iPad Pro Lightning Digital AV Adapter resolution?

Discussion in 'iPad' started by dennya, Mar 10, 2016.

  1. dennya macrumors regular

    dennya

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    #1
    Saw a bunch of complaints about the Lightning HDMI adapter running in a fairly low resolution on iPads when it was first introduced. (1080x900 or 1600x900).

    Anyone know if it does true 1080p with the iPad Pro? Or does it have the same issues?
     
  2. Gav2k macrumors G3

    Gav2k

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    Jul 24, 2009
  3. dennya thread starter macrumors regular

    dennya

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    Seattle-ish
  4. LiveM macrumors 6502a

    LiveM

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    Oct 30, 2015
    #4
    It might be 1080p but the adaptor transcodes and degrades the image quality so that is probably what the complaints are about. It is not like other signal adaptors. The image will be soft.
     
  5. TrueBlou macrumors demi-god

    TrueBlou

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    #5
    Strictly speaking it's up to 1080p, there may, and will be, be some things which output at a lower resolution.
    And as mentioned there is a degree of compression when using it, though I've never found it to be too bad. I certainly wouldn't use it as the source for a high quality cinema setup, but that's not really its target market. For impromptu movie watching away from home it's a handy thing.
     
  6. nbourbaki macrumors member

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    #6
    I was under the impression that the adapter only downgraded the stream if the IOS device was in mirror mode.
     
  7. temna macrumors 6502a

    temna

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    May 5, 2008
    #7
    Wasn't there talk about it decoding a signal from the iPad to Apple TV 3 level quality?
     
  8. TrueBlou, Mar 11, 2016
    Last edited: Mar 11, 2016

    TrueBlou macrumors demi-god

    TrueBlou

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    #8
    Here's a quote from an "anonymous Apple engineer" regarding the Lightning Digital AV Adapter. He's responding to an article from the guys at Panic who found that in some cases the adapter was only outputting a 900p image.

    I'm just dropping it in to shed a little more light on the Lightning AV system and, if true, the potential for future improvements to the quality it outputs.

    Oh, and just in case anyone wasn't aware, the Lightning Adapter has both a processor and memory. Essentially a very low powered iOS device. That's why he mentions offloading work to the adapter.


    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. If you wanted to produce a Lightning adapter that offered something like a GPIB port (don’t laugh, I know some guys doing exactly this) on the other end, then the only support you need to implement on the iDevice is in software- not hardware. The GPIB adapter contains all the relevant Lightning -> GPIB circuitry.

    It’s vastly the same thing with the HDMI adapter. Lightning doesn’t have anything to do with HDMI at all. Again, it’s just a high speed serial interface. Airplay uses a bunch of hardware h264 encoding technology that we’ve already got access to, so what happens here is that we use the same hardware to encode an output stream on the fly and fire it down the Lightning cable straight into the ARM SoC the guys at Panic discovered. Airplay itself (the network protocol) is NOT involved in this process. The encoded data is transferred as packetized data across the Lightning bus, where it is decoded by the ARM SoC and pushed out over HDMI.

    This system essentially allows us to output to any device on the planet, irregardless of the endpoint bus (HDMI, DisplayPort, and any future inventions) by simply producing the relevant adapter that plugs into the Lightning port. Since the iOS device doesn’t care about the hardware hanging off the other end, you don’t need a new iPad or iPhone when a new A/V connector hits the market.

    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.
     
  9. nbourbaki macrumors member

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    #9
    Yes, I followed that thread for more than a year. I was hopeful at first when newer versions of IOS were released the original author would update the test results, but that didn't happen.
     
  10. TrueBlou macrumors demi-god

    TrueBlou

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    #10
    Yeah it's fallen by the wayside, but still, I find it interesting to know a bit more about how these things work. And I'll hold hope that Apple does indeed improve the system, you just never know with them.
     
  11. lixe macrumors member

    Joined:
    Jan 26, 2010
    #11
    Since they are also talking about AirPlay and encoding, I have a question about that. If I mirror my iPad screen using AirPlay, decoding is of course necessary. But if I play a video in the YouTube app and then simply activate AirPlay, does the iPad encode the video signal? I would guess, it just transfers the whole stream to the Apple TV? Same for playing an iTunes movie on the iPad and activating AirPlay then. I guess the iPad just transfer the video file to the Apple TV, which then does all the decoding? But maybe I'm all wrong?
     

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