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RPi + Other Software USB grabber with internal loop

Discussion in 'Hardware Support' started by Refthoom, 30 August 2020.

  1. Refthoom

    Refthoom New Member

    Messages:
    14
    Hardware:
    RPi3
    I've tested this USB grabber with my setup of Rpi 3B+ with HyperBian alpha7 and it works great. The advantage of this device is that is has an internal HDMI loop so it eliminates the need for an HDMI splitter. Less parts is less clutter, right?

    It is powered solely by the USB port's 5V, unlike other USB grabbers that can utilize the 12V from HDMI. Also, unlike the term 'loop' might suggest, as soon as USB power is removed, the HDMI connection is lost.
     
  2. pho08

    pho08 Member

    Messages:
    38
    i have a similar usb grabber with loop. unfortunately it does not pass through HDR signal, so i still need the splitter (feintech)
     
  3. Refthoom

    Refthoom New Member

    Messages:
    14
    Hardware:
    RPi3
    Somehow when it says 'loop' I expect the signal to go through untouched. But that's Chinese products I guess ...
     
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  4. Sparky Lyon

    Sparky Lyon New Member

    Messages:
    7
    Hardware:
    RPi1/Zero, RPi2, RPi3, 32/64bit
    Hi, I'm currently only 1080p, so this grabber looks like it will suit my needs perfectly, if it supports passing of CEC commands. My wife likes the one remote for all devices, so this is a must. Do you know if it passes through CEC commands? ARC would also be nice, but this I can live without.
     
    Last edited: 4 September 2020
  5. AirZeee

    AirZeee New Member

    Messages:
    10
    Hardware:
    RPi3
    Hi Refthoom, regarding the USB Grabber you linked, can you advise if the USB output is a 4k signal, and to your knowledge does the Rpi3 have any USB3 ports - i’m thinking not.
    I currently have this USB Grabber, which claims to accept a 4K input, however in practice I’ve had to downgrade my SkyTV output to 1080p to the grabber for the Rpi3 to pick it up. This renders the Ambilight mostly pointless as we have a 4k TV ‍♂️
    Thanks!
     
  6. Sparky Lyon

    Sparky Lyon New Member

    Messages:
    7
    Hardware:
    RPi1/Zero, RPi2, RPi3, 32/64bit
    I have a Pi 3, 3+ and 4. Only the Pi 4 has USB3 slots. The Pi 3 is USB 2 only.
     
  7. NeeeeB

    NeeeeB Member

    Messages:
    110
    Hardware:
    RPi3
    Strange, that grabber is supposed to accept 4k input and output a 1080 signal, which should work for the pi.
    I don't understand why you have to input 1080 in order for it to work...
     
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  8. AirZeee

    AirZeee New Member

    Messages:
    10
    Hardware:
    RPi3
    i don’t understand it either, but once i downgrade the input from the SkyQ box to 1080p, or load a bluray disc the led’s work as intended.
    think I’ll look into a pi4 & 4k loop through usb grabber
     
  9. AirZeee

    AirZeee New Member

    Messages:
    10
    Hardware:
    RPi3
    I expect it’s drawing power via usb & relaying a boosted 4k signal.
     
  10. Refthoom

    Refthoom New Member

    Messages:
    14
    Hardware:
    RPi3
    I haven't tested that so I don't know, sorry. (CEC doesn't work for my setup because my AV receiver is rather old and doesn't support it.)

    It does support ARC on my setup.
     
    Last edited: 4 September 2020
    • Like Like x 2
  11. Refthoom

    Refthoom New Member

    Messages:
    14
    Hardware:
    RPi3
    Hmmmmmmm not sure what you want to achieve. The one that I linked to supposedly has 4k input and output, and grab [email protected] This provides more than enough information for Hyperion to be able to control your ledstrips, there is absolutely no need for the pi to grab 4k. And no, the pi3B has no USB3 ports. The pi 4B is the first pi to have USB3. But again, you really don't need that.

    I have no clue why you would need to lower the resolution to 1080p for the pi3 to pick it up. In my tests (with a similar grabber to yours but 1080p) I did find that it helps if HDMI is connected first and only after that connect to USB. Then with the Hyperion app, disable and re-enable Hyperion (that stops and starts hyperion deamon). In my setup that delivers the best results. I'm guessing this may be due to the fact that type of grabber is powered by either the 12V from the HDMI or the 5V from USB. When connected to HDMI first it can set itself up to the proper resolution of the connected device. If USB is first connected, it is powered by the 5V first and I guess it defaults to some resolution since there is no HDMI input at that moment.

    Please beware that, like I mentioned before, I did not test 4k signals since I don't have those in my setup. Someone else (other forum) stated that it could handle 4k in and out and together with the 'loop' made my decision to buy it and be somewhat future proof.
     
    • Like Like x 1
  12. AirZeee

    AirZeee New Member

    Messages:
    10
    Hardware:
    RPi3
    Hey,
    I’m simply trying to watch a 4k image, with LEDs matching the display with reasonable refresh rate.
    My AV receiver (Denon AVRX3600) has dual output for the main channel, so no need for a splitter. Of those, output 1 is coming from, and sending out a 4k signal from a Sky TV box (satellite TV, like cable?), and because the outputs are resolution matched, output 2 is also a 4k signal.
    with that signal set to 4k, i get no output from the LEDs, when I drop it to 1080p, or use another non 4k source, the system works just fine.
     
  13. Asda

    Asda New Member

    Messages:
    1
    Hardware:
    RPi1/Zero, RPi3, 32/64bit
    Hey can you talk about what the latency with this is. I'm currently using this usb capture card and while it works well, the lag between what's on the screen and the LEDs is noticeable enough that it really bother's me.
     
  14. NeeeeB

    NeeeeB Member

    Messages:
    110
    Hardware:
    RPi3
    Playing with resolution and size decimation in the settings helps with the lag ;-)
     
  15. Sparky Lyon

    Sparky Lyon New Member

    Messages:
    7
    Hardware:
    RPi1/Zero, RPi2, RPi3, 32/64bit
    I had the exact same issue. In capture hardware settings tab, i set a custom 'device resolution' of 768 x 429 and set the 'Size decimation' to 4. No lag whatsoever on my Pi3
     
  16. peskdale

    peskdale New Member

    Messages:
    2
    Hardware:
    RPi3, +Arduino
    I bought one of these off Amazon the other day. Good news is that it does accept and onpass a 2160p60 HDR signal, whilst grabbing at 1080p. And Hyperion on my Pi 3 picked it up straight away.

    Latency is good with automatic settings, although I have turned down the resolution just to be safe.

    Unfortunately, it looks like when you go full-on at 2160p60 HDR, the power draw can be slightly too much for a Pi 3 to keep up with. Occasionally, this will result in the HDMI loop dropping out for a moment (exasperated by my TV then taking an age to lock back onto the signal).

    I tried plugging it into a 5V/2.4A USB hub, and experienced the same issue. However, when connected to my USB3 laptop, no such issues occur. I'm hoping that a proper USB3 hub, or a Y-splitter, can solve this. Suggestions welcome.... bought this to keep the clutter down, so doesn't really want another box just to power it properly.


    EDIT: This was down to a bad HDMI cable causing my AVR to occasionally drop out. Coincidentally started happening after I installed the grabber. 2160p60 HDR is stable on a Pi 3 without any additional power.

    Interestingly, my PS4 couldn't make much sense of it to begin with. Seemed to believe it wasn't capable of YUV420, but was able to do RGB and YUV422 HDR fine. Kept changing mode until I set a manual resolution.

    In short, this is a great capture device, and can be paired directly with a Pi 3 so long as you aren't after the full 2160p60 HDR.
     
    Last edited: 4 October 2020
  17. Jesper Kjær Pedersen

    Jesper Kjær Pedersen New Member

    Messages:
    2
    Hardware:
    RPi3, +PhilipsHue, +nodeMCU/ESP8266


    Just to be absolutely sure before I order another hdmi grabber. Can this garbber receive HDR signal?
    My amplifier has 2 hdmi out ports which defaults to the worst signal = no HDR on any of the outputs if the grabber is not compatible with HDR.
     
  18. peskdale

    peskdale New Member

    Messages:
    2
    Hardware:
    RPi3, +Arduino
    Yes - this will accept and passthrough HDR signals fine. My issues were just bad cabling in my setup.

    The grabbed image is not tone-mapped, so will be washed out (which is normal for almost all affordable grabbers).

    What I can’t advise on is how this will behave without a display connected to it’s output. Mine is connected between my amplifier and TV.
     
  19. Jesper Kjær Pedersen

    Jesper Kjær Pedersen New Member

    Messages:
    2
    Hardware:
    RPi3, +PhilipsHue, +nodeMCU/ESP8266
    Great! Thank you peskdale :)
     
  20. Refthoom

    Refthoom New Member

    Messages:
    14
    Hardware:
    RPi3
    Most is said here already, no need to add solutions.

    Some theory about lag optimization from the notion that lag is caused by the grabber hardware and the Hyperion software.
    1) Start with the default automatic settings. If that works for you, leave it as it is. If not, read on.
    2) Theoretically, the number of LED pixels that you have in your setup is the minimum resolution needed. So if you have 55 LEDs left and right and 75 LEDs top and bottom, the minimum resolution to capture accurate colors is 55x75. Most grabbers won't go that low, so choose the setting in Hyperion that is best handled by the grabber hardware to get the least lag on the grabber. This is different for each brand so you have to do some digging.
    3) Your LED pixels have a maximum data / refresh rate so it's no use choosing a higher frame rate in Hyperion than what your total LEDs are capable of. A single pixel needs a minimum time to set the colors of the individual LEDs and recreate the data for the next pixel. Multiply that time with the number of pixels you have to get the time of 1 'frame'. Times the number of bits per pixels for the maximum bitrate. Divide in a second for the frames per second.
    4) Performance of your Pi influences lag as it has to do the calculations. Use the command htop in a terminal window to check performance. If you use the pi only for Hyperion and choose wisely with the above in mind, a Pi3 should have ample CPU cycles to make the necessary calculations without any trouble. If you use it for other tasks as well, htop will show you what process is hogging CPU resources, giving you a starting point to further optimize things. That is however beyond this forum I think.
     
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