeah, square bracket is the same where, well, actually I should write it down there. Let me be very correct. So it's the symmetric product of two spinners. And that defines a Lorentz-Envariant product of these spinners. What's important about this product is that it's Lorentz-Envariant. So if we look at per Yang-Mills, so when we scatter, we have polarization vectors. A good thing about this formalism is that it allows us to get rid of the polarization vector. So the M2 doesn't depend on polarization explicitly. So what are the polarization expressed in terms of lambdas? If we have a plus polarization, you can write it as denotation. The simplest guess for a polarization vector will be something like lambda, lambda, alpha dot. That's the simplest thing you can write in terms of lambdas. But that's proportional to p, p, alpha dot. And that decouples by gauge invariance. So how do we write polarization vector? We write lambda for actually, we write it for plus. It would be proportional to one lambda. But for the other guy, we can choose lambda. We choose some arbitrary reference. And we divide by something which somehow removes the dependence on this reference. So that would be the definition of polarization vector. So we have to introduce a gauge choice to write this polarization. However, it turns out that this gauge choice doesn't matter at all, and the amplitude does not depend on it. And one way to check this is you take epsilon 1 of mu 1. You take the difference between different polarization vectors. The difference is proportional to mu 1 alpha over mu 1 lambda minus mu 2 alpha over mu 2 lambda times lambda tilde alpha dot. And this combination, the numerator is proportional to mu 1, mu 2 lambda, antisymmetrized in 1, 2. And there's a very useful identity, which comes from the fact that the mu lives in the two-dimensional vector space. If you're antisymmetrized with respect to 2, that's equal to lambda to 1. So that way, you see that if you change the gauge choice, you get something proportional to p, and it decouples. So the absolute doesn't depend on, it never depends on this choice of mu, and it only depends on the lambda. It's very convenient. So what is the three-point vertex of the theory? Well, if we plug in this epsilon in the expression for the three-point vertex, we can compute, we get an answer, just some Feynman diagram. But we don't have to compute to know what the answer will be, because these lambdas have a very nice property that p is invariant under the following, what's called a little group ambiguity. If you take lambda goes to e to the i theta lambda, and lambda tilde goes to e to the minus i theta lambda, and the tilde, then p is unchanged. p goes to p. And under, actually, let me put over two here. Under this phase ambiguity, and this is just saying there's a phase ambiguity in choosing your spinors. Under this phase ambiguity, epsilon plus goes to e to the, let's see, epsilon plus goes to e to the minus i theta epsilon plus, and epsilon minus goes to e to the plus i theta epsilon minus. So this phase ambiguity track what is called the elasticity of the particle. The exponents are always related to the elasticity of the particle. As general, it's true for fermions also, for scalars, there's no phase ambiguity, of course. And just because of this phase ambiguity, so what do we know about this vertex here? If we take, for example, I will take this plus plus minus vertex. Because the lambdas are aligned, it can only depend on lambda tilde's. It has to have these phase ambiguities, so that it needs to have two lambdas, so this is two, three, one. It needs to have lambda tilde two, lambda tilde three, lambda tilde one, upstairs, square. And we have to contract this into Lorentz-Envarn quantity. And one can see that there's only one way, actually, to contract these things together, which is to write the following combination. Sorry, something is wrong. One, two, three. So this vertex is proportional to square bracket of two, three, cube divided by two, one, two, three, one. Let's see, oh, I got it backwards, sorry. Of course, yeah, lambda tilde's on top, okay, good. Lambda tilde two, lambda tilde three, over lambda tilde one. And you see, indeed, that this few kind of weights in two, there's three on top, one down, so there's two on top, two threes on top, and one down downstairs. And it's the only contraction, which has this homogeneity. So without doing any calculation, the vertex has to be proportional to a number times this. And the calculation tells you what the number is. It's FABC, the structure constant. Other minus sign? Sorry, I'm very, yeah, so it's for the lecture, I'll be sloppy with signs. I will give reference to the literature. So they are very good reviews and lectures notes on this on the internet, and for the signs I would refer to the reference. Yeah, pleasing your all signs in this lecture. And similarly, this other vertex is FABC, and now two, three to be minus, minus, plus one. Okay, so what about other possible vertices? For example, plus, plus, plus, if we have this guy here and plus, plus, plus. Now it will have to be proportional to all lambda tilde's on top. That will have to be proportional to, and one can see that the only thing consistent to this homogeneity is this quantity. Times some coefficients, C, one, two, three. However, in that case, the dimension of this is different. So each of these brackets is dimension one, and the two point vertex needs to have dimension one. So C will have dimension minus two, mass dimension minus two. So this coupling here will be irrelevant in the inference. So, and I started this lecture discussing, I will discuss the long distance, so I will ignore such term. So that would be a higher dimensional operator either through the theory. So you could generate this term only by adding higher dimensional operator. And for the Yang-Mills Lagrangian, it will not appear, because the coupling is dimensionless. And another case you could consider is what about minus, minus, minus. Then you get one over all that. Now the coupling constant as dimension plus four, which is really bad. And as we'll see shortly, this will lead to, it's not consistent. You cannot find, it's inconsistent with four-particle scattering. So I will discuss four-particle in a second, but this does not correspond to any self-consistent theory. So it will not consider it. So now that we've discussed three point, let's move on to four-particle. So we can imagine, again, doing the Feynman diagram calculation. Many of you have sort of done it in many, many classes as students to do it. All the permutations, this diagram, this diagram. We could imagine doing this calculation and plugging in the explicit expression for this epsilon, and we would get an answer. But there's no need, again, to do it. And this is one thing I want to emphasize in this lecture, is that self-consistency of the theory basically fixes the answer, again. So, and what makes this possible is the fact that we're scattering particles with spin, and the spin comes with this little group ambiguity. Because of this little group ambiguity, we can say, for example, that the scattering amplitude for four-particle, two of them, negative elicity and two of them, plus elicity, must be equal to something which has the correct phase ambiguity, and that something would be one, two, I just write, can write anything. So that's an example of some dimensionless thing which has the correct phase ambiguity. And then some function which doesn't have phase ambiguity, so it depends only on S and T, where S and T are the Mandelstam invariants. Well, that's the case. And at three level, this function here would be a rational function. What can we say about it? Well, it's a rational function and we never get double poles. So, can only have single poles, one over S, one over T, okay? It would be dimensionless, four-particle scattering is dimensionless, and yeah, in general the dimension, yeah, anyway. So it could be, I could write S over T, S over U, but the one for S here is actually pretty bad because S, which I define as P one plus P two square is equal to one, two, let me write bigger, sorry. One, two, one, two is also equal to three, four, three, four. This has a cubic pole at three, four goes to zero. That's very bad. The physical amplitude never has anything stronger than single pole. So not only this is ruled out, but actually we need an S on numerator or both terms. And we cannot even have a constant because it's not proportional to S. So the amplitude must be of this form for two constants, C one and C two. So we don't have to do a calculation, we know the amplitude has to be like this. And this is actually very constraining because the amplitude has three factorization channels on which it must factorize. But it only has two coefficients, C one. So somehow there's some identity that's required for the theory to make sense. And consider for example this, what's the simplest way to fix this C one is to look at what happens when T goes to zero.  If you take T goes to zero, the amplitude must factorize on a product of three point vertices. And let's say that T is a, let's say that two, three goes to zero more precisely. And as I mentioned, it's useful to consider limits in which not only particles become collinear but consider complex momenta where I'm allowed to take two, three goes to zero but two, three fixed. If you insist the momenta are real, both of them will have to go to zero at the same time. But we get much more information by considering these two limits separately and we have the right to do that because amplitude is defined as a complex function. And if we take two, three goes to zero, then the only vertex which is non-vanishing when these are zero is this vertex. The amplitude has to proportional to product of this vertex times one of it. And the coefficient of course is the structure factor air. Let's call this F, let's say a B, C, D. Let's say the colors are B, C, D, A. So this is F, B, C, E, F, A, D, E. So this product of color factors times one over T. I will not evaluate the vertices explicitly but basically the vertices as required as you will expect give you exactly this structure so that C one is equal to this. So you fix C one from this factorization. Similarly, you fix C two and that would be basically F, A, B, sorry, F, B, D, E, F, A, C, E over U. I'm sorry, the one where T is, is, is, is not, yeah. So the C is just this numerator. And C two is just this, but now, so that's the U channel. So we've used these two channels and we'll fix all two coefficients. So now what do we get from the third channel? For the third channel, now we know C one and C two so we predict what the amplitude is and the S channel, the amplitude, of course, must be proportional to F, A, B, E, C, D, E. And it actually works because of the Jacobi identity. If you take C one minus C two, you get that. Again, I'm missing things, but the point is the theory will not make sense. You could not construct a consistent four point amplitude if the Jacobi identity was not satisfied. And the reason this, you get this kind of constraints for particles with spin is that we're forced to pull out these phases. And these phases always come with some pull. So the fact that we have to pull out these factors leads to these kind of constraints. And yeah. So yeah, for spin one, the Jacobi identity can derive it from, consistency of the four-point function. This analysis has been done later for IR spin. For spin two, we derive in this way the equivalence principle so that all particles must couple in the same way to the graviton, and there can be only one graviton and so on, massless graviton. And for massless IR spins in flat space, you get that there's no solution. And the reason these constraints get so much stronger at IR spin is that you get these factors with IR and IR power. So if you have graviton, four graviton, you have something like that. There's a quadrupled pole, and you need to cook up something which cancel three powers of it for the amplitude to make sense. And it's very difficult to have this cancellation without introducing poles in the other channels. So the higher the spin, the more constraints you get. For massless scattering. So that's an important lesson. So move on to, so that's the five-point amplitude. We obtained it in some form in terms of FABCs. At IR points, IR points, we could keep going and just make an ansatz and fix all the coefficients using factorization. Because we already have four points, it will somehow be useful as a building block, but there's a better way. And yeah, the reason it would work at IR point is that, and you just say that if you have a five-point amplitude, the dimension is minus one. In general, the dimension of the amplitude is equal to, because the S matrix is dimensionless, the S matrix is a delta function times the T matrix. So the dimension of the T matrix, the momentum considering the delta function, so the dimension of the T matrix is four minus number of particles. Because four comes from cancelling this delta four, delta function, and each particle, each unshelt state is dimension one. So as you go for, so this is an example for n equal three, the three-point vertex as dimension one, which is indeed what we add here, this is dimension one. The four-particle amplitude is dimensionless, that we just saw. And the five-particle amplitude as dimension of one over mass. So basically, this analysis becomes more and more constraining at IR points because, just by dimension analysis, you need more and more denominators at IR points. So it's just impossible to write something at five points which doesn't have a denominator. And then if it has a denominator, it has a pole somewhere and can constrain this pole by factorization. So once you have the three-point particle, you construct the four-particle amplitude, and then all our points are fixed by factorization. And the efficient way to solve this factorization constraint, there's at least one efficient way is recursion relation. So that's a way to solve factorization constraints. Systematically, that's much, that IR points becomes more practical than just listing all the possible structures you can have. But conceptually, it's solving, it's doing exactly what we did by hands here for four-particle. And the idea of the recursion is to introduce, so you might think that to use solve factorization can be difficult because amplitude depends on many, many variables. If you have a five-particle amplitude, if you scatter five particles or two particles, move to three particles, there's a lot of angles and relative energy fractions. There's a lot of variables that these amplitudes depend on. And if you try to solve, if you try to think of it as a function of, I don't know, five complex variables, it's very difficult analysis. The trick is to restrict it, project it into some plane so that you look at it as a function of just one variable at a time. And so you introduce one parameter, the formation of the amplitude that Brito-Cachezzo-Feng-Witten introduced. And this, the simplest deformation is the one they used is you take, it's likely, the simplest thing you would try is just take lambda one, sorry, let's take lambda n, let's define the shifted one as lambda n plus z lambda one. So that changes lambda. That doesn't work because total momentum is not conserved. And you have to respect momentum observation. But you can fix it in a simple way by shifting lambda tilde one in the following way, minus z lambda tilde n. And so I'm just, the only modifying I went up p1 and pn, but in such a way that pn of z plus p1 of z, which by division is lambda, so if I put alpha, alpha dot in this case, this is lambda n alpha of z, lambda tilde n alpha dot plus the one alpha and then lambda tilde one alpha dot at. And it's only these two guys depend on z. So this guy, this guy are not changed. And if you compute this quantity, so the lambda n, lambda tilde n term and lambda one and the tilde one term are there. And then the z term, you get a cross term which exactly cancels in those two terms. So total momentum remains conserved for all values of z. So it's a smart, it's really the simplest deformation that you can do, which is consistent with momentum conservation and for which your particles remain on shell plus two. So if we look at the M2 as a function, so now we look at the M2 as a function. Actually, yeah, this is what I will not need. Yeah, so we're looking at this M2 as a function of z. So what can we say about this amplitude? There's a bunch of poles. And the poles come from when, in some channel, all the poles in an absolute comes from factorization. So we will have some diagram on the left where n at, sorry, let me put one at, two bunch of labels here. And we call these labels I. Can you see what's to I? Let me call this set of label I. And then there's some amplitude on the other side where n at shifted momentum and other stuff here. So all these poles occur when the momentum in that propagator go to zero. So the poles are p1 at of z plus pI total momentum in that channel. Is equal to zero. And that is a linear polynomial in z. Because yeah, p1, this is basically p1 plus pI square plus two.  Where this by definition is the vector which corresponds to lambda one, lambda tilde n of alpha dot, dotted into pI. So that notation should be, I hope it's sensitive. If anyone's confused by it, just please stop. But the point is that, yeah, that is what this notation is. So the pole condition is that this is zero. And the point is that this is linear equation in z. So it's easy to solve. That deformation is very convenient. So in the complex plane, we have a bunch of poles because in general the solutions are complex. There's a bunch of poles. And there's one pole for each channel in which one is on one side and then the other side. And the residue of each pole we know, at least recursively because it's a lower point amplitude. It's a product of two things that are lower points. So we know all the poles. So if we're lucky, if az goes to infinity, if az goes to zero, at z goes to infinity, then from all its poles, we can reconstruct what a is. And the question which demonstrates that is the question, if this limit is true, then this is true. And that is equal to a of zero plus sum over poles, one over z on the pole times a, times the residue. So from the residues, which are product of amplitudes, you can reconstruct the function. What we want, which is the function, the undeformed amplitude, the function here at z equals zero. Sorry, I'm tilting down. So the solution to that can be written very much, can be written in a compact form. Yeah, let me erase this. And the solution, basically, yeah, the statement is that a n is equal to sum over all the channels i of an amplitude on the left, which would depend on particle one, all the particles in i, and some intermediate pole label, which call n, some amplitude on the right, right here. And then, let's call this j, and then n at. So very related to the shifted momenta. And in front, there's just the pole, p one plus, but in that channel, square, which is just this propagator. So that's a recursive formula for three amplitudes. So I will keep that thing. Just need to keep the vertices here. Keep the four point amplitude. So, yeah, so I have 15 minutes left, so I will briefly discuss the simplest solution of this equation. And yeah, and there are, for the simplest elicities. And at the same time, I will introduce a useful concept, which is that of color order amplitude. So if we look at the four particle amplitude, it involves these gauge theory structure constants. And a good way to deal with them is to, so for example, if we have this structure constant, it's to write it as a trace of generators. This can be written as trace, if we, yeah, if we write that e and f and delta e f, you can write this like that. And using that delta e f is trace of t e, t f, you can write that as t a, t b, t c, t b. So it's a trace of product of two commutators.  And this you can expand basically as this trace, t a, t b, t c, t d, minus plus and some other guys. And what is called the color order amplitude is the coefficient of this guy in the expansion of the amplitude. So there is n minus one factorial color order amplitude. So in other words, you write the amplitude as sum over trace, but sum over permutation of n minus one particles. This tree, it's called t a one, t sigma a two, t sigma a n times the amplitude times the amplitude for one sigma a two, sigma a n. And it's n minus permutation of n minus one guy because the trace is cyclic, you can always put one guy first. And actually the trace is a flip symmetry, it's really, it is this really number, but yeah. But basically each of these cyclic amplitude is defined and tested symmetry on the, on the reversing the order. So these amplitude here are contrary to the reason there are, the main reason they are useful is that they are unambiguous because if you look at this amplitude here, you can define c one is the coefficient of this and c two is the coefficient of this in a basis where there's all your two building blocks. But you could use the Jacobi density to rewrite this as this minus this. And then this quotient c one will be different. So the quotient of these f's is not uniquely defined because of the Jacobi identity. But this coefficient here are unambiguous. So they are, they are, and one, one simple way to see that they are unambiguous is to imagine you have SUN gauge theory where n is big enough, SUN c, if nc is greater than number of particles you're scattering. And if you consider the scattering amplitude where particle one is just above the diagonal like that, ta two is equal to the next guy just above the diagonal and so on. Then out of all these products, the only products which survive would be ta one, ta two, ta three and so on. So just by evaluating the amplitude on that specific configuration of color, you extract this. So that shows that it's completely unambiguous. Yeah, in string theory these are what would correspond to an amplitude with the topology of the disk. And the ordering is the ordering of the vertex operators on the outside of the disk. So this was inspired in the 80s by this. But yeah, so useful notation gauge theory. And for the four particle amplitude, if you compute this guy and write it in terms of angle brackets, turns out to have a very simple expression which is just one, two to the four divided by one, two, two, three, three, four, four, one. This is basically what this c one, yeah, it's basically what this s over t times this is. It doesn't come deeper than that. This is compact and elegant expression. And for solving the recursion, it's also relatively, this notation also helps because you have much fewer factorization channels which preserve given ordering. So if you want to compute, basically you have to write down factorizations which preserve the psychic ordering. So for, if you deform in N one, you only have three channel for the five particle amplitude. One of them is one, actually just two channels. One, two, three, four. And the other is one, two, three, four, to be five at. So in the planar limit, the number of factorization channel is very small. It's just number of particles minus three. And if you consider a partially simple elicity structure, the simplest, actually I don't need this anymore. Now that I've written this. So just as a one illustration of the recursion relation, discuss the amplitude where you have all, but two particles are plus elicity when everybody has the same elicity, but two guys. This will turn out to be a simple generalization of this formula. And what happens in this special case is that, let's write, let's put the elicities here. This is one, two. So one is minus, two is minus, three is plus, and these are plus. And this is minus, minus, plus, plus, plus again. What you see is that this is a four point amplitude with a minus, with three plus and one minus. And this, I haven't discussed it so far, but it's actually zero, and you can basically show by showing that it cannot have any pole. It's a, I leave that as an exercise. Give it a different argument, but yeah. This is zero, so this amplitude is zero. There's just one diagram, this one. And this is non-zero because we have a plus, plus, minus three point vertex, which is non-zero, and this is a minus, minus, plus, plus vertex, which we just computed given by this guy. So this amplitude, so let's evaluate this graph. So we get one over the total momentum in that channel, which is P four plus P five square, evaluating this factor in front. And one over P four plus P five square is one over four five, A of five pluses. Then there's a factor which is the amplitude on the left. So just write A four, one at two, three. Let's call this guy, intermediate guy, middle guy M. And then there's this amplitude on the right, which is the three point vertex given here, which is plus, plus. So the two plus, the two same go on top. Five is shifted downstairs, this four M, M. This we know, so basically we just have to evaluate this. So what is the momentum five on the solution? So, sorry, yeah. What is the momentum? We need to know, we need to know five at, and we need to know four. It seems like I miss one information here. Let me just check. One thing which we can see on the pole, actually very simple, is that since we've deformed lambda, what is zero on the pole on that white vertex here? We have that four five at, sorry, M five at is equal to zero on the pole. So that tells us that M, remember that M is defined after rescaling is, sorry, wait a second. Just, just, just wait, yeah. It's equal to zero and the five five at is not, sorry. Five at is deformed. Yeah, that's what I was missing, okay. So this deformation I deformed five, but not five at. Not five tilde, sorry. So this angle bracket with five is on deformed. The only thing I need to compute is this M. This five at is such that four times five at is equal to zero because I'm on this factorization pole. And that basically tell me, and also four M is equal to zero. So I can take M, well, I think I can take M equal to, up to a choice, up to an irrelevant phase because M lambda, this is a short answer for lambda, M is equal to lambda four alpha. That's true because they're proportional to each other and the overall normalization doesn't matter. The overall normalization cancels between, the overall phase ambiguity cancels between these two factors. So I can take this and what can I say about M? Well, the vector M is P four plus P five at. And it's a null vector. So to extract its lambda tilde, I can project it on anything. And the convenient thing to projecting on is P one, sorry, P four plus P five at. If I project it on one and that's convenient because then the shift disappears because the shift of P five is proportional to lambda one. I can just write it like that. And now I'm done. And okay, I actually have to normalize it such that this product is equal to this. And basically normalization, you can work it out but just whatever, the simplest thing you will think which cancel the weight with respect to one and four. I'm saying this because you can do this calculation but after you've done it once, you can basically guess the answer. So telling you how to guess it, I think it's more useful. So M is this. And if we plug this into this factor, a brief algebra shows that, well, when we compute four M, let's actually do it. Four five cube, four M, for four M, the four cancels here. So we have four five, one five. Four five, one five. And for the other guy, we also get four five, but one four. And now we have one four squared from this guy two times. That cancels this. That's one. The four five, two of them cancels. And this four five cancels this. So in the end, if I write there, you will not see. So I will write here. In the end, we just get that a five is equal to one over four five. This and this cancels. Then there's one five, four five, five one. And then there's four one on top. Times a four of one minus two minus three plus four plus. And again, this only lambda tilde one is shifted, but a four depends only on lambda one. So you can ignore the at here. So the solution of this recursion relation is very simple. Well, so a five is, and yeah, let's write it explicitly so that you remember the pattern. So basically the four one cancels this and the product gives you one two to the fourth times one two, two three, three four, four five, five one. So the cyclic product of denominators. And obviously this recurses and you can keep going. So that's for the simplicity, this class of, this family of amplitude is given by this one line calculator credited to parameters who guessed it from a error six point calculation in 1980s. It's very, they really have to pull all the tricks and you use extensive computer power to manage to get this result by famine diagrams. But the end result is rather simple. But you can apply this recursion relation not just to this illicit, but actually at five point they're more or less all simple, but even for six point you can have more complicated things. And for all of these illicit, this formalism give you rather compact formulas. And which just are incredibly simpler to what you would get from something famine diagram. So this is the efficient way to think about, about three answers. So not only you get answers quickly, but you get answers which are compact enough that you can actually stare at them. Okay, so I was planning to discuss some supersymmetry, but I would conclude here. So yeah, so all I've said today is there's no supersymmetry. It's very, it's very, very quite general. Discussed amplitude in three level Yang-Mills theory. And the reason trees are so important, well first of all, you see that they're quite simple. They're much simpler than what you would think from famine diagrams. So you want to use them as a building block to compute loops. So what I will discuss in next lectures is how you go from trees to loops and trying to explore this simplicity. And I will make contact with intergability in a special case of, so that's roughly the plan of these lectures. Thank you.


What is the benefit if we? Starts with Bismillah ar-Rahman ar-Raheem Manqaraa color as Sula Allah Muhammad sallallahu alaihi wa alaihi wa alaihi Manqaraa Bismillah ar-Rahman ar-Raheem Kata ballahu lahu be kulla harfin Arba ata ala f hasala When we read Bismillah ar-Rahman ar-Raheem for every words every alphabet which is 19 alphabet which is Bismillah ar-Rahman ar-Raheem Allah will write us 4,000 hasan wa maha anhu arba ata alaaf sayyia and he will remove and delete 4,000 sins with every word within Bismillah ar-Rahman ar-Raheem wa rafa alahu arba ata alaaf daraja and Allah will elevate us 4,000 Levels for every word within Bismillah ar-Rahman ar-Raheem


We also have a detailed side panel in the old app. This was a model dialogue that blocks data entry while it looked at things like the history, the audit log, setting in max and so on. So now we have this as a always visible side panel, which allows you to kind of look at history, look at the audit log while you enter data. So that should also help in terms of making this information more accessible. So let's have a look. So now when you enter data, you can go and click the View Details button to bring up the side panel. Here you can see we have information about the data elements, the description codes, data element ID, carry option combo ID, which is going to be helpful for implementers admins. You can mark the follow-up by clicking this button. There's a common field you can put in a comment about the value. It can go and set mean max limits. So if you want to constrain the absolute mean and max values for this, you can go ahead and save the limits. There's also a nice history chart which shows the last 13 values. So they can see the previous values and to kind of figure out if the new value is reasonable or not. And finally, we have a new audit log section where you can basically look at the changes to this value over time. So you can see when and who and what change have taken place for this particular value in a nice and easily readable interface like this. And again, you can also tab along the values. And you see this side panel basically updates as you scroll through the form like this.


Okay, welcome. 4k video lessons learned. Cisco Systems Norway is actually the first I've been presenting for seven, eight years at conferences like this and this is the first time I actually tell a bit about what we are doing because it's actually of relevance to this talk. Usually I talk purely the technical stuff but to understand the challenges that we had it is useful to first see what exactly we were building. So Cisco Systems Norway used to be called Tundberg until we were acquired by Cisco several years ago. We make video conferencing equipment and one of those, oh one too far, one of those is the Cisco Spark codec kits plus I don't make up these names that's marketing so I just tell it how they call it. So we make a whole range of video conferencing equipment from desktop systems to full immersive rooms and one of those is this box and it is primarily meant for integrators. So that means as a company you can call up on an integrator and they buy this box and usually a Cisco camera as well and then you can add your own microphones, your own sources, your own cameras if you want, your own displays. This box has three HDMI inputs, two HDMI outputs so you can hook up two screens, you can hook up a camera up to two laptops for presentations and the box itself takes care of the video conferencing part, encoding and decoding etc. and sending it over to remote sites over the network. But the critical point here is that we have to deal with a variety of displays and a variety of sources and we have no control over what the customer uses. If you sell an integrated system you can control the display, you can control the cabling, you can control just about everything except the presentation source which is usually a laptop provided by the customer. That's not the case in a system like this and that has some makes this a lot more complicated than it otherwise would be. So first, let me see, first some bit of an explanation about the HDMI connector. So this talk is primarily about HDMI. We don't use DisplayPort because pretty much every laptop has HDMI support through adapters or whatever and there are several lines on the HDMI connector. One of them is three differential pairs for data and a differential pair for the clock and that is where all the data, the video data goes through. This is high speed obviously. Then you have the DDC channel that is basically an I2C bus that is used to read out an EDID. The EDID is a piece of eProm that the display has and that tells the source, your laptop, what capabilities the display has. It is also used to negotiate HDCP which is the HDMI encryption and it is used for HDMI 2.0 for what is called the status and control data channel which is new for HDMI 2.0 and that allows a source to interrogate the display about things like error detection and how well it's handling the data but there are any issues. We never had that feedback before so that's new for HDMI 2.0. There's a five volt line. It's supplied by the source. If the sync the display detects a voltage between 4.7 and 5.3 then that means there is a source present. That's according to the specification. There is a hot plug detect line that is extremely important that goes back from the sync to the source or display to your laptop saying hey there is an EDID that I have that you can read now. It's setup. You can read that. Again there is a voltage range that you would have to look at to detect whether there is something connected or not. It was designed in such a way that the five volt line that your laptop provides can power an eProm and be looped back as hot plug detects so you can even read the eProm when the display is completely off. Not all displays support this. A lot of them actually only do this when the power is on but they can design the hardware in such a way that this happens. The important thing is that it can also happen on adapters. So adapters can do the same trick. They may even have an eProm inside. It's an EDID. There are more lines. CEC or your return channel. I maintain CEC so if you want to know more about that look up on YouTube. I recently had a presentation at Kernel Recipes about CEC. There is a lot of information there but that won't be discussed in this talk. Next thing what on earth does 4K actually mean? So it really only means the resolution. 3840 by 2160 pixels. If you're pedantic then there is a variation. 4,160 by 20 I think by 2160 but that's rarely used. This is the 4K resolution that almost everybody uses. It comes in a whole range of frame rates. In practice only 30 and 60 hertz are of relevance. All the ones that are lower are done by increasing the blanking. So the actual bends with and the frequencies used over HDMI remain the same. Next thing is you can send out. I'm still in the definition phase of what this all means. So you can send out video in different ways. You can encode the pixels in different ways. One of them is the common red, green, and blue. Eight bits. You can go to deeper bits so 10, 12 up to 16 bits. Our equipment does not support it. It is generally achieved by just increasing the clock frequency so you can accommodate the extra data. I won't discuss that any further. I'm sure that will have its own issues but since we haven't used it in our equipment I can't really tell about it. Not meaningful. The other one is YUV where Y stands for brightness and UV encodes the color. So if you would just look at a picture just with the Y component it would look like a black and white picture. This is ideal for video. What is nice about it? It separates the detail of the picture. That's in the brightness, the gray colors from the color itself. And the eye is much more sensitive to brightness differences than it is to color. So it allows you to reduce the amount of color information. And for the eye it still looks good. If you have a video it still looks fine when you do, when you reduce the amount of color information. So you have YUV 444. There is still each pixel has its own luma and color information, chroma information. YUV 422. There you halve the amount of color. So for every two pixels, every pair of pixels has just one chroma information. Totally interesting since under HCMI it will just add padding. So you do not actually save any bandwidth with this. YUV 420. That becomes more interesting. There every group of four pixels shares one chroma pixel. So that means that you have halve the bandwidth of RGB. And that's actually how it's implemented in HCMI. However, not every display or source will support this. It's a relatively, well you wouldn't say that, but it was really made, it's a bit of a hack. It was created to allow old HCMI installations without the high-speed versions of HCMI to still do 4K. Then you have a number of different pixel clock rates that you can use. I'm just rounding it up, saying 148.5 takes too long. So it's just 150 for me. So you have to 150 MHz. That is the old 1.2 HCMI. F to 300 MHz. HCMI 1.3 and 1.4. That doubles the rate. And HCMI 2 goes up to 600 MHz. So what is nice about YUV 420 is you can actually do 4K at the old bandwidth of 150 MHz. 420 at 60 Hz and RGB at 4K at 30 Hz. You can do a 300 MHz. If you want to do RGB 4K at 60 Hz, you will need 600 MHz. HCMI 2.0. The problem in our products is that we use it both for video, via conferencing. So there we could use YUV 420. That would be enough. By the way, all Blu-ray and Ultra HD Blu-ray, they all use YUV 420. So you don't gain anything if you're playing back a video by going any higher. But when you connect a laptop and you show a presentation, that is all graphics. And using 420 with subsampling means that the cores are a little bit bleeding. It becomes a little bit fuzzy. And that's not a good experience. So for presentations, we want the best possible quality. So we want to use RGB. But the frame rate doesn't matter that much. I don't have to show this presentation at 60 frames per second because not a lot changes. If you use a system as a desktop at the same time, so we have some systems where you can do that. So you can connect your laptop to it and use it for work. Then again, 60 frames per second becomes important because 30 is too slow for the mouse. You will notice that it's lagging behind a little bit. So if you want to connect a TV to your PC and use it as your main screen, which I do at home, it's by the way fantastic. 48 inch screen, 60 frames per second. I can highly recommend it as your work environment for developers. But you need 4K P60 RGB for that. 4K only refers to the resolution. It says absolutely nothing about which bands with you using, what's sub-sampling.  You need to look very carefully in specifications.  Then you have to go to the forums where people actually tried connecting the TV to a PC. And they tell you, yeah, unfortunately it uses 420, so you get sub-sampling and you can't use it as a PC for your PC. This is a common threat throughout my presentation. That's the terminology that sales people use is extremely confusing and it's not detailed enough.  So what does this all mean? So if you want to support 4K P60 RGB, that's 600 megahertz. That is at the edge of what is possible. That requires really good cabling, really good and very clean signals. You really need to check that with an oscilloscope, check the eye diagrams. Are they clean? Do we have enough margin there? Clock signals, voltages. And when you measure it as a source, it might be still within spec, but you add a long cable and at the end it won't. So you need to have enough margin there. You really need to pay attention to that when you design the hardware. I'm not a hardware guy, so anything regarding hardware and FPGA that I do wrong, all my fault, but they checked it so it should be okay. The other thing to realize that when you measure on a device like this is that actually the clock, TMDS clock runs at a higher frequency when you're doing 300 megahertz then it does at 600 megahertz because at 600 the divider changes. So with 300 megahertz you do 10 bits, transfer 10 data bits per clock cycle. For 600 megahertz you transmit 40 bits per clock cycle. So actually the clock frequency is half that at 600 megahertz compared to 300 megahertz. So you have to test that 300 megahertz as well because it's different. I'm sort of working my way up from, so we had hardware, we're going through the protocol layers and so up further through the stack. So ACMI protocol, one thing that we had major issues with was hooking up our codec to certain screens and it started flickering. We couldn't understand what the hell was going on there. It turns out that the ACMI specification allows you to send null packets, sort of a no operation. You can use that during blanking just to send something. It's allowed by the specification, but clearly some manufacturers never read the specification because they didn't like it. So we had to change the IP to send nothing. And that works. We don't really know the cost because we can't look inside the vendor's code. We don't know what they are doing, but it was really frustrating for us. It took a long time before we figured out that it was related to that. Another nice catch was with reading EDIDs. So we are, as I've shown in the beginning, we have both source and sync.  So we have our own EDID. So the laptop tries to read the EDID to get the capabilities of our codec. What can we handle on that input? Normally, pretty much everybody in the world that has to read an EDID starts at zero, reads 128 bytes, and it checks if there is another block. Yes, and it reads another 128 bytes. Everyone except Apple, they do random access. So we didn't support that originally in our IP FPGA where the EDID was stored. We were assuming everybody was just reading from the beginning to the end. So when Apple was reading bytes 32, it actually got byte zero. It caused a lot of confusion. We had some really strange errors due to that. So if you design something like that, just remember, Apple always does things differently. So from what I heard, from the people who are researching this, the question is how can you do that because each block is checksummed. So my understanding is that they first do some random access to read out a few bytes, to be honest, I don't know which ones, and then they read the whole block. But just those initial byte reads already give you a wrong offset, so everything goes wrong. This is really Apple. It's weird. Status and control data channel. That's quite interesting new feature for HDMI 2 because it allows you to check your sending data to your display and you can get some feedback. Does it actually understand what I'm sending? Does it get bit errors? Can it lock through all two or three channels? It also can be used to enable scrambling. You need that for high bit rates. It's nothing to do with encrypting. It's just scrambling to reduce interference. It is highly recommended when you write drivers that you can dump this information because it's very useful when you debug. Put it in debug.fs or in the kernel log or whatever. You want to know this so it makes it easy to see how the display is handling your data. Before I start on this topic, I need some water because this is the hard one. Quantization range. Oh my God. So what is it? You have two ways to send. So this is specific for RGB encoding, not for YUV. This is RGB. You can send your RGB data in two ways. Full range where you use for red, green, and blue components, you use the full range, 0 to 255 in the bytes. Limited range goes from 16 to 235. Why do we have limited range? That goes all the way back to old analog TV where you didn't have nice digitized bytes, but you had this voltage and you got overshoots because it was not digital, so you got and it was clamped or they did several things to make the picture look good. So you had the full range was this, but actually white and black levels were at these positions. When they digitized that, they allowed to actually have that additional information so you could see those overshoots and handle them accordingly when you digitize. Another reason for limited range are certain transport mechanisms like SDI where sync information is transmitted, is embedded in the data stream as special values, 0, 255, and 1, and 1. Now there are several values that are reserved, so that is another reason why you use limited range. HDMI spec is a problem with this. It's difficult to understand how to use it, but the main thing if you interpret it wrong, you get really wrong colors. The main one that causes problems that customers will immediately see is if you are sending full range and it is interpreted as limited range, because for example Excel sheets, they have this white and light gray backgrounds alternating in the rows. That light gray is value 16, so if you, sorry, that's of course value 240, and white is 255. So if it's interpreted as limited range, you suddenly lose that light gray information, it all looks white, and they no longer see the alternating backgrounds, and they complain quite rightly. The other way around is harder to see, so what happens is that everything gets a bit washed out, so instead of getting white, you get light gray on your display. It's surprising how long it will take before you realize that I myself, and I know this stuff once ran with a display that had to set up the wrong way, and I didn't realize for months, and then you change it and you think, yeah, this looks much better. The problem here comes with that interpreting the quantization range in the HMI protocol depends on what timing you are using, and this is particularly a problem when you start mixing laptops or IT systems with consumer electronics like Blu-ray players and TVs, because they do things differently. So you have timings that are, let's say VGA based. They come from the PC world. They are full range traditionally. You have timings like 4K and 1080p, 720p, they come from the TV world, and they are traditionally limited range. So how to interpret it depends on your timing, type of timing, whether it's IT or CE, consumer electronics. This is already very confusing. Then SYNX display can support what's called selectable quantization range. If they turn that on, that bit on in the EDID, that means that the source, your laptop, can actually signal what they're sending. They can say, I'm sending full range or limited range, and the display will interpret that correctly and do the right thing. But that requires that sources will actually read that bit and do the right thing, and that's not a given, and it requires that displays enable it. We enable this bit on all of our systems, because it's a major pain if you only allow the default rules. So if you ever make a display, if you ever make a sync, always enable this bit in the EDID. Please, please, please, please do that. If you make a source, always check if the EDID supports it and signal it explicitly. Please, please, please do that. That saves so much really annoying things for us. To check what is in an EDID, just a little plug, there is an EDID decode utility. Recently it was upgraded with a long patch series that I did that syncs it up to the very latest standards, and you can give it an EDID, and it gives you in human readable format what it all supports, including this. Highly recommended. It also does sanity checks, is your EDID sane, so it also helps you when you create an EDID. The same with logging HDMI info frames. An info frame is metadata that you send during blanking, and it gives information like what is the quantization range that I'm using. There, too, there is support in the kernel to lock that. Please use it in your driver. Very, very useful for debugging. Now, this is the theory. Now practice. So the reality is for our codex, people have presentations on their laptop. There are three types of laptop that they use. Mac, Windows, Linux. While engineers use Linux, everybody else uses the other two. They're all from Intel, almost without exception, because Intel is the chipset most commonly used on laptops, so that's what you get. They all behave differently. An Apple Intel driver will always use full range for RGB. They completely disregard all of the rules that the HDMI specification sets. They don't look at the selectable quantization bits in the EDID, they just send full range. Windows driver, they always use the default rules for RGB, so they correctly change between full and limited range, depending on the timings. They don't support selectable quantization range, to my knowledge, haven't seen it work. The Linux driver, fantastic, does everything right. This is from the same company, right? But I know it's different teams, but really, Windows, Apple developers, you can learn something from the Linux guys here. And just add support for detecting the selectable quantization bits in the EDID. That's enough. Just please help us out here. So you have a little problem here, because an Apple laptop will send full range, a Windows laptop will send limited range for, say, 1080p, and a Linux laptop is explicit. The solution here, and it's really the only way you can make sure that you can always decode the information correctly. From our perspective, we can't tell whether it's Apple Linux or Windows. We just get video. That means that you have to enable YUV 4.4 in the EDID, because Apple, and only Apple, if it detects YUV support in the EDID, it will start sending YUV, and that is always limited range. All the others will still send RGB, and they do the right thing for that. So if you want to support all three variants, this is the only way you can make it work. This is a big issue, because if you do it wrong, it is really visible. You look at what people are doing, and I'm waiting to have to be a bit quicker, I see. This is an important one. You need to pay a lot of attention to this. A few display supports selectable quantization range. I don't know why not, because it's really not hard to do. If you go into the menu of the display, they tend to call it a weird name, like black level. They have several values. They don't document what they do, so the best thing is just to try out what looks best. 4K introduces yet another problem. You have Vic codes that basically tell you what timing it is. It's sent in the info frame. If Vic code is zero, it's an IT format, uses full range, otherwise it is a CE format, and it's limited range. Then when they introduced 4K, the HDMI committee added their own HDMI Vic codes for several 4K values. That's separate from the original Vic code. The idea was that you set those, and the older Vic code stays zero. But if it's zero, then 4K, P30, for example, would be full range. But they also say the 4K, those HDMI Vic codes behave exactly the same like all other CE timings, which would mean limited range, and nobody actually defines what you should do. This is really two committees, standardization committees, working at cross purposes and not communicating, so we get a really mess. And based on testing, what we can say is that 4K, P30 is sent as full range, almost every source, or basically all sources that we test do that. 4K, P60, that's the weird bit, they don't have an HDMI Vic code. They have their own nonzero Vic code, and that's limited range. This is very much specific to 4K and is really confusing, and it is basically not documented correctly, and it is complete chaos, quantization range. Very quickly here for drivers, I see receivers in particular, they seem to be poorly tested in my experience when it comes to interrupts. They tend to get into situations, we've seen it with different vendors and at different times, where the interrupts lock up. Particularly if you do tests like quickly connecting, disconnecting an HDMI cable, you get really, it's a really good stress test, and a lot of interrupt handling, their fields, so it appears to be in the hardware that they get in an inconsistent state that you can't get out of. So quite often we have to replace interrupt handling by polling, just to make it work. I've never seen this with, say, platform HDMI drivers, HDMI hardware, that works fine. It seems specific to iSquad C. In the interest of time, I'm skipping the next one, because the next session is also very important, because this is the part that we don't control. We don't control what sort of adapters and cables the customer uses, and there are some really nasty surprises there. So display ports to HDMI adapters, like this one, it's also on the picture, mini display port to HDMI. It's a passive adapter. It turns out there are two types, type one that goes up to 165 MHz, and a type two that goes up to 300. For type two, there is a little chip inside with some registry information, a little e-prom that tells you that it's a type two. Type one doesn't have that chip. So a driver should, a sync driver should detect, or sorry, a source driver should detect whether it's type one or type two, and then it notes its rating. Again, Linux Intel driver, fantastic job, guys. You check that. If you have type one, if you run X-Render, you only get resolutions up to that frequency. Unfortunately, the Intel Apple and Windows drivers do not check for this, so they will just say, yeah, you can do 4K, P30. But if it's a type one, you have no idea if it can actually do that. You might get lucky and it works. It may not work at all. It may work intermittently. You have no idea. And the only way I found to test this, to test an adapter, is to connect it to a Linux laptop, run X-Render, and then I see what it can do. This is a problem when you don't know what your customers are using. They start complaining to you, yeah, I don't see my presentation. Yeah, you have the wrong adapter. And for this one, this is a Lenovo. They actually mentioned it, type two, in extremely small print. Most don't at all. And you have no idea what they can actually can do until you test it with a Linux laptop. Another very nasty one, USB-C to HDMI adapters. They tend to lose a lot of voltage on the 5-fold line. And that can have real problems where you just don't see, if you hook up a display through that adapter, you don't see the display at all. If the 5-fold is looped back as a hot plug detect pin, then it would fall below the minimum voltage. Or you can't power the e-prom on the display or other reasons. You need to check the 5-fold. And a lot of adapters fail that test. They're out of spec. And then you don't know what happens. Some display can handle it, other displays can't. You have no idea what is done there. So that is a very difficult problem. Again, you literally have to list to your customers what are good adapters. Another really big problem with those is that they tend to try to negotiate HTCP encryption, which is a killer for video conferencing because we cannot, if we receive encrypted video, we cannot send that to a remote site. We can only send it out encrypted again to a local display. They have to feed the purpose of video conferencing if you can't show your presentation. So if you have an adapter that just starts trying to encrypt, that's no good for us. In some cases, it can be done with a firmware update. Unfortunately, that firmware update is hard to get and only runs on the windows. So that's a bit of a pain for people with Macbooks. This is really, again, a very big problem and it is basically out of our control. And another issue with HDMI cables, because of the high speeds, if you want to do 600 megahertz, they actually had to set up a certification program so that you can certify your cable, but it actually complies to the specification. If you buy cables and you want to use this, always buy certified cables. The problem is that, again, with labeling, you can label it on the cable, but most of the time they don't do that and it's only labeled on the packaging. Which is fine when you buy it, but then you've used it, you've thrown away the packaging and you throw the cable in the box and two months later you pick it up, but you don't know what it can do. There are no rules that there's nothing in the specification that cable or adapter manufacturers have to label their cables or adapters according to specific standards. So you don't know what you have. Finally, another issue, five-fold. Again, with very long cables, you get a voltage drop. I had a great cable. For several people it worked fine. It could do 600 megahertz, no problem. I hook it up on my laptop. I don't see the display at all and that's because of the voltage drop. It's just completely unknown whether or not that will work. It depends on your whatever environment you have.  In general, our experience with HDMI accessories is that it sucks. They're very difficult to get good specifications about what you buy. They just say, yeah, it's a 4k. It's meaningless. It could be 150 megahertz. It could be 300. It could be 600. You don't give me any useful information. They're poorly tested. There is no, as I said, there's absolutely no standard of labeling cables. Like in Ethernet, you can see a cut four, cut five, cut six, cut whatever, what the highest number is. It's standardized how they should be labeled. There's nothing like that for HDMI. And if you think HDMI is bad, wait for USB Type-C. We're looking into that.  You buy a USB Type-C adapter. You don't know what it can do. There's nothing on it. It could be USB 2. It could be 3. It could be Thunderbolt. You have no idea. I think that it's really, really bad from the committees that make these standards, that they don't have anything for that. Because you have no idea what you're buying. Some resources here you can find the EDID, decode utility. I think it's very useful, whether you're making EDIDs or whether you just want to read an EDID and see what it can do. My email. And I have, well, a few minutes for very few minutes. Say one or two questions. Oh, wait. Mike. Can most of these problems with HDMI be solved by switching to a much more modern protocol like a DisplayPort? No. Not for us. So DisplayPort uses, the only place where DisplayPort is used is in PC monitors and PCs. You don't see it outside of that. So all the installed base for HDMI is huge, far larger than that for DisplayPort. We just cannot offer it on our systems, because it's just not common enough. And we typically, the displays that customers use tend to be TVs, large displays, not the small ones that you use for a PC. And they're all HDMI. So we, it might change at some point that something else comes up. As I said, HDMI USB Type-C, that is definitely interesting development. But a lot of the cabling problems and labeling is way worse there. That is really going to be a big problem with that standard. It's not, the technology is fantastic. The fact that you can insert it in either orientation is, it's such a small thing, but it is so nice. But it's all let down by very poor specification. You don't know what you buy. Very fuzzy and very unclear what is happening there. All the questions? Wait for the... You spoke about long cables could being a problem potentially. Do you have a range of length that are safe towards not safe at all? Depends on the bandwidth. So 300 megahertz, you're probably okay for up to four or five meters. After that, the quality really becomes important and you need to do very good quality testing. You can get longer, but if you just buy it off the shelf, it might work for you, but not for someone else. That's the big problem. So if you simply do not know, and it is... So for 600 megahertz, at least you have a certification program. So you can check for that. For 300 megahertz, you don't. So you have no idea what you're buying. Okay, thank you. Okay, one last question. Everybody wants to go to the next session. Okay, thank you very much.


April is Sexual Assault Awareness and Prevention Month and officials want to raise awareness about sexual violence and let sailors know that sexual assault will not be tolerated in the Navy. Mike Stevens told us why preventing sexual assault is so important and why it's everyone's duty. We must have the courage to intervene when we witness a shipmate crossing the line and ensure that everyone is treated with dignity and respect. We have the power to overcome sexual harassment and assaults in our Navy. Continue to zero in on excellence with good order and discipline. We control what we own. We are Sailors 24-7. We must demonstrate honor, courage and commitment. From Defense Media Activity, I'm Petty Officer Andrew Johnson.


ompson van blitz let's do a recap here again another solid box there here we go we have blue to 99 kairi for the nets stearn fox kings and for any simons blazers purple to 49 kevin herder hawks scary trend junior raptors nix's cladston nets white to 25 germaya robinson url thunder and montage donovan mitchell for the jazz our autos brain embossed and junior clippers jalen sucks for the magic metaworld peace lakers and our two magic cards we had the ssp rookie eruption of jaylon johnson for the hawks and then a redemption rookie autographs mosaic kade cutting him for the pistons all right that'll do it for number 48 thanks again everyone for the film oh yeah timmy that's all but aria all that is all for me for the daytime thanks again so much for getting everything filled up do appreciate all your support as always again sam will be live here in about two hours or so about our 45 minutes for more group breaks there is the link to the um schedule but thanks again y'all have a fabulous rest of your weekend and i will see you all back tomorrow for sunday daytime personals again thanks so much everyone for all your support and we'll see you back in a bit bye