Quote:
Originally Posted by inedible
On a fast wifi (or USB networking) connection, VNC is fast enough. I think the eink display is the bottleneck here. I think it takes something like 80ms to refresh the eink. VNC is faster than that.
As far as decoding HDMI, forget it. Doing it in software, in realtime, using generalized CPUs would take many many many gigahertz. You'd have to capture the stream, analyse it, decode it, etc. Even with the oldest and most primitive HDMI1.0 spec, you're looking at 165MHz of compressed datastream that has to be captured and processed.
They make specialized chips for that. FPGAs and the like that do this a thousand times more efficiently than a general-purpose CPU. You could buy one, figure out how to build a breakout board for it, try and attach it to some bus in the kindle, write drivers for it and compile a new kernel for the kindle, or you could simply take something that already has HDMI input, and run a VNC server on it.
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VNC option has its uses and offers some advantages.
When it comes to the eink screen speeds I believe your estimate is not far off from what is currently believe to be an inherent limit of the epaper tech at the moment.
There are also two examples that made me scratch my head though,
https://youtu.be/ldBbVd0kBGE
https://youtu.be/QXF_5zxGkp
The use epaper monitor is a recent enough example(new batch allegedly being shipped in March 2016). While I don't know the precise EPD controller(might be a batch of I.mx7 duo they somehow got hold of ahead of everyone else, the old I.mx6 sololight or something else entirely). The eink screen used in the product as published on their website has a resolution of 1600x1200 on a 13.3" screen and suggests to me that it's the same eink panel that Sony's digital paper DPT-s1 uses.
The other demo is Epson controller based circa 2013 at most and is a fine example that maybe eink screens can be a bit more responsive than what is currently being offered. Question stays open on whether the I.mx6sl as used in all current ereaders is underpowered and exactly how much latency of the screen can be attributed to that.
Here is something that the VNC option can't take advantage of on all ereaders hardware - the present and fairly old I.mx6 provides a mipi dsi and mipi CSI plus a few other interfaces....In other words going the extra mile by doing custom hardware addition on an existing ereader should allow for an extra hdmi out, hdmi in and camera input...
I.mx7 which has a new EPD controller built in too is a good candidate to go the extra mile...
I mean some people on this forum have long gone beyond simple software tinkering...rooting the kindle after all requires soldering wires, Jims usb dongle ...