HDMI Light V2: Open-Hardware FPGA-Based Clone of Philips Ambilight (2014) | Hacker News Reader

HDMI Light V2: Open-Hardware FPGA-Based Clone of Philips Ambilight (2014)

hacks.esar.org.uk

170 pointswalterbell33 comments

Something similar to this was commercialized as lightpack: https://lightpack.tv

The first version of lightpack was usb driven, and it’s software (prismatik) is open source: https://github.com/woodenshark

I was an early backer, and my Lightpack is still working just great. I don't drive it from Prismatik though, I use Boblight... although I see that it hasn't been developed in a while.

I also have the 1st-gen lightpack, but just use it as 'bias' lighting set to one static color. For some reason never got around to making it more programmable to track time-of-day.

I've also used them from https://www.dreamscreentv.com/

The poor man's version of this is to place an old monitor at the back facing the wall and then clone and flip the screen.

But ofcourse never as good looking as this. Those examples are great!

all those projects are dead on the water thanks to DRM.

I look into them from time to time. If your source is a topbox or smarttv itself, you can't get any signal because those things use drm protocols that only allow one source. you can get around it with chinese hdmi splitters that will have their own problems.

if your source is a computer, then all those hdmi solutions are overkill vs doing it on software and then output to usb to a dumb and extremely cheap LED controller.

The author actually has a separate blog post where he talks about this, and uses a modified HDMI splitter to allow the device to work with encrypted content. It involves more soldering, of course. http://hacks.esar.org.uk/hdmi-splitter-hack/

exactly. its yet another project to jump in :)

HDCP is pretty much a solved problem for STBs, as you've said, a £14 HDMI splitter will do the job unless you're pushing 4K. Which most people aren't. Only thing I've seen to be picky is the PS4 (which was a ballache for PSVR).

Even if you are using 4K, 4K30 splitters that'll deal with the HDCP are what, $80, 4K60 for $150, tapping out at $300 for top-of-the-line 4k60 4:4:4 600Mhz with a shedload of additional functionality?

There's also Hyperion. You can do something similar (via screen capture). Here's a Pi running Kodi with Hyperion in the background. There's an Arduino connected over usb to the Pi collecting serial data and sending pixel data via PWM. https://m.youtube.com/watch?v=nXGoJT2Xdk0 Not nearly as soon as OP but it's a really cheap way to get into it.

Compared to solutions intercepting HDMI output, such solutions have the advantage to only use the original video as input, without the subtitles or the user interface.

This is really cool! I've never seen an Ambilight in person, or even heard of it, which I'm surprised by considering this is old (by today's standards) tech.

I have some spare LEDs lying around, so I might even give it a go. I'd like to see how it works for just a regular old movie.

I made one for my computer monitor and it looks really impressive, particularly with games. Unfortunately it's much harder to do on a television DIY nowadays because you have to decode the HDMI signal in realtime, which isn't really feasible with a 4K picture on any remotely affordable FGPAs (AFAIK... I'd really like to hear if someone knows a part or combination of chips that would make this feasible at a hobbyist price, even hypothetically).

A computer monitor is easier, though, because you can run a program in the background that does screen capture.

The Hue software philips came out with for computers is a cheap way for people to get into this if they already have a computer, bridge, and some colored lights. https://www2.meethue.com/en-us/entertainment/hue-sync

I have a bunch of Hue devices myself, but I wouldn't exactly call it "cheap" considering how much the colored bulbs cost. You can build your own with a cheap Arduino clone and some addressable RGB LEDs for well under $20.

In addition, Hue Sync is kinda different. To me a proper ambilight goes around the edge of a display to cast light on a wall with a decent resolution (20ish or more LEDs), while Sync is more for a few bulbs and synchronizing the room lights. You can get kind of a similar effect with Sync and a couple bulbs behind the screen but it's just not as impressive.

Phillips sells hue led strips now, wouldn't that work with hue sync?

The Hue strips aren't addressable so all the LEDs are set to the same color.

Hence my caveat about already having said expensive bulbs. The possibility exists that someone could to real time whole room color effects right now and they just didn't know it.

If you want actual ambilight tech hue is definitely not directly analogous and not cheap either.

I came across Lightberry [1] recently that claims they can do 4k @ 60 Hz from an HDMI signal, and is also HDCP compliant.

This talks to a Raspberry Pi using USB 2, and on their site [2], it talks about using the UTV007 [3] and STK1160 [4] chips, both of which are only 720x480px @ 30fps. As you really don't need high resolution for the LED lighting, what they must be doing is using an HDMI splitter and then converting to a lower quality signal, and then capturing/sampling that. Normally HDMI doesn't allow this but it's probably not too hard to find splitters that silently do this anyway.

In fact, here's a write-up [5] on using the "HD Fury Linker" [6] to basically upgrade the "Lightberry HD" to work with 4k. HD Fury makes some interesting products to manipulate the HDMI handshake an EDID [7] and an HDMI splitter that has HDCP decryption/encryption and "comes with USB upgradable firmware that allow you to unleash furious features" [8].

The last time I looked at this was about 10 years ago and I remember being put off by the compromises and complexity the HDMI signal path issues caused. Looks like that is no longer an issue (provided you are willing to pay for the gear).

[1] https://lightberry.eu

[2] https://lightberry.eu/getting-started/#grabberAccordion

[3] https://www.linuxtv.org/wiki/index.php/Easycap#USBTV007_Easy...

[4] https://www.linuxtv.org/wiki/index.php/Stk1160_based_USB_2.0...

[5] http://www.chewie.co.uk/general/how-to-get-lightberry-hd-to-...

[6] https://hdfury.com/product/linker-4k60-444-600mhz-scaler/

[7] https://hdfury.com/product/dr-hdmi/

[8] https://hdfury.com/product/splitter-4k/

Yeah, I have thought some sort of downsampling chip was probably the way to go, but I'm not that familiar with products in that area. This is exactly why I am asking here, thanks!

You don't have to decode a full frame. Just throw away the middle you don't need. Skipping every other frame would also buy time for a slower decoder.

It's not so much the decoding and memory as it is that the timing of the HDMI signal waveform at 4K/60fps is a bit too fast to read any portion of with an affordable FPGA. There are FPGAs with specialized DSP hardware that can probably do it, but the ones I know of require pricey IP core licenses and the chips themselves aren't terribly affordable.

That's kinda what I'm asking about here, if there is a something like a specialized chip that can be used to capture single frames from an HDMI stream to act as a buffer, because yeah obviously you don't need most of the data and you only really need to update at a few Hz.

The other option I've thought of is a chip to downsample the signal, as there are plenty of cheap FPGAs or even micros that can handle resolutions below 1080p. Again, I'm pretty sure such chips exist but I don't really know of them because this is just something I am interested in for fun.

A Xilinx one with transceivers should be able to do it though. Yes, not cheap as such, but oh well. Depending on resolution, a 3 or 5GHz transceiver chip from lattice should be reasonably cheap, and IIRCV they have special HDMI chips.

Ambilight is nice because it allows you to play / watch in a dark room. In my case at least, I don't get eye fatigue as it lights up the room enough to be comfortable.

Is hdcp involved and how do you intercept the encrypted video?

No HDCP but there is an update on how the poster got around HDCP: http://hacks.esar.org.uk/hdmi-splitter-hack/#more-3279

Have a look at https://www.instructables.com/id/DIY-Ambilight-with-Hyperion... for a video by Scott doing this with a raspi and Hyperion.

Reminds me of this arcan blog/demo: https://arcan-fe.com/2017/05/21/playing-with-leds/

Boblightd (https://github.com/bobo1on1/boblight) is great if your source is a computer. There is a plugin for Kodi - I personally haven't tried and just start boblight-X11.

Since boblight can use a capture source, at one point I did get something working with a HDMI spliter -> composite -> USB composite capture card so I could use boblight with any hdmi source.

At some point I'd like to pickup one of those android boxes that include HDMI input and try and get boblight built on android.

This is a really cool board however, i'd love to buy one.

I've done a similar project in 2008, only it was about the backlight of the LCD itself. Also, we used a CPLD, not FPGA; there was an effort to improve it (and it was supposed to run on a Spartan 3E) but then the customer's own funding ended, and the project was halted.

The demo videos are super impressive, wow!

Wow this is amazing!

You can do all this with the MagicShifter3000:

http://magicshifter.net/

.. and more! It has WIFI, MIDI, OSC, Serial I/O, an onboard Webserver for the UI, and more!

(DISCLAIMER: I'm a developer on the MS3000 project .. We'll be releasing a new OS for this soon, which includes a lot of great features .. a MIDI sequencer and arpeggiator, easy remote programming of light patterns..)

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