HDMI in and out

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Rickles

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#224312 12-Nov-2017 15:51

Met an interesting scenario today -

Friend has a satellite box sitting beside all-in-one desktop, and cabled HDMI to it ... great, can now view TV/Freeview channels on PC screen.

The same PC has an HDMI out, which when cabled to another TV shows everything on the PC screen, and used for OnDemand etc etc.

However, the HDMI out seems to only transmit whatever is onscreen that is generated by the computer itself, NOT, for example, anything that is onscreen from the HDMI input (STB).

Seemed a little odd, but maybe there is a good explanation?

Apsattv

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#1899684 12-Nov-2017 17:38

The monitor has a Source button? and he's simply is selecting the Freeview box as the input?

e.g

Freeview STB on HDMI2

and the PC output display from PC video card goes direct to the TV display?

seems straight forward enough?

If you want to go Freeview STB to PC then out again to another tv you would need an HDMI capture card for the pc...or an HDMI splitter, to feed both the TV and the monitor as a source at the same time.

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richms

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#1899690 12-Nov-2017 18:05

I have never seen one that will pass it thru. It is just a second input for the monitor on it, not a HDMI capture device. The HDCP issues that a legit manufacturer would have to jump thru to allow for that would be crazy bad.

Richard rich.ms

siyuan

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#1899705 12-Nov-2017 18:39

This is just my guess, your desktop is probably prohibited from transmitting the HDMI input to its output due to the type of HDMI compliance it was certified for.

I recently worked on a consumer electronic product that also does HDMI in and out, we have just been told by the HDMI compliance lab that in order to pass the compliance test, the product must pass the HDMI repeater test. The requirement comes from the fact that we have HDMI in that goes out of HDMI out. There are two problems for us, in order to qualify as an HDMI repeater, the product must:

Support audio
Correctly handle HDCP, i.e. any digitally protected content must still be protected on its output

Both of these two requirements would be technical complication for the product, I guess this is likely why your desktop blocks the HDMI input from going to the output as it likely has only been certified as an HDMI sink (input) and HDMI source (output), but not a repeater. This is exactly the approach we are going to take with our product as well since implementing the repeater functionality would significantly delay the launch of our product, not to mention the higher cost involved.

Rickles

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#1899711 12-Nov-2017 18:41

All comments make sense

JimmyH

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#1899764 12-Nov-2017 20:48

Some of the cheap splitters that you can get on Aliexpress for around $20 reportedly remove the copy protection on HDMI signals.

Otherwise, get an HDMI Matrix splitter. The 4x2 units aren't that expensive. Inputs from the set top box and the PC. Outputs to the TV. That will let you pipe the STB to the PC, and also view whichever of the PC or STB output that you want on the TV.

richms

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#1899765 12-Nov-2017 20:49

They sure do remove it ;) there are also HDCP 2.2 to 1.4 converters available as well for if you have something that sulks unless it sees 2.2 support. Only pass 4k 30 tho so no use for gaming thru.

Richard rich.ms