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(Presumably) Apple engineer comment on Lightning AV adapter design

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

#151

Post by makomk »

scott_karana wrote: post #63
buro9 wrote: post #58

Earlier quoted context omitted.

That is a problem entirely of our own making. The stereo beside me has components that span 30 years and uses the same cabling for all components. I realise someone will come back with "Oh, but DRM, encryption, needing more information about the source and destination"... but I'd counter by pointing out that telecoms cabling works perfectly well for transporting all kinds of things across it. You can put into protoco…

While I sympathize, this isn't just about A/V standards. This allows for absolutely ANYTHING, barring bandwidth concerns. Ubiquitous body computers with skin access ports? We can make an interface for that. "Quantum broadcast" antenna technology? We can make a dongle for that.

It's not clear that it can support "absolutely ANYTHING" for values of anything that are any greater than can be achieved with USB 2.0 OTG though. So far it hasn't.

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

#152

Post by erichocean »

nier wrote: post #76
hosay123 wrote: post #73

Earlier quoted context omitted.

Perhaps you didn't experience the PR storm around the time OS X was initially released: it was heavily geared towards nerds and the literal phrase "open source" was extensively employed in their marketing material. This aside, you're basically trying to write off nirvana's (IMHO excellent) rant using a minor technicality, one of the common features of the discussions here that tends to make my skin crawl.

The technicality being that Darwin seizes to be an open source operating system once it is shipped with closed source components. Why would this be true?

The technicality being that Darwin seizes [sic] to be an open source operating system once it is shipped with closed source components.

GNU/Linux is therefore cough nVidia cough completely, 100% open. Thanks for clearing that up. Darwin sux!1!

/sarc

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

#153

Post by Strshps1MoreTim »

revelation wrote: post #25
taligent wrote: post #20

Earlier quoted context omitted.

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.

Yeah right, my PC happily sends 2560x1600 picture to my monitor over DVI right now. All HDMI ports I've seen are limited to 1920x1200.

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

#154

Post by makomk »

StringyBob wrote: post #77
seabee wrote: post #70

Earlier quoted context omitted.

You'd need 3Gbps to push uncompressed 1080p data. If you look at USB 3.0 and make a not-unreasonable bet that Lightning is slower, then you simply don't have the bandwidth to do so.

As well as bandwidth, power consumption. Chucking 3Gbps down a long wire is going to reduce battery life for a mobile product. Perhaps the controller can support it, but heat dissipation in the phone is significant?

Actually, that doesn't make sense - the adapter is powered from the iPhone or iPad and still has to chuck 3 Gbps down a long wire, except now you're using the iPhone's h.264 encode hardware and an entire ARM SoC in the adapter which you have to power too.

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

#155

Post by jessewmc »

nirvana wrote: post #67

Ideology has trumped engineering, and as hackers, you shouldn't tolerate it. Frankly, all of this has been obvious all along to any competent engineer, since the moment Apple introduced lightening. They described it as a serial bus and talked about how it gave more flexibility. If you think about it for 2 seconds its obviously better to run protocols over a serial bus than to run 30 lines of individual signals, with…

Can you explain a little more what you're getting at? I'm not very familiar with hardware and don't know anything about video. The adapter seems like a neat hack, but definitely a workaround for something. I can't really tell if you're defending it or not.

What's the win from an engineering standpoint here? And why is this an inevitable design (which you suggest if I understand you right)? What are some other options and what are the reasons those might not have been used?

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

#156

Post by derekp7 »

mikeash wrote: post #144
jws wrote: post #124

Earlier quoted context omitted.

I appreciate reversibility once per day. In 2074 days of owning an iPhone and 1065 days of owning an iPad I have never used or wanted an HDMI output. I'd say they made the right tradeoff.

I agree. I don't even have a device with the connector (yet?), but it seems like a major advantage. Who are all these people popping out of the woodwork wanting a wired connection from their phone to their TV? I'm sure some people do this sometimes, but so many? Why would you even do that? Perhaps this is uncharitable, but it makes me think that most of the people complaining here have never done it, never will, prob…

The only two use cases I can think of is playing a video you recorded on your phone at a family gathering, or for playing Netflix on your TV without needing to hook up a Roku or similar.

Edit: third use case, hooking this up to a monitor to turn your smartphone into a desktop computer.

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

#157

Post by wlesieutre »

TorbjornLunde wrote: post #113
rossjudson wrote: post #108

Earlier quoted context omitted.

What you're saying is true from an engineering standpoint (serial vs parallel), but has to be placed in the customer's context. In this specific case the quality is bad, operation is unreliable, and the price is high. Consumer devices accept HDMI as input. Serial to parallel video (Lightning to HDMI) is tough without some heavy-duty hardware -- hence the exorbitant cost of these adapters. The SoC design introduces a…

I strongly disagree that reversibility is a small feature. Whenever Plugging the chargers to new iOS devices is effortless the same way as headphones jacks. Non-symmetrical connectors are an affront to usability.

Asymmetric connectors weren't bad, it's when you have asymmetric connectors in rectangular plugs that it becomes a problem. I never tried to put FireWire 400 in backward, but USB is awful.

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

#158

Post by rscale »

mikeash wrote: post #144
jws wrote: post #124

Earlier quoted context omitted.

I appreciate reversibility once per day. In 2074 days of owning an iPhone and 1065 days of owning an iPad I have never used or wanted an HDMI output. I'd say they made the right tradeoff.

I agree. I don't even have a device with the connector (yet?), but it seems like a major advantage. Who are all these people popping out of the woodwork wanting a wired connection from their phone to their TV? I'm sure some people do this sometimes, but so many? Why would you even do that? Perhaps this is uncharitable, but it makes me think that most of the people complaining here have never done it, never will, prob…

It's especially strange because if you want to do that, you can Airplay the video to the TV, and not have to deal with a cable from your phone to your TV.

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

#159

Post by mbell »

revelation wrote: post #24
mbell wrote: post #19

Earlier quoted context omitted.

> 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.

The only difference between what you've described and what is going on in this adaptor is the inclusion of h264 decoding. The use of this is an argument that can be had (personally I think it was a great play on Apple's part, see my comment here: http://news.ycombinator.com/item?id=5308345)

The rest of this is ancillary stuff. They aren't decoding h.264 on an ARM core, that's impossible for any significant bit rate, they are doing it with a purpose built bit of hardware, just as the HDMI encoding is done in a purpose built bit of hardware. Incidentally the encoding of HDMI is a mess, the spec is worth a read some time.

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

#160

Post by rossjudson »

makomk wrote: post #148
rossjudson wrote: post #108

Earlier quoted context omitted.

What you're saying is true from an engineering standpoint (serial vs parallel), but has to be placed in the customer's context. In this specific case the quality is bad, operation is unreliable, and the price is high. Consumer devices accept HDMI as input. Serial to parallel video (Lightning to HDMI) is tough without some heavy-duty hardware -- hence the exorbitant cost of these adapters. The SoC design introduces a…

The problem isn't even serial-to-parallel - HDMI is serial based - the problem is that Apple apparently designed Lightning with insufficient bandwidth for uncompressed video, then kludged around it. Then Apple fanboys went on and on about how much more elegant it is than MHL, which has much cheaper HDMI adapters and better video quality because all the MHL adapters have to do is convert one uncompressed serial video…

Thanks for the correction -- it is a bandwidth issue. Lightning has less capability than what it replaces. But hey -- it's reversible!

Good trade? No.

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