4 ms·

I think they're way off on the theory the cable is running iOS. I think what's most likely is the phone is putting out a h264 stream and the chip is just decod

I think they're way off on the theory the cable is running iOS. I think what's most likely is the phone is putting out a h264 stream and the chip is just decoding it. Rather than a whole ios stack & AirPlay protocol. Sure this shares some similarities with how AirPlay works (showing a h264 stream from the device ) but wouldn't require a whole system on a chip just for showing this feed.

jey 14y ago
Why not? AirPlay is a pretty high-level protocol, and it's got an ARM SoC, so the natural thing for Apple to do would be to use the ARM version of XNU with a minimal userland that has their AirPlay implementation and whatever codecs it needs. At least, If someone handed me one of these dongles with a copy of the protocol spec and asked me to write the software for it, I'd do something similar except using Linux. (Sidenote: buildroot is great for creating embedded systems running Linux.)
deleted 14y ago
[deleted]
acgourley 14y ago
Right, definitely just the video transport part of AirPlay. This is exactly how Miracast works too, except that's over a direct wifi connection between 2 devices.
userna 14y ago
Actually, they're dead on. (And no, I won't corroborate that further. But it does download a stub copy of iOS.)
- pifflesnort 14y ago
  This provides no useful information whatsoever. I wouldn't be hugely surprised if they wrote code to the ARM MCU (if it has 2GB of RAM to work with), but what does "stub copy of iOS" even mean? Also. Jimmy Hoffa is buried inside that microcontroller. I won't corroborate this further, but this is the dead-on truth.
  - mortenlarsen 14y ago
    2Gb = 2 GigaBit = 256MB RAM. It is common to measure individual RAM chips in bits, not bytes.
  - millerc 14y ago
    No need to be sarcastic. I find it interesting that somebody goes through the trouble of creating a new user account, just to confirm a theory that nobody could confirm without getting in trouble. It doesn't prove anything, but it certainly fits the context. I would say the theory (and the extra bit of information) merit being analyzed further. FWIW, a "stub copy of iOS" would mean in this context "a copy of iOS where every OS function is stubbed except what's necessary to run AirPlay."
    - micampe 14y ago
      > creating a new user account that gives me less confidence, not more.
      - jacquesm 14y ago
        Apple has fired people over less. /. has a long standing tradition of ACs breaking rank and posting insider stuff, I see no reason why the same couldn't happen on HN.
adamisen 14y ago
It makes a lot of sense to me now. The adapter is tied to iOS's supported video formats. If it will play on the device, it will play on the adapter. The downside being that mirrored content has to go through the not-awesome encoder (at least on the A5). Using the same optimized software stack and shared SoC logic probably eliminates a bunch of headaches and saves money. If it really works like that it's kind of brilliant. Future devices will have better mirroring output due to better hardware encoders (I haven't scrutinized the mirrored output from an A6, it may already be a lot better than the output pictured in the post). It ought to work with every Lightning device. The only question is future video format support, but since it's limited to 1080P it's probably future proof enough.

jey 14y ago

Why not? AirPlay is a pretty high-level protocol, and it's got an ARM SoC, so the natural thing for Apple to do would be to use the ARM version of XNU with a minimal userland that has their AirPlay implementation and whatever codecs it needs. At least, If someone handed me one of these dongles with a copy of the protocol spec and asked me to write the software for it, I'd do something similar except using Linux. (Sidenote: buildroot is great for creating embedded systems running Linux.)

deleted 14y ago

[deleted]

acgourley 14y ago

Right, definitely just the video transport part of AirPlay. This is exactly how Miracast works too, except that's over a direct wifi connection between 2 devices.

userna 14y ago

Actually, they're dead on. (And no, I won't corroborate that further. But it does download a stub copy of iOS.)

pifflesnort 14y ago
This provides no useful information whatsoever. I wouldn't be hugely surprised if they wrote code to the ARM MCU (if it has 2GB of RAM to work with), but what does "stub copy of iOS" even mean? Also. Jimmy Hoffa is buried inside that microcontroller. I won't corroborate this further, but this is the dead-on truth.
- mortenlarsen 14y ago
  2Gb = 2 GigaBit = 256MB RAM. It is common to measure individual RAM chips in bits, not bytes.
- millerc 14y ago
  No need to be sarcastic. I find it interesting that somebody goes through the trouble of creating a new user account, just to confirm a theory that nobody could confirm without getting in trouble. It doesn't prove anything, but it certainly fits the context. I would say the theory (and the extra bit of information) merit being analyzed further. FWIW, a "stub copy of iOS" would mean in this context "a copy of iOS where every OS function is stubbed except what's necessary to run AirPlay."
  - micampe 14y ago
    > creating a new user account that gives me less confidence, not more.
    - jacquesm 14y ago
      Apple has fired people over less. /. has a long standing tradition of ACs breaking rank and posting insider stuff, I see no reason why the same couldn't happen on HN.

adamisen 14y ago

It makes a lot of sense to me now. The adapter is tied to iOS's supported video formats. If it will play on the device, it will play on the adapter. The downside being that mirrored content has to go through the not-awesome encoder (at least on the A5). Using the same optimized software stack and shared SoC logic probably eliminates a bunch of headaches and saves money. If it really works like that it's kind of brilliant. Future devices will have better mirroring output due to better hardware encoders (I haven't scrutinized the mirrored output from an A6, it may already be a lot better than the output pictured in the post). It ought to work with every Lightning device. The only question is future video format support, but since it's limited to 1080P it's probably future proof enough.