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One caveat of these dummy plugs is that they don't do HDCP. They handle the typical use case of forcing a specific resolution output for headless machines rathe
by avidiax 1y ago
One caveat of these dummy plugs is that they don't do HDCP. They handle the typical use case of forcing a specific resolution output for headless machines rather well, but fail for the use case that you need to run something that expects HDCP.
This seems a good place to ask: does anyone know of a good solution like this HDMI dummy plug, but that negotiates HDCP? I need to test video streaming apps that require HDCP to play at full resolution, but it is inconvenient to have a full TV for every test.
The one solution I've found is an HDMI multiviewer, which seems to negotiate HDCP to each port individually.
- mschuster91 1y agoTry one of these HDMI splitters that are more or less openly advertised as "HDCP strippers" on Amazon.
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- crazysim 1y agoI think multiviewer might have been a synonym for that. I wonder if the chips on these dummy plugs are powerful enough to hack in HDCP support though.
- aappleby 1y agoThe dummy plugs are literally just a 256-byte eeprom hooked to the I2C lines, there's nothing else inside the shell.
- dcan 1y agoTerminating HDCP is difficult, you’d have to downgrade it to HDCP 1.4 and then have a 1.4 ‘compliant’ (see: device on the end for it to be a dummy monitor. If you need anything newer than HDCP 1.4, it’s likely not possible.
- tverbeure 1y agoI did a tear down of this Monoprice dongle: https://tomverbeure.github.io/2023/11/26/Monoprice-Blackbird-4K-Pro-HDCP-Converter.html https://tomverbeure.github.io/2023/11/26/Monoprice-Blackbird.... It terminates as an HDCP 2.0 endpoint and converts to HDCP 1.4. You’d still need an HDCP 1.4 sink to make it work though.
- avidiax 1y agoI'm using the Monoprice multiviewer. It negotiates HDCP without a display attached. Other than being a bit big and expensive, and being unable to strip HDCP, it's a good solution. I found the same device in generic packaging on AliExpress, but haven't had the chance to order that version, yet. There are lots of professional SDI converters and such, but they are either $3k+ or "call for price".
- kevin_b_er 1y agoThat was written by you? I don't agree with this section: > The HDCP converter simply announces itself as a final video endpoint… yet still repeats the content to its output port. Without a very expensive HDMI protocol analyzer, we can’t check if the source is tagging the content as type 0 or type 1, but there is no reason now to think that it’s not type 1. There's no magic in the HDMI protocol that says type 1 vs type 0. Its just another HDCP message over DDC, but it is only sent to repeaters. In this case, since the HDCP Repeater is lying about not being a repeater, it isn't getting sent the StreamID Type information.
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- tverbeure 1y agoYou’re probably right.
- Sporktacular 1y ago
- ndiddy 1y agoI use this HDMI splitter. It lets you either set a preprogrammed EDID, or learns an EDID from whatever you plug into HDMI output 1, and then shows up as a connected monitor for as long as the splitter's plugged in without having to connect anything to the outputs. I believe it negotiaties HDCP between the computer/console/whatever and the splitter, then sends the signal to the output monitor without HDCP. https://www.amazon.com/dp/B07VP37KMB https://www.amazon.com/dp/B07VP37KMB
- amelius 1y agoI have a different usecase. I have an embedded system that sends out HDMI. However, its boot screen is something I want to replace by another HDMI stream (a static image would suffice). I specifically don't want to change anything on the embedded system for a thousand reasons I won't go into. How do I cheaply and robustly do this?
- atoav 1y agoProbably not the most elegant solution, but there are many HDMI switchers out there that can be talked to using gpio and/or RS-232. You could use one of those and a Raspi, feed the image in from the Raspi, detect the power of your embedded device via GPIO and then switch over to the other HDMI input. Whether that is a feasible solution mostly depends on other requirements, e.g. regarding power consumption or space. I used a similar solution once in an AV context and it has been running reliably for years now. If you want something less hacky Blackmagic has the Atem Mini, a good HDMI switcher that can also store multiple stills and can be switched via ethernet (among other things)
- indrora 1y agohttps://www.ti.com/product/TMDS261B https://www.ti.com/product/TMDS261B This and an RP2040 to generate the second signal would probably work just fine; see https://learn.adafruit.com/picodvi-arduino-library-video-out-for-rp2040-boards/overview https://learn.adafruit.com/picodvi-arduino-library-video-out... for an example of how to stretch the rp2040 to do HDMI
- hedora 1y agoAliexpress sells things that claim to terminate hdcp and forward hdmi. Caveat emptor.
- kachapopopow 1y agoI find it crazy that the signal between our monitors and desktop computers is encrypted when these exist.
- wkat4242 1y agoYes though for monitors displayport is better anyway and it doesn't do hdcp.
- wolrah 1y agoDisplayPort has supported HDCP (as well as its own DRM scheme DPCP) since version 1.1. I agree that DisplayPort was better for monitors, but HDMI has basically become DisplayPort so these days they're more or less two sides of the same coin. Both use data packets over fixed rate links now.
- AshamedCaptain 1y agoYou may be thinking of HDMI vs DisplayPort over USB-C, because otherwise they couldn't be more different. In any case, HDMI is still heavily patent and royalty encumbered, to the point it is going to be difficult for opensource GPU drivers to support native HDMI 2.1 or higher going on, while DisplayPort is still royalty free. The situation is so bad Intel has pretty much skipped native HDMI ports in recent chipset graphics to focus on DP only (motherboards can still install off the shelf DP->HDMI converters), while on AMD the newer HDMI features won't be supported at all on Linux.
- kachapopopow 1y agoyep, I'm running an hdmi to dp converter to make linux work.