Aspects of aspect ratio

Still having fun exploring the features of my new HDR-FOX T2.

One thing which I've noticed regarding aspect ratio settings: my Panasonic plasma is set to 16:9, as is the Humax. With Display Format set to 'Auto' it slightly squeezes the centre of the picture and stretches the sides on some channels, most notably BBC News Channel. Not as obvious as the 'stretch 4:3' setting you get on some TVs but still noticeable. This was throwing me for a while as 'Auto' appears to be the default.

Setting Display Format to 'Letterbox' cures the problem. Is this because BBC News Channel is broadcast in something slightly less than than 16:9? I've never noticed this problem with my Virgin Tivo box or my old 9200T.
 
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selectortone

Member
Coming back to the slight squishing effect in the middle of the picture and stretching at the edges I mentioned above - the BBC News Channel pictures on my Virgin Tivo box, and on the built-in Freeview tuner in my Panasonic plasma TV, sometimes have thin black bars on each side. The aspect ratio changes slightly at times. Set to 'auto' the Humax doesn't have black bars ever. So 'auto' on the Humax obviously doesn't mean what I have come to expect it to mean from other systems - i.e. select the correct ratio; it means something else - lost in translation I suspect.
 
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selectortone

Member
Auto does what I wrote in the second link in post 2.

Not exactly - it also slightly compresses the picture horizontally in the middle. And I don't believe this "non-linearity in the image should be ascribed to the TV" as you have previously asserted because the phenomenon isn't apparent on my Tivo box or the TV's built-in freeview tuner.
 

Black Hole

May contain traces of nut
Under what exact circumstances? I can't see any compression (nor can I understand why it should).

Currently viewing All Creatures on Yesterday, 4:3 source output to 16:9 screen ("screen fit" - no overscan) with the Humax set to Auto (yuck). I'm looking for circular objects changing shape as they pan across the screen. Anything that changes angle produces a weird effect. I see what you mean, things at the edge appear as if they are more stretched than in the middle, but I cannot see any shape shifting on pan shots. The perception could be a brain thing.

The only way to resolve it for sure is to put up a grid test card - I will have a go at that later.
 
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selectortone

Member
It varies from channel to channel. Try Channel 80 - BBC News, set Display Format to auto and look closely at the newscaster's face when they are mid-screen. Does it look a bit pinched?
 

Black Hole

May contain traces of nut
I'll have a look, but BBC NEWS is transmitting 16:9 so Auto shouldn't have any effect at all.
 

Black Hole

May contain traces of nut
I paused an image (BBC ONE channel ident with the "o" in the centre of the screen) and then flicked between pillar box, zoom, and auto. With a 16:9 source outputting to 16:9, they should all be the same - and indeed they were, showing no shifts at all. I am preparing a pair of test grids to check screen linearity, but I'm pretty sure I know which way this is going.
 
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selectortone

Member
As I said previously - it is most apparent on the BBC News Channel and doesn't happen all the time. The picture is most often 16:9, but sometimes it's a little less horizontally - there are thin black bars on the sides. That's when the non-linearity and the squished centre occurs if display format is set to 'auto'.

Sorry if you feel you're on a wild goose chase but I'm definitely seeing something, but not all the time.
 

Black Hole

May contain traces of nut
Sorry if you feel you're on a wild goose chase but I'm definitely seeing something, but not all the time.
I view it in the spirit of scientific enquiry. There is a point to be resolved, and I am not satisfied until there is clear indesputable evidence to resolve it.

Regarding thin black bars to the left and right, I think you should read THIS (click).

I have prepared two 30-second test card MP4s - TestCard16x9 is a 1280x720 field ruled in squares with diagonal lines, and TestCard4x3 is a 640x480 field similarly ruled. If the TV is overscanning it will not show the grid lines at the border of the frame. The rules are a 16x9 or 12x9 grid respectively, so they should be squares. The diagonals will not be straight if there is non-linear distortion horizontally or vertically (but not if the horizontal and vertical distortions are the same).

The result of me displaying these via my HDR-FOX and HDMI to my Samsung 32EH5000, Samsung set to "Screen Fit" (ie no overscan), using any combination of test card and pillar box, zoom, or auto, is absolute linearity.

Case closed as far as I am concerned.

TestCard4x3.mp4
TestCard16x9.mp4
(Right-click and select "save target as", copy to USB and transfer to HDR-FOX.)

Here is what you should see (widescreen TV, ie 16:9, Humax video preferences set to 16:9):
  • With overscan turned off (TV settings), TestCard16x9 shows a matrix of squares, 16 horizontal x 9 vertical, with a white edge all round. Diagonal lines meet at the edge of the frame The squares are of even size across the whole frame, and the horizontal, vertical, and diagonal lines are all straight (compare against a ruler). Changing the Humax "WIDE" button setting between "Pillar Box", "Zoom", and "Auto" makes no difference whatsoever.
  • With overscan turned off (TV settings) and the Humax "WIDE" button set to "Pillar Box", TestCard4x3 shows a matrix of squares, 12 horizontal x 9 vertical, with a white edge all round. Diagonal lines meet at the white edge of the test card. The squares are of even size across the whole frame, and the horizontal, vertical, and diagonal lines are all straight (compare against a ruler).
  • With overscan turned off (TV settings) and the Humax "WIDE" button set to "Auto", TestCard4x3 is stretched horizontally so that it now fills the TV frame, with the white edge visible all round. The "squares" are now rectangles and the diagonals are no longer at 45 degrees, but all the lines remain straight.
  • With overscan turned off (TV settings) and the Humax "WIDE" button set to "Zoom", TestCard4x3 is stretched horizontally so that it now fills the TV frame, with the white edge visible at the left and right edges, and it is also stretched vertically so that the top and bottom portions of the test card are no longer visible. The squares remain squares and the lines are all straight.
  • With overscan turned on (TV settings), the above results are similar except the edges of the test card exceed the edges of the TV frame (the white border is not visible and the diagonals do not meet at the edge of the frame). Overscan is the default TV setting for the internal tuner and typically TVs do not allow an overscan-off setting when using the tuner.
If during these tests the TV shows any non-linearity (the lines, including diagonals, are not straight and/or squares are not of even size across the whole frame), this is the fault of the TV or its settings. Some TVs have a "panoramic" setting, typically used to fit a 16:9 picture onto a 4:3 display by squashing the image horizontally progressively towards the edges.

If the TV shows no non-linearity but broadcasts appear to be non-linear, this must be due to the broadcast itself. The camera in use could be fitted with a wide-angle or anamorphic lens - these distort the image in a non-linear way.

To view Humax output (recorded or live) in the same way as the TV would have displayed it from its own tuner, the TV must be set to overscan on the HDMI input. Broadcasters appear to expect an overscan region and do not always provide picture content right up to the edge. On the other hand, for the best possible HiDef picture (mapping the content pixels exactly with the TV screen pixels without interpolation) it is necessary to turn overscan off.
 

Ezra Pound

Well-Known Member
Just generated this, it might be of some use :-

16X9.jpg

click on image then right click and select 'save image as'

Or MP4 Movie version HERE
 

Black Hole

May contain traces of nut
As far as I can remember, still images displayed by the Humax as photos are always stretched to fill the display frame.
 

dandnsmith

Forum Supporter
I downloaded BH's test card files, and tried to play them - but they both gave a 'bad format' report.
I have no trouble with mp4 files generated by me, so I wonder what the problem can be.
 

prpr

Well-Known Member
As far as I can remember, still images displayed by the Humax as photos are always stretched to fill the display frame.
Which is OK in itself, but it also distorts the aspect ratio on every picture I have tried it with. This makes it completely and utterly useless for its intended purpose. One wonders why Humax bothered implementing a feature that nobody can/will use. Perhaps they just did it because everybody else does it. They obviously put no thought into it.
The MP3 playback stuff is similarly crap in that you have almost no transport controls and it behaves in a completely illogical way.
 

Black Hole

May contain traces of nut
Agreed. We (the collective) dismissed the HD/HDR-FOX for anything other than video a long time ago. As it happens I do use MP3 playback occasionally, but never photos. One could press it into service if a background slide show was required at a party or something, but one would have to pre-process the images to 16:9 landscape.
 

Black Hole

May contain traces of nut
I downloaded BH's test card files, and tried to play them - but they both gave a 'bad format' report. I have no trouble with mp4 files generated by me, so I wonder what the problem can be.
The original files played for me - I will try them downloaded later.

I used the links to download the files to a fresh UPD, and plugged it into HDR1 (I used HDR3 last time). I then played the files from Media >> Storage (blue) >> USB, and they were fine. In the absence of any further information*, I'm sorry to say the problem seems to be your end.

* The only difference I can think of, apart from operating system differences (Win7, IE8), is that I am logged in to my Dropbox account. Can somebody else confirm the files download and play correctly/incorrectly?
 
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