What is "enhanced HDMI" ? - Page 1
Forum section: electronics / projects

author: TimCambridge
author_rank: Regular Contributor
timestamp: January 29, 2024, 03:53:44 am
content: The HDMI source is a macBook USB-C output with a USB-HDMI adapter/converter.This source worked well with the old/noisy projector but when we got a new/quiet projector HDMI input gave us a blank display with a message "are you using enhanced HDMI?" What is that?Amazon sells HDMI boosters/enhancers/extenders for between $5 and $250.Perhaps $5 is a scam... But maybe the signal has the edges sharpened? Maybe the levels are bumped up to standard levels? Or maybe ....? Whatever it is must be tough to design, build, and sell for less than $20 unless it's a few transistors, Rs, and Cs.Any ideas as to what might be going on? And any suggestions as to what I should buy?Tim

author: Someone
author_rank: Super Contributor
timestamp: January 29, 2024, 04:42:27 am
content: What resolution, frame rate, bit depth, and color sampling are you trying to output to the projector?Consumer cabling works pretty well on short runs and under 4k30p, but increasing any of that gets expensive.

author: Jeroen3
author_rank: Super Contributor
timestamp: January 29, 2024, 07:19:42 am
content: It's a setting in the projector for compatibility of 1.4 devices because iterating versions didn't go fast enough for some.https://www.anandtech.com/show/8191/nvidia-kepler-cards-get-hdmi-4k60hz-support-kind-of

author: NiHaoMike
author_rank: Super Contributor
timestamp: January 29, 2024, 01:54:29 pm
content: Quote from: TimCambridge on January 29, 2024, 03:53:44 amThe signal buffer chips are really cheap and common. That said, I would try a newer USB-C dock first, preferably one that supports HDMI 2.0 or later.

author: sparkydog
author_rank: Regular Contributor
timestamp: January 29, 2024, 07:40:31 pm
content: Quote from: TimCambridge on January 29, 2024, 03:53:44 amRetransmitting a digital signal is definitely a thing thatcanreduce noise and/or extend range. IthinkHDMI allows for a certain amount of power transmission that might allow for something that doesn't need an external power supply. However, something thatdoeshave an external power supply is probably more likely to be "quality". That said, without testing a specific device and knowing whether signal degradation is actually an issue in your setup, we can't really say whether such a device would actually be useful to you.Imagine a digital signal is like a QR code. Conceptually this exists as an abstract representation of digits that is lossless. However, the real world isn't digital. When you need to send the signal somewhere, you're doing something not unlike printing the QR code onto a piece of paper and hoping the other end can reconstruct it. What makes this "digital" rather than purely analog is that the analog signal (the printed QR code) is representative of abstract units in a way that can recover from a certain degree of noise and signal loss. For example, if a 1mm×1mm square represents a bit and is nominally either "black" or "white", you can imagine quite a bit of variance in both size and shade before you can no longer reconstruct the original data with 100% fidelity. (And even then, there are error correcting schemes that can be added to further improve matters.) Compare that to analog, where the square is some shade of gray (and perhaps the size is relevant), and you can see it's much easier for the original representation of the data to change.When you send that signal down a wire, you can lose signal strength and noise can be introduced. Imagine if every meter of wire was like making a photocopy of the QR code. After a short distance, you can probably still reconstruct the original data, but after a long enough run, you're going to start having problems from the combination of noise and fading (loss of signal level). A repeater/booster reconstructs and retransmits the original signal; to continue the photocopier analogy, it's like taking the less-degraded copy you have after a shorter distance and printing out a fresh, pristine copy before continuing to pass it along. Given the ability to do this indefinitely, it's easy to see how you could (theoretically) transmit a signal over an indefinite length like this. (In reality, a protocol like HDMI may become unhappy if too much latency appears between the endpoints. More expensive repeaters may act like signal endpoints and mitigate this, although features like eARC and CEC may not work correctly or at all. This is especially a problem for e.g. USB, while on the opposite side you have protocols like TCP/IP that are specifically designed to cope with high latency; the ability to indefinitely reconstruct and retransmit digital signals is why the Internet works!)Now... all that said, I think it's unlikely a new projector would fail to recognize a signal that an old one accepted, unless you've also (a) changed out the cables to something non-trivially worse or (b) increased the cable run. (Or your "new" projector for some reason has really terrible HDMI support. When you say "new", is themodelactually newer than the old one? Or is it just "new toyou"?) Actually, it's a surprising problem to have, period. I'm going to agree with NiHaoMike and suggest fiddling with your USB-C-to-HDMI step first.If you're trying to run HDMI over more than ~3m, you might also consider a fiber-optic HDMI cable. They're not dirt-cheap, but they're not prohibitively expensive, either.