Apple's Lightning Digital AV Adapter is a Full-Fledged Computer

Panic, the developers behind apps like Coda and Transmit, spent some time disassembling the Lightning Digital AV cable that allows iOS devices like the iPad mini and the iPhone 5 to output HDMI to televisions.

The company discovered that, like its Lightning to 30-pin brethren, the Digital AV adapter is considerably more complicated than it would appear. Among other discoveries, Panic found an ARM chip and 256MB of RAM inside.

Digitalav

There are a lot of questions. What OS does it boot? @jmreid thinks the adapter copies over a “mini iOS” (!) from the device and boots it in a few seconds every time it’s connected, which would explain the fairly lengthy startup time for video out. Why do this crazy thing at all? All we can figure is that the small number of Lightning pins prevented them from doing raw HDMI period, and the elegance of the adapter trumped the need for traditional video out, so someone had to think seriously out of the box. Or maybe they want get as much functionality out of the iPad as possible to reduce cost and complexity.

Panic conjectures that for some reason the Lightning port isn't capable of outputting raw HDMI -- something that should give an extremely high quality image -- and instead uses a form of AirPlay to output video, delivering a lower quality video signal.

Update: Panic highlights this comment from an anonymous reader hinting at being an Apple engineer, which offers more details about how the adapter works and indicating that code updates are being made to improve the video quality.

The reason why this adapter exists is because Lightning is simply not capable of streaming a "raw" HDMI signal across the cable. Lightning is a serial bus. There is no clever wire multiplexing involved. Contrary to the opinions presented in this thread, we didn't do this to screw the customer. We did this to specifically shift the complexity of the "adapter" bit into the adapter itself, leaving the host hardware free of any concerns in regards to what was hanging off the other end of the Lightning cable. [...]

Certain people are aware that the quality could be better and others are working on it. For the time being, the quality was deemed to be suitably acceptable. Given the dynamic nature of the system (and the fact that the firmware is stored in RAM rather then ROM), updates **will** be made available as a part of future iOS updates. When this will happen I can't say for anonymous reasons, but these concerns haven't gone unnoticed.

Top Rated Comments

(View all)
Avatar
100 months ago
Listen sonny!

Back in my day the only thing our cables had in them was Lead and Copper, and that is how we liked it!!!
Score: 57 Votes (Like | Disagree)
Avatar
100 months ago
256MB?!??!?!?!!
That's how much RAM my iMac G5 had.
Score: 51 Votes (Like | Disagree)
Avatar
100 months ago
Overkill for inferior performance.
Score: 49 Votes (Like | Disagree)
Avatar
100 months ago
Kind of sad that the 4th gen iPod Touch that they still sell for $199 and up only has as much RAM as an AV Adapter.
Score: 49 Votes (Like | Disagree)
Avatar
100 months ago

Yet more proof that lightning is a junky and expensive connector. 2013 and can't output 1080p?

This is the year of the Android.

Isn't this an apple fan site?!!! Why are you here instead enjoying the company of your brethren on an android site?
Score: 48 Votes (Like | Disagree)
Avatar
100 months ago
Yet more proof that lightning is a junky and expensive connector. 2013 and can't output 1080p?

This is the year of the Android.
Score: 41 Votes (Like | Disagree)

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