Un-scaled output on Freesat?

idleandy · 12-01-2009, 4:22 PM

HI all, furthering on from a previous question I had answered re upscaling Im keen to eliminate as much 'rescaling' steps as I can as it can only be detrimental to the end picture. I would like my Freesat Humax Foxsat receiver to just to pass on over HDMI what it has received with no rescaling. I'll let my Panasonioc Viera do that bit! Ive scanned the settings and cannot see anything obvious, anybody know if this is an option and how do I select it if not default?

Many Thanks, A.

u006852 · 12-01-2009, 5:00 PM

Press the Vformat button on the remote until "original" is shown on screen.

This will output 576i with SD and 1080i with HD.

idleandy · 12-01-2009, 5:09 PM

I did wonder what that meant thanks! OK follow on question then..... At the risk of completely confusing the issue, Do you happen to know if my Panasonic TX-37LZD70 would then up-scale automatically to suit its requirements? Again not sure how I control that if at all???

determined to work out this scaling stuff!

alsina · 12-01-2009, 5:22 PM

Everything received by the tv is automatically upscaled to 1080p before being processed, then displayed. There is the 'Overscan' setting in the 'Setup' menu, but this should be left on for SD broadcasts if you don't want to see noise around the edges of the picture.

grahamlthompson · 12-01-2009, 6:52 PM

Quote:

Originally Posted by alsina

Everything received by the tv is automatically upscaled to 1080p before being processed, then displayed. There is the 'Overscan' setting in the 'Setup' menu, but this should be left on for SD broadcasts if you don't want to see noise around the edges of the picture.

It's not 1080p it's 1080i A frame is built in two passes (interlaced) and then passed to the TV so although the display is inherently progressive the data to build the picture is not. Only blue ray (an HD) can produce a 1080p picture and the majority of HD TV's can't handle 1080p.

And this is only if the TV has a full 1920 x 1080 display. A HD ready TV will scale to something like 1320 x 768 or whatever it's native screen pixel count. Again as the source is interlaced so will the screen picture be.

alsina · 12-01-2009, 6:56 PM

Sorry, to clarify, I meant that the first thing the processor in the OP's tv (TX37LZD70) does is upscale the signal to 1080p before processing it and then displaying on the screen. I realise the Humax receiver's output only goes up to 1080i.

col996s · 12-01-2009, 11:17 PM

Quote:

Originally Posted by u006852

Press the Vformat button on the remote until "original" is shown on screen.

This will output 576i with SD and 1080i with HD.

This only seems to work for me when I am outputting an HD channel ie on BBC HD, 108. When I am watching an SD channel the vformat button does not scroll through and just says "1080i" Is this correct?

grahamlthompson · 13-01-2009, 10:04 AM

Quote:

Originally Posted by alsina

Sorry, to clarify, I meant that the first thing the processor in the OP's tv (TX37LZD70) does is upscale the signal to 1080p before processing it and then displaying on the screen. I realise the Humax receiver's output only goes up to 1080i.

It's very unlikely that the TV scales to 1080p for any input pixel dimensions, this requires a complex delinterlacing process. The signal will most likely be scaled to 1920 x 1080 pixels but will remain interlaced. (Half the picture data based on the first half of the frame data and the other half of the picture data based on the second half). A 1080i signal will not be processed at all (unless it's a 100Hz set) but simply passed to the screen as it already has the right pixel count.

idleandy · 13-01-2009, 10:36 AM

Quote:

Originally Posted by col996s

This only seems to work for me when I am outputting an HD channel ie on BBC HD, 108. When I am watching an SD channel the vformat button does not scroll through and just says "1080i" Is this correct?

Col, This should work on both SD and HD channels...... just tried it OK on mine! Are you connected using HDMI cable?

col996s · 13-01-2009, 12:05 PM

Quote:

Originally Posted by idleandy

Col, This should work on both SD and HD channels...... just tried it OK on mine! Are you connected using HDMI cable?

Yes I am. I'll try again tonight.
Do you notice a difference in the picture when in the different modes?

idleandy · 13-01-2009, 12:38 PM

Quote:

Originally Posted by col996s

Yes I am. I'll try again tonight.
Do you notice a difference in the picture when in the different modes?

To be brutally honest Col...... no not really!! Now whether that says more about my eyesight or how wonderful my Panasonic is at handling inputs Im not sure!!

Good Luck tonight!

Andycole1970 · 13-01-2009, 1:16 PM

I have a Panny 42PZ800 connected to my HDR and I tried changing the Vformat setting as some other people on here suggested. I noticed a slight difference in picture quality on SD broadcasts - a negative one. I preferred it when the box is set to 1080i. Also, and this is a big difference - when you have it set to 'original' and then use a menu on the HDR box, all the drawn menus will be in the native resolution as well, so all of a sudden the menu system looks blocky and blurred.

Lastly, when the HDR box switches between 1080I and 576i, there is a slight pause in transmission and my screen goes black while the TV re-sets it's input.

So, in summary, I think it's best to leave it at 1080i

Andy

idleandy · 13-01-2009, 1:43 PM

Actually just been re-checking and certainly you get a truer sharper picture when viewing HD at 1080i (Original) as one would expect.....if youve been watching an SD channel with original set (576i) dont forget to change it to proper 1080i when viewing ch108 (HD). I think thats where I was going wrong..... as Andy suggests better to perhaps leave it set to 1080i and 'suffer' the upscaling to your SD pictures!?

alsina · 13-01-2009, 8:32 PM

Quote:

Originally Posted by grahamlthompson

It's very unlikely that the TV scales to 1080p for any input pixel dimensions, this requires a complex delinterlacing process. The signal will most likely be scaled to 1920 x 1080 pixels but will remain interlaced. (Half the picture data based on the first half of the frame data and the other half of the picture data based on the second half). A 1080i signal will not be processed at all (unless it's a 100Hz set) but simply passed to the screen as it already has the right pixel count.

Unlikely, but in the case of Panasonic tv's from 2007 onwards, it seems to be the case from our Panasonic training at work and the attached documentation.

col996s · 13-01-2009, 8:35 PM

Just tried it again on my Humax box and when watching an SD channel no matter how many times I press the V-format button the screen goes blank for a few seconds and then always comes back with "1080i" It only seems to work in HD mode!

grahamlthompson · 13-01-2009, 9:14 PM

Quote:

Originally Posted by alsina

Unlikely, but in the case of Panasonic tv's from 2007 onwards, it seems to be the case from our Panasonic training at work and the attached documentation.

Well you live and learn don't you. I still wonder if this is not exactly the true case as the original signal contains only interlaced frames the second half of the frame can only be a guess based on the previous and next but one half frame. I guess this might be better for fast movement than 1080i but it can't be true 1080p. It would be very interesting to find out more about how it works.