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  1. If a HDMI cable is compatible with 4k TV, is it also backwards compatible with 1080p and 1080i and 720p?

    This cable says it is compatible with both 4k TVs and 1080p TVs
    http://www.monoprice.com/Product?c_id=102&cp_id=10255&cs_id=1025507&p_id=9169&seq=1&format=2

    But this cable only says that it is compatible with 4k TVs. It does not say anything about compatible with 1080p or 1080i or 720p.
    http://www.monoprice.com/Product?c_id=102&cp_id=10255&cs_id=1025508&p_id=10767&seq=1&format=2

    Just curious as to why first cable says it is compatible with both 4k and 1080p but second cable says it is only compatible with 4k?
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  2. Member Cornucopia's Avatar
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    Yes.

    For HDMI cables, the important thing is the speed rating. From this point onward, you should basically only be looking for good quality hi-speed cables. As long as you got that, you will be good to go for anything 4k or less.

    Note that both of those examples are thin, active types, so they have a shorter maximum length and can only be used in ONE direction (because the electronics inside usually get their power from the source not the sink)

    Scott
    Last edited by Cornucopia; 29th Apr 2015 at 00:18.
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  3. I don't understand why some cables are 18Gbps data throughout while some are less. If I am connecting a blu Ray player to the TV, it doesn't matter right?

    I thought Gbps only matter if I am connecting two computers with the HDMI cable and are transferring files between.
    Last edited by jyeh74; 29th Apr 2015 at 00:27.
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    HDMI is a digital connection, which means it does transmit data (uncompressed digital video and digital audio). Hence the data transfer rate in the specs. You cannot transfer files over HDMI. Where did you ever get that idea? HDMI is only for video and audio.

    10.2Gbps isn't enough for 4K, but it is perfectly fine for 1080p Blu-Ray. 18Gbps works for today's 4K video, but will be insufficient in the near future, as will be HDMI as we know it today.
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  5. Originally Posted by usually_quiet View Post
    HDMI is a digital connection, which means it does transmit data (uncompressed digital video and digital audio). Hence the data transfer rate in the specs.

    10.2Gbps isn't enough for 4K, but it is perfectly fine for 1080p Blu-Ray. 18Gbps works for today's 4K video, but will be insufficient in the near future, as will be HDMI as we know it today.
    But the cable that has 10.2Gbps says it supports 4k. Must be something to do with the 24Hz. (I am not familiar with Hz) wheareas the other 18Gbps cable says it will support 4k at 60Hz.
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    Originally Posted by jyeh74 View Post
    Originally Posted by usually_quiet View Post
    HDMI is a digital connection, which means it does transmit data (uncompressed digital video and digital audio). Hence the data transfer rate in the specs.

    10.2Gbps isn't enough for 4K, but it is perfectly fine for 1080p Blu-Ray. 18Gbps works for today's 4K video, but will be insufficient in the near future, as will be HDMI as we know it today.
    But the cable that has 10.2Gbps says it supports 4k. Must be something to do with the 24Hz. (I am not familiar with Hz) wheareas the other 18Gbps cable says it will support 4k at 60Hz.
    Yes, that is right. 4K at 24 frames per second and 1080p, but not higher frame rates at 4K.
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  7. Don't most 4k TVs these days have 240Hz, not 60Hz?

    I don't even know why that cable says it supports 4k at 24Hz. No TVs run at 24Hz these days.
    Last edited by jyeh74; 29th Apr 2015 at 00:43.
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    Originally Posted by jyeh74 View Post
    Don't most 4k TVs these days have 240Hz, not 60Hz?
    You can't do 4K/240P over current versions of HDMI.

    Maximum currently is 4K/60P with HDMI 2.0.
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  9. So does it mean that 4k TVs that boast it can run 240Hz, you aren't even realizing its full potential? i.e. if you watch a ballgame, the most it will run is 60Hz.
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    Originally Posted by jyeh74 View Post
    So does it mean that 4k TVs that boast it can run 240Hz, you aren't even realizing its full potential? i.e. if you watch a ballgame, the most it will run is 60Hz.
    Well I suppose theoretically it could run a 60 Hz source at 240Hz, it won't really do much. It may be able to run 240Hz sources overthe lower resolution of 1080P.
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    Originally Posted by jyeh74 View Post
    Don't most 4k TVs these days have 240Hz, not 60Hz?

    I don't even know why that cable says it supports 4k at 24Hz. No TVs run at 24Hz these days.
    The cable says it supports 4K at 24Hz because the video is delivered at 24 frames per second. The TV processes the video so it is displayed at whatever frame rate the TV is set up to use. Some TVs repeat frames, while other TVs have a smooth motion setting to insert interpolated frames.

    I don't own a TV that goes above 60Hz/60 fps. I have seen 120Hz and 240Hz and don't like the smooth motion effect.
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  12. Member Cornucopia's Avatar
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    The "240Hz" thing is a red herring in this context, as that describes only the (interpolated) internal refresh rate of displays, NOT the acceptable input framerates of the display or the cabling.

    UNLIKE HDMI equipment, HDMI cables don't give a crap about specific HDMI levels, but are only described by their speed rating: normal & hi speed. So both the 10Gbps and 18Gbps ratings fall under this same hi speed designation. The listed 10/18 is a manufacturer-specific feature listing, which may or may not be factual. Regardless, it is quite possible that the difference is one of "guaranteed performance" and so the lower rated cable might still work just fine with higher bandwith streams (e.g. 4k@60p), just maybe not always in a consistently reliable manner. Unfortunately, active electronics in the cable might throw a monkey wrench in this cabling universality, but at least so far there is no official HDMI 2.0-specific requirement designation. (sorry I didn't notice that bit earlier).

    Scott

    <edit>Note also that as far as bandwidth is concerned, 10bit 4:2:2 4k@60p = 3840 * 2160 * 59.94 * 20 / 1024 / 1024 / 1024 = ~9.26Gbps so (not counting overhead + audio + aux data) it is still below even the lower rating and SHOULDN'T have any trouble.
    Last edited by Cornucopia; 29th Apr 2015 at 03:09.
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    Originally Posted by Cornucopia View Post
    The "240Hz" thing is a red herring in this context, as that describes only the (interpolated) internal refresh rate of displays, NOT the acceptable input framerates of the display or the cabling.

    UNLIKE HDMI equipment, HDMI cables don't give a crap about specific HDMI levels, but are only described by their speed rating: normal & hi speed. So both the 10Gbps and 18Gbps ratings fall under this same hi speed designation. The listed 10/18 is a manufacturer-specific feature listing, which may or may not be factual. Regardless, it is quite possible that the difference is one of "guaranteed performance" and so the lower rated cable might still work just fine with higher bandwith streams (e.g. 4k@60p), just maybe not always in a consistently reliable manner. Unfortunately, active electronics in the cable might throw a monkey wrench in this cabling universality, but at least so far there is no official HDMI 2.0-specific requirement designation. (sorry I didn't notice that bit earlier).

    Scott

    <edit>Note also that as far as bandwidth is concerned, 10bit 4:2:2 4k@60p = 3840 * 2160 * 59.94 * 20 / 1024 / 1024 / 1024 = ~9.26Gbps so (not counting overhead + audio + aux data) it is still below even the lower rating and SHOULDN'T have any trouble.
    I think Monoprice's 4K specs for its Redmere cables are somewhat optimistic, although they should be fine for 1080p.

    There is a review from someone who attempted to use 15' and 10' 18Gbps Redmere cables from the same product line the OP linked to with a 4K TV for PC gaming at 2160p60 with 4:4:4 chroma sub-sampling but found they didn't work. He reported that a regular 24AWG high-speed HDMI cable did work for him.
    Last edited by usually_quiet; 29th Apr 2015 at 09:32. Reason: grammar
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