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  1. Hello. I need to output video from a computer to a far away projector, using DVI out of the computer. I know that fiber optic HDMI can run a long distance, and is less expensive than fiber DVI, but it needs power injected at the source side. Can I use a USB-powered DVI to HDMI adapter, or is that USB power only for audio? Like this product here.
    Thank you!
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  2. Member Cornucopia's Avatar
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    First: Fiber does not and cannot carry power. Think about it - those are light beams. Ethernet, being electrical wire CAN (PoE). Depending in the length and whether you have facility for power at the far end (beyond that needed for the display), you'll need to decide whether Ethernet will be acceptable to you or not.

    Second: What you are looking for is known as an HDMI (or DVI) extender. Either ethernet-based (where it's known as HDbaseT) or Fiber-based. Ethernet-based ones can go up to ~330 feet (~100meters), whereas Fiber-based ones can go up to miles/kilometers.
    A new pair (transmitter+receiver) of extenders costs, for example, ~$800-1100USD (list price) for Extron-brand ones in HDbaseT, or ~$4000-5000USD (list price) for that brand in Fiber. You can find consumer brands that are cheaper (though caveat emptor), and commercial brands that are equal or more expensive.

    What you will NOT find, is something of good quality to do the job you asked, for less than ~$300USD for the pair - Unless used, ebay/craigslist, personal ad, gray market, etc. Ebay might be OK if the seller is reputable and the quality is money-back guaranteed.

    Third: DVI and HDMI share common protocol/data types & packet layout, so can often (but NOT always - YMMV) be interchangeable. On either one end or the other.

    Hope that helps,

    Scott
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    Originally Posted by cancolby View Post
    Can I use a USB-powered DVI to HDMI adapter, or is that USB power only for audio? Like this product here.
    Thank you!
    There are many passive, pin-to-pin DVI to HDMI adapters but I can recall none that are able add audio obtained from a separate audio connection to HDMI out.

    So, the biggest reason why the Startech DVI to HDMI converter needs to be powered is probably to allow audio from USB to be added to the HDMI output from the device. However, DVI doesn't supply power but HDMI can supply power. (MHL standard) If HDMI out from the device can provide power (I can't confirm that it does or doesn't) it has to come from somewhere.
    Last edited by usually_quiet; 27th Jan 2020 at 11:02.
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  4. Member Cornucopia's Avatar
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    Uq is correct. To add audio with dvi video, this requires buffers for timing, embedding into the packet/stream structure of the hdmi signal, etc. Cannot be done passively.

    In that device, usb may be supplying both power and audio.
    Won't really work for the intended purpose though (extension).

    Scott
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    I don't think I provided a clear explanation in my previous post, so I'll try again. Unlike most HDMI ports, DVI doesn't provide power. So, the USB connection on the Startech device not only supplies audio but also powers the device so it can convert the USB audio input for output over HDMI, as Cornucopia explained.

    However, I can't tell if the USB connection also supplies power for output over HDMI so the HDMI connection on the Startech DVI to HDMI converter can power other devices connected to it, such as an HDMI extender. Startech doesn't have any information about that on their product page for the DVI to HDMI converter.

    You might also need an HDMI voltage inserter.
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  6. Member Cornucopia's Avatar
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    At least one end of an extender pair must be traditionally powered. So even if it could power the transmitter (highly unlikely), it couldn't ALSO power the receiver. All the extenders I am familiar with inject the voltage not through the hdmi, but straight into the ethernet, though the alternate option is theoretically possible.

    For a $27 device, I would have serious reservations about it doing (even some of) the things you want it to.

    Scott
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    Originally Posted by Cornucopia View Post
    At least one end of an extender pair must be traditionally powered. So even if it could power the transmitter (highly unlikely), it couldn't ALSO power the receiver. All the extenders I am familiar with inject the voltage not through the hdmi, but straight into the ethernet, though the alternate option is theoretically possible.

    For a $27 device, I would have serious reservations about it doing (even some of) the things you want it to.

    Scott
    I looked at some ethernet and optical extenders. Most of the extenders I looked at were indeed powered via a wall wart, as you stated. One rather expensive model was powered via USB:https://www.amazon.com/Extender-Optical-Transceivers-Connector-850nm/dp/B073SRLNCJ/

    Maybe cancolby is thinking of using something like this cable, which appears to be powered via HDMI: https://www.amazon.com/HDMI-FURUI-HDCP2-2-Vision-Subsampling/dp/B07LD4CR2R/

    Perhaps cancolby could provide a link to the kind of extender or cable that he wants to use.
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    I think alot of the people who have posted here should watch this.

    https://www.youtube.com/watch?v=nva6oPszm60

    Its the second half thats most interesting.
    Last edited by isapc; 28th Jan 2020 at 19:16.
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  9. Member Cornucopia's Avatar
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    Well, that was good for a laugh. Wow, $100 for a 15' cable. ooh, it LIGHTS UP!

    --SPAM--

    Plus, the person doing the unboxing doesn't seem to understand much about AV.

    There's nothing here that would help the OP's needs directly.

    Scott
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