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News Archive >> 3D WILL run through existing HDMI cables

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Comments were put together by CEDIA members David Meyer (Kordz) & Michael Heiss

3D WILL run through existing HDMI cables. However we do believe that 3D will ‘up the ante’ in terms of quality of cable, but from a bandwidth perspective, nothing changes... yet. Virtually all currently deployed HDMI over 5m in length (generally) are NOT High Speed, rather Standard Speed certification level, but with sufficient headroom to enable 1080p operation. Note that these cables are only certified to 720p/1080i (provided they are certified at all!), and used without compliance to 1080p level. Most installers don’t really care about certified performance, just “whether it will work” – unfortunate, but fact. This will however become more of an issue moving forward.

1. 3D from Blu-ray has been mandated at an initial maximum of 1080p/24 per eye, meaning effectively 1080p/48 combined data rate – less than the current 2D standard of 1080p/60. So if the HDMI cable supports 1080p/60 fine now, it will also support 3D from Blu-ray no problem. Note: it is insufficient to talk resolution without referencing frame rate as it does not otherwise define the data rate. Gaming has been defined under the new specification 1.4a (out just last week) that 720p/60 per eye be supported, but gamers will likely want 1080p in due course. When this happens I predict that we’ll see gaming go to 1080p/60 per eye, meaning nearly 9.0Gbps – DEFINITELY High Speed and nothing less – currently cables that support 1080p/60 in 2D, but without High Speed certification, will NOT support 1080p/60 in 3D. In the meantime though, support for such high res/frame rate has not been made mandatory, and is merely speculative.

2. It is NOT necessary to upgrade to a so-called “HDMI 1.4” cable to enable 3D support. Also, any cable which is referred to by the manufacturer as “HDMI 1.4” is in fact non-compliant due to its breach of the HDMI Logo & Trademark guidelines. So, should you care if a cable is simply mislabelled? Absolutely! Labelling the cable in a compliant manner is the easy part; making the cable to perform in a compliant manner is actually the really hard part. If a manufacturer can’t get the small stuff right, how can they be trusted with the big stuff?

3. For broadcast, the HDMI 1.4a specification mandates support for 720p & 1080i @ 50/59.94/60 refresh rates (NOT 1080p at all), using “over and under” and “side by side” 3D formats. This means both left and right eye images share the same frame, keeping bandwidth the same as current 2D equivalents, but effectively halving the resulting resolution per eye when displayed on screen. Bottom line, Standard Speed HDMI is fine for broadcast

4. So will HD Set top boxes need to be HDMI 1.4 compliant to handle 3D? This all depends on whether the set top box will have any requirement to know that an incoming broadcast signal is 3D, and flag it as such. If so, then firmware will need to be upgraded, effectively changing the device to HDMI 1.4a compliance (I suspect this will be the case). If it’s just a slave and throughputs the signal passively, with the broadcaster flagging the content for a display to recognize it as 3D and do its thing, then the boxes wouldn’t need an upgrade and 1.3 spec is fine (highlyunlikely). Either way there will not be any hardware change, at least not specifically for the 3D feature. That is, it is expected that all devices will require 1.4a compliance to support 3D, but that does not mean having to buy all new devices – some will simply be firmware upgraded. Sony are already offering this with some of their Blu-ray players.

As for HDMI Ethernet Channel (HEC), this is an optional extra feature of both devices and cables, with the latter requiring the additional label “...with Ethernet” on cables. As Michael says, HEC is not used at all for 3D – this is absolutely true. The Audio Return Channel will use the HEC for best results, but can also still work in “Single Line” mode through cables without the Ethernet Channel. So choosing a HDMI cable with Ethernet Channel opens up support for distribution of Ethernet over HDMI, and the most robust operation of Audio Return Channel. It is NOT required for 3D.

So, suffice to say that HDMI cables that currently support 1080p/60 can continue to be used for 3D from all sources, but with new installations, upgrading to true certified High Speed will certainly give a far superior degree of “future proofing”, especially when considering where gaming is likely to go.

We hope this helps answer some of the mysteries out in the industry.

Date

Thursday 11 Mar 2010 - Friday 11 Mar 2011