HDMI 1.2a was introduced in Dec. 2005 with either HDCP version 1.2 or 1.3, so you are using technology that's over 15 years old. Incompatibilities with older technology and newer technology is bound to happen. HDMI protocols are built into the HDMI chipsets so you can't just flash them or rewrite the protocols to make them more compatible.
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Complex HDMI problem between old source and modern displays
Hello,
I have a pretty difficult problem to debug/solve (at least for my limited knowledge of the HDMI protocol). I'm going to explain what the problem is providing as more details as possible, and all the attempts I've done.
I own a Chroma Video Pattern Generator (VPG), model 23291. This is quite an old model, but it provides several features I like especially for calibrating old CRTs with RGBs input and so on. Also, I paid almost nothing for it. This VPG is also programmable, meaning I can program it to generate the type of video signal and pattern I prefer.
For my problem, let's limit the outputs of this VPG only to the HDMI and DVI ports. Note that, there are several standard signals memorized and ready to use such as 720p, 1080i(50/60), 1080p(50/60) etc. This VPG supports up to HDMI 1.2a (according to specs).\
PROBLEM: The problem is that the HDMI port does not work with many monitors/displays, no matter what is the signal outputted.
Let me give you some facts that I believe are important to understand such problem, which I think is 100% related to the VPG device somehow.
My feeling is (considering facts 1 and 2) that there is some problem in the HDMI protocol that I'm missing. Unfortunately, I don't know if there is a cheap way to debug/monitor the HDMI protocol or maybe rebuild it (??) to make it compatible for new TVs.
If someone can suggest any experiment/solution to solve this problem, I'll be happy to perform it.
Thanks a lot.
I have a pretty difficult problem to debug/solve (at least for my limited knowledge of the HDMI protocol). I'm going to explain what the problem is providing as more details as possible, and all the attempts I've done.
I own a Chroma Video Pattern Generator (VPG), model 23291. This is quite an old model, but it provides several features I like especially for calibrating old CRTs with RGBs input and so on. Also, I paid almost nothing for it. This VPG is also programmable, meaning I can program it to generate the type of video signal and pattern I prefer.
For my problem, let's limit the outputs of this VPG only to the HDMI and DVI ports. Note that, there are several standard signals memorized and ready to use such as 720p, 1080i(50/60), 1080p(50/60) etc. This VPG supports up to HDMI 1.2a (according to specs).\
PROBLEM: The problem is that the HDMI port does not work with many monitors/displays, no matter what is the signal outputted.
Let me give you some facts that I believe are important to understand such problem, which I think is 100% related to the VPG device somehow.
- If I connect the VPG to any display using a DVI TO HDMI cable (thus VPG DVI PORT -> DVI TO HDMI -> MONITOR HDMI PORT), every single digital signal works perfectly. (This proves that the digital signal generated by the VPG is in fact a valid one).
- If I connect the VPG to (almost) any display using its HDMI port (thus VPG HDMI PORT -> HDMI cable -> MONITOR HDMI PORT), I get a NO SIGNAL error on any digital video signal I can generate (my reference TV is the Panasonic TX-P60ZT60).
Now, I said 'almost' because I have three old Samsung TVs (all model T220HD) where the direct HDMI connection with the VPG works perfectly on every digital signal I can generate. (So, it looks like there is some signal coming out from the VPG's HDMI port that works). - I tried to disable the HDCP both from the VPG options, and also using an HDCP stripper (commonly used for streaming/recording encrypted sources such as PSX or XBOX signals), with no results.
- I tried to add an EDID Feeder Manager (kwmobile) in between the direct HDMI connection from the VPG to the display, with no results.
- I tried to play with several options regarding EDID and HDCP in the VPG menus, with no results. (I can upload the manual of the VPG if anyone is interested to dig more... maybe I'm missing something).
My feeling is (considering facts 1 and 2) that there is some problem in the HDMI protocol that I'm missing. Unfortunately, I don't know if there is a cheap way to debug/monitor the HDMI protocol or maybe rebuild it (??) to make it compatible for new TVs.
If someone can suggest any experiment/solution to solve this problem, I'll be happy to perform it.
Thanks a lot.
1 - 6 of 6 Posts
True. For rewrititing/rebuilding the protocol I meant intercepting the signal out of the VPG, reprocess it to adhere a modern standard and then send it to the display. Kind of using a device in between the VPG and the display to re-adjuat the signal. Also wasn't the HDMI protocol proudly claimed to be back compatible? Like a new device should be able to support the signal from an older source (protocol wise). Maybe this is just a big lie in the endHDMI 1.2a was introduced in Dec. 2005 with either HDCP version 1.2 or 1.3, so you are using technology that's over 15 years old. Incompatibilities with older technology and newer technology is bound to happen. HDMI protocols are built into the HDMI chipsets so you can't just flash them or rewrite the protocols to make them more compatible.
HDMI is backwards compatible only to the in-common protocol sets. So, sending an HDMI 1.2 signal to an HDMI 2.0 device will only utilize the HDMI 1.2 option sets. Throw in copy protected material (HDCP) and you have a potential for incompatibilities. You can't force a device to reprocess older technology to meet the new standards especially if the newer technology requires a higher bandwidth than the older tech is capable of sending. Again, you're back to what is baked into the HDMI chipsets.
That's exactly what gives me hope to get a picture on screen.HDMI is backwards compatible only to the in-common protocol sets. So, sending an HDMI 1.2 signal to an HDMI 2.0 device will only utilize the HDMI 1.2 option sets.
HDCP has been disabled on the VPG and eventually even stripped from the HDMI signal (before it reaches the display). Note that, I get a No Signal message even if I connect the VPG directly to an HDMI acquisition hardware for PC (which are well-known to ignore HDCP protection).Throw in copy protected material (HDCP) and you have a potential for incompatibilities.
I've never even mentioned this option to 'force' an endpoint device to reprocess the signal.You can't force a device to reprocess older technology to meet the new standards especially if the newer technology requires a higher bandwidth than the older tech is capable of sending. Again, you're back to what is baked into the HDMI chipsets.
Removing HDCP is illegal in a lot of cases and that may be part of the problem as the signal has been altered so the sink device may not be able to properly decode it.That's exactly what gives me hope to get a picture on screen.
HDCP has been disabled on the VPG and eventually even stripped from the HDMI signal (before it reaches the display). Note that, I get a No Signal message even if I connect the VPG directly to an HDMI acquisition hardware for PC (which are well-known to ignore HDCP protection).
I've never even mentioned this option to 'force' an endpoint device to reprocess the signal.
My apologies if I misinterpreted your statement "For rewrititing/rebuilding the protocol I meant intercepting the signal out of the VPG, reprocess it to adhere a modern standard and then send it to the display."
1 - 6 of 6 Posts
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