Hmm... for CRT users, there may not be the issues that a DLP may have, but it's pretty easy to match timings with Powerstrip... You can get pretty close to any kind of refresh rate and pixel timings with custom resolutions. I might be missing the issue, I suppose, but if you're looking for 48Hz with DLP resolutions, Powerstrip should be able to do it without a problem at all!
smoothest at 48Hz?
I recently determined that my 3-chip DLP projector can display 48Hz signals at their native refresh rate. So I am trying to find out the best way to play DVDs at 48Hz (or 48/1.001=47.952Hz to be exact).
Ideally I would like to use a combination of hardware and software that never stutters. This combo would provide the smoothest playback possible because the video clock and audio clock must be locked together. Does such a combo even exist? If not, what combo comes closest to perfectly smooth at 48Hz?
Ideally I would like to use a combination of hardware and software that never stutters. This combo would provide the smoothest playback possible because the video clock and audio clock must be locked together. Does such a combo even exist? If not, what combo comes closest to perfectly smooth at 48Hz?
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I have been using Powerstrip to set the video card to 48Hz, and my projector displays the signal. So my question is not really about Powerstrip.
I am looking for the most stutter-free combination of video card and DVD player software, or possibly a standalone device.
I am looking for the most stutter-free combination of video card and DVD player software, or possibly a standalone device.
I believe the most stutter-free combination is an external DVD player with the Holo3D card (Use either component or SDI inputs). The next most stutter-free is TheaterTek 1.5. You will want a Radeon-based video card for either of the above situations.
Do some Radeon-based video cards come closer to 47.952Hz than others?
Does there exist any DVD player (either HTPC or standalone) that has perfect 47.952Hz output where the video clock and audio clock are locked together?
Does there exist any DVD player (either HTPC or standalone) that has perfect 47.952Hz output where the video clock and audio clock are locked together?
The ability to reach 47.952Hz (I run at exactly this refresh) comes from Powerstrip. The different Radeon models all support 47.952Hz provided you use Powerstrip. The syncronizing of the video and audio clock is a responisibility of the DVD software/hardware. In the case of TheaterTek, except for an issue (that has now been fixed thanks to new M-Audio Beta drivers) involving M-Audio card drivers in Win2K/XP, there are no issues about syncronizing the video and audio clock. In the case of a standalone DVD player with the Holo3D, I have not heard of any issues with the video and audio being out of sync.
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I have never heard of a PC where the video clock on the graphics card and the audio clock on the sound card are actually locked to each other or locked to a master clock (i.e., genlocked). Usually the DVD software/hardware must compensate for the slight timing difference between the video clock and audio clock by occasionally dropping/repeating either video samples (i.e., frames) or audio samples, in order for the video and audio to be as nearly synchronized as possible.
| Originally posted by vrindner The syncronizing of the video and audio clock is a responisibility of the DVD software/hardware. |
Erik, maybe I didn't understand your question correctly.
What is your primary concern? That the video and audio will be out of sync?
What is your primary concern? That the video and audio will be out of sync?
My ultimate goal is to completely eliminate both "judder" (by using 2:2 pulldown at 48Hz instead of 3:2 pulldown at 60Hz) and "jitter" (by locking together the video clock and audio clock). Right now I can eliminate one or the other but not both.
On the one hand, I can eliminate judder by using a PC because it can be configured for 48Hz output. However, I have not heard of one that locks together the video clock and audio clock, so jitter is not eliminated.
On the other hand, I can eliminate jitter by using a standalone DVD player because it locks together the video clock and audio clock. However, I have not heard of one that has 48Hz output, so judder is not eliminated.
On the one hand, I can eliminate judder by using a PC because it can be configured for 48Hz output. However, I have not heard of one that locks together the video clock and audio clock, so jitter is not eliminated.
On the other hand, I can eliminate jitter by using a standalone DVD player because it locks together the video clock and audio clock. However, I have not heard of one that has 48Hz output, so judder is not eliminated.
Well, a standalone player is going to output 480i timings regardless... it's still up to the HTPC to scale and output it at 48Hz. With the stand-alone player, you don't have to worry about the audio/video clock differences.
For me, an external DVD transport with SDI output, and the use of an SDI capture card would be the ultimate. Dream transport/signal path? Tag McLaren or Proceed MDT with SDI output. Tag ain't gonna do the SDI, so you need the PMDT with a $1500 SDI output card (Vigitech), along with the $500 SDI capture card. That totals out to be... roughly $7500, right? Sure would be nice clean audio, and about as judder free video as possible
For me, an external DVD transport with SDI output, and the use of an SDI capture card would be the ultimate. Dream transport/signal path? Tag McLaren or Proceed MDT with SDI output. Tag ain't gonna do the SDI, so you need the PMDT with a $1500 SDI output card (Vigitech), along with the $500 SDI capture card. That totals out to be... roughly $7500, right? Sure would be nice clean audio, and about as judder free video as possible
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Jitter still exists if the video output of the graphics card is not genlocked (with an exact 48:60 ratio) to the video input of the SDI capture card. So that would not be the ultimate for me, but it would be close.
| Originally posted by Aaron Oz For me, an external DVD transport with SDI output, and the use of an SDI capture card would be the ultimate. |
How 'bout a Teranex outputting HDSDI into a digital projector with HDSDI input?
Okay, the upcoming Rock Pro should have the HDSDI output too.
Realistically, a DVI connection maybe?
Okay, the upcoming Rock Pro should have the HDSDI output too.
Realistically, a DVI connection maybe?
Hi Eric,
I've been able to get the jitter down to a level where it's barely noticable, but it seems to be hit & miss to get the right combination of driver, software player and settings.
I'm using a Radeon LE with PowerDVD and 7199 driver. Powerstrip is set exactly to 47.952Hz (you'll need to play with the porch settings or sync width to get the rate perfect, and use "ultra-fine granularity").
Even so, it wasn't until I re-installed the driver a few times that the jitter noticably improved. Weird. Jitter is still a fundamental flaw of HTPC's - I'm still waiting for a combined audio/video card with a single clock or a better frame flipping algorithm.
Cheers,
Dave.
I've been able to get the jitter down to a level where it's barely noticable, but it seems to be hit & miss to get the right combination of driver, software player and settings.
I'm using a Radeon LE with PowerDVD and 7199 driver. Powerstrip is set exactly to 47.952Hz (you'll need to play with the porch settings or sync width to get the rate perfect, and use "ultra-fine granularity").
Even so, it wasn't until I re-installed the driver a few times that the jitter noticably improved. Weird. Jitter is still a fundamental flaw of HTPC's - I'm still waiting for a combined audio/video card with a single clock or a better frame flipping algorithm.
Cheers,
Dave.
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One issue to consider is the accuracy of the audio clock on the sound card, assuming PowerDVD is locked to it. For instance, if the audio clock is not exactly 48,000Hz but rather is 47,999Hz, then Powerstrip should be set to 47.951Hz instead of 47.952Hz.
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It may be possible to implement some kind of software PLL (phase locked loop) to compensate for the lack of a hardware PLL in HTPC's. Perhaps the software PLL could dynamically tweak the vertical refresh rate of the video card's output by some small amount (e.g., 0.001Hz), assuming that such a small tweak would not cause the display to briefly lose sync. The tweak would kick in automatically whenever the video clock has drifted from the audio clock by that small amount.
| Originally posted by David Panko I'm using a Radeon LE with PowerDVD and 7199 driver. Powerstrip is set exactly to 47.952Hz (you'll need to play with the porch settings or sync width to get the rate perfect, and use "ultra-fine granularity"). |
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| Jitter is still a fundamental flaw of HTPC's - I'm still waiting for a combined audio/video card with a single clock or a better frame flipping algorithm. |
For Silky smooooth DVD playback at 47.952 Hz I use a Radeon based HTPC with an SDI Silk card running DScaler. The DVD player is a SDI modded Denon 1600. Dscaler has judderterminator support similar to what is in the Rock video processor altough I would say my setup is smoother than what I have seen from the Rock plus. I have also tried the Holo3Dgraph card but for some reason I didn't get the same level of smoothness at either 47.952 or 71.928 Hz that I get with the Silk card. For extra help I disable all non essential hardware on the PC and run a highly stripped down version of Windows 98SE (less than 100MB).
Yes, software PLL is definitely possible on Radeon. Superfine Hz increment/decrement during vertical blanking is another safe method of realtime PC genlock. It just hasn't been done yet. Buffering of a few frames is necessary for safety margin in smoothing out erraticness in the incoming stream. (May cause lipsync delay, but can be compensated within the PC if the soundstream is processed too or externally.)
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