I have an older 360 (no hdmi) and a sony kds-50a2000. I achieve 1080i w/ component and my set will only allow 720p w/ vga. I was wondering what would be the better picture quality of the two. I'm not looking to upgrade to a newer 360. But I really want to know if i go with the MS VGA cord if it will be worth it. Thanks fellas!

I had the same situation with my LCD. 1080i over component but component doesn't allow upscaling of dvds so I switched to vga. I set the black levels to extended and I can honestly say that I have noticed little or no difference between 720p vga or 1080i component. Except now my dvds are upscaled to 720p so I'm sticking with vga.

thanks for your input!

720p would be better for games because of the better frame rate (60fps vs 30fps for 1080i). Besides, your display is progressive. The 360 renders progressive frame buffers. You wouldn't want to interlace the video just to get it to the TV.

Find out what your TV's NATIVE resolution is and set it to that CASE CLOSED.

Find out what your TV's NATIVE resolution is and set it to that CASE CLOSED.

His TV's native resolution is 1080p. He can't set it to 1080p because his TV doesn't support 1080p over component. I would avoid interlacing at all costs in games because interlacing adds artifacts and you lose some of the pixels in 60fps games since 1080i is only 30fps.

So 720p is the best resolution for games.

For HD-DVD, 1080i would be the best resolution.

i'd go 720p on vga if it were me.

720p would be better for games because of the better frame rate (60fps vs 30fps for 1080i). Besides, your display is progressive. The 360 renders progressive frame buffers. You wouldn't want to interlace the video just to get it to the TV.

Umm, no.

1080i does 60fps EASILY. You can play CoD4 and notice there is no framerate change between 1080i and 720p.

It all comes down to the native resolution of your TV set.

Also, VGA seems to be too soft and less detailed than Component and HDMI, from my experience.

If you have an LCD, ALL resolutions will be scaled up or down to fit your TV.

For a 1280x720 native lcd, 720p is best.

For a 1366x768 set (which seems to be the majority of 720p sets), I believe 1080i keeps more detailed as 1920x1080 is scaled down to 1366x768, while 720p is a 1280x720 signal being upscaled to 1366x768, which loses some detail. On my ps3, I definitely noticed that Ridge Racer 7 was sharper and more detailed on 1080i than 720p.

On a 1080p native LCD TV, 1080i is DEFINITELY better than 720p, as it keeps all 1920x1080 pixels, and deinterlaces the signal. 1080i is 99.9% the same as 1080p on an LCD screen.

Umm, no.

1080i does 60fps EASILY. You can play CoD4 and notice there is no framerate change between 1080i and 720p.


When the image in the frame buffer is interlaced, it will be throwing away pixels on 60fps games. In fact, it will be throwing away half the image of every frame. What if the sniper that shot you was one of the pixels that got thrown away?

1080i does not do 60 frames per second. It does 60 fields per second. A field is either the odd or even scan lines.

If the entire frame buffer updates 60 times a second, and only half of the scan lines in the buffer are output 60 times a second, then the other half of the image in the frame buffer will never be displayed.

If it is at all possible, it is best to keep a game progressive if the game runs at 60 frames per second.

Honestly, just try them both and see what you are happiest with. If you are already happy with component, chances are the VGA cable isn't going to be a noticeable improvement. These matters really come down to how your TV handles different signals, and that's specific to the TV... and since we don't all have your set, it's kinda hard to give you an answer. You can always try doing 720p vs 1080i over component as you already have that cable. VGA "should" look VERY similar to component (at progressive resolutions).

@Shin - What Shape was getting at is that you DO lose detail from a 60fps game when you use an interlaced signal (as opposed to the progressive signal of the same resolution). You can use a 1080i signal all you want on a 1080p set. The fact of the matter is that you are still only going to get 30 full frames of information per second (as you are getting 60 half fields). This is perfectly fine for movies that are only 24fps to begin with (you don't lose any detail). All sets handle scaling and de-interlacing differently... what is best varies from set to set.

Wouldn't it have been nice if manufs wouldn't have screwed everyone by limiting component to 1080i and VGA to lower than native rez when they made their sets...

"Umm, no.
1080i does 60fps EASILY. You can play CoD4 and notice there is no framerate change between 1080i and 720p.
It all comes down to the native resolution of your TV set.
Also, VGA seems to be too soft and less detailed than Component and HDMI, from my experience.
If you have an LCD, ALL resolutions will be scaled up or down to fit your TV.
For a 1280x720 native lcd, 720p is best.
For a 1366x768 set (which seems to be the majority of 720p sets), I believe 1080i keeps more detailed as 1920x1080 is scaled down to 1366x768, while 720p is a 1280x720 signal being upscaled to 1366x768, which loses some detail. On my ps3, I definitely noticed that Ridge Racer 7 was sharper and more detailed on 1080i than 720p.
On a 1080p native LCD TV, 1080i is DEFINITELY better than 720p, as it keeps all 1920x1080 pixels, and deinterlaces the signal. 1080i is 99.9% the same as 1080p on an LCD screen."


You are missing out on a huge fact. Taking a 1280x720px60hz image and converting it to 1080i throws away information. Suddenly you have to cram a 1280x720 frame into a 1920x540 field. Hmm. The resulting image contains real pixel data of 1280x540, a loss of 230,000 pixels. The other option would be to maintain all the spatial pixels, but drop the framerate to 30hz. In this case, you of course lose 50% of your pixels, vs 25%. :) Either way, converting a 720p image to 1080i is a pretty dumb thing to do on any fixed pixel display. Why would you want to introduce interlacing artifacts on top of throwing away information? Or put a different way, why would you make a conscious decision to reduce image quality?

Additional: To compound the silliness even further, the information that is lost is primarily vertical. The exact kind of resolution the human vision is most sensitive to. So even though the numbers say that you are only losing 25% of your total resolution, subjectivly that percentage would be higher. These problems can of course be avoided by keeping progressively generated images progressive.

I'm not sure how some people are confusing this. but 1080i does not lose pixels compared to 1080p there just not displayed all at the same time. There is also no artifacts caused by converting 1080i to 1080p only the 60Hz to 30Hz because HDTV's just have to wait for the second set of the signal for the rest of the 540 lines to be put out by the video feed. Then your tv displays the image.If this guys HDTV is 1080P native then 1080i would be his best bet hands down, no ifs ands or buts.

I'm not sure how some people are confusing this. but 1080i does not lose pixels compared to 1080p there just not displayed all at the same time. There is also no artifacts caused by converting 1080i to 1080p only the 60Hz to 30Hz because HDTV's just have to wait for the second set of the signal for the rest of the 540 lines to be put out by the video feed. Then your tv displays the image.If this guys HDTV is 1080P native then 1080i would be his best bet hands down, no ifs ands or buts.

Sorry, you are wrong. Not everyone can get their head around the words. I'm sure if I spent some time making illustrations, I could help people understand. But I don't really have the time for that.

For 60 frames per second video games, you will be throwing out half the pixels on the screen if you use 1080i/30.

Besides, most games are rendered at 720p, so there really isn't a resolution advantage to letting the 360 do the scaling instead of the TV.

So if your TV can't accept 1080p over your chosen output cable, use 720p for video games.

For HD-DVDs, use 1080i. They are 24fps, and can be displayed without any loss of pixels at 1080i.

Sorry, you are wrong. Not everyone can get their head around the words. I'm sure if I spent some time making illustrations, I could help people understand. But I don't really have the time for that.

For 60 frames per second video games, you will be throwing out half the pixels on the screen if you use 1080i/30.

Besides, most games are rendered at 720p, so there really isn't a resolution advantage to letting the 360 do the scaling instead of the TV.

So if your TV can't accept 1080p over your chosen output cable, use 720p for video games.

For HD-DVDs, use 1080i. They are 24fps, and can be displayed without any loss of pixels at 1080i.

You wouldn't want to display 720p on a 1080p tv when you can go with 1080i. Even if the 360 has a better scaler then the TV, since your TV will have to upconvert it to 1080p anyways your gonna get artifacts that way compared to going from 1080i to 1080p.

I understand where your getting confused yourself. Losing Hz does not equate to losing pixel or image content just means it not updated as much as 60Hz. Yes going from 60Hz to 30Hz means every other milliseocond, or what ever it is, your not going to see a new image update. But when the image does come it will still in fact have all the pixel and image as the original output signal

Loosing pixels is when your output signal puts out a 1080p signal and your TV only has 720p worth of LED to display it. Your TV will down scale image thus removing pixels from the image. Going from 60Hz to 30Hz does not remove anything from the image at any time, just doesn't update the change in imagery as fast.

Your argument should say that the game won't seem as smooth since the refresh is lower NOT that he will be loosing pixels.

If only half the pixels of a 60fps frame buffer are output every 1/60th of a second on a 1080i signal, what happened to the other half of the pixels? When do they get displayed?

Answer that question for me. If you think about it enough, I think you will understand why I am right about this.

They get outputted 1/60th of a second right after the first half of the pixels are sent out. Then the TV takes both signals puts them together to form a complete scene then displays it on the screen, This delay is why its technically only 30Hz instead of 60Hz.

No pixel loss since the image does not lose not even 1 pixel of the image when the HDTV finally displays the complete image in its entirety.

like its been stated.

720p > 1080i

UNLESS you're dealing with 24fps content!

They get outputted 1/60th of a second right after the first half of the pixels are sent out.


The image in the frame buffer already changed before this could happen.

The frame buffer is changed every 1/60th of a second.

Only half of the scan lines are output every 1/60th of a second.

The other half of the scan lines from the frame buffer are thrown away because the frame buffer is already overwritten by the time the next interlaced field is ready to be displayed in the next 1/60th of a second.

shape is right, the frame buffer isnt going to keep a queue of all rendered fields and frames, when a new field comes in, the buffer is wiped and re-written, and that information is forever lost.

Are you speaking about the TV or the output device? I shouldn't of re-used Shape's "frame buffer" terminology.

I was speaking in reference to the HDTV which does wait for the 2nd half of the image to come in before displaying any of the image. Not sure what the exact name of where each half of the image is stored then merged then displayed onto the screen but this really can't be contested on how newer HDTVs work. Anyone with decent knowledge of how newer TV's work will explain this. This is the exact reason why any interlaced signal runs at half of the native refresh rate because it spends half the time waiting for the other half of the image.

Now on the xbox side when you set your video to 1080i, the Anna scaler chip is going to output an interlace signal. Pretty much the xbox will output every other line of the image every other 60th of a second, then outputs the other set of lines every other 60th of a second. Mean time the HDTV gets the first set of lines then waits for second set of lines merges them(aka de-interlacing them) into a progressive image. At no time do you lose image quality or lose any pixels, only down side is the lower refresh rate. But my point from the beginning is that no artifacts are introduced in this process, only loss of refresh rate. So when comparing 1080i and 720p there are pros and cons for both sides, definantly not an instant win for either side.


like its been stated.

720p > 1080i

This is a very generalized statement which does not hold true for every circumstance.

At no time do you lose image quality or lose any pixels, only down side is the lower refresh rate.

You're wrong. I've explained why this is. Half of the pixels of every frame buffer will not be sent out of the XBox if you use an interlaced display resolution on a 60 frames per second game, like Call of Duty 4.

If you have a 30 frames per second game like Gears of War, all of the pixels will be sent out of the XBox with an interlaced display resolution. There is no issue with 30 frames per second games because 1080i is 30 frames per second.

But with 60fps games, you will definitely lose half of the pixels that the 360 is rendering with 1080i.

If you use 720p, you will see all of the pixels that the 360 has rendered.

"There is no issue with 30 frames per second games because 1080i is 30 frames per second.

But with 60fps games, you will definitely lose half of the pixels that the 360 is rendering with 1080i."

I'm on your side Shape! You just errored on these two parts. :)

1080i is 60 fields per second, not 30 frames per second. Those 60 fields can contain 60, 30, 20, 15, 12, 10, 6, 5, 4, 3, 2, or 1 real frames per second off of a vsynced signal, or any number of frames from 0 to 60 when not vsynced. When the framerate is 30 or below, wether a movie, TV show or game, 1080i will carry all the information needed in it's 1920x540 fields to rebuild a full 1920x1080p frame at full framerate. As soon as 30 frames per second is exceeded, 1080i will no longer carry all of the available information in a 1280x720p or 1920x1080p source.

Slowing down the process really slow, and greatly simplifying the scaler....!

An Xbox 360 makes a 1280x720 (920,200 pixels) frame in the first 1/60 second. That frame is converted to 1080i. A 1080i field is 1920x540 (1,000,000 pixels). That is enough width to hold all 1280 horizontal pixels, but not enough height to fit all 720. 180 vertical pixels are set aside for transmission in the next field (1280x180=230,000 pixels). The 360 spits out a 1920x540 field containing the 1280x540 (690,000 pixels) of data that it could fit.

Field one is done! Time for field two, where we find out what happens to those 230,000 remaining pixels!

This example Xbox 360 renders a new 1280x720 frame in the second 1/60 of a second! Now we have a decision to make. Do we make a new 1920x540 field consisting of all new information, while throwing away the remaining 230,000 pixels from the last frame? Or do we ignore the new frame and build a new 1920x540 field that consists of only the 230,000 pixels to finish the last frame?

If we finish the last frame, then the TV gets all required information to fully rebuild the original 1280x720 image. The TV got the first 690,000 pixels in the first field, and the remaining 230,000 pixels in the second field. All 920,000 are here, we have full 720p wrapped in a 1080i container. Great! All of the pixels! The only thing we had to sacrifice was 1 of the 2 frames rendered! Carry that out to a full second, and we throw away ever other frame. 30 of the 60 rendered frames are thrown away, therefore half of the pixels that the 360 generated are thrown away. Hmm. Yes it is full resolution, but it is only 30 frames per second instead of the generated 60 frames per second.

If we instead focus on the new image (which is common, but wholly the choice of the developer), then we start the whole process over. No time for those extra pixels, we got a new frame coming in! The remaining 1280x180 from the last frame is tossed out, the new 1280x720 image is scaled to 1280x540, 230,000 pixels are set aside again, and the image is spit out as 1080i field number 2. Well, now we have 690,000 new pixels instead of only 230,000, right? That's good, huh?

Now the TV has two 1080i fields that it wants to rebuild into 1080p. Problem is, these two fields came from two distinctly different momments in time and do not match up perfectly like film does. So now deinterlacing comes into play. The TV needs to blend these two frames together into one to output to the TV. This of course brings with it all the regular deinterlacing artifacts like feathered edges during pans, blurred horizontal resolution, vertically moving characters becoming double-image ghosts, etc. All of these artifacts further reduce the percieved resolution by some percentage.

Lets recap! We started with 920,000 pixels. We threw away some of those and ended up with 690,000 left over. Then we made it into a blurry mess by deinterlacing non-matching frames! Woot! We win!

I guess we only had to chose the lesser of two evils right? Lose 25% of the pixels, but have a blurry mess. Or lose 50% of the pixels, but keep the images progressive.

Now lets look at 720p.

The 360 in question makes a 1280x720 image. It spits this 1280x720 image out to the TV as 720p. TV recieves all 1280x720 (920,000) pixels. The TV then stretches the image to it's internal resolution of 1920x1080 in this example, guessing at what the new pixels should be. The TV makes up 1.1 million pixels (900,000 -> 2,000,000), but that is better than making up 1.3 million pixels from 720p scaled to 1080i. :)

Do we get it now sonypete and Shin? What part are we having trouble with here? I really do want to guys to understand! :) Being missinformed is okay! Spreading that missinformation is not!

You're wrong. I've explained why this is. Half of the pixels of every frame buffer will not be sent out of the XBox if you use an interlaced display resolution on a 60 frames per second game, like Call of Duty 4.

If you have a 30 frames per second game like Gears of War, all of the pixels will be sent out of the XBox with an interlaced display resolution. There is no issue with 30 frames per second games because 1080i is 30 frames per second.

But with 60fps games, you will definitely lose half of the pixels that the 360 is rendering with 1080i.

If you use 720p, you will see all of the pixels that the 360 has rendered.

See this is how I know you don't have 100% of your facts straight. As it does not matter what the FPS of a game is 30 or 60 since most games are not locked at a certain FPS only what there allowed to go past. So a game that 30 FPS is just what the game will run at on average and if its locked at 30 FPS it means its not allowed to go over 30 but can drop lower occasionally.

I will point out one more time the FPS or Hz of a signal has no effect over how many pixels lost, NONE WHAT SO EVER. This is a completely valid fact of the matter. Your just confusing two totally seperate concepts.

Your assumption is that with interlaced you loose half the pixel quantity of an image, never to be shown. Which is incorrect as all the pixel will be shown at once on HDTVs since they wait for both signals to bring all the odd and even lines of the image into play.

I think your confusing older CRT technology and newer HDTV a bit. Since older CRT alternate back and forth so they might not show both lines at once, but all the pixels of the image will eventually be shown, never lost, like your saying. And newer HDTV will merge both sets of the lines from the original into one before displaying anything on the screen.

Darklordjames, one thing I disagree on is the 1080i loosing any pixels. Yes it displays 1920x540 per pass but then shows the other 540 lines on the next pass on older CRT, thus not loosing any of the image. On newer HDTRV it waits for both 1920x540 to be put out then merges them into on 1920x1080 which is then displayed at 30Hz. I have read this in numerous places and spoke to very knowledgeable people about this.

<sigh>

Darklordjames, one thing I disagree on is the 1080i loosing any pixels. Yes it displays 1920x540 per pass but then shows the other 540 lines on the next pass on older CRT, thus not loosing any of the image. On newer HDTRV it waits for both 1920x540 to be put out then merges them into on 1920x1080 which is then displayed at 30Hz. I have read this in numerous places and spoke to very knowledgeable people about this.

You are only talking about the TV displaying the information that the 360 has already output. I'm not arguing about this. We agree on how this works.

I'm talking about the pixels that the 360 never even get the chance to output, which if you don't know how a frame buffer works, you would be blissfully unaware of.

Two completely different concepts.

I'm fully aware Shape and darklordjames are right about videogames but I have a movie question and it's a little off subject and, admittedly, the wrong forum. But if is it better to send 720p or 1080i to my 768p TV when watching Blu-Ray movies? I would assume 1080i as it would simply interlace 1080p, then de-interlace and downscale to 768p retaining more information where as outputting 720p would require a downscale from 1080p to 720p then an upscale to 768p losing more information. Problem is a lot of movies aren't filmed at 24fps anymore, they're filmed at 60fps since everything is going digital. So if I output 1080i on a 60fps movie am I going to lose more information than if I output 720p.

I guess where my difference in thought is when it splits it into 1920x540, that there are two 1920x540 parts of the image from the same time frame, which is why its 30Hz on the newer HDTV not the older CRT. Thus eliminating the artifacts caused by using two different 1920x540 images from two different times frames.

Don't go "sigh'ing" on me Shape cause you never explained anything or came close to what James did. This is good conversation no need to get all wound up :)

darklordjames, I agree with your description, mostly. However, the 360 would first have to upscale the image to 1920x1080, and then interlace it. So really, the 720 scan lines would be scaled up to 1080 scanlines. Then the 360 would output either the odd or even scanlines (540 of them). So, in reality, you lose half of the original 720 scan lines, which is 360 scan lines.

I'm fully aware Shape and darklordjames are right about videogames but I have a movie question and it's a little off subject and, admittedly, the wrong forum. But if is it better to send 720p or 1080i to my 768p TV when watching Blu-Ray movies? I would assume 1080i as it would simply interlace 1080p, then de-interlace and downscale to 768p retaining more information where as outputting 720p would require a downscale from 1080p to 720p then an upscale to 768p losing more information. Problem is a lot of movies aren't filmed at 24fps anymore, they're filmed at 60fps since everything is going digital. So if I output 1080i on a 60fps movie am I going to lose more information than if I output 720p.

Yes, you are correct. I believe 1080i is best for your situation. But really, you have to go with what looks the best.

However, films are still 24fps, even though they are going digital. Analog projectors are still the norm, so films have to be mindful of the bulk of film. A 24fps, 50mm film is still REALLY big and REALLY heavy.

24fps will be the norm for movies for a long time to come.

"But if is it better to send 720p or 1080i to my 768p TV when watching Blu-Ray movies?"

1080i for anything film, because the framerate is below 30 frames per second. As with games, anything below 30fps can be rebuilt fully with 60 fields per second. The answer is very questionable for TV shows on Bluray/HDDVD. If the source is 1080p or 720p, then 720p will look better, if the source is 1080i/60hz, then the device with the better deinterlacer will decide wether 1080i or 720p is the better choice.

"darklordjames, I agree with your description, mostly. However, the 360 would first have to upscale the image to 1920x1080, and then interlace it. So really, the 720 scan lines would be scaled up to 1080 scanlines. Then the 360 would output either the odd or even scanlines (540 of them). So, in reality, you lose half of the original 720 scan lines, which is 360 scan lines."

That's why I started out with "and greatly simplifying the scaler....!". :) Yes, the 360 would take the 1280x720p frame and scale it to 1920x1080, then interlace that, throwing away 540 lines. That starts moving away from the simple concept that I was trying to show though. :) You don't end up losing half of the original scanlines, you lose half of a 1080p representation of 720 scanlines. The math isn't perfect, but the end result is far closer to a 540p image than a 360p image. Without hard information about each scaler in question, I would estimate the process maintains between 500 and 600 lines of vertical information per frame. "540" is a lot easier number to work with than "500 to 600". :)

sonypete - Read that long previous post of mine again. And then read it one more time.

"I guess where my difference in thought is when it splits it into 1920x540, that there are two 1920x540 parts of the image from the same time frame, which is why its 30Hz on the newer HDTV not the older CRT. Thus eliminating the artifacts caused by using two different 1920x540 images from two different times frames."

This is where the confusion is coming into play. Yes, at sub 30 frames per second, a 1080i encode of a 720p image is functionally the same (give or take scaler qualities, etc). Hey look! I already started the last post by saying that! :) The issue is that you need at minimum 2 times the number of fields to build a particular set of frames. What you have failed to explain to us is where you are getting "2 times greater than 30" fields out of a video system that only has 60 fields. The piece that you seem to hold as hard fact, yet you need to let go of, is that nothing is ever more than 30 frames per second. That is absolutley wrong, and you need to let it go. :)

On modern equipment, 60 frames per second material output to 1080i only makes sense in one instance, and one instance only. If the display is an HD CRT and won't try to scale or deinterlace the image.

Please, read my previous piece again, and ask questions! As I said before, having misinformation is perfectly OK and nothing to worry about. Trying to pass that misinfo off as fact is where one starts to do a disservice to the community.

What you have failed to explain to us is where you are getting "2 times greater than 30" fields out of a video system that only has 60 fields. The piece that you seem to hold as hard fact, yet you need to let go of, is that nothing is ever more than 30 frames per second. That is absolutley wrong, and you need to let it go.


James I'm understanding this all a bit better. But not sure where you got the above quote. I don't believe I tried pushing that or that nothing is more then 30fps. I was only speaking about how saying games were rated at 30FPS or 60FPS is not a good reference point for the above discussion since most games will fluctuate how fast there running unless locked then we know they don't go above said FPS but can dip below the said FPS.

One thing I would like you to explain is how interlaced signals going to an HDTV coincide, since all non-CRT HDTVs don't display interlaced like the older CRT did.

"explain is how interlaced signals going to an HDTV coincide"

That all depends on the source. Take something like 24 frame per second film for example, and lets say that it is encoded to 1280x720p at 24 frames per second, just to keep this all in the same world of 720p transcoded to 1080i. If we take this 720p/24 video and spit it out as 1080i/60, then we essentially split each frame in half, send out the first half in the first 1/60 and the second half in the second 1/60 of a second. All told it takes 48/60 of a second to transfer all 24 frames. On the TV side it takes the first two fields, blends them together, and shows them as a full frame. Then it waits a momment and does it again for the next frame. The key here is that because the frame rate is lower than 30 frames per second, full resolution is maintained.

Now let's take something like TV programs. Let's say we record a TV program at 60 frames per second at 1920x1080p. Then we interlace it for transmission at 1080i. Let's say that full spatial resolution is the most important thing to us, so we take frame 1 and split it in half, transmitting all the even lines in the first 1/60th and all the odd lines in the second 1/60th. We throw away frame 2, and then split frame 3. Rinse and Repeat. The TV takes the first 2 frames, blends them, and displays them. It does this every 1/30 of a second. We lost half of our framerate. But we maintained full resolution for the frames that were kept.

The other option, just like with the Xbox, was to take half of each frame and blend them together. The even lines are taken from frame 1, odd lines from frame 2, transmit to TV, TV blends them together, the resulting frame is a little bit of each of the 2 sampled. This tends to be full of general interlacing artifacts.

That's a good example. I think a calculation can make it clear.

1080p/60 is 1920 x 1080 pixels x 60 frames a second = 124416000 pixels per second displayed to the screen.

1080i/30 is 1920 x 540 pixels x 60 fields a second = 62208000 pixels per second, which is half the pixels per second of 1080p/60

If you upscale a 720p/60 animation to 1920x1080/60 and then output it as 1080i, you will not output half of the pixels that were in the 1920x1080/60 frame buffer.

That is exactly what the 360 does when it scales a 720p/60fps game to 1080i.

So James, then my thinking from earlier was correct but only with 24frame Films and TV broadcasts in 1080i, not the xbox. Only time artifacts are introduced is when you grab half the lines from one image then grab the other set of lines from a different image in time which I guess the xbox does. I wonder why Microsoft chose to interlace the signal like that?

Does anyone know how the PS3 Handles their 1080i output? is it similar to the xbox?

So James, then my thinking from earlier was correct but only with 24frame Films and TV broadcasts in 1080i, not the xbox. Only time artifacts are introduced is when you grab half the lines from one image then grab the other set of lines from a different image in time which I guess the xbox does. I wonder why Microsoft chose to interlace the signal like that?


They didn't really have any choice.


Does anyone know how the PS3 Handles their 1080i output? is it similar to the xbox?

Should be the same way. The scaling in the PS3 allows you to scale to either 1080i or 1080p, and I haven't heard that it affects frame rate. So a 60fps game should still be 60fps when it is scaled. Then the output in 1080i would lead to the same issue. Although the PS3's scaling leaves a lot to be desired.

So James, then my thinking from earlier was correct but only with 24frame Films and TV broadcasts in 1080i, not the xbox. Only time artifacts are introduced is when you grab half the lines from one image then grab the other set of lines from a different image in time which I guess the xbox does. I wonder why Microsoft chose to interlace the signal like that?

Does anyone know how the PS3 Handles their 1080i output? is it similar to the xbox?

What was the other choice, to grab both fields from every other 60P frame? You definitely don't want to do that. That's just robbing Peter to pay Paul. With the method they use, you still get some semblance of 60fps temporal resolution, at the expense of vertical resolution and potentially some interlace artifacts. A TV with a good motion adaptive de-interlacer can greatly reduce the appearance of such artifacts. Interlacing the way they've done it, does make motion appear smoother. Throwing away every other 60P frame would result in more juddery motion, though it would completely eliminate interlace artifacts.

I'd be astounded if Sony didn't do it exactly the same as MS in this case.

P.J.

"1080p/60 is 1920 x 1080 pixels x 60 frames a second = 124,416,000 pixels per second displayed to the screen.

1080i/30 is 1920 x 540 pixels x 60 fields a second = 62,208,000 pixels per second, which is half the pixels per second of 1080p/60

If you upscale a 720p/60 animation to 1920x1080/60 and then output it as 1080i, you will not output half of the pixels that were in the 1920x1080/60 frame buffer."

Adding to the calculations:
720p/60 is 1280x720x60=55,296,000 pixels per second
720p scaled to 1080i is 1280x540x60=41,472,000 pixels per second

Under the HDTV standards, it is impossible to cram 55million pixels worth of visual data in a 41million pixel stream. :)

"So James, then my thinking from earlier was correct but only with 24frame Films and TV broadcasts in 1080i, not the xbox ... I wonder why Microsoft chose to interlace the signal like that?"

Microsoft chose nothing. It is the individual developer's choice on what to feed the relatively dumb scaler. The dev can take a game that runs at 720p/60fps and lock it's framerate down to 30fps when the output is set to 1080i, if they choose to do so. It is the developer's choice on wether they value spatial (pixels per frame) or temporal (framerate) resolution higher. The same holds true for the PS3.

And yes, 1080i carries all needed information for 24fps material, like film. Interlaced TV is a different matter entirely, as it tends to be 60 half frames pulled from 60 distinctly original frames per second. Just like a 60fps game, this creates deinterlacing problems.

"A TV with a good motion adaptive de-interlacer can greatly reduce the appearance of such artifacts. Interlacing the way they've done it, does make motion appear smoother"

TVs with good scaler's are very few and far between though. Again, everyone, there is no "interlacing the way they've done it". There is no "they". This choice is the choice of every individual developer and no matter which way you look at, neither choice makes any sense when outputting to a fixed pixel display. Especially when all of the pixel loss and temporal resolution loss can be avoided by simply keeping the source progressive.

"1080p/60 is 1920 x 1080 pixels x 60 frames a second = 124,416,000 pixels per second displayed to the screen.

1080i/30 is 1920 x 540 pixels x 60 fields a second = 62,208,000 pixels per second, which is half the pixels per second of 1080p/60

If you upscale a 720p/60 animation to 1920x1080/60 and then output it as 1080i, you will not output half of the pixels that were in the 1920x1080/60 frame buffer."

Adding to the calculations:
720p/60 is 1280x720x60=55,296,000 pixels per second
720p scaled to 1080i is 1280x540x60=41,472,000 pixels per second

Under the HDTV standards, it is impossible to cram 55million pixels worth of visual data in a 41million pixel stream. :)



That's uncompressed. HDMI is definitely capable of that many pixels per second, and even more.

Broadcast TV is compressed using MPEG2.

Only time artifacts are introduced is when you grab half the lines from one image then grab the other set of lines from a different image in time which I guess the xbox does. I wonder why Microsoft chose to interlace the signal like that?


thats how the fields work, an odd and even field cant be "grabbed" at the same instance, they will always be apart on the timeline, and thats where you get artifacting when the fields are de-interlaced.

even at just 1/60th of a second later, more often than not you're looking at 2 different images.

"That's uncompressed. HDMI is definitely capable of that many pixels per second, and even more.

Broadcast TV is compressed using MPEG2."

What? Seriously? :) We aren't even talking about broadcast TV. Where did that come from?

Beyond that, it doean't matter if it's compressed or not, as we are not talking about bitrates and haven't the entire conversation. Compressed or not, 55million pixels in a second is still 55million pixels, wether raw and uncompressed, compressed with MPEG2, or h264. Hell, I could crush 720p video down far enough to transmit it over a analog modem and still have it spit out 55million pixels upon decompression! They would be 55million really blurry, messed up pixels, but 55million they would be. :)

We weren't even talking about wether particular connection types were capable of a certain amount of bandwidth. I was simply pointing out that you can't cram the 55million pixels a second of 720p into a 1920x540 stream, just like you did with 1080p vs 1080i at 60 frames per second.

If you can't tell, I am vastly confused as to how that comment has any relevance to the conversation at hand, and beyond that, how it is supposed to be an argument against the text of mine that you quoted. :)

Let's go one step further even! "That's uncompressed" make no sense at all, as we aren't talking about uncompressed anything. 1280x720x60hz=55million pixels, yeah. Add on a color depth, and we can start talking about uncompressed vs compressed bitrate numbers. :) 55,000,000pixels at a 24-bit color depth is about 1.3gigabits a second, or 165MBps. And yes, for broadcast HDTV that is squeezed down to about 2.4MBps (19mbps) using MPEG2. This is all of course completely irrelevant to the conversation at hand.

thats how the fields work, an odd and even field cant be "grabbed" at the same instance, they will always be apart on the timeline, and thats where you get artifacting when the fields are de-interlaced.

even at just 1/60th of a second later, more often than not you're looking at 2 different images.

I disagree. I don't see why you can't take a 60P source and grab odd and even fields from the same frame and simply discard every other frame. Then send odd and even fields alternately at 60 fields/sec. In that case, there will be no deinterlacing artifacts, since any TV can "weave" the odd and even fields back together and display them progressive. Each pair of odd and even fields originated from 1 progressive frame. Of course, there is loss of 1/2 the pixel info with this scheme, just like there is with the other scheme. I'd expect panning motion to be a bit more jerky, but there'd be no combing artifacts. I'm not saying that any equipment out there does this, but there isn't any reason that it couldn't.

P.J.

So, if I have a native 1080p tv, what should I set my resolution to on the Xbox?

So, if I have a native 1080p tv, what should I set my resolution to on the Xbox?

In order of desirability:

If you have an HDMI output on your 360, and your TV can take 1080p as an input over HDMI, use 1080p.

If you have a 1080p compatible component input on your TV, use 1080p over component.

Otherwise, use 720p for video games. Use 1080i for HD-DVD with the 360.

In order of desirability:

If you have an HDMI output on your 360, and your TV can take 1080p as an input over HDMI, use 1080p.

If you have a 1080p compatible component input on your TV, use 1080p over component.

Otherwise, use 720p for video games. Use 1080i for HD-DVD with the 360.

Thanks