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Discussion Starter · #1 ·
Can jitter be resolved with a driver update or does one need to continue to look at different sound cards or jitter attenuators?
 

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If you are referring to the jitter you see when the camera is panning, I think this is an inherent problem with software playback of DVD's. You may be able to minimize it somewhat, but I don't think it will ever be eliminated.
 

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Quote:
Originally posted by Crescent
Sorry. I was speaking of audio jitter via S/PDIF.
Jitter over S/PDIF is determined by the clock driving the S/PDIF encoder.
 

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Quote:
Originally posted by Crescent
Pardon my ignorance, but same question.
Jitter (audio) is determined by the clock driving the S/PDIF encoder chip.
 

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Discussion Starter · #8 ·
Thanks for the responses.


So it's hardware. WinDVD, PowerDVD or TheaterTek won't make a difference in sound for S/PDIF.


It's been plaguing me why my HTPC sounds slightly worse than my STB DVD player and have been grasping at straws to find an inexpensive solution. I have OEM versions of WinDVD 4 and PowerDVD, and a full version of TheaterTek.


The only game plan I have right now is to try the RME HDSP9632 when it comes out or a Holo3d and forget about the sound card.
 

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AFAIK audio jitter really only affects PCM streams, but doesn't affect DD/DTS at all since they're compressed/encoded streams that are buffered on both sides. However, then I'm confused as to why various software DVD player audio filters supposedly sound better(example PowerDVD vs WinDVD audio filters). Nobody ever gave me a straight answer to that before.
 

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Quote:
Originally posted by Goi
AFAIK audio jitter really only affects PCM streams, but doesn't affect DD/DTS at all since they're compressed/encoded streams that are buffered on both sides.
I'd say that PCM streams are buffered too, in any receiver or DAC worth that name, even on average ones. I'd say the clock is recovered same way no matter if it's a PCM or a DD/DTS stream. I don't know for sure, but it seems the most logical thing. At last, they' re both a stream of bits that is received and processed inside the receiver.

Quote:
However, then I'm confused as to why various software DVD player audio filters supposedly sound better(example PowerDVD vs WinDVD audio filters). Nobody ever gave me a straight answer to that before.
Well, if you are talking about just DD/DTS undecoded output or passing, the difference is clear: it's your mind playing tricks on you, or in other words, expectation effects or placebo effect entering into scene. There's no other explanation, and this is a verified and quite common thing.
 

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"There's no other explanation, and this is a verified and quite common thing."


Prove it! Show me a study conducted where PowerDVD vs. WinDVD proves that it is all in the user's mind.
 

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Let's not reopen this again ...


Almost all manufactures use the same code for decoding DD and DTS. The end result is 2-8 streams of PCM data which are pretty much the same for all manufacturers. LFE processing might vary from implementation to implementation.


Jitter if audible at all impacts the sound if the clock at the digital-to-analog conversion for one of those PCM streams is not stable. Whether this clock is stable has nothing to do with decoding or buffering but how the oscillator works that drives the clock signal on the DAC.


If this clock is slaved in any way (usually a PLL) from the incoming signal then jitter in that signal will likely make it to the DAC chip doing the final conversion. This means jitter in the input signal will impact your DD and DTS sound!


Newer designs implement a completely independent clock and do various methods of sample rate adaption or implement a deep jitter buffer to account for the inevitable differences in the clock speeds of the independent local clock vs the symbol rate of the incoming signal.


You can clearly measure this jitter in the digital domain and it is understood how it manifests itself after the conversion in the analog signal. Whether you can hear this depends on your system, your ears, and likely many other factors but not your imagination.


Cheers


Thomas
 

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I guess you didn't understand what I wanted to say. I meant that, if there is a difference with UNDECODED DD/DTS output passed to a receiver depending on the software player, this difference can only be on the listener's mind, since the output stream will be identical with any player.
 

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What I was asking was an explanation to the apparent audible differences between the passing through of the undecoded DD/DTS stream by various software DVD players to the soundcard's S/PDIF output. I myself have heard such differences, and I don't pride myself in having golden ears. I can't tell the difference between 16/44 and 24/96 most of the time, and I can't tell the difference between 192Kbps CBR mp3 and VBR mp3, but I'm pretty sure PowerDVD and WinDVD sound different when passing through DD/DTS via S/PDIF, just don't ask me why.


I'm not sure if this has anything to do with jitter, but I doubt so though, since everything from the software DVD player to the soundcard is via the PCI bus, which is clocked, so I don't think jitter could be a problem there. My understanding of jitter is that it happens either at the DAC side, or is a line induced one(i.e. via the cable/connector, since S/PDIF doesn't contain a clock signal IIRC). That's why optical Toslink cables are more prone to jitter than coaxial ones. At least, that's what I read. I'm sure many of you have other opinions, since jitter is a hotly debated topic that seems to have supporters on multiple camps.
 

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Quote:
Originally posted by KikeG
I guess you didn't understand what I wanted to say. I meant that, if there is a difference with UNDECODED DD/DTS output passed to a receiver depending on the software player, this difference can only be on the listener's mind, since the output stream will be identical with any player.
I understand you perfectly! When was the last time you heard UNDECODED audio?

"since the output stream will be identical with any player."


Can you prove it, including headers and all S/PDIF control bits, in addition to the compressed frames? Have you ever captured and compared the digital streams from both software players and compared to a STB player or each other?


There has been far too many members in this forum, over the years, that had no expectation of hearing a difference between WinDVD and PowerDVD for it to be imagined.
 

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My PCM/DD/DTS all sound great to me. I hope no one ever tells me what jitter sounds like or I might start noticing it :p


edit: I can't detect a difference between HTPC (onboard S/PDIF) and my standalone (Pioneer 525). But I'll admit I am more critical of video than audio.
 

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Discussion Starter · #20 ·
I reopen the topic because it really bugs me that I researched the heck out of the HTPC, but somehow overlooked the jitter issue. So, I've spent $1400 for a PC that sounds worse than my $300 standalone player. I want a solution of reasonable cost. I can't sell the darn thing for what I paid for it. I don't want to use it analog mode. I have a prepro that I like.


There was a post a while back about current best configuration. Tedd said to build a cheap HTPC with a Holo card. I think he may have been right.


The other night I thought my ears detected that WinDVD was better than TheaterTek sound wise. It was so close I wasn't sure. There is no doubt the standalone player sounds better than the HTPC in any case. How can an inexpensive standalone DVD player get it right (or better)? Is it that Toshiba is such a financial powerhouse that they have the technology? It stands to reason that inside the DVD player there is probably a sound card like board of some kind.
 
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