Why does HMDI need such high bandwidth compared to Ethernet?

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When we stream 4k video from Netflix for example, they recommend a minimum speed of 25 mbps.But HDMI 2.0 has a bandwidth of 18.0 Gbit/s

How can we recieve 4k video with a connection speed of only 25 mbps when we need 18.0 Gbit/s to send the video to our TV?

I think it is to do with compressed vs raw 4k but do we really compress it to this an extreme? I would have thought this would result in so much loss that we are no where near 4k in the end.

In: Technology

7 Answers

Anonymous 0 Comments

4K video is 3840 × 2160 pixels with 3 colors and 8 bit per color.

So you need 3840*2160*3*8=199,065,600 bit for a single frame. At 60 frame per second that is 11,943,936,000 bits or 11 Gbit/s

The first 4K video at 60 Hz on Youtube I founds was https://www.youtube.com/watch?v=LXb3EKWsInQ it is 961.43 MB for 5:13 video

The amount of data per second is 961.43*1024^2*8/((5*60+13))=
25,767,000 bits per second. This includes audio so the video size is smaller

That is a compression range of 463:1 even if audio is included in one but not the other.

So the answer is compression that reduces file size but factors of a couple of hundred times.

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