Why can't iPad Pro drive 4K display at 60Hz?

[hajime]

4k = (3840 x 2160 pixels) x (4 bytes per pixel for 32bit color) = 31.6MBytes
4k60fps = 31.6MBytes x 60 images per second = 1.9GBytes / second

1.9GBytes / second = 15.2Gbps (gigabits per second)

You'd need at least a Thunderbolt 2 cable to carry it (maxes out at 20Gbps) - HDMI 2.0 could do it theoretically (max 18Gbps) but you can see you're reaching the upper limits of throughput, and real life throughput is rarely that high.

You want to drive 2 4K@60 monitors? You're going to need Thunderbolt 3 levels of throughput.

Excellent calculations. Why Apple uses Lighting instead of Thunderbolt 3 on the iOS devices? I thought they want to make iOS devices powerful.

 

[masotime]

Excellent calculations. Why Apple uses Lighting instead of Thunderbolt 3 on the iOS devices? I thought they want to make iOS devices powerful.

No idea. Could be high power requirements, thermal issues, etc. I would say the current port of the iPad Pro is likely maxed out at USB 3 speeds given that it supports USB 3.0 speeds via the SD Card reader. That would max out the throughput of the lightning port at 4 Gbps (ref: https://en.wikipedia.org/wiki/USB_3.0#Data_encoding), which is far short of 4k60, probably short of 4k30 come to think of it.

Is there a tablet out there that can actually drive 4k60? Where we define a tablet as basically a touchscreen with no built-in input other than capacitive touch - does the detachable screen of the Surface Book or the Surface Pro support external 4k60?

I think it's possible, but I can't think of one in recent memory - the Microsoft line of devices are presumably the best candidates.

 

[sparksd]

No idea. Could be high power requirements, thermal issues, etc. I would say the current port of the iPad Pro is likely maxed out at USB 3 speeds given that it supports USB 3.0 speeds via the SD Card reader. That would max out the throughput of the lightning port at 4 Gbps (ref: https://en.wikipedia.org/wiki/USB_3.0#Data_encoding), which is far short of 4k60, probably short of 4k30 come to think of it.

Is there a tablet out there that can actually drive 4k60? Where we define a tablet as basically a touchscreen with no built-in input other than capacitive touch - does the detachable screen of the Surface Book or the Surface Pro support external 4k60?

I think it's possible, but I can't think of one in recent memory - the Microsoft line of devices are presumably the best candidates.

While possible, does it make sense economically, i.e., the added cost vs projected consumer demand for the functionality?

 

[masotime]

While possible, does it make sense economically, i.e., the added cost vs projected consumer demand for the functionality?

Heh... I'm an engineer (literally), not a product manager. Frankly I would assume Apple would prefer a wireless / AirPlay approach, but I really doubt wireless tech can transmit 4k60 at this point in time.

Still, it may be possible if you compress 4k60 with, e.g. HEVC, reducing the bandwidth to say 100Mbps, but that will require significant computational power on the transmitter, and to a lesser extent the receiver.

 

[gobikerider]

Apple has never released raw bus speed details on the lightning cable/protocols but currently the main reason is the Lightning Digital AV Adapter is based off the Samsung S5L8700 series of SoCs which have a video output limit of upto 1600×900 resoultion upscaled to 1080p with visible compression artifacts.

so assuming the physical cable and protocols can handle it a new lightning to HDMI adapter is needed.

This is exactly what I figured the issue was. The A10X has the decode and encoding on the gpu but the interconnects are simply dated.

 

[xraydoc]

Excellent calculations. Why Apple uses Lighting instead of Thunderbolt 3 on the iOS devices? I thought they want to make iOS devices powerful.

There are no TB driver chipsets for ARM processors.

 

[Anarchy99]

There are no TB driver chipsets for ARM processors.

Yet
its hypothetically possible Apple is one of the rare few that has an Architecture License with ARM on top of that they co-developed thunderbolt with Intel, not saying it will happen but could

that wouldnt help with current models though

 

[xraydoc]

Yet
its hypothetically possible Apple is one of the rare few that has an Architecture License with ARM on top of that they co-developed thunderbolt with Intel, not saying it will happen but could

that wouldnt help with current models though

But does the rest of the system even have the throughput to even bother? I suspect we’re still a few generations of ARM from enough bandwidth to even bother with a thunderbolt 3 interface. The current iPad barely even make use of USB 3 speeds let alone TB.

 

[masotime]

But does the rest of the system even have the throughput to even bother? I suspect we’re still a few generations of ARM from enough bandwidth to even bother with a thunderbolt 3 interface. The current iPad barely even make use of USB 3 speeds let alone TB.

I would agree with this assessment. Eventually the argument goes back down to the standard “the iPad Pro isn’t pro enough”, which frankly depends on the context of “pro”.

The typical executive isn’t going to need 4k60 anyway, and will probably just push text and numbers around on your standard office suite + mail. If you are in a specialized STEM profession, Apple expects to sell you the MacBook Pro, not the iPad Pro.

 

[Anarchy99]

But does the rest of the system even have the throughput to even bother? I suspect we’re still a few generations of ARM from enough bandwidth to even bother with a thunderbolt 3 interface. The current iPad barely even make use of USB 3 speeds let alone TB.

currently not really but hypothetically utilizing thunderbolt which is basically PCIe lanes with little overhead means it would get rid of USB's overhead that would be a small benifit without even changing the NAND, but realistically if they changed to thunderbolt they would tout the speed and design newer iDevices to utilize it properly.
they would do what is currently done with SSD's to get more throughput, they would put several smaller nand chips rather than one large as it allows for sequental read/writes.
they have no purpose to do this now as USB isn't fast in the same ways
[doublepost=1527124083][/doublepost]

I would agree with this assessment. Eventually the argument goes back down to the standard “the iPad Pro isn’t pro enough”, which frankly depends on the context of “pro”.

I liked Apple's original idea for pro, for this reason when Jobs made the product quadrant (desktop, laptop for Pro and Average user) pro was suppose to be the Best hardware they could reasonably put in a machine for your IT professional or atleast Creative Professional.

now even the Macbook Pro's arn't pro

its easy for the "fake pro's" (your execuitive types, lower white-collar whos workload could be done on a old core2duo etc.)
they can make do with either a lower machine apple offers or certainly can expense a overpowered machine if there budget allows but if i can't get the power I need I can't work or have to hackintosh, use VMs or hypothetically abandon macOS

TLDR version i miss Apple Computer Inc.

 

[gobikerider]

Heh... I'm an engineer (literally), not a product manager. Frankly I would assume Apple would prefer a wireless / AirPlay approach, but I really doubt wireless tech can transmit 4k60 at this point in time.

Still, it may be possible if you compress 4k60 with, e.g. HEVC, reducing the bandwidth to say 100Mbps, but that will require significant computational power on the transmitter, and to a lesser extent the receiver.

Doesn’t YouTube do this already?

 

[Kal-037]

[doublepost=1527060693][/doublepost]

Apple was forced to put a better cooling system including a fan in the ATV 4K.


The A10X can do it, but it needs better cooling than what the iPad provides is my guess. You’d probably encounter major throttling after a short while.

https://www.ifixit.com/Teardown/Apple+TV+4K+Teardown/97511

Yes absolutely agree with you, but I just meant the A10X and Apple’s GPU is capable of it.


Kallum

 

[acorntoy]

Yes absolutely agree with you, but I just meant the A10X and Apple’s GPU is capable of it.


Kallum

Makes you wonder what they could do in a properly ventilated laptop

 

[Anarchy99]

Makes you wonder what they could do in a properly ventilated laptop

Why wonder ?
we know what apple would do with a properly ventilated laptop.

1)make it pointlessly thinner just so you can remove upgradability, then the next generation make it worse just for under 3mm more thinness

2) make the keyboard travel worse but still usable, then the next generation make not usable, prone to breaking and remove more then 10% of the keys for a nonstandard oled strip Apple themselves havent even fully embraced.

3) dont forget the smaller battery do to all the thiness, but dont worry your CPU/GPU will be thermally throttled so battery life wont be affected much

 

[rmanbike]

USB-C will never happen. It's about twice as thick and more prone to damage. If a USB-C Micro standard was put forward that was very similar to a lightning connector then I could see Apple potentially adopting that. But right now I don't think it's something that is concerning Apple because they are clearly moving away from wires entirely. I bet 802.11ax and AirPlay 2 will probably enable 4K60 streaming with some fancy compression algorithms. I don't see 4K being replaced by 8K any time soon (aside from large, high-end monitors that you sit close to) because for most consumers 4K doesn't even provide much benefit over 1080p at typical viewing distances and display sizes so I feel like we're finally at an end point of this race for some time. This will allow wireless to catch up and provide a better way.

Looks like your prediction "never happen" was way off the mark ...

 

[sparksd]

Looks like your prediction "never happen" was way off the mark ...

Kind of late to be rubbing it in about a post almost 4 years old.