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Someone is very confused as to what "AirPlay" is. This doesn't make any sense. AirPlay is a network protocol tied to mDNS/Bonjour. There's no way the Lightning

Someone is very confused as to what "AirPlay" is. This doesn't make any sense. AirPlay is a network protocol tied to mDNS/Bonjour. There's no way the Lightning controller is supporting an entire network stack plus video transcription. Calling this only half-thought-out seems generous. I thought it was well known that these were smart cables. Thunderbolt is the same way. At best the SoC is some sort of smarter adapter.

tptacek 14y ago
You think Cabel Sasser doesn't know what Airplay is?
- drivebyacct2 14y ago
  I honestly don't know. Someone is somehow implying that the adapter is implementing a full stack capable of being an AirPlay receiver and transcoding video on the fly. I think Cabel is wrong or has explained what they think is occuring incorrectly. /shrug
  - tptacek 14y ago
    Sorry, I don't mean to sound like I'm attacking. Was seriously asking.
    - drivebyacct2 14y ago
      No, I understand. "Someone is confused about AirPlay" was more accusatory than I meant. I genuinely don't know if Cabel knows much about AirPlay, I only know what I know from working with it and uPnP/DLNA for the last some months, and it made this seem unlikely to me. He may well know more than I and I learn something new and useful. :) Based on the anonymous comment in this thread and this tweet, I'm potentially happy to eat my words. https://twitter.com/jmreid/status/306987650001301505 https://twitter.com/jmreid/status/306987650001301505
  - cabel 14y ago
    In this case, AirPlay is our easier-to-understand way of saying "the results you're getting are exactly the same as when you stream iOS video using AirPlay". (Which is really weird for a video-out dongle! Especially since the former, non-Lightning one did proper video out.) I've tweaked the post to make it clearer that AirPlay isn't _necessarily_ the _exact_ mechanism being used! It could just be H.264 or MPEG or whatever. Mostly I'd love to know exactly what this chip/system does, so if anyone here with far more advanced hardware knowledge than any of us have feels up to hacking around, that'd be amazing! :) The key takeaways from the post are: 1. It's feels unusual that a AV adapter would have a full SoC ARM-based CPU with RAM etc, not just a video encoder/decoder chip. Is it unusual? Let me know. :) 2. It's a bummer that the Video Out isn't very good, and not true 1080p, and has MPEG artifacts. (Thanks for sharing the link.)
    - drivebyacct2 14y ago
      Yeah, someone mentioned something similar elsewhere in the thread and it certainly makes sense to me. It fits in with the comparison to Miracast, the need for hardware support for full screen mirroring over AirPlay. I can see the adapter processing a stream in a similar format or some such as AirPlay (without being a classic "AirPlay receiver" which is what I was hung up on) For your two points: 1. I think that comes with the territory of being a Lightnin accessory and makes sense if they're doing some sort of compression or something before hand. It certainly fits with Apple's persona. Control the content, don't let any-old-body create a video adapter. They have to deal with Apple's handshake/stream/whatever because Apple doesn't pin-out the HDMI for the Lightning connector... 2. That is a major bummer and seems like one of those "details" that Apple would get right. I'm certainly curious the more I think about it as well.
    - mbell 14y ago
      > Mostly I'd love to know exactly what this chip/system does, so if anyone here with far more advanced hardware knowledge than any of us have feels up to hacking around, that'd be amazing! :) Its converting an encoded steam to HDMI output. There aren't enough pins on a lightning connector to directly output HDMI and even if it could, you still need a transceiver somewhere (not particularly trivial in terms of space or power to stuff in the phone). The SoC is most likely a little ARM core to manage stuff (Cortex-M0/3) with a video decoder and HDMI transceiver, the 256MB of ram is there primarily for the decoder to use. It also needs to mux the audio stream into the HDMI encoding. As for 'it runs iOS', your really splitting hairs, its pretty normal for the master devise to load a slave device with its firmware when plugged in (rather than storing the firmware in flash on the slave). The fact that they would use some knocked down version of iOS isn't terribly surprising. Embedded versions of more powerful OSs are used all the time; There is a non-zero chance your stove and microwave are 'running linux'.

tptacek 14y ago

You think Cabel Sasser doesn't know what Airplay is?

drivebyacct2 14y ago
I honestly don't know. Someone is somehow implying that the adapter is implementing a full stack capable of being an AirPlay receiver and transcoding video on the fly. I think Cabel is wrong or has explained what they think is occuring incorrectly. /shrug
- tptacek 14y ago
  Sorry, I don't mean to sound like I'm attacking. Was seriously asking.
  - drivebyacct2 14y ago
    No, I understand. "Someone is confused about AirPlay" was more accusatory than I meant. I genuinely don't know if Cabel knows much about AirPlay, I only know what I know from working with it and uPnP/DLNA for the last some months, and it made this seem unlikely to me. He may well know more than I and I learn something new and useful. :) Based on the anonymous comment in this thread and this tweet, I'm potentially happy to eat my words. https://twitter.com/jmreid/status/306987650001301505 https://twitter.com/jmreid/status/306987650001301505
- cabel 14y ago
  In this case, AirPlay is our easier-to-understand way of saying "the results you're getting are exactly the same as when you stream iOS video using AirPlay". (Which is really weird for a video-out dongle! Especially since the former, non-Lightning one did proper video out.) I've tweaked the post to make it clearer that AirPlay isn't _necessarily_ the _exact_ mechanism being used! It could just be H.264 or MPEG or whatever. Mostly I'd love to know exactly what this chip/system does, so if anyone here with far more advanced hardware knowledge than any of us have feels up to hacking around, that'd be amazing! :) The key takeaways from the post are: 1. It's feels unusual that a AV adapter would have a full SoC ARM-based CPU with RAM etc, not just a video encoder/decoder chip. Is it unusual? Let me know. :) 2. It's a bummer that the Video Out isn't very good, and not true 1080p, and has MPEG artifacts. (Thanks for sharing the link.)
  - drivebyacct2 14y ago
    Yeah, someone mentioned something similar elsewhere in the thread and it certainly makes sense to me. It fits in with the comparison to Miracast, the need for hardware support for full screen mirroring over AirPlay. I can see the adapter processing a stream in a similar format or some such as AirPlay (without being a classic "AirPlay receiver" which is what I was hung up on) For your two points: 1. I think that comes with the territory of being a Lightnin accessory and makes sense if they're doing some sort of compression or something before hand. It certainly fits with Apple's persona. Control the content, don't let any-old-body create a video adapter. They have to deal with Apple's handshake/stream/whatever because Apple doesn't pin-out the HDMI for the Lightning connector... 2. That is a major bummer and seems like one of those "details" that Apple would get right. I'm certainly curious the more I think about it as well.
  - mbell 14y ago
    > Mostly I'd love to know exactly what this chip/system does, so if anyone here with far more advanced hardware knowledge than any of us have feels up to hacking around, that'd be amazing! :) Its converting an encoded steam to HDMI output. There aren't enough pins on a lightning connector to directly output HDMI and even if it could, you still need a transceiver somewhere (not particularly trivial in terms of space or power to stuff in the phone). The SoC is most likely a little ARM core to manage stuff (Cortex-M0/3) with a video decoder and HDMI transceiver, the 256MB of ram is there primarily for the decoder to use. It also needs to mux the audio stream into the HDMI encoding. As for 'it runs iOS', your really splitting hairs, its pretty normal for the master devise to load a slave device with its firmware when plugged in (rather than storing the firmware in flash on the slave). The fact that they would use some knocked down version of iOS isn't terribly surprising. Embedded versions of more powerful OSs are used all the time; There is a non-zero chance your stove and microwave are 'running linux'.