60 replies
1d20h
For the longest time (like, the past 15 years) I’ve wanted a cheap small box that can overlay custom info, eg text, on the TV. The reason such a thing does not exist, other than projects like Bunnie’s NeTV (https://makezine.com/article/technology/review-hardware-hack...) is that decoding HDMI signals is illegal if you’re not in the club. I think the ELI5 reason is that content providers are afraid of unauthorized copying of DVDs (try taking a screenshot of a frame from your DVD player on your laptop).
I’d be willing to pay up to $199 for such a box if it has an open API to input overlay text and icons.
While reading your comment I was reminded of the much touted key capabilities of the Video Toaster (late 80s), it's character generator and chromakey, used to do exactly that: overlaying text on video, for a fraction of the cost of what professional video production cost. And now, 30+ years later, we still don't have an accessible way to do that using modern video tech/protocols, but now it's about rent seeking and licencing rather than technical capability.
There's tons of stuff out there. The ATEM Mini Pro can do keying and a bunch more for $300.
In general, audio and video production have never been cheaper or more accessible. There's no conspiracy of The Man keeping people down.
Thanks for the suggestion; however, this is a video production device which aims for different functionality than the broad one I had in mind.
The simplest useful app would be: watching a movie together with friends, have them type their comments on their phones and display them on my TV, in a lower third. The chat part is trivial but how to get that from a server to the video stream? Maybe there’s a simple way to do it using a device like the Mini Pro but when I search I do t see it.
While it's not the same as what you're asking for, you could do this pretty easily with a Raspberry Pi.
That feels like such an obvious thing to say that I hesitated even saying it, but then I started thinking about how funny it is. A solution to HDMI being so locked down is to buy a $20-ish computer, that does all the things a computer can do, so that we can feed the TV the video stream we want. Over HDMI.
Given that it's so easy to circumvent now, I wonder why anyone even bothers with HDMI any more, aside from inertia.
Totally, or one of those hdmi usb capture devices that are similarly cheap
This is what twitch streamers do all day using OBS and twitch chat. Hang out with their followers and watch/react to YouTube videos and read chat comments.
The Atem can definitely do this. There are youtube tutorials on it.
You use one of the many apps that can output your text, set it to output the background as green or whatever.
Then you can use the Atem to do one video stream inside the other, picture in picture, you can customize the size of the picture in the picture.
You can also have ot chroma key out the green (or whatever) from the text app, so it will only display the text, and the background will be the main video stream.
Bam.
There certainly is a conspiracy of industry players to keep people down. It is well documented and sadly part of our devices.
That brings back some good memories. I had access to a video toaster setup a couple days a week after school as well as library checkouts of big vhs camera recorders. We'd get a stack of tapes, do the 1 day rental of a camera and record all over the neighborhood, then after school we'd take the tapes in to the studio and mix them together.
All dumb shit, but you know we were kids.
From what I understand (and I could be very wrong here) the biggest issue here is simply the amount of memory that is required in order to keep a copy of the current frame from a HDMI signal, and the fact that to modify anything in the HDMI signal, you need to decrypt (if watching a HDCP protected stream), decode each frame, and then finally re-encrypt the HDMI signal.
I was looking into what would be necessary to build a HDMI switch that allowed for seamless switching of video between different inputs, and basically there was no hardware for it. The closest chips that I could find was Analog Devices' ADV7626 and Lattice's SiI9777S.
Lattice CP9777 might be worth having a look at if you can understand anything about the datasheet :)
As far as I can see there's no need to re-encrypt the signal - just leave it as a non-HDCP stream?
There are HDMI splitters which silently strip HDCP to output to two screens at once - they don't advertise this feature but they do it anyway in order to function. In order to achieve the overlay you'd just need one of these and then a non-HDCP-aware overlay apparatus before the display.
https://www.reddit.com/r/VIDEOENGINEERING/comments/xme482/hd...
You won't be able to get keys for HDCP if your device isn't compliant
I believe these kind of cheap, no-name converter/adapter boxes use leaked HDCP keys.
The master key was cracked long ago. You can generate as many of your own unique keys as you want.
This only works for old HDCP versions though
It would be a LOT more seamless if the output didn't have any HDCP to re-synchronize. Though the different frame timings (gen-lock is a term you want to search for) between the inputs and outputs so such a system might introduce presentation latency which would have to be accounted for in the audio streams.
Is there a reason a RPi or whatever with a cheap USB HDMI capture card isn't a good option? I guess there might be a minor quality loss but it should do what you want.
HDCP usually is an issue if you can't turn it off on the source. There are ways around that, though those are more than $199 if you're dealing with an HDMI 2.x source.
I thought there were cheap converters that could go HDMI 2->1?
Back in 2019 I paid $399 for a Vertex2, but if there are cheap options now in 2024, that would be awesome!
I bought a random HBVALINK branded splitter on Amazon last month for $29 that works perfectly for this purpose.
I bought a HDMI 2.0 splitter that strips HDCP a while back for $20.
Usually the lack of supporting 4:4:4 colorspace, and 4k video at anything over 30hz.
There is a lot of answers here already, but I would remind everyone, what if your target is 38-in-1 DVD/HD/whatever to resell for $5 the only thing you need is a $30 cam pointed at the display.
Yes, it's not pixel perfect. Thing is, the people who buys 38-in-1 do not care about pixel perfect picture. They just want an affordable way to spend an hour and half with their family.
Can you describe what a "38-in-1" device is? Is it even a device?
38-in-1 is some random storage media (USB stick, DVD. SD card, CD ) with "38" (or 45 or 2, or 99, pick a number) media files (movie, TV show, YouTube series whatever ) in various resolutions, formats, modes etc sold for next to nothing in the street.
Can be played Android-type boxes or even on phones / tablets
Essentially sneaker-net but for watchable media.
Not something you will see in much of in NA or Europe but very common in Asia and Africa where bandwidth /internet and more important, electricity, is relatively expensive.
The 90 minutes with your family comment is spot on.
in NA and Europe, this is mostly because folks don't have access to continuous internet. You are in back-country or don't have service or whatever.
In the Africa / Asia case, its because you don't have internet and / or power.
Most of the time, this media is viewed off TVs running on batteries, charged by solar, off an USB port. The electricity budget (because battery) says you get "90" mins of TV a day (not exactly 90: the power is shared between lights, charging phones, would be be more time but because electricity is limited, "TV time" is limited).
So those "90" minutes are family time, we all watch the same thing together.
Point being, in that world, Cam or SD of whatever works, no need for HD, or UHD or 4k or 8k - it is completely worthless. The screens that the content is being watched on are 720p most of the time.
Something like this (edit replaced original link with a new one that explains what is happening better)
https://www.npr.org/sections/goatsandsoda/2021/11/10/1052926...
I think this is also the reason most "scene" releases of TV shows and movies were xvid encoded, and capped at 175MB and 700MB respectively for so long. So that they wouldn't break compatibility with burned CDs on existing players.
The reply by @throwaway201606 is on point, though I would add what it was extremely popular in Eastern Europe too, till the broadband/4G became ubiquitous.
I think the last time I saw a 9-in-1 DVD on sale there is somewhere around... 2018 probably?
Yeap, for most they try, the a-hole (analog hole) will remain unplugged.
Hdmi has zero illusions about being ineffective. It was cracked the first day it was released.
It's a mechanism to force you to pay a licensing fee to manufacture hdmi devices.
It's why display ports are the way to go.
I never gave display port any attention, what's the appeal? Open-source?
Also higher speeds. HDMI 2.1 has a bandwidth of 48 Gbit/s. But because of driver shenanigans in the linked article, us pesky computer users are stuck with HDMI 2.0, which has a bandwidth of 18 Gbit/s.
The latest version of DisplayPort has a bandwidth of 80 Gbit/s, and you get drivers on day 1.
Thinking about it more, there's no down side to DP. Every card manufacturer should spend an extra $2 and ship with a DP -> HDMI adapter and drop HDMI universally. There's no down side. And that $2 will be well worth the licensing fees they don't have to pay, and the software they don't have to write.
Its a less confusing standard too. The versions are sane.
Also i love that DP-plugs have that latch thing so the cable always stays attached
Hdmi without the leagal issuses. There are other differences but the leagal is why it exists.
The really dumb thing is that nobody wants to copy DVDs or Blu-Rays via HDMI anyways. It's much more convenient to decrypt the discs directly with tools like MakeMKV.
However, I suspect that isn't the real holdup here since DisplayPort also fully supports HDCP
Most of the stuff people want to preserve nowadays is never made available on a disc.
like?
Content on streaming services - Netflix, AppleTV, Amazon, etc.
Exactly. The same streaming services that have recently gained a reputation of straight up deleting entire movies and series.
It sounds like you've taken a deep long journey into the mess here: I'm curious, what does it take to be a member of the club?
I hope it's not just FAANGs and blessed hardware OEMs...but it also sounds likely it must be, you can't let just anyone in if you're worried about the specs leaking...but then again that sounds weird too, in that, they used to provide the spec more openly until 2.1?
HDMI adopter registration details here[1]; in general, $10k annual fee + royalties and of bunch of legalese. Prevailing list of 2451 adopters and affiliates here[2]; yes, AMD (listed as unabbreviated Advanced Micro Devices) has been a registered Adopter since Aug 2006 and is currently listed as a 2.1b licensee.
[1]https://www.hdmi.org/register/adopterregister
[2] https://www.hdmi.org/adopter/adoptersaffiliates
Is registering as an adopter the only way to gain participation in their decision making process?
You can get devices that "hack" HDMI to various other unprotected signals such as SDI. So you get a Decimator or something, covert HDMI to SDI, and then do the needful.
Now that may not help you, as the devices that do SDI overlays run in the $1k range, but maybe something is out there like a ATEM SDI https://www.blackmagicdesign.com/products/atemsdi
Blackmagic's Mini Converters are at their core nothing more than SerDes chips and an FPGA that does the protocol translation. I _think_ that the recent models with USB-C power supply inputs also have the data pins connected to the FPGA.
Might be worth a try to check how hard BMD has locked down the FPGA bitstream.
I know the Decimators would remove HDCP, as it's a known "trick" when trying to project from a Mac. But not sure which versions, and how well.
You are correct. Pay attention to the conspicuously lacking feature. Odds are there's industrial collusion to keep it that way.
Chinese don't care, if there is a market they will produce it.
Maybe the closest thing to this is a Blackmagic box of some sort. I use a the Ultrastudio 4K to capture 4K60 output, pipe through OBS and pass through as well.
Will run you $1K though. Corsair/Elgato has some solutions in your price range but the devil is in the details of precisely what you're trying to accomplish.
An HDMI splitter (i.e. an HDCP down converter/stripper) and a video capture dongle or card can be had for like $60, plus a computing running OBS. It’s not an elegant small box, but it’ll get the job done for lower resolution needs.
I don't know about quality but I guess a Raspberry Pi, HDMI Capture Card and OBS would do the trick and are within that price range.
If it's to watch a movie, why bother with the capture card at all? Why not throw together a way to stream the video from the Pi doing the text overlay to all the remote participants.
Is the GP commenter suggesting that they'd like to have people in remote locations each load a copy of their DVD into a player at the same time so they can comment on it together? If so, then yeah, you need a capture card I guess, but the notion of doing that seems a bit bonkers.
There appears to be at least one open source HDMI implementation https://github.com/hdl-util/hdmi
Relevant caveat from its readme: https://github.com/hdl-util/hdmi?tab=readme-ov-file#hdmi-ado...
Bunnie's work on HDMI mitm is really cool.
https://fahrplan.events.ccc.de/congress/2011/Fahrplan/events... (Slides and long write up)
His 28C3 talk https://www.youtube.com/watch?v=37SBMyGoCAU
I’ve made such a box myself. It cost me $20 in hardware and many hours of effort.
https://tomverbeure.github.io/2018/04/23/Color3-HDMI-RX-to-H...
Right now it’s just a proof of concept (check out the video with a moving overlay rectangle and the red 8 that is converted into a partially green 8), but it wouldn’t take a whole lot of work to add support for subtitles.
There are still some of these boxes for sale on Amazon, but supply is limited.
I don't know if the ~$20 HDMI USB capture cards work on a raspberry pi, but connecting one to a pi or laptop and capturing the signal to a v4l stream, overlaying in software and then outputting on built-in HDMI out might work?
I have an HD Fury Arcana 2 VRR which overlays text (eg: bitrate information) on top of my normal HDMI signal. (https://hdfury.com/)
I don't think this behavior is customizable.. (but maybe with some hacking).
If you can find a way to do this using DisplayPort instead, you can use an active HDMI to DisplayPort adapter:
https://www.amazon.com/Cable-Matters-DisplayPort-Adapter-Res...
There are some no name USB capture sticks that take any HDMI signal and expose it as a standard USB UVC camera, no drivers required. This could be a start of a DIY project.