[HDMI plug tests] Access even HDMI screen is OFF (Xvnc APKG for ex.)

[father.mande]

HI,

This is a short information about tests I have done to access my ASUSTOR Applications (Asportal, Desktop_Engine, etc.) using HDMI screen when the screen is disconnected
ATTENTION not sure this also work for you ... depend of context, hardware and link ... so just to share with you
feel free to share also your own experience ...

Test platforms :
AS5002T (1080P)
TV Samsung D5700
Monitor (with sound) BENQ senseye3

Problem :
When HDMI screen is disconnected ... and you use a remote connection to access Asportal (ex. using XVncServer Community APKG) or the Ubuntu Desktop from "Desktop Engine" (XVncServer APKG or any Vnc server inside the Ubuntu chroot) YOU MUST have problem due to the fact that HDMI can appear as disconnected or with invalid resolution to use Vnc Client

Solutions :
A) It's always possible to play with xrandr to manage a false frame buffer size or generate false mode and virtual screen
... BUT first it's not easy ... two in lot of case this can be break by any program reallocating xrandr AND if your program need to have sound configured (even you can't hear the sound (except specific pulseaudio usage) from remote ... BUT it's not the purpose ... of this topic) sometimes program refuse to start ...
B) a good solution is a HDMI Plug that reply to EDID request from Xserver and deliver valid information ... and support (even fake) the DCC/CI interface
EDID VESA provide (shortly) :
... name of the screen provide ... product name ... video format supported (1080P, 1080I, etc. ) ... audio format supported ... color depth ... etc.
DCC/CI
... is a set of command use by Xserver (ex. brightness, contrast, etc. )

B 1 )
PASSIVE HDMI PLUG :
This plug are "plugged" directly to the back of the Asustor and REPLACE the HDMI cable
tested models :
Compute-lab FIT Headless (support full HD or (another model 4K) definition) : work as expected ... EDID returned is correct screen appear to be "connected" sound supported
... application using xrandr (like kodi) can be launched remotely, idem for Chrome and other tools fillezilla, etc.
FOR this solution :
... FullHD work as well
CONS. :
... need to disconnect HDMI cable ... so if another person want to use it ... localy ... need a manipulation (clearly a problem if the NAS is in a cabinet for ex.)

B 2 )
ACTIVE PASS-THROUGH PLUG :
This plug are installed at the back of the NAS and have a female plug to put the ordinary cable ... so the real TV or screen keep connected ..
some plug propose a standard VESA response ... some other can be "programmed" to clone the screen definition ...
tested model :
HDMI Lindy 32103 emulator adapter with standard definition for FullHD (even last model support 4K after programmation)
CASE 1 : without clonage ...
... Work as a PASSIVE plug + you have a correct image ... BUT NO SOUND
... ... NO sound and NO error ... the plug said that sound exist but without valid value ... so this generate NO ERROR ... BUT NO sound
... ... so it's not the target expected ... keeping the local access without having to do somethings locally ...
CASE 2 after clonage ... to clone I have use the Lindy 32100 Emulator programmer (hum! a cost for a unique use (not for me but for standard user) )
... after cloning my TV screen value ( in fact all is done in less of 2 minutes)
... ALL WORK as expected ... SOUND, Asustor see the plug exactly as the TV ... same sound definition and screen resolution are available ... and keep it even screen is OFF
... ... AND the TV can be use as well
... ... BIGGEST advantage ... the cable after the plug can be long, can be use Ethernet extender or what else when in real case it don't work (Asustor don't receive correct EDID) ... so it's really an amazing solution ...
... ... programmer support also 4K ...
... ... also interesting to be used with AUDIO player interfaced by HDMI ... to get the best visibility of the twice (Sound from player + TV definition)
FOR this solution :
CLEARLY ONLY if you use the programmer ... it's the full good result ...
... add possibility to have long space between the Asustor and the screen, accept any kind of extender ...
IN native mode ... it's like the passive model ...
CONS. :
... need to buy the programmer (if nobody can lend you ... one for 5 minutes)

Please don't hesitate to add here your OWN experience.

Philippe.

[MikeG.6.5]

What you are trying to do here is something like TeamViewer? Remotely logging in to the NAS and using a second computer to take over the NAS's HDMI, mouse and keyboard? Couldn't you do this with off the shelf products like TeamViewer already?

I would think it would be much easier, as they already have the interconnections set up. I've just been unable to get a working copy of TeamViewer installed at this point.

[father.mande]

Hi,

What you are trying to do here is something like TeamViewer? Remotely logging in to the NAS and using a second computer to take over the NAS's HDMI, mouse and keyboard? Couldn't you do this with off the shelf products like TeamViewer already?

I would think it would be much easier, as they already have the interconnections set up. I've just been unable to get a working copy of TeamViewer installed at this point.

Teamviewer use a similar (in fact same at original step) possibility that Vncserver / Vncclient do ...
... the major difference is to use a server in their company ... so the usage is :
teamviewer server -> connect (output so no NAT, etc.) to Teamviewer company server
... then company server send back a SessionID
teamviewer client -> connect (output so no NAT, etc.) to Teamviewer company server
... use the SessionID to use the Teamviewer server as a ROUTER / GATEWAY (applicatif)

THIS imply you trust teamviewer ... because all your screen refresh, image, key in, etc. are ALWAYS intercepted and know by teamviewer ...

You can do the same with lot of VNC software ... in fact
all vnc server can listen or connect to a viewer (or intermediate server)
all client can listen or send a connect to viewer or intermediate server OR also vcnserver proxy

In this case the purpose of the plug (but more generally) is
in NAS you have a x11vnc server waiting for connection (APKG Xvncserver)
At any place in the world a VNC client to connect to the server and get screen image + keyboard and mouse control
To secure and don't have to open another port in the router/box serving the VNC server ... it's easy (very) to use a SSH tunnel
... .... so all at client place ... is encrypted, security is done by SSH (password or certificate) and ssh redirect the request to the remote server (local port to some remote host + remote port)

So this solution is similar to teamviewer solution (but without to trust anybody ... except yourself)

PLUG ? ... plug is only to solve the problem that if NAS is up, Asportal or other graphic is Up BUT TV or real HDMI screen is OFF ... you can't have the screen access

VNC solution offer also other interesting possibility for confirmed or expert ...
... use an external server as gateway ... like teamviewer do (interesting to bypass any firewall ... all is output only)
... add java interface (if browser support it) ... so you can use any web browser
... use a proxy (for ex. in a server or in a router ... I use them in my Linux DD-WRT router) so only the proxy is visible from Internet ... and it route the request automatically to the real target ...
... share the screen by multiple users (ex. for student course)
... permit to use specific access for view only
etc. etc.

SO YES the purpose is to be able to use any application (BUT no sound and no video acceleration) from any point in the world ...
This is interesting for :
hx-engine (full desktop)
for integrating new APKG when you are not near your NAS (like me frequently)
etc.

Philippe.
NB I can have a look to teamviewer ... BUT if a Linux free solution exist for server side ... no reason to don't be able to use them IMMEDIATELY inside hx-engine (desktop_Engine)