HDMI protocol.

[Dave Liquorice]

Yes, but they ain't cheap by comparison with the analogue ones.

[Fredxxx]

The output will follow the Sink capabilities, up to the maximum you specify in your PVR.

Your PVR will interrogate a Sink and set its output accordingly. If one set says no signal, it's quite likely it doesn't recognise it. The bit I don't understand is why your kitchen set should behave differently when using HDMI input 1 or 2.

Either the signals are marginal or the standard is one the set can't cope with.

[Dave Plowman (News)]

You are trying to compare audio and video bandwidth?

Novel.

With the PAL system, the theory was the eye has a different bandwidth at different frequencies.

So PAL had a wide luminance bandwidth and lower (and different) bandwidths for RG&B.

Basically, a high resolution B&W picture with low resolution colour information washed over it.

[Fredxxx]

The colour subcarrier for NTSC was indeed 3.4MHz and that for PAL was

4.4MHz, with different national variants.

I see the wiki quotes a colour bandwidth of 1.3 MHz, but I believe the number quoted is full bandwidth so the signal bandwidth is halved, say

650kHz.

An HD 1080p or 1080i system will generally have 1920 horizontal samples of Luma and colour difference. The colour difference will be alternate blue and red difference signals, so 960 samples. For 1080p at 50Hz, the line-rate would be 50kHz, so 960 samples would be 50MHz.

So simply 80:1 difference in quality in one form of comparison. In practice the square root would be a better measure, so say 9:1?

Of course there are other considerations such as artefacts that MPEG produces and the appalling compression broadcasters are forced to use on their limited bandwidth. Hence the DAB fiasco!!

[Dave Liquorice]

"levels of HD" isn't quite right. As I understand it a HDMI destination device such as a TV/monitor tells the HDMI source device what it supports, in terms of frame rate and pixel ratios. They then select the highest quality common format. I'd guess that active splitter box looks at the the two lists of capabilties chooses common settings between them and forwards that combined list to the source so that the highest common setting across all three devices is choosen.

There is also automatic input selction and various settings associated with that. The HDMI settings page of my OSMC media player has "Physical address (Overules HDMI port)" and "COM port (leave empty unless needed). The former looks as if it overides the default HDMI port number being used, ie your HDMI 1 and HDMI 2 input issue. Donno about the latter, things do seem to be talking to each other, but it might be another lead.

[Dave Plowman (News)]

Which is what seems to happen. Both sets work perfectly with either an SD or HD signal from the PVR.

That's promising. My initial thoughts were something doesn't like seeing two inputs both called HDMI 1

It really isn't that much of a problem in practice. But if there were a simple cure, I'd use it.

[Fredxxx]

Correction NTSC subcarrier was 3.58MHz.

[Dave Liquorice]

player

default

issue.

other,

I guess it depends if the menus on either telly allow the "physical address" to be set by the user. I can't say I've ever seen that but it might be in a hidden engineering menu.

[Fredxxx]

Yes, I agree, but doesn't HD video have a similar split of bandwidth between Luma and Chroma? I recall most MPEG transmissions use YUV-4:2:2 format.

As are most non RGB video standards.

[Lee]

Just to clarify, the CEC command is switching the main TV to HDMI 2, when the PVR is powered on, not that the switcher box is selecting it's own HDMI 2 output?

My guess is that it's a CEC issue - good luck with that, it's difficult enough to get the same brands working together at times :( Link to a pdf explaining CEC:

[Dave Plowman (News)]

Both TVs are fed from the DA. The main TV using HDMI 1. The second TV won't work using its HDMI 1, but does on HDMI 2.

If you bring the PVR out of standby so the main TV switches on - or to the PVR if already on - it selects HDMI 2. Select HDMI 1 manually, and everything is tickety boo.

So not a deal breaker - just slightly annoying.

The other thing I haven't mentioned is the run to the kitchen is too long for HDMI cable (about 15 metres). So there is a passive conversion box at either end to CAT5E cable. Which seems to work just fine.

Thanks.

[Lee]

I don't know if the hdmi->cat5e and back again will even pass CEC information, but if it does then maybe look at disabling CEC on the second set first, it's usually buried in the menus somewhere.

I have read about people disabling Pin 13 by bending the pin/butchering the cable - but fortunately I've not had to do that. Yet.

Oh, I have one of those "active" 3 way HDMI splitters as well, technically it "works" I guess but very temperamental on which of it's outputs it decided to switch to and annoying to have to keep manually selecting the right one. Threw it in the back of the cupboard when I upgraded the amp :)

[John Rumm]

There would be little point since there is nothing in the TV that could decode it. You would have to down convert the HD signal to SD first to make that idea work.

[Dave Plowman (News)]

I was assuming it plugged into an HDMI port and coded up either SD or HD as required to be fed into the aerial of another set.

If it were to work like the older UHF ones you got on VCRs etc.

But I've not heard of such a device.

And I don't have a TV anywhere with an analogue tuner, so couldn't use the older UHF type even if I wanted to. Which I definitely don't. Even when it was the norm with a crappy device like a VHS, you still got better results with a composite feed. And S-Video even better.

[Andy Burns]

Bill has mentioned such devices for use in distribution systems

They're not exactly household items, I saw a price ~£380

[Dave Plowman (News)]

Yes - I can see they might be needed to feed something extra into an estate aerial distribution system or whatever. But with smart TVs at home you could probably do much the same via Wi-Fi or BlueTooth, without the extra expense.

[tony sayer]

In article , Dave Plowman (News) scribeth thus

Sure about that as we bought a TV the other week for a job and it still had an analogue tuner in it!.

[John Rumm]

In fact I just realised I misread what you posted anyway - I waws assuming you meant encoding HD video for UHF modulation.

If you can get from HDMI to SD analogue, then you could UHF modulate that.

Something else you can do (not that it necessarily helps here) is convert from HDMI to 2xCAT5e and back to HDMI - it makes running long distances easier without needing HDMI repeaters etc.

CYP/Lektropaks would be one maker of gadgets to check.

A surprising number of modern DTTVs still have analogue tuners...

[Dave Plowman (News)]

Yup - had to do that for the run to the kitchen which is about 15 metres. Works very well. Cheap too - if it were available, a HDMI cable of that length would cost more than the CAT5 plus adaptors.

[John Rumm]

I had to try some recently as well... I have a client in the process of building a call centre / training suite which will be needing multiple screens on the wall for various applications - most driven from a central PC with multiple video outputs. I drop shipped loads of long HDMI leads to the builder to plaster into the walls so that each TV position was wired and ready. What I did not realise was that the leads had a repeater mid length, and hence were directional. They were also somewhat inconsistently marked. Needless to say we got a random distribution of lead orientations, and hence several non usable ones. Fortunately each position also has a pair of CAT5s so those adaptors will prove to be a quick way out, without having to chase the wall again after its all finished.