Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

(Presumably) Apple engineer comment on Lightning AV adapter design

panic.com

Post reply on HN
Print view View original

21–30 of 175 posts

Re: (Presumably) Apple engineer comment on Lightning AV adapter design

#21

Post by bitcartel »

dmishe wrote: post #2

I think the main takeaway is that yes, lightning is future proof and can adapt to any output you want it to. I do wonder what's the reason for encode/decode cycle was in the first place though.

I think the main takeaway is, why pay for a $50 widget when a $5 cable will do the job?

For the consumer who just wants to connect their device to a HDTV, it's crazy they have to pay 10x more just because they're in the Apple ecosystem and not Android.

As for being future-proof, by the time some cool new A/V interface hits the market, and we've all updated our TVs, the Lightning devices of today will be in a museum.

Re: (Presumably) Apple engineer comment on Lightning AV adapter design

#22

Post by revelation »

taligent wrote: post #10
revelation wrote: post #3

Earlier quoted context omitted.

He doesn't say, but probably because they just don't have the bandwidth. And thats where all this future proof talk goes deaf. New interfaces will only have more bandwidth, thats the whole point. Meanwhile, Lightning still has the same bandwidth and theres still a considerable penalty in serializing any other interface. If they can't even do 1080p lossless right now, they are in much deeper trouble for the future.

I might be really confused but why is Apple going to be in deeper trouble ? Surely the future will be H.265 content which will have better quality for the same bandwidth. And it's unlikely that people are going to be demanding a higher output resolution than 1080p from their mobile device for anytime soon.

Again, this is a connector from your mobile device to a display. Nobody has ever done any lossy compression on that pathway; both because you can drive simple circuits at frequencies high enough to have plenty of bandwidth and because it would actively destroy information (hence lossy). This is such a big problem because the video you are playing has already been lossy compressed (H.265) and it will most certainly not get better by a second pass that only has the raw pixel data available.

I could imagine people want to play 4k movies from their mobile device on their TV, but you wouldn't install a 4k screen as the display on the mobile device.

Edit: Yes, computer is inaccurate. I wanted to get the idea across that we are talking about connectors (DVI, HDMI) that you would normally use to hook up a computer or laptop to a TV or LCD. They have only recently appeared on mobile devices, but serve the same purpose here: video (and audio, for HDMI) out.

Re: (Presumably) Apple engineer comment on Lightning AV adapter design

#23

Post by taligent »

bitcartel wrote: post #21
dmishe wrote: post #2

I think the main takeaway is that yes, lightning is future proof and can adapt to any output you want it to. I do wonder what's the reason for encode/decode cycle was in the first place though.

I think the main takeaway is, why pay for a $50 widget when a $5 cable will do the job? For the consumer who just wants to connect their device to a HDTV, it's crazy they have to pay 10x more just because they're in the Apple ecosystem and not Android. As for being future-proof, by the time some cool new A/V interface hits the market, and we've all updated our TVs, the Lightning devices of today will be in a museum.

You know you can buy Lightning cables off eBay for $5.

And that the original dock connector first appeared in the iPod 3G nearly a decade ago. So yes today's devices will be in a museum. But the connector could still be in use in 2023 and beyond. Worth keeping in mind.

Re: (Presumably) Apple engineer comment on Lightning AV adapter design

#24

Post by revelation »

mbell wrote: post #19
revelation wrote: post #9

Earlier quoted context omitted.

And HDMI does it effortlessly. That's exactly what these interfaces were designed to do: raw massive data with low latency over short distances, suitable for processing in dedicated circuits, not SOCs.

> suitable for processing in dedicated circuits, not SOCs. Your splitting hairs. Pretty much all HDMI transmitter ICs have a microcontroller on board, they need a processor to deal with the protocol configuration, DDC and HDCP. Probably most are using some 8051 design plunked into the chip. They are SoCs by any reasonable definition.

Yes, of course. But they have the the actual transfer of the raw data offloaded onto specific circuitry that mostly just passes it through, something the processor part of a SOC would be terrible at. That's not what Apple is doing; they take in a normal lossy compressed video stream (H.264, who knows) and then reconstruct a HDMI signal.

Re: (Presumably) Apple engineer comment on Lightning AV adapter design

#25

Post by revelation »

taligent wrote: post #20
revelation wrote: post #17

Earlier quoted context omitted.

This isn't streaming, its the last 50cm from your computer to your display. The 200 times more of data are already handled without a sweat by today's interfaces. Dual link DVI, from 1999, can already do more than 1080p.

Sorry but are you talking about the right connector here ? Lightning is for the iPod, iPhone and iPad. Of course dual link DVI et al can do more than 1080p. They are all huge. Apple's needs to support not just today's thin devices but those for the next decade (iWatch ?).

DVI is inferior to HDMI in bandwidth, and plenty of mobile devices have been offering that.

Re: (Presumably) Apple engineer comment on Lightning AV adapter design

#26

Post by drewcrawford »

revelation wrote: post #3
dmishe wrote: post #2

I think the main takeaway is that yes, lightning is future proof and can adapt to any output you want it to. I do wonder what's the reason for encode/decode cycle was in the first place though.

He doesn't say, but probably because they just don't have the bandwidth. And thats where all this future proof talk goes deaf. New interfaces will only have more bandwidth, thats the whole point. Meanwhile, Lightning still has the same bandwidth and theres still a considerable penalty in serializing any other interface. If they can't even do 1080p lossless right now, they are in much deeper trouble for the future.

> If they can't even do 1080p lossless right now, they are in much deeper trouble for the future.

Let me try and shed some light on this mystery. Consider this rumor. Also, I am not an electrical engineer, so I may be talking out of my ass.

As best as I can tell, Lightning is not (yet, anyway) a real protocol like Firewire, USB, etc. What it is so far is USB with a different connector and some negotiating chips.

So when connect your lightning-USB cable to your iPhone, your iPhone squawks and says "What is this?" and the cable says "I'm USB". The iPhone then sets its pinout to USB mode and off you go.

What's so great about this, why not just use USB? I think the secret sauce is that Apple wants to surreptitiously invent new pinouts with faster data rates, without consulting any standards bodies and having to rally industry support on TVs, computers, et al. They just build some new controller to push Lightning at 2Gbps+, put it in new iPhones, and build active cables that spit out HDMI or UHDTV or USB3 or whatever it is the kids are doing these days. The active cables degrade gracefully for hardware running at the slower data rate.

What I think you are seeing right now, is the dry run with the off-the-shelf controller. Get manufacturing ramped up. You need this to plug your phone into a computer anyway. But it's just the tick. Wait for the tock.

Now the only thing that puzzles me is why they settled on 8 pins, when USB3 is 9. Obviously they wanted an even number so you could plug it in every which way, but you would think stepping up to 10 pins would let them use off-the-shelf USB3 controllers instead of USB2. Maybe they can do USB3 on 8-pins somehow, or maybe the tock will be ready fast enough that it's not worth it.

Further reading: http://brockerhoff.net/blog/2012/09/23/boom-pins/

Re: (Presumably) Apple engineer comment on Lightning AV adapter design

#27

Post by mbell »

revelation wrote: post #22
taligent wrote: post #10

Earlier quoted context omitted.

I might be really confused but why is Apple going to be in deeper trouble ? Surely the future will be H.265 content which will have better quality for the same bandwidth. And it's unlikely that people are going to be demanding a higher output resolution than 1080p from their mobile device for anytime soon.

Again, this is a connector from your mobile device to a display. Nobody has ever done any lossy compression on that pathway; both because you can drive simple circuits at frequencies high enough to have plenty of bandwidth and because it would actively destroy information (hence lossy). This is such a big problem because the video you are playing has already been lossy compressed (H.265) and it will most certainly no…

> Again, this is a connector from your computer to a display.

Huh? Its the plug on the bottom of a phone (and ipads now i guess). Lightning isn't on any computers.

Re: (Presumably) Apple engineer comment on Lightning AV adapter design

#28

Post by taligent »

revelation wrote: post #22
taligent wrote: post #10

Earlier quoted context omitted.

I might be really confused but why is Apple going to be in deeper trouble ? Surely the future will be H.265 content which will have better quality for the same bandwidth. And it's unlikely that people are going to be demanding a higher output resolution than 1080p from their mobile device for anytime soon.

Again, this is a connector from your mobile device to a display. Nobody has ever done any lossy compression on that pathway; both because you can drive simple circuits at frequencies high enough to have plenty of bandwidth and because it would actively destroy information (hence lossy). This is such a big problem because the video you are playing has already been lossy compressed (H.265) and it will most certainly no…

a) This is a connector from a mobile device to a TV. That is the primary use case here. I doubt anybody is hooking up an iPhone to any other type of display.

b) Why is there a second pass compression/decompression stage ? Isn't iOS outputting the compressed H.264 stream and the adapter decoding it i.e. one stage ?

c) Given that Retina displays by definition are the best resolution we will need and it is far less than 4K it is questionable whether there will be a use for 4K on mobile devices. Other than using your iOS device as a media player for your TV (very small use case).

Re: (Presumably) Apple engineer comment on Lightning AV adapter design

#29

Post by dmishe »

bitcartel wrote: post #21
dmishe wrote: post #2

I think the main takeaway is that yes, lightning is future proof and can adapt to any output you want it to. I do wonder what's the reason for encode/decode cycle was in the first place though.

I think the main takeaway is, why pay for a $50 widget when a $5 cable will do the job? For the consumer who just wants to connect their device to a HDTV, it's crazy they have to pay 10x more just because they're in the Apple ecosystem and not Android. As for being future-proof, by the time some cool new A/V interface hits the market, and we've all updated our TVs, the Lightning devices of today will be in a museum.

>the Lightning devices of today will be in a museum.

Why? They'll plug another $50 adapter on it and it'll work.

Re: (Presumably) Apple engineer comment on Lightning AV adapter design

#30

Post by noonespecial »

There’s no shell in the image, there’s no utilities (analogous to what we used to call the “BSD Subsystem” in Mac OS X). It boots straight into a daemon designed to accept incoming data...(and the fact that the firmware is stored in RAM rather then ROM)...

But there could be. In fact, it could do almost anything as its a powerful little computer in its own right and it sounds an awful lot like it boots the kernel and then runs a daemon in a most familiar fashion. I can think of a few delightful applications off hand. There will be some epic hacks. Is there like a "Bunnie" signal?

Post reply on HN