Confused about 1080i vs 720p

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The HD TV marketing is all agog over 1080i because it comes with the
wider resolution (1920x1080), but they gloss over the "i" part.

As I understand it the interlacing basically skips every other line in
the source, so when you are looking at 1080i you really only get 540
worth of vertical scan lines...

Now, I've also heard it said that you should to set your TV and DVD to
only upconvert to 1280x720p for a better picture from your SD DVDs. Even
tho the horizontal is 1280 which is less than the 1920 that comes with
the 1080 size.

Crunching the numbers gives about 1 million pixels of information for
either setup but with a slight edge to the 1080i setup (if you use 540
for the vertical resolution).

From an AVS perspective, which will give the better picture for
upconverted SD DVDs?

For that matter is there any way to turn off the interlacing on the
digital HDTV signal coming in from the cable or OTA so that it defaults
to 720p rather than go to 1080i... ?

Thanks in advance for any insights

Re: Confused about 1080i vs 720p

somefool wrote:
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Not quite.   Interlacing alternates between the even and odd scan lines
to lower the bandwidth requirements for video transmission.  Nothing is
thrown away, except possibly in the deinterlacing process, and even then
that's only if a terrible deinterlacing process is used.  All recent
HDTV's (LCD, Plasma, etc.) are inherently progressive scan, like a
computer screen.

1080i means that the picture is sent to the display one field
(half-frame) at at time.  So in the US, your 60Hz 1080i broadcast is
equivalent to 30 frames per second.  720p, on the other hand is a full
60 frames per second.   They both use about the same bandwidth, but
1080i has a higher spatial resolution (more lines per frame), and 720p
has a higher temporal resolution (more frames per second).


Re: Confused about 1080i vs 720p

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Thanks. That is a nice setup for trading image clarity against response
time. A trade I don't wish to make, yet. I've ordered an OPPO DVD player
that upconverts SD DVDs to my TV's native resolution of 1080p, that way
I don't have to choose.

Still, I've since been advised elsewhere that overall Picture Quality
will be better with upconversion to 720p rather than the 1080i because
of the number of times that interlacing is done/undone in order to get
the data off the DVD and onto the screen. Even the best TVs do not work
hard at making this conversion as efficient as it can be.

Re: Confused about 1080i vs 720p

Sony DVP-NS71HP ($129) versus OPPO DV-981HD ($229)

I've had both of these to play with over the weekend and I've sampled
various content in each. Battlestar Glactica s2.5, Kill Bill Vol I, The
Incredibles THX setup...

Relevant Sony custom settings:
RESOLUTION:         1280x720p
HDMI:             RGB
4:3 output:         NORMAL

Relevant OPPO custom settings:
HDMI resolution:    1920x1080p
Truelife:         ON
CCS:             ON
RGB Range:         Normal

Everything else was either set to OFF or to "0" so as not to introduce
any additional variations. No sharpening or noise reduction. The Sony
has a thing called BLACK LEVEL which when set to ON produces what they
call the "standard" black levels... if set to OFF it reduces the black
level, so I left it ON for my testing. Both claim to have some way to
enhance the still frame of a DVD so I set them both up to do so (PAUSE
MODE on the Sony and CCS on the OPPO). Also not documented in the manual
the OPPO offers an RGB Range choice between Normal and Enhanced which
did not seem to have any effect.

First I set my 46V25L1 as noted and used the THX set on The Incredibles
DVD to adjust the brightness, color, and sharpness (both players
produced the same settings):

Backlight: 3
Picture: 98
Brightness: 50
Color: 33
Hue: 0
Color Temp: Warm2
Sharpness: 10
Noise reduction: Off

Black corrector: Off
Advanced C.E.: Off
Gamma: Off
Clear white: High
Live color: Off
Color space: Wide
MPEG Noise Reduction: Low

Power saving: Off
Light sensor: Off


Both players look amazing and do a fine job of upconverting/scaling your
legacy DVD collection for display on the Sony LCD (Full Pixel mode).

During the THX Contrast setup the OPPO showed a slight green tinge on
the 2nd block in from the upper left where the Sony did not. Hue and
Color changes on the set did not affect it, nor did the Saturation or
RGB Range choices offered on the OPPO.

The THX Brightness setup showed with the OPPO having a slightly brighter
picture than the Sony that equate to about 1 notch on the Brightness
scale (51 on the Sony = 50 on the OPPO). Some of the gray blocks had a
slightly green tinge again on the OPPO that was not evident on the Sony.

The THX 16:9 Aspect Ration set showed better on the Sony with the OPPO
having distinct jaggies around the circle where the Sony was smooth.

The sample playback scene on the THX setup showed very well on both
players (jaw dropping in fact) with a slight edge to the OPPO for
shadows and a decidedly better treatment of edges when the scene stops
going to the Sony for not having jaggies (stair steps) like the OPPO.

For Kill Bill I used the duel scene near the end of the movie (Scene 16
on the menu) to audition both players. The OPPO again with the green
tinge evident in the snow where the Sony shows a bluer cast (which would
be more accurate for snow). The details imprinted on Lucy's robe
(Kimono?) was quite evident on both players as was the shine of the
blade in the close-ups. The snow falling was exquisite in detail on both
players. Both players displayed a slight bit of jumpieness during the
scrolling of the credits at the end.

The opening credits were a good source of comparison as I had the same
images on two different DVDs that I could quickly flip source between.
The Sony showed a slight edge in detail as you pan over the water toward
the city. There is a fade scene of some text and a cylon robot's head
the OPPO handled better with fewer jaggies and the text faded smoothly
with no interlacing type gaps in the image. The OPPO also showed the
text of "49,284 Lives" in a more uniform way without looking like it was
shadow font. However this was all during frame advance, and completely
undetectable during normal playback speed.

The remotes are vastly different. The Sony offers some controls the OPPO
lacks such as skip fwd/back with will move about 15s for easy skipping
of credits or to repeat a scene. And the OPPO offers some features that
the Sony does not, like bookmarks (separate from the A>B loop thing) and
On Screen Display of the motion controls that can be operated via the
cursor controls (neat but not that useful).

The layout of the buttons on the Sony are easier to maneuver in the dark
(neither remote is backlit) and fit better in the hand. Both offer a
Slow Play feature but the Sony has sound with it while the OPPO does
not. The OPPO also combines both fwd/back on one button which makes it
harder to change direction.

The OPPO offers more intermediate levels of Zoom and even offers a
couple of Zoom Out positions where you can shrink the image on the

Many of the buttons on the OPPO cycle thru their functions (and return
to the starting point after several presses) where the Sony has more
buttons dedicated to specific functions or directions and only have 2 or
3 levels to cycle thru. One quirk about the Sony that is annoying is how
sensitive the cursor buttons are, often causing one to overshoot the
target with anything but the lightest of touch.


Both players offer superb image quality and will extend the life of your
DVD collection on your HDTV. I honestly could not tell the difference
between 720p and 1080p on the screen. I'm sure there are scenes on some
DVDs that will be better under 1080p but I did not find them in my
auditions. For the extra $100 the state of the art video processing from
the OPPO was wasted on me. In fact, I liked the more natural looking
images from the Sony. Plus the remote was the kicker... better control,
better ergonomics. I'll be requesting an RMA from OPPO and sticking with
my original purchase of the Sony. For what it's worth the OPPO does come
with a higher quality HDMI cable than the Sony.

Re: Confused about 1080i vs 720p

Thanks for the report!

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