[NWhiteley]

I have been searching this forum for advice on the purchase of a projector, and i have have pretty much decided on getting a AX100. During my searches, i have read about stutter when playing HD-DVD's, something to do with 60/50/24. Naturally i am concerned about this, but the more i search, the more i am confused and concerned about potential problems with this stutter.


My equipment....

A US import Tosh HD-DVD HD-A2 via HDMI to Pio AX4i AV amp
UK 360 via component to AX4i
UK DVD via component to AX4i
Sky HD via HDMI to AX4i

AX4i via HDMI to Panny 42" PHD8 plasma

I was planning to get a HDMI splitter to feed both the plasma and projector directly from the AV amp, and im not intested in feeding both screens at the same time, so.......

Will this set up work?
Will i get stutter from this set up?
If so, how would i eliminate the stutter?

Neil.

[stuartbrown21]

The judder is due to Blu-Ray & HD-DVD being encoded at 24 frames per second, like the original film at the cinema. HD-Ready displays have to refresh at both 50 & 60 hz. Your A2 outputs 1080i/60 to the projector, and the projector then reassembles the image into progressive frames, but will display at 60hz eg the first frame is repeated three times, the second twice, the third 3 times etc. This slight speeding up and slowing down causes the judder.

You may have heard talk of 1080p/24 signals. This is where the player reads the 1080p/24 data from the disc, and outputs this directly to the display. The display then repeats these frames at a multiple of 24, probably 72 or 96 hz. Thus every frame is on screen for an equal length of time, and there's no judder!!

The thing is, to benefit, you need a player that will output 1080p/24, and a display that will accept it, and display at a multiple of 24 (some displays accept it but then infuriatingly change it to 60hz, and introduce the judder).

The good news is that the PT-AX100 accepts this signal and displays it at a multiple of 24, thus no judder!! The bad news is that the A2 will never be able to output 1080p/24, it will always be limited to 1080i/60. The only way to get around this is to either use a video processor to reassemble 1080p/24 from the 1080i/60 from the Tosh, then send this to the pj, or alternatively sell your A2 and but either a A20 (EP10) or AX2 (XE1), as both of these players are to receive a firmware update in September to enable 1080p/24 output.

Some 'issues' that get raised on these forums tend to get blown out of all proportions, but I personally find judder to be a real pain. I found it bearable with my E1 connected to my AX-100, but once I had a PS3 feeding it 1080p/24 I could no longer bear to watch the E1 as the judder was suddenly really apparent to me, nearly all the time. It may be a few hundred quid in expense, but i'd seriously consider upgrading your HD-DVD player to make the most of judder free playback. I sold me E1 due to judder, and will purchase a new player once the firmware update is released.

I'm not sure which brand a PH8 plasma is - I know that Pioneer plasmas accept 1080p/24, and magically they will also take a 1080i/60 signal and reconstruct 1080p/24, then display at 72hz, thus eliminating judder!!

[NWhiteley]

Originally Posted by stuartbrown21

The judder is due to Blu-Ray & HD-DVD being encoded at 24 frames per second, like the original film at the cinema. HD-Ready displays have to refresh at both 50 & 60 hz. Your A2 outputs 1080i/60 to the projector, and the projector then reassembles the image into progressive frames, but will display at 60hz eg the first frame is repeated three times, the second twice, the third 3 times etc. This slight speeding up and slowing down causes the judder.

You may have heard talk of 1080p/24 signals. This is where the player reads the 1080p/24 data from the disc, and outputs this directly to the display. The display then repeats these frames at a multiple of 24, probably 72 or 96 hz. Thus every frame is on screen for an equal length of time, and there's no judder!!

The thing is, to benefit, you need a player that will output 1080p/24, and a display that will accept it, and display at a multiple of 24 (some displays accept it but then infuriatingly change it to 60hz, and introduce the judder).

The good news is that the PT-AX100 accepts this signal and displays it at a multiple of 24, thus no judder!! The bad news is that the A2 will never be able to output 1080p/24, it will always be limited to 1080i/60. The only way to get around this is to either use a video processor to reassemble 1080p/24 from the 1080i/60 from the Tosh, then send this to the pj, or alternatively sell your A2 and but either a A20 (EP10) or AX2 (XE1), as both of these players are to receive a firmware update in September to enable 1080p/24 output.

Some 'issues' that get raised on these forums tend to get blown out of all proportions, but I personally find judder to be a real pain. I found it bearable with my E1 connected to my AX-100, but once I had a PS3 feeding it 1080p/24 I could no longer bear to watch the E1 as the judder was suddenly really apparent to me, nearly all the time. It may be a few hundred quid in expense, but i'd seriously consider upgrading your HD-DVD player to make the most of judder free playback. I sold me E1 due to judder, and will purchase a new player once the firmware update is released.

I'm not sure which brand a PH8 plasma is - I know that Pioneer plasmas accept 1080p/24, and magically they will also take a 1080i/60 signal and reconstruct 1080p/24, then display at 72hz, thus eliminating judder!!

Thanks for the reply and the original post has been edited to accurately name the plasma.


I think that i understand the problem now, but would a different choice of PJ elimate the problem, or is it a characteristic of them all?.

Also, what will my AV amp be outputting as it upscales to 1080p?

[stuartbrown21]

Originally Posted by NWhiteley

Thanks for the reply and the original post has been edited to accurately name the plasma.


I think that i understand the problem now, but would a different choice of PJ elimate the problem, or is it a characteristic of them all?.

Also, what will my AV amp be outputting as it upscales to 1080p?

In all honesty it is the HD-DVD player that is the limiting factor here, as the pj has the ability to refresh at a multiple of 24, provided it is fed a 1080p/24 signal. It is the A2 that is unable to supply that signal.

As far as I am aware, the only way to provide judder free playback from your A2 is by using a video processor (very expensive) or by using a Pioneer plasma. I think I'm correct to say that no other display apart from Pioneer plasmas will change 1080i/60 into 1080p/24 to eliminate judder. I'm almost certain that no projectors will do this. Plus, I've heard varying reports as to whether this 'reverse engineering' of the signal harms the picture quality in any way. The best thing to do with the signal is to feed it directly to your display without any manipulation of the refresh rate from 24 to 60 and back to 24, or any interlacing / deinterlacing. Feed your AX100 a direct 1080p/24 signal and all it has to do is downscale it to 720p (quite a simple thing to do).

I think the cheapest option is to just buy an A20 once they are updated to output 1080p/24 - it will cost you a few hundred quid but from my experience it will definitely be worth it. It's a rather silly analogy, but watching HD with judder is like suddenly being given the best pair of trainers in the world, but they have a tiny stone stuck in the sole. In every way imaginable they are ten times better than what you had before, but you are constantly aware of the stone (judder). It's really only a little thing, and it doesn't hurt, and some people wouldn't even notice it, but you know it's there, and sometimes it's more obvious than others, and all you can think is that you have the best pair of trainers in the world, but I'd have spent another £200 if only they didnn't have this tiny blasted stone stuck in the sole!!!!

Pardon my crap analogy.

Your receiver upscaling to 1080p won't eliminate the judder from HD-DVD, and none of your other sources will have judder anyway, so it won't harm them either way.

[stuartbrown21]

Just for clarification, judder is an issue with HD film material as it is encoded at 24 frames per second, as explained above.

With standard definition, the UK PAL system refreshed at 50hz. DVD's therefore were encoded at 25 frames per second, and each frame repeated twice. Thus UK DVD's play 4% faster than the films at the cinema, but have no judder as each frame is repeated twice. The US NTSC refreshes at 60hz, and so US DVD's have always played at the correct speed, but with 'judder'.

So in the standard definition era, we always had either 4% speed up, or judder. We notice it a lot more than the Americans because they've always had it.

HD films are encoded at 24 frames per second worldwide, so the speed up is gone for everyone. New displays such as the AX100 are starting to have the ability to refresh not only at 50hz & 60hz, but also at a multiple of 24 (probably 48, 72, or 96) hz, and HD players are starting to provide 24 frames per second output. Thus, for the first time, consumers are gaining access to film based material, that runs at the correct speed, and without judder.

[NWhiteley]

Originally Posted by stuartbrown21

I think I'm correct to say that no other display apart from Pioneer plasmas will change 1080i/60 into 1080p/24 to eliminate judder

Im more confused now, given the above, why do i not get judder from my Panasonic plasma?

[stuartbrown21]

I did a bit of reading in the plasma forum about your display and found this thread:

Pioneers - No love for 'Pure Cinema'?

It may give you some interesting reading around this topic.

From what I've seen, I don't think your plasma can handle 24 frames per second material correctly, so there will be 3:2 judder in it's HD-DVD playback. Bear in mind that my analogy of a very small stone in the sole of your shoe is probably not too inaccurate in terms of scale - the judder is quite subtle, not like a massive earthquake going off or anything like that. Some people don't notice it, some can and aren't too bothered.

I personally thought I could only see it occasionally (panning shots are the worst offenders). However, once I got used to watching the PS3 Blu-Ray without judder, I started to detect 'slight' judder even during non-panning shots. The motion on the PS3 just looked more natural and I was able to relax and watch movies without the fear that the judder would suddenly take me out of the zone.

If it doesn't bother you, then don't worry about it!! There is also the fact that my pj can go to 120" diagonal, which is 9 times the screen area of your plasma, so any judder may well be more noticeable simply due to the size of the image.

[NWhiteley]

Originally Posted by stuartbrown21

I did a bit of reading in the plasma forum about your display and found this thread:

Pioneers - No love for 'Pure Cinema'?

It may give you some interesting reading around this topic.

From what I've seen, I don't think your plasma can handle 24 frames per second material correctly, so there will be 3:2 judder in it's HD-DVD playback. Bear in mind that my analogy of a very small stone in the sole of your shoe is probably not too inaccurate in terms of scale - the judder is quite subtle, not like a massive earthquake going off or anything like that. Some people don't notice it, some can and aren't too bothered.

I personally thought I could only see it occasionally (panning shots are the worst offenders). However, once I got used to watching the PS3 Blu-Ray without judder, I started to detect 'slight' judder even during non-panning shots. The motion on the PS3 just looked more natural and I was able to relax and watch movies without the fear that the judder would suddenly take me out of the zone.

If it doesn't bother you, then don't worry about it!! There is also the fact that my pj can go to 120" diagonal, which is 9 times the screen area of your plasma, so any judder may well be more noticeable simply due to the size of the image.

Now im beginning to get a decent understanding of what you have been saying. I have just re-watched the segments of 300, on HD-DVD, that are in slow motion, so obviously there are a number of slow panning shots and i did notice some very minor judder. This is not the first time i had seen this, but i had dimissed it as a characteristic of plasma/large screen technology, and not as a by-product of 3:2 pull down. (although, not really knowing what 3:2 pulldown was didnt help)