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tb_forum
Aspiring Contributor
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Message 11 of 28

Re: Ultra HD Not Ultra

55", approx 3m viewing distance.

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ozsat
Recognised Expert
729 Views
Message 12 of 28

Re: Ultra HD Not Ultra

When you press the 'info' button on the Samsung tv remote - what resolution does it say it is receiving when tuned to BT Ultra?

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using Superfast Fibre 2 Unlimited with BT TV Box Pro (UHD/HDR).
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delliott
Aspiring Expert
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Message 13 of 28

Re: Ultra HD Not Ultra

I have just flicked between BT sportEurhd on sky & BT 434 while watch the Liverpool man u game & picture & sound is miles better on uhd channel. Like flicking betwen a SD v a HD channel.
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653 Views
Message 14 of 28

Re: Ultra HD Not Ultra

The reason why UHD looks better is not so much the resolution that you cannot really see unless you are close to the screen but the bandwidth

An HD stream is around 3 mbps in H264 UDH is 25 Mbps in HEVC so at least 8x more information and HEVC is better than H264

 

In terms of being able to see all pixels you need 85" at 3 meters to see the difference nobody has got that

 

Alternatively you sit much closer

 

With a 55" TV you don't even see the benefits of HD at 3 meters you need to be around 2.1

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Keith75
Aspiring Expert
643 Views
Message 15 of 28

Re: Ultra HD Not Ultra

If you can't see the difference between SD and HD from 3 meters you need your eyes tested.
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umpire
Distinguished Guru
634 Views
Message 16 of 28

Re: Ultra HD Not Ultra

The BT TV multicast HD streams are much higher than 3Mbps. More like 8+Mbps for the sport channels.

These are not device adaptive unicast streams like on-demand services. These are fixed high quality multicast streams shared by many customers. Similar to terrestrial / satellite broadcast TV channels in that respect.
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620 Views
Message 17 of 28

Re: Ultra HD Not Ultra

Multicast is a way to reduce bandwidth consumption compared to on demand
Looking at the box recording specs it would indicate 3.5 mbps for SD and 7 mbps for HD on average
Those may make sense for live stream but considering that other than sports there is not much live mostikely those would be less
To the previoua person at 3 meters you see some benefits with a 55" but full benefit is at around 2.1 meters
This is based on 20/20 visual acuity

The reason why you see a larger difference is because Sd tv is **bleep** super compressed even more.
Try and get a DVD a bluray disk and a 4K professional clip at 3 meters of the same content to compare

So UHD better than HD that is better than SD simply because there is higher bitrate and more data not because of more pixels alone
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umpire
Distinguished Guru
615 Views
Message 18 of 28

Re: Ultra HD Not Ultra

Multicast is a transmission method designed for delivering shared linear 'live' streams. It is used for all the extra BT TV live channels over broadband, not just the sport ones. Often it is higher quality and higher bandwidth than device adaptive unicast on-demand streams. As I said previously, similar to broadcast channels in that respect. One single level of high quality for all viewers.

The BT boxes use unicast for on-demand which can't be recorded. The average figures for SD / HD based on disk space usage only relate to multicast live channel stream recordings.

Your earlier statement of an HD stream being only 3Mbps is incorrect for the multicast live streams BT TV uses for extra channels.
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605 Views
Message 19 of 28

Re: Ultra HD Not Ultra

Being multicast does not mean higher bandwidth by itself
From the spec of the recorder it would seem that the rates are 3.5 and 7 for SD/HD but those look very high for non live TV
Regardless this was not the point I was making. The point is the higher the bitrate the better resolution is just the banner of this
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umpire
Distinguished Guru
599 Views
Message 20 of 28

Re: Ultra HD Not Ultra

The HDD can be used to record broadcast as well of course.

Don't believe the multicast figures if you don't want to but there have been many threads about it. You can view the low quality 544x576 3/4 SD preview channel 399 on a PC and see the rate for that is 2.5 - 3.5. People have also run speedtests with streams running or not and one customer posted charts from a tool monitoring the BT Sport 1 HD 1080 stream. It ran normally at around 7.5 - 8.5 during the football.

Not sure why you are so sceptical. Satellite HD channels can run at much higher rates. Freeview HD channels are also of that order.
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