kvncviewer - a VNC viewer (not only) for Kobos

[hawhill]

I used some spare time to hack a bit on the VNC viewer I published here before, KindleVNCviewer (https://www.mobileread.com/forums/sho...d.php?t=150434). I reused framebuffer code from Koreader and now it also works on Kobos. Thus, I decided a slight rename: It is now known as "kvncviewer" :-)

Source code is available on github in the place where the old codebase could be found: http://github.com/hwhw/kindlevncviewer (name change not reflected here since I like my URIs to be stable)

The new code brings some new options. It is written in Lua, and that I took a bit further than with the old codebase, which used Lua for configuration, too. The new code is implemented using LuaJIT. It re-uses the framebuffer code from Koreader and is quite versatile. It allows for rotation options, b&w dithering on all devices, configurable refresh timeouts (though this won't make your screen faster than the hardware can do, but you might want to fiddle with the options and report your experiences here) and some more things I forgot about.

Attached is the compiled version for Kobos.

It comes without a way to start it. That's for a reason, though: you probably want to use it via USB networking anyway. In that case, the shell access provided by USB networking is arguably the best way to start the viewer, too. If noone beats me to it (feel invited!), I'll try to make up a script for the default Kobo USB networking setup.

[Markismus]

First link is dead.

Can I remote control my kobo or my desktop with this? `Share desktop' seems to suggest using the kobo as remote for the pc...

[hawhill]

Thanks, link is fixed. Looking it up might answer some questions.

This software allows to use the Kobo like a eink Monitor for another computer, like a desktop PC. Started as a fun project, but is actually used by some people for e.g. making a nice low-energy screen for embedded projects (though arguably the Kobos CPU is faster than that of a Raspberry Pi - it's a strange combination). Eye-impaired people having problems with LCDs use that too, I've been told. Its productive use came as a surprise to me, too, but I can see the use cases now.

As for a full remote - well, it has no input handling for touchscreens yet. The needed bits and pieces are mainly there, but the layer that actually generates RFB (the VNC protocol) messages from input events is missing. That function only handles buttons as for now - which are present on Kindle 2/3 devices only. It could also handle touchscreen input events if me or rather someone else actually bothered enough to write the few lines of code it would take.

[kenoi]

This should also be great for taking your laptop outdoors, and actually seeing something in the sun -- since eInk screens are like paper in sunlight, while LCDs disappear.

I'm surprised no-one has come up with an eInk based laptop yet. In the meantime this VNC based solution is a great substitute.

So, steps to get it working (from my understanding so far):

1. Enable USB connection for Kobo via hack.
2. Copy kvncviewer files over to Kobo.
3. Run the VNC server from laptop/computer.
4. Run kvncviewer through the command provided in the README in remote shell via USB connection.

Am I getting this right?

[hawhill]

Yep :-)

[kenoi]

Okay, I'm still in need of detailed instructions... Where can I find a step by step on how to enable a USB shell connection with the Kobo?

EDIT: I think I found it: https://wiki.mobileread.com/wiki/Kobo_Touch_Hacking

Does this work for Kobo Glo, too?

[The1andONLYdave]

Long time ago since i used a shell on my kobo

do i miss something obviously?
copied the files from .zip to kobo, telnet to it and tried to run ./luajit, but it wont work. it's chmod +x already.
doesn't matter if i use relative or absolute paths.
same error every time:

sh: ./luajit: not found

any suggestions?

//edit: my kobo is a kobo touch with 2.5.2... will try to update

//edit2: after updating to 3.0.1 it works without problems (for all other having same problems)

[exachillus]

@hawhill

Would it be possible to capture only certain window on the server that has a certain name? That way only a single window will be sent to the reader client which can be immense help in certain situations, or even when reading manuals, help files, wikipedia pages etc only. Some clients let you do that.

[hawhill]

I've never seen VNC clients doing that. There might well be _servers_ doing that, i.e. offering only the screen part that is used by a certain application. And RDP can do it, too. But not VNC, I think. The protocol hasn't really a notion of "windows". So unfortunately this won't fly, I guess.

But good to have this thread back in my attention focus - I need to flesh out the racing condition that brings the application to a stall or makes it break sometimes.

[exachillus]

Originally Posted by hawhill

I've never seen VNC clients doing that. There might well be _servers_ doing that, i.e. offering only the screen part that is used by a certain application. And RDP can do it, too. But not VNC, I think. The protocol hasn't really a notion of "windows". So unfortunately this won't fly, I guess.

But good to have this thread back in my attention focus - I need to flesh out the racing condition that brings the application to a stall or makes it break sometimes.

Hi

If I remember correctly Ultra vnc was able to do that. Basically when the client logins, the user clicks on a particular window. Then the client focuses on that window and make it screensize and does not update the rest or put some background over them. I might be wrong. I used it long time ago.

I was just referrring a wanna be useful feature. In anycase this app is a great addition to ereader tools.

[mostafa.dkhissi]

Hi,
Thank you for this awesome work!

I've tried it with usb tethering and it works! But I've a problem: graphic is bad, ugly.
I've tried bVnc in kobo glo(android v2) and graphic is far better, but slower (since using just wifi not usb tethering).

what to do ?

[hawhill]

Screenshots! :-) What does "far better" mean? There is not *that* much room for improvement. Two things come to my mind: RGB to grayscale formula, and on the other hand, dithering for 16-grayscale mode, too. The latter would certainly produce nice looking graphics, but might also bleed out text and certain combinations of hard contrast.

[mostafa.dkhissi]

Hi,

dither improve image but small text is unclear, terminal text is better but not like bVnc. I use krfb in Ubuntu, when I use x11server with kvncviewer it show very ugly image compared with krfb. what to do please?

[hawhill]

Re-read my post: *Screenshots* ! I don't have the slightest idea what you mean by "very ugly" and how bVnc does it. Show us, if you want help.

There is *no* 16-grayscale dithering in the viewer yet. There is 1-bit dithering, and *of course* it creates a much more ugly image for everything except high (grayscale) contrasts. It is and will always be a trade-off. It's e-ink after all, and that will only be so fast.

[nomeata]

I basically bought my Aura HD for this particular application, so thanks a lot for the tool.

I found the --rotateFB 90 option, which is useful.

The dithering plays bad with antialiasing, I need to find a way to disable anti-aliasing on my Desktop. And probably configure lots of things to be less colorful :-)

Is there maybe a VNC server or setting that can already provide a suitable format (i.e. greyscale) to the client? Might save resources on the device, and possibly allow for better algorithms