Freeview widescreen - what aspect ratio is it, 16/10?

Charlie Pearce wrote:
On Sat, 15 Oct 2005 23:04:44 +0100, "Ian" wrote:


"HS Crow" wrote in message
...
I have a Humax PVR connected to a CRT TV via SCART. If I set the
Humax to TV=4/3, Output = 16/9, I get a letterboxed image as
expected. However, the image is not as widescreen as when playing
DVDs. I measured the image and it appears to be roughly 16/10. Is
this correct? My reason for asking is that I'm looking to buy a new
Freeview PVR and widescreen TV and I'm trying to discern if there
are any interoperability issues that I need to be aware of.

If you set the TV to 4:3, you must be getting an incorrectly
distorted image. Broadcasters settled on 16:9 (1.85:1) some years
ago as a compromise, and to view these images correctly, you need to
set your TV type to 16:9, whereupon the picture will (correctly)
fill the widescreen TV display completely.

I don't think the OP has a widescreen TV...

Charlie

It could be my weekend for misreading posts!! Doh!




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"John Porcella" wrote in message
...

"John Rumm" wrote in message
...
HS Crow wrote:

I have a Humax PVR connected to a CRT TV via SCART. If I set the
Humax to TV=4/3, Output = 16/9, I get a letterboxed image as expected.
However, the image is not as widescreen as when playing DVDs. I
measured the image and it appears to be roughly 16/10. Is this
correct? My reason for asking is that I'm looking to buy a new
Freeview PVR and widescreen TV and I'm trying to discern if there are
any interoperability issues that I need to be aware of.

16:9 is not the only widescreen format used for films.

I was not aware this was a format for cinema films! TV yes, but
cinema...I
am not so sure.

What about Cinerama? They ought to broadcast them on three TV channels so
you can feed them into three TV projectors (or three TVs side by side if
you're a cheapskate).

--
Max Demian

HS Crow wrote:

I have a Humax PVR connected to a CRT TV via SCART. If I set the
Humax to TV=4/3, Output = 16/9, I get a letterboxed image as expected.
However, the image is not as widescreen as when playing DVDs. I
measured the image and it appears to be roughly 16/10.

There are a number of possible explanations.

Many films, and therefore DVDs, are at an aspect ratio of 1.85:1 or
2.35:1, as already discussed in the thread. 1.85:1 is *almost* 16:9 but
not quite, so you might perhaps be seeing this difference. Bear in mind
that sometimes films are cropped a bit for DVD, so on a poorly mastered
DVD you might different ratios again.

Widescreen broadcasts on terrestrial DTV (Freeview) for non-film material
are indeed at 16:9. If you have a DVD made from a TV programme, such as
the BBC's "The Planets", "Walking With Dinosaurs" or similar, it ought to
be the same shape as on-air TV material from your PVR.

If you still see a difference, your Humax PVR is probably providing a
14:9 signal. This is a compromise aspect ratio used for compatibility
with 4:3 TV sets like yours. If you're watching a widescreen BBC 1
broadcast on your PVR and you switch back to analogue BBC 1, is the size
of the black bar roughly the same? A great deal of 16:9 TV material is
shot within a 14:9 "safe" area, and the MPEG datastream broadcast over
the air preserves this information. Your PVR, if it has full support for
this information, may well be deciding to show you a 14:9 letterboxed
image rather than full 16:9 "deep letterbox". In this case, your PVR
ought to sometimes still show full 16:9 for broadcasts flagged as
requiring it (usually, films).

If that doesn't account for it, it is possible that your Humax PVR is
doing a certain amount of cropping and scaling of the picture which is
producing an incorrect aspect ratio. This would be a fault in the PVR,
probably in the firmware (software it runs).

When measuring aspect ratios on your set, you might not expect to see an
exact 16:9 ratio unless you have set up the geometry on your set using
the service menu. Most TVs out of the factory are really badly set up,
and often have varying amounts of overscan left/right and top/bottom that
result in a picture not quite at the right shape. Circles won't quite be
circular, and so-on.

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Thanks for all the detailed replies. The Humax PVR does have a 14:9
setting as well as 4:3 and the 16:9 that I'm using.
It may be that my mind is playing tricks with me and simply seeing the
difference between Freeview @ 1.78:1 as being more noticeably
different than DVDs @ 1.85:1…

I just dug out a DVD that is 16/9 and it is almost the same as my
Freeview aspect ratio, the image is just slightly less tall. So oops,
looks like I have been deluding myself.
But, I'm grateful for all the info as I'm starting to get my head
around all these technicalities.

Moving on from the Freeview widescreen aspect ratio, I'm now puzzled
why some of the LCD TVs that I'm looking at are 1280 by 768 pixels,
which is a ratio of 1.67:1 rather than the 1.78:1 of 16/9. Others are
1366x768 which is 16/9; a subject for another post.

On Sun, 16 Oct 2005 18:46:16 GMT, HS Crow wrote:

Thanks for all the detailed replies. The Humax PVR does have a 14:9
setting as well as 4:3 and the 16:9 that I'm using.
It may be that my mind is playing tricks with me and simply seeing the
difference between Freeview @ 1.78:1 as being more noticeably
different than DVDs @ 1.85:1…

I just dug out a DVD that is 16/9 and it is almost the same as my
Freeview aspect ratio, the image is just slightly less tall. So oops,
looks like I have been deluding myself.
But, I'm grateful for all the info as I'm starting to get my head
around all these technicalities.

Moving on from the Freeview widescreen aspect ratio, I'm now puzzled
why some of the LCD TVs that I'm looking at are 1280 by 768 pixels,
which is a ratio of 1.67:1 rather than the 1.78:1 of 16/9. Others are
1366x768 which is 16/9; a subject for another post.

Go to bed ;-)

Marky P.

On Sun, 16 Oct 2005 18:46:16 GMT, HS Crow wrote:

Thanks for all the detailed replies. The Humax PVR does have a 14:9
setting as well as 4:3 and the 16:9 that I'm using.
It may be that my mind is playing tricks with me and simply seeing the
difference between Freeview @ 1.78:1 as being more noticeably
different than DVDs @ 1.85:1…

There *is* a difference between them, so I wouldn't say your mind is
playing tricks :-)

I just dug out a DVD that is 16/9 and it is almost the same as my
Freeview aspect ratio, the image is just slightly less tall. So oops,
looks like I have been deluding myself.
But, I'm grateful for all the info as I'm starting to get my head
around all these technicalities.

Moving on from the Freeview widescreen aspect ratio, I'm now puzzled
why some of the LCD TVs that I'm looking at are 1280 by 768 pixels,
which is a ratio of 1.67:1 rather than the 1.78:1 of 16/9. Others are
1366x768 which is 16/9; a subject for another post.

I believe this comes from the fact that display manufacturers have
been making screens for computers for a while now - see:

http://en.wikipedia.org/wiki/Wide_XGA

It's presumably cheaper and easier to use existing displays, which
they've had a few years to get good at, than "invent" new ones.
Assuming the 1280x768 screen has square pixels, then it
would/could/should display 720p HDTV by simply not using the top and
bottom 24 rows...

Charlie

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