View Full Version : [Zgemma H7] Aspect ratios and Scaling.
BrianTheTechieSnail
06-07-20, 19:51
I have set my box to always output 1080p to match the native resolution of the TV I use with it.
That way the on screen text (menus and so on) are always nice and sharp and legible.
In most cases the box can be correctly fit and scale programs if I use the V.MODE button on the remote.
If the program is correctly identifying itself as 4:3 or 16:9 then "PanScan" seems to be the correct setting,
but why? Surely one would expect "Auto" to be correct?
Unfortunately no option can correct the case of a 4:3 program that incorrectly identifies itself as 16:9. Why?
A 16:9 program that incorrectly identifies itself as 4:3 is easily fixed, why not the opposite case?
Also is there any way to cope correctly with program that identifies as 720x576 but actually only uses 704x576 as the active area?
I don't like the narrow black bars down the sides.
Also I notice that when playing bacl a recording the V.MODE button does nothing! Why?
BrianTheTechieSnail
11-07-20, 03:27
Nobody cares at all?
I wish I'd hadn't made those contributions to the running of this board now.
Nobody cares at all?
I wish I'd hadn't made those contributions to the running of this board now.
This is a hobby, I make contributions but don‘t expect applause for doing so.
So having spent the last 3 weeks in hospital and rehab I will try some answers.
1st all remotes are different, the fact that you have a vmode button on the zgemma remote is a pure fluke - none of the other remotes for the selection of receivers that I have, offer this button.
At the moment, there are people that also actually add features to the image, trying to unify the remote code over all the major images that hopefully will help move forward.
In the meantime, I have no issues with running at 1080/2160 and auto - it all works for me........ and black bars might be ‘ugly‘ but thats because thats the format of these old programs
BrianTheTechieSnail
11-07-20, 13:45
This is a hobby, I make contributions but don‘t expect applause for doing so.
So having spent the last 3 weeks in hospital and rehab I will try some answers.
1st all remotes are different, the fact that you have a vmode button on the zgemma remote is a pure fluke - none of the other remotes for the selection of receivers that I have, offer this button.
At the moment, there are people that also actually add features to the image, trying to unify the remote code over all the major images that hopefully will help move forward.
In the meantime, I have no issues with running at 1080/2160 and auto - it all works for me........ and black bars might be ‘ugly‘ but thats because thats the format of these old programs
That's odd. I find auto displays everything so that it fills the whole screen.
You didn't quite understand what I meant.
I do want 4:3 stuff to have black bars and the correct aspect ratio.
What I'm also hoping for is 16:9 stuff that is actually 704x576 but identifies as 720x576 to have just the 704x576 part displayed correctly as 16:9, not the whole 720x576 which gives slightly wrong aspect ratio and tiny black bars on the sides.
Compare BBC 1 SD and BBC 1 HD. BBC 1 SD is slightly squashed horizontally, often with thin black bars at the sides.
The that is more likely your TV set and its display options - make sure its set to “just fit“ or the equivalent on your TV
BrianTheTechieSnail
11-07-20, 15:15
The that is more likely your TV set and its display options - make sure its set to “just fit“ or the equivalent on your TV
No.
OpenVIX is set to always output 1080p and the TV is set to 'just scan' so it displays the whole 1080p image on it's 1080p screen.
That's odd. I find auto displays everything so that it fills the whole screen.
You didn't quite understand what I meant.
I do want 4:3 stuff to have black bars and the correct aspect ratio.
What I'm also hoping for is 16:9 stuff that is actually 704x576 but identifies as 720x576 to have just the 704x576 part displayed correctly as 16:9, not the whole 720x576 which gives slightly wrong aspect ratio and tiny black bars on the sides.
Compare BBC 1 SD and BBC 1 HD. BBC 1 SD is slightly squashed horizontally, often with thin black bars at the sides.
I think the black bars you are seeing on BBC 1 SD are in the broadcasted picture. I was just observing the local news and the black bars were varying in size between different reports and also between the weather segments. It is the same when viewing on my Humax Foxsat.
However when viewing directly on my Freesat LG TV it doesn't show the bars so it must be detecting them or doing some overscanning by default.
What I'm also hoping for is 16:9 stuff that is actually 704x576 but identifies as 720x576
Isn't that the answer to your question - "identifies as". You possibly haven't enabled the recievers' cystal ball and it doesn't know that it's 704x576. Sometimes the black bars at the edge of the picture are not constructed in the reciever but are actually broadcast as part of the overall active picture - transmitting a static part of a picture takes little bandwidth.
BrianTheTechieSnail
11-07-20, 23:43
Isn't that the answer to your question - "identifies as". You possibly haven't enabled the recievers' cystal ball and it doesn't know that it's 704x576. Sometimes the black bars at the edge of the picture are not constructed in the reciever but are actually broadcast as part of the overall active picture - transmitting a static part of a picture takes little bandwidth.
But doesn't ITU-R BT.601-4 mean that for 16:9 broadcast TV you should only display the middle 704 (or is it 702) pixels of something that's encoded as 720x576?
Edit: Maybe it doesn't now that there is no analog TV anymore?
Thats an old recommendation. Its been revised to BT 601-7. Its a recommendation not a standard btw and even then will only refer to transmitting 525/625 line analog in digital format (not SD as such). Anyway you had better get writing to the broadcasters if you feel its being done wrong.
BrianTheTechieSnail
12-07-20, 13:42
Thats an old recommendation. Its been revised to BT 601-7. Its a recommendation not a standard btw and even then will only refer to transmitting 525/625 line analog in digital format (not SD as such). Anyway you had better get writing to the broadcasters if you feel its being done wrong.
Er. Wouldn't what I'm saying amount to saying that when it's done right OpenVIX still displays it like it's wrong?
The receiver can only display what it receives - if the format is wrong in the first place don't be expecting openvix devs to be correcting it. Black bars are used to maintain correct aspect ratios. I think you are going too far down a rabbit hole here. BBC SD is 720 x 576 on satellite. Of course the aspect ratio is different to 1920 x 1080 HD (do the maths) and believe it or not you will have to live with it. The edges of the analog SD picture can be used by old fashioned teletext among other things that is why there is overscan on modern TVs. With digital the full area may be used. BBC uses 720x576, ITV uses 704x576 and so what - neither are wrong. Some HD is 1440 x 1080 and people live with it. Instead of nit picking just watch the HD variant.
Er. Wouldn't what I'm saying amount to saying that when it's done right OpenVIX still displays it like it's wrong?
Is it a (VIX) software issue or a function of the native hardware?
Does it really matter that the aspect ration is out by 0.6%. Most people put up with a lot worse streching 4:3 to 16:9 without destroying their enjoyment of the content.
Menu/Information/Service might give you a clue what's being sent to your tv.
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