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Microsoft and frame rate synchronization

Discussion in 'Computer Components' started by Ar-Jar, Feb 3, 2005.

  1. Ar-Jar

    Ar-Jar
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    Hi, my first post here, bear with me... I've been trying to find out quite hard what Microsoft is doing with the issue of mismatching frame rates at the video source (such as the DVD navigator) and display, (such as my projector connected via DVI) causing the well-known pan judder. I'm using Reclock together with Zoom Player and it works fine but I'm surprised how little I can find about this issue at microsoft.com. Maybe I'm not looking hard enough or missing something. What I found was a very good "call to arms" article from 1998 to hardware vendors to fix this but then nothing. Does anybody out there in have any inside info on when we can expect this to be robustly fixed by Microsoft? Or is it maybe fixed in the latest MCE version?

    Thanks!

    Arto
     
  2. drummerjohn

    drummerjohn
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    Its not an issue to Microsoft if its not an issue to the public. How many people do you know that notice juddering. 90% dont even notice incorrect aspect ratios.
     
  3. Ar-Jar

    Ar-Jar
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    I guess you're right. I was just thinking that since Microsoft is touting their MCE quite hard and have gone to great lengths implementing the DirectX library for media applications, they could have fixed this issue too. It can obviously be done with, in Microsoft terms, very little effort. And the article they wrote about this in 1998 is still there on their site: http://whidbey.msdn.microsoft.com/library/default.asp?url=/library/en-us/dndevice/html/vidsynch.asp. It says e.g. "The bottom-line question in considering PC video remains, "Is the picture quality better than television?" Otherwise, why spend $2,500 on a PC-TV system for a picture that is worse than a $250 television set?"

    Arto
     
  4. KraGorn

    KraGorn
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    Also, the 'problem' only affects those with mixed NTSC and PAL DVD collections, if you only watch NTSC or PAL then there's never a need to change refresh rates so the factory-set 60hz or 50hz suffices. True, even in this situation refresh rates will rarely be set properly, ie. 59.94 for NTSC and 50.00 for PAL (anyone who's used Reclock will know how bad some video cards are without being twiddled by Powerstrip), but the occasional judder is even less likely to be spotted than the steady stuttering when playing PAL at 60 or NTSC at 50.

    As John said, Joe User doesn't know any better when he's exposed to it, he just assumes that's what watching a DVD is like .. heck, I can remember it was some time after I built my first HTPC before I began to understand there was a problem, let alone a solution. :)
     
  5. Ar-Jar

    Ar-Jar
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    It does become noticeable when playing 24 f/s DivX on a 720p 50 Hz display too. But Reclock is the cure here as well. I guess a part of my frustration is that if I have spent € 2000 on an HTPC, it's gotta be better *in every aspect* than the €60 DVD player from the superstore.

    Arto
     
  6. MikeTV

    MikeTV
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    I must confess to being blissfully ignorant of this issue. I regularly watch PAL digital broadcasts at 60HZ, and had always assumed any quality issues were due to the mpeg compression only. I have noticed judder in motion on dvd's (mainly NTSC), but undestood this to be a different problem relating to the frame rate of 24 for movies. It seems unlikely that display manufacturers will ever produce displays that would sync exactly with 24fps material. But perhaps I'm misunderstanding the issue? Usually TV displays are 50hz, 60hz or 100hz, and that's that. They don't seem to produce multi-sync TV's. Since movies are often watched on these displays, hasn't the problem existed since TV's were invented? I appeciate that PAL TV's will work well with genuine PAL video material, and the same for NTSC, but for movies, I'm a bit confuse as to what the solution should be (multi-sync TV's?). Can anyone explain?
     
  7. Ar-Jar

    Ar-Jar
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    If you haven't noticed this phenomenon, and want to keep your peace of mind, then stop reading here :) There are two problems (that are really the same): that of matching any 24 f/s DivX to your 50 f/s display and that of matching the ~50 f/s (PAL) of your motherboard (DVD playback) to the ~50 f/s of your graphics board (and thus display). Both can be done by adjusting the playback framerate to keep it synchronized with the display framerate. But the intrinsic framerate of the material must be close to that of the display for this to work. For a detailed and very good explanation of all this, please download Reclock and read the "Readme first" file.

    So, there is a problem, but there is also a solution. What I wanted to know is if Microsoft is addressing this problem at all.

    Arto
     
  8. drummerjohn

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    Computer says "no"

    (for all you Little Britain fans)
     
  9. MikeTV

    MikeTV
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    Cheers for the reply. I think I understand the reclock solution, but still, if you are watching PAL video-based material on an NTSC display, or vice versa, you are always going to be out of luck, because of the framerate mismatch?

    And similarly, NTSC display viewers are always going to suffer with film-based material?

    Anyway, I'm off to scrutinise scrolling news tickers...
     
  10. Ar-Jar

    Ar-Jar
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    Hi, you're right. I don't watch a lot of NTSC so I usually have my projector humming at 50 Hz. That works fine for 24 f/s DivX material (which is speeded up to 25 f/s by Reclock) and for 25 f/s PAL DVDs (that are actually also speeded up from the original film's 24 f/s). Would I watch an NTSC DVD, I would select a 60 Hz update frequency for the projector. (The new NVidia driver has both the 720/50p and the 720/60p resolutions predefined.)

    Arto
     
  11. MikeTV

    MikeTV
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    Well, I have to admit, my tickers aren't perfectly smooth (PAL video @ 60hz), and they seem a bit blocky too. I guess I'd always assumed they were broadcast that way. When I first got the nebula, it seemed very jumpy/blocky, particularly on motion scenes. To some extent, I've got used to it. But I think they have improved the deinterlacing algorithm which helped noticebably.

    And I can't even buy NTSC dvd's as a solution - because of the 24fps problem (which is very noticeable). So, the lesson I've learnt is when choosing displays, get one that supports 50/100hz, or is multi-sync.

    Unfortunately, I think you have to look quite hard to find displays in Europe that compare (in terms of clarity and definition) with the HD displays in the US (within the price range). But that's another discussion, and will no doubt improve in time.
     
  12. Ar-Jar

    Ar-Jar
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    Are you saying that the 3:2 pulldown algorithm used to convert 24 f/s to 60 f/s leaves noticeable artifacts? Or is the problem something else?

    For maximum flexibility, choose a display that supports both 50 and 60 Hz (or their multiples). I'd guess that at least most projectors do that. Computer LCDs don't always support 50 Hz.
     
  13. TheCrow

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    Yes it does, and that plus the lower resolution is why I don't buy NTSC DVDs.
    Fortunately my plasma and PC will both do 50Hz via DVI at NR :)
     
  14. stlic

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    Okay I havn't got a fancy projector or plasma but I get a perfectly smooth image using a Radeon VGA---> Rgb Scart on my Philips 9308 by using interlaced 24 Hz for film NTSC and 25 hz for PAL. VMR9 still suffers because of microstutters which are a well recognised problem hopefully resolved by using VMR9 renderless. Thankfully my DVD playback is great using overlay so for the most part I have little issues.

    The downside is that 30 fps NTSC does judder which can be seen on the extras on many DVDs. Having a dated 933 procesor doesn't help with my VMR9 issues. I can't use any fancy ffdshow processing and am limited to overlay but finances are limited.
     
  15. drummerjohn

    drummerjohn
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    I use VMR9 for PAL playback - but I had to use Reclock with it to stop it stuttering.
     

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