Guide to HDMI and EDID the standard that got too complex.

Discussion in 'Functions Operation Guidance' started by Nice Monkey, Apr 21, 2019.

  1. Nice Monkey

    Nice Monkey Active Member

    The HDMI standard and with it EDID is getting more complex by the day. This in fact is not good news.

    For those asking what EDID is this is the information exchange using a specific PIN on the HDMI interface to exchange capabilities between devices talking to each other. EDID in fact happens on the total chain for the signal so it may involve a device ==> Amplifier ==> TV/Projector and if used any other components like switches in-between those.
    Only manufacturers can deal with EDID exchange problems and is mostly done via FW updates. All brands occasionally have problems here as it is very complex as the number of variables to deal with keeps on increasing.

    Problem areas to look for:
    1) To start with I don't really like the HDMI connector as it the first source for potential problem. It has many pins which all need to make perfect contact, it is really small, has no lock and cables got bulky and heavier with each generation. So trying multiple cables one in fact may work perfectly between a device and a TV/AMP but won't work between another device and the same AMP/TV. Not what one would expect.

    2) The HDMI standard was updated/enhanced many times with new capabilities. HDMI 1.3, HDMI 1.4, HDMI 2.0 and the most recent one HDMI 2.1 not only added new features but also increased the bandwidth supported between the components used. Mostly a new HDMI standard and the features associated with it where fixed, but recently they even screwed that one. A good example is HDR10+ which really was associated with HDMI 2.1 but now moved also to HDMI 2.0 on some components. It is also possible that some features are present only on specific ports on a TV/AMP and dual port players.
    UHD, ARC, HDR10, DV, MHL, HDCP2.2 are all good examples of features which may require specific port(s) to be used. So looking just at the HDMI version it is not possible to tell for sure which features are supported on a port. One needs to read the manual specifically for feature support and also associations/restrictions per port.

    3) As mentioned bandwidth was increased with the HDMI version, so that specification should tell the upper limit of bandwidth supported. Obviously a HDMI cable must match the required bandwidth too:
    I hope that helps to get a functional cable.

    4) A cable may seem to work perfectly well but may produce artifacts under specific conditions when stressed by higher signal rates (bandwidth). There are may factors contributing to the bandwidth: Video resolution and frame-rate are the obvious ones but also other variables like Audio (Atmos/DTS-X) , HDR (HDR10, DV, HDR10+) and above all the chroma settings (4.2.0, 4.2.2 or 4.4.4 and 8, 10 or 12 bit) will have a serious bandwidth impact. There are tables and pictures trying to visualize which feature came with which standard and/or bandwidth requirements but these never cover the complete picture.
    Most of mentioned factors also have a matching effect on bit-rates for I/O. So problems like stuttering should not be confused as these are more likely caused by a problem due to I/O limitations. Seen I/O problems myself with UHD/HDR/ATMOS specifically.

    5) Unfortunately there may be obscure (backward) compatibility problems too. I ran into unspecified compatibility problems using my Pioneer CD/SACD/DVD/BD player. It works perfectly with my AMP but not with my brand new fancy UHD/OLED TV. When connected via my AMP to that TV it will work only on ports 3 and 4 not on the ARC/HDR enabled ports 1 and 2. As the AMP needs to be in the chain the only solution was using the Dual HDMI port feature on the Pioneer. Audio out to the AMP and Video out to TV (dammed yet another cable needed to run to that TV). It now seemed to work but alas not for SACD as my TV clearly can't cope with the DSD signal of SACD (audio still forwarded also via the AMP to port 1 on the TV). This is even the case with the TV on standby (still doing EDID). So the cable must be unplugged to listen to SACD/DSD via discs which I do only for MCH SACD's.

    6) Last but not least there is HDMI-CEC which ought to make live easier. HDMI-CEC facilitates command control between all components connected together. It uses a specific set of pins on the connector. Having a full installation of the same brand HDMI-CEC may do magical things for you but having many brands as I do then it may do more harm than good. Fortunately HDMI-CEC can be disabled altogether or for specific functions. Mostly this is not specific enough with very few selections in my perception. Turning off the lot is then the better choice. Specifically Android media players are hampered with bad implementations of HDMI-CEC on earlier Android OS versions and may even require a HDMI-Blocker (interrupting the corresponding pins) to get rid of negative side effects when impossible to disable via settings.
    Be aware that HDMI-CEC is unlike EDID a bus type communication protocol making all components talk to each other on that HDMI bus. So all components connected to your AMP + all components connected to your TV in fact may and will interact which each other also indirectly. This is potentially very strong but alas also error-prone between brand specifically.
    As a start it is a good strategy to first disable HDMI-CEC on all gear and next gradually enable desired features one by one. Take your time doing so as undesired side-effects are to be expected and dealt with. Seen very strange interactions myself like a component always be switched to a wrong HDMI port automatically even when done by remote control. Last but not least be aware components typically react on HDMI-CEC also when in standby!
    Last edited: Apr 21, 2019

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