HDMI cables and 4K

Just a quick note on cheap HDMI cables. I’ve previously ranted about the unfortunate fact of expensive HDMI cables being sold in consumer shops, the outlandish claims so often made for them.

A while back I purchased from The Cable Connection a bunch of cables, including a ten metre HDMI one plus a 5 metre one plus some shorter ones. The cost of the ten metre one? Just $49.95 (one of my other ten metre cables retails for about $700!).

As it happens I for the moment have a full 4K system — UHD TV, Oppo Blu-ray player with 4K upscaling and home theatre receiver with 4K passthrough and upscaling. Which makes for an opportunity to test out the cables. 4K worked fine via 2 metre from Oppo to the receiver and thence via 5 metre cable to the Sony 4K TV. The signal was 24p.

All cables were low cost ones from TCC. I switched to a ten metre TCC cable from receiver to TV. Still perfect performance. The Oppo wouldn’t upscale 1080i60 to 4K at 30p, which is the highest bandwidth signal the TV is capable of accepting. But the receiver could, so I put on a 1080i60 Blu-ray disc and had the receiver upscale it. Still perfect performance at 4K and 30p.

Don’t get ripped off on your HDMI cables.

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2 Responses to HDMI cables and 4K

  1. Craig says:

    Hi Stephen,

    What did the 60i converted to 30p (@4K) look like?

    Assuming it was true 60i, with each field different in the temporal domain, it would have to either throw out every second field and upscale each 540 line field to 2160@30p, or try to blend or weave both fields (all 1080 lines) into 2160p, possibly resulting in combing or other unwanted artifacts.

    Either way you look at it, it’s halving the number of pictures per second from 60 to 30.

    Not until HDMI v 2.0 will it be capable of true UHDTV (4K) at 60 frames per second.



  2. Hi Craig

    It looked variable. All I was interested in testing was whether the cable worked, so I grabbed something I knew to be 1080i60, and that was a Dolby demo Blu-ray. The interlaced content looked okay, but now that you mention it I was probably losing half the frames. That all depends on the processing in the receiver. The film clips looked bad, but that was because they were juddering due to the 24fps to 30fps conversion when the disc was made.

    Fact is, I don’t really care too much about 4K picture quality from these sources because I always recommend that you deliver 1080p stuff at 1080p and let the 4K TV/display do its processing on it.

    When we go full 4K — with actual 4K sources — then all bets are off on cables since the bandwidth will be increasing yet again. But actual 4K sources still seem to be quite some way off, and the bulk of 4K material is likely to remain 24p into the future (I’d like to see 48p included as a standard, too, so we can get The Hobbit the way it was shot.)

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