I was reading through the recent archives, and the question of displays and upsampling caught my eye.
On list it was noted that upsampling is an expensive operation (and it certainly is), but I'm not sure it has to be.
As I recall, most LCDs when driven with a lower resolution than native, will simply repeat interspersed rows/columns as needed to fill the display. It looks dreadful, but it works.
Alternatively, is there any reason a display for type I couldn't be set to recognize a type II 1366x768 and display it in the centre of the display to avoid artifacts? Or should such a display have a button to switch modes so that it can display full screen with anything?
Tor
On Fri, Dec 23, 2016 at 12:00 AM, Tor, the Marqueteur Marqueteur@fineartmarquetry.com wrote:
I was reading through the recent archives, and the question of displays and upsampling caught my eye.
On list it was noted that upsampling is an expensive operation (and it certainly is), but I'm not sure it has to be.
turns out that there's line-buffer ICs rather than full framebuffer, which will be cheaper.
As I recall, most LCDs when driven with a lower resolution than native, will simply repeat interspersed rows/columns as needed to fill the display. It looks dreadful, but it works.
.. but they need to be scaled on an arbitrary basis on both row *and* column. so you need at least a line-buffer to store a couple of rows so that you can use samplerate conversion on y coordinates as well as x.
Alternatively, is there any reason a display for type I couldn't be set to recognize a type II 1366x768 and display it in the centre of the display to avoid artifacts?
bleuch :) it's not unreasonable but i think you'd find that users complain a lot!
Or should such a display have a button to switch modes so that it can display full screen with anything?
honestly i don't care: if people want to make Housings that do that, it's up to them: market forces will decide whether their product is successful or not.
l.
On 22/12/16 17:38, Luke Kenneth Casson Leighton wrote:
On Fri, Dec 23, 2016 at 12:00 AM, Tor, the Marqueteur Marqueteur@fineartmarquetry.com wrote:
On list it was noted that upsampling is an expensive operation (and it certainly is), but I'm not sure it has to be.
turns out that there's line-buffer ICs rather than full framebuffer, which will be cheaper.
As I recall, most LCDs when driven with a lower resolution than native, will simply repeat interspersed rows/columns...
.. but they need to be scaled on an arbitrary basis on both row *and* column. so you need at least a line-buffer to store a couple of rows so that you can use samplerate conversion on y coordinates as well as x.
In hindsight, colour me unsurprised on the cheaper line-buffer IC. AFAIK, every bargain basement LCD monitor and every laptop screen in the last two decades has had that capacity.
Alternatively, is there any reason a display for type I couldn't be set to recognize a type II 1366x768 and display it in the centre of the display to avoid artifacts?
bleuch :) it's not unreasonable but i think you'd find that users complain a lot!
Let them eat cake. :) More seriously, I can think of times when, while rare and less than ideal at best, I might prefer a clean small image to that kind of "upsampled" image.
Or should such a display have a button to switch modes so that it can display full screen with anything?
honestly i don't care: if people want to make Housings that do that, it's up to them: market forces will decide whether their product is successful or not.
Fine by me. From the PCB thickness measurements I recall reading, I suppose manufacturers will be trying to figure out how to make type II compliant cards capable of feeding 1920x1080 to housings with that capacity.
While I'm technical enough to handle some need to take care in selecting parts, I applaud your efforts to ensure that anything will work with anything in fits. Much the way a mini-LCD can be driven from an output suitable for a 4K HD display or a 4K HD display can be fed a DVD size stream, and get something useful, or at least intelligible.
I'm looking forward to my card from the first batch. Whether I can manage it remains to be seen, but I'd love to see a 10" e-paper screen tablet with enough USB to run arbitrary keyboards, etc and Emacs with a <1W average power consumption.
Tor
--- crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68
On Fri, Dec 23, 2016 at 6:41 AM, Tor, the Marqueteur Marqueteur@fineartmarquetry.com wrote:
Fine by me. From the PCB thickness measurements I recall reading, I suppose manufacturers will be trying to figure out how to make type II compliant cards capable of feeding 1920x1080 to housings with that capacity.
the only thing to watch out for, the high-frequency over PCMCIA connectors (90ohm impedance when RGB/TTL is supposed to be 33) is going to result in signal-bounce and EMI.
the "gold cover" of Cardbus is there to help reduce that, but i haven't been able to find a supplier of the Cardbus kits.
l.
arm-netbook@lists.phcomp.co.uk
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Luke Kenneth Casson Leighton -
Tor, the Marqueteur