Newbie with weird setup - a few questions...

  • So I am taking the plunge here - as much about learning how to do pixels effectively as it is about having a really cool home theater. What makes this a little different is that I am using a projector, so there is going to be a LOT of pixels. So here are my questions...

    • Amount of pixels. I am using WS2812B strips from BTF. They are the 5050 variety with 300 LEDs/M. The outside dimensions of the screen frame are 51" tall by 86" wide and due to the way the screen attaches to the wall the only place I can attach the pixels is the back of the frame right at the perimeter. which calculates to 128 pixels across v 76 pixels high for a total of 408 pixels. When I did the calculations yesterday I started thinking about processing power and scaling. I am using a Pi4 with 8gB of ram which I have a big cooler attached to so I can overclock it a little if necessary, but will it be necessary? How many pixels can be processed?

    • Distance to the wall. Currently I have the screen attached to the wall using 1x2, which moves it out from the wall by 0.75". I plan on adding another 2x2 to this which will move it out to 2.25", but compared to a flat panel, it is still really close. What distance from the wall do you guys find works best for you?

    • Pi alone or use a controller and why. I have seen some videos where people say to run the pixels directly from the Pi, and others that let the pi feed data to a controller. If the Pi can do it, wouldn't that potentially be lower in latency than adding another device? Do I need a separate controller and what are the pros / cons specific to Hyperion NG?

    • Power supply... Ii have a Mean Well 60A 5V supply and have no problem injecting power to the strips wherever it's necessary, but I don't want to run that much current through the Pi, so I would think to feed the strips their DC directly. But the Pi would at least need to share the ground in order for the data feed to mean anything correct? So should I use the same supply to power the Pi?

    • HDCP. My projector is 4K and all of the sources are either 4K native or upscaling (My Roku will deliver 4K all of the time, regardless of the source native). There will NOT be HDR All of my sources are connected to a Marantz preamp with two separate HDMI outputs and can also internally direct the secondary monitor output to analog video (either composite or Y/Pb/Pr component). I have an HDMI to RSB 3 gaming adapter that can stream 4K/60 to the USB, but I'm sure it would clog up the front end of the Pi. But the bigger concern is HDCP. I am using a TV tuner, a Roku Ultra and a UHD Blu-Ray player along with a PC all feeding to the Marantz Preamp. I am a video product engineer and have had enough bad experiences over the last 20 years with HDCP to know that it is bound to be a problem. So here is my question: How do you guys deal with HDCP?

    I know this is a lot of questions, but I could not find any FAQ or setup docs here. If anyone can direct me to where they might be, that would be great too.

    Thanks in advance.



    • 1 you can make it even with PIzero so no problem, will support "endless" lights. But, signal on D1 and Clk from gpio's needs to be high enough especially for a large number of LEDs.
    • or only 1 dataline.

    • 2 LEDs have a angle of 120 degrees so you can set them in a big angle instead of shining towards the wall. See my setup, I think my clearance from LEDs to wall is 2 Inch
    • You have to think; the further the wall/ the more brightness you need. You can experiment with 30/60/ or 144 leds/mtr. I have 30leds/mtr (in total 130) and this is enough for a small gap from leds to the wall, but the bigger the gap the longer distance so lights will be less strong colours.
    • I like them to be powerfull but thats a preference

    • 3 I would use a level shifter in your case because PI can't steer that much leds out of Gpio without noticable lag or not firing at all/flickering on the ledstrip

    • 4 my advice is always use one PSU for everything! Much cleaner/easier, because you have a 300watts is no problem to steer all the devices and LEDstrip. Remember to stabilize everything to ground (-) and...... it doesn't matter your PSU is powerful, the device/PI/ledstrip is only drawing amps it needs so doesn't matter. Make sure voltage of PSU isn't exceeding 5 volts! Better to have 4.9 than much to high.
  • Drawing leds is: (full brightness)

    0.049 x 408= 19.992 so 20 amps or 100 watts, only for leds.

    So you have no problem use your mean well for the whole setup.

    I also would recommend to use a LEDstrip with 2 datalines instead of one with this much lights. Now all the data has to go over only 1 dataline (pwm gpio12) so don't have experience with that but with 2 datalines type LEDstrips like the apa102 everything will run much smoother if you have to steer more then 200 leds.


  • I actually returned the WS2812B strips and am getting 2 rolls of SK9822s - still from BTF (according to a couple of the Amazon reviews they are actually legit APA102s - we'll see. But they're the next best thing). From what I read the Pi can control them much better because of the separate clock channel.

    The hardest part for me is that this is my living room and my home office - what I am typing this on right now. So I need this to be as bulletproof as possible before I do this install, because taking the screen down and putting it back up is not easy.

    What advantages are there to using a separate controller? Are there some that are more liked for this than others?

    And my biggest concern is HDCP. Working from the PC I don't really care, but this PC is also a server for ~24 TB of ripped Blu-rays, all of them either FHD or UHD. And HDCP is a nightmare. I know because I am a field engineer for Panasonic and can't tell you how many unexplained problems eventually got explained by HDCP issues. If it was as simple as "it either plays or it doesn't" that wouldn't be a problem because it is easy to identify. But it's more like: image shuts off after 45 minutes into a show or movie, shifting between a digital snow picture and normal, AV sync getting horribly messed up - like seconds instead of ms.

    Another question: I see some people - like you for example - have a converter for HDMI to composite and then a separate grabber. Others are using (and what I am trying first) a single unit capture device - in with HDMI and out the back with USB3. The one that I am using is this:

    Obviously I know that I won't be using a 4K stream to the Pi, but I figured if it was powerful enough to stream 4k, then it should do 1080 with little to no latency. Or do I want to feed an even lower resolution into the Pi?

    I should have all the gear in place by tomorrow. Then I have to cut and solder strips, power insertion, etc... Hoping Thursday will be the go day.

    Thanks for everything so far...

  • Hoping Thursday will be the go day.

    let us know if you have questions when you are building your setup.


  • Hi everybody,

    I searched this forum for over a week and it helped me answering a lot of questions but some stuff I am still struggling to figure out.

    I am new to this and like Dan (my namesake) I am getting everything together for my first built. I do not want to use an external grabber and initially only plan to run the LED's via Kodi/ (internal grabber) in the Pi. I will have c.3 m total LED strip length (I like to use 60 LED's per meter strips) around the TV but since I do not have space behind the TV for the Pi or a power unit I will also have c. 2m cable from the PI and the LED powersource to the LED's behind the TV.

    I received the the raspberry 4 (4GB) today, installed LibreElec and am currently installing via the script provided here:…ziell-unofficially.10463/

    I still need to get the LED strips, LED power supply and cables of correct gauge and have a few questions the community here may be able to help me with.

    (1) RGB vs RGBW (natural white) LED strips: The latter need less amps to show proper white but I read in a lot of amazon customer reviews that the Blue LED kinda activates the white LED at the same time and thus there is not deep blue with these LED's and it looks more like a sky blue. Anyone has experience with RGB vs RGBW strips and could recommend one over the other?

    (2) I saw Dan asked this a few times but did not get a real answer on this. I am wondering the same. What is the benefit of having an external controller attached to the LED strip which itself is then connected to the Pi. I get this if you want to have the LED's controlled via wifi but what is the benefit (if any) if the controller is hooked up directly to the Pi? Eventually, would you recommend a controller or just connect the LED's directly to the Pi if one is not bothered about Wifi connection? I like to keep the setup as simple as possible

    (3) If I am not wrong for calculating power supply I would need to plan with 10.8 Amps just for the LED's (60 LED's/mtr * 3m * 60mA = 10.8 Amps) but I also need to account for loss of voltage within the LED strip plus the 2m power cable from the power supply to the LED's. I plan to connect/ branch out power to the LED strips every 1m to reduce loss of voltage. So my question: How many Watts/ Amps do I need for my power supply and what cable Gauge would you recommend for a) from Power Supply to LED terminal (c. 2m), b) from Power Terminal behind TV to my 3 soldering locations on the LED strip (c. 50cm each and i like to keep the wires as thin as possible here) and c) for my data line from the Pi to the LED strip (c. 2m).

    (4) If I am going for LED strips with a separate line for CLOCK (is it necessary?) would I still need a level shifter for the data line and would I also need a level shifter for the clock line?

    Every help is much appreciated.

    Thank You!

  • hello,

    1, no answer/no experience with RGBW strips, there's a option in Hyperion.NG to activate RGBW protocol.

    2, there is no advantage but sometimes its nessecary to use a levelshifter. Why? because GPIO on a raspi only put out max 3.3volts on datalines when ledstrips wants to have 3.5volts to prefer. Some types of ledstrips don't fire without a "boost" most of them will run directly on SPI GPIO connected without anything fancy
    that depends also of your PSU which have to be really clean and steady output of 5 volts.

    3, a 5050 SMD led uses at full brightness 0.049 amps not 60. So your calculation is off. Ledstrip isn't loosing voltage because you can power it from both sides, with this setup the power is spreaded evenly. You are talking about 3mtr of 60L/mtr so calculation is 0,049 x 180 = 8,82 amps or 45 watts of power for ledstrip only
    I recommend to use 1 PSU to power everything

    4, its said already 4 line ledstrips runs better and more fluid then 3 line strips, but a levelshifter is only needed in some cases. If you need it you see that in flickering/off colours and not responding ledstrip. You can connect more channels than one on a levelshifter so data/clk is no problem to connect simultaneously

    goodluck with your build man

  • Hi Jeroen,

    Thanks a lot for your reply. Much appreciate it. Further comments:

    (3) I am currently also building a Lightsaber with addressable Neopixels and in that community everyone calculates with 60mA per Led that is why I used this number but I am just going to plan conservatively then. Any advise on thickness for the wires?

    (4) The 4 line ledstrips are also more expensive. Is the difference in lag "very" noticeable between the 3 line and 4 line strips? Yeah I already got a levelshifter with 4 channels so that should not be a problem.

  • Like 2x 2mm2 wire gauge should do it. I connected mine with only 2x 1.5mm2 speakerwire.

    The more leds you want to fire over only 1 data lead it will become slow, the reason is that data and later clk (too reset ledcolor) have to follow up on same lead. At certain point you loose data so also colour and sync will be off between leds and screen. Invest in a good ledstrip I would say, 4lines is always better then 3, more fluid

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