Confused about 1080i vs 720p

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

Reply to
somefool
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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).

-WD

Reply to
Will Dormann

Will Dormann wrote in news:nLidncZnT8zvK-HYnZ2dnUVZ snipped-for-privacy@comcast.com:

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.

Reply to
somefool

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 BLACK LEVEL: ON

4:3 output: NORMAL PAUSE MODE: FRAME

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

RESULTS:

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 screen.

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.

CONCLUSION:

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.

Reply to
somefool

Thanks for the report!

Reply to
Jon Woellhaf

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