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Discussion Starter · #1 ·
As my DVD's are PAL ie 25fps 50Hz I found perfect stutter free nirvana playing PAL dvd's at 50hz to my Sony 10HT projector.


To get to 50Hz I use powerstrip.


However, it doesnt matter what SW player I use (PoerDVD, WinDVD, TT, NVDVD) after approx 15-20mins I will start to get horrendous (and I mean 10frames missing) stutter. Play them back at 60hz no problems.


Its almost as if the SW players are incapable of handling that refresh rate.


The vid card can handle 50Hz as I use Dscaler with no probs. But then Dscaler is not trying to synch video to audio and this where the problem lies I beleive.


I have tried all the following without success:

Reclock

Adjusted latency of video card and audio card

turned off Vsync


My setup is:

Abit BH6

Pentium 2.4b

512mb PC2700

Radeon 9200 128mb

Pioneer 106s DVD

M-Audio Revolution
 

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I am surprised that the Sony 10HT is capable of benefitting from 50Hz input. 99% of LCDs that I have ever heard of are fixed at 60Hz, in the same way that they are fixed at (e.g.) 1024*768 native resolution. It's a result of the way the electronics driving the display work. (Similarly, DLP is fixed at 60Hz, otherwise the speed of the colour wheel would need to change.)


It seems to me most likely that the major stuttering you are seeing is caused by some internal adjustment in the Sony, which has been busy converting that 50Hz you so laboriously achieved back to 60Hz.


Another possible source of the problem is a slight difference between 50Hz on your video card, 50Hz on your DVD, and 50Hz on the Sony.


Are you able to connect a multisync CRT monitor to see whether it is the Sony or your software/firmware that is the cause?


I watch mainly PAL DVDs (gotta love the 20% boost in resolution) but on a 60Hz projector, with my laptop's 60Hz LCD screen as a monitor. I find the results perfectly smooth enough for my tastes; I guess that strictly there must be judder (every third and fifth frame lasts for 3/60 of a second instead of 2/60, so that 5 frames last 12/60 of a second) but I don't really notice it except on otherwise very smooth sequences, like the zoom out from Earth to the entire universe that forms the opening sequence to Contact. Possibly it is less noticeable on an LCD-based display which has a latency of 25ms-40ms, which could work to smooth out such problems.


The one thing that seems to be impossible currently is to slow down PAL DVDs by 4% so as to get 24Hz output, and yet retain the DD/DTS soundtrack (similarly slowed down). It is impossible because DD and DTS need to drive the receiver at a fixed digital frequency, so to slow the audio down you would need to decode it in the computer, digitally pitch-correct it (yuk! Peter Jackson you should be ashamed of yourself), and re-encode it as DD or DTS. I am not aware that, apart from N-force 2 mobos, it is possible for a PC to recreate DD or DTS content on the fly.


Roll on HD-DVD, which could eliminate all of the above problems although it would then be necessary to work out how to feed the projector 48Hz or 72Hz.
 

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Discussion Starter · #4 ·
The 10Ht can handle 50,60,70,72,85hz inputs.


I can feed the 10Ht with [email protected] no problems using Dscaler - but as I said Dscaler doesnt synch audio to video as does DVD.


So it must be the DVD software. I guess that SW dvd players were made for PC's, and who runs there monitor @50hz? No one. So why would they even look at a player being capable of doing this?


BTW - 99% of PAL dvd discs already have the audio altered by half an octave to compensate for the 4% increase in speed. So to get the true audio you would have to electronically bring it back up half an octave before doing anything else to it. Now that would be messy.


And yes - you are right. I have NTSC and PAL discs and the PAL is so much better in resolution.
 

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Sorry, I do not agree with you at all on the above details.


You say the Sony "can handle" those different frequency inputs but do you not think it is converting them to 60Hz internally? I think it is more than likely that that is what it is doing, unless the Sony has a very unusual approach. (The only way to test would be some kind of strobe effect, which would be tricky to set up.)


The SW players are feeding to the video card exactly 'what they see on the disk' and doing it to timings based on the audio signal. It is most unlikely that the SW players are attempting to convert 50Hz PAL to 60Hz. The renderer (which is always the same renderer if using a filter graph) simply feeds the video card the frames at 50Hz. (It's similar to a game, which could feed the video card images any number of fps depending on image complexity. The video card has the tricky job of displaying that smoothly at 60Hz.)


All PAL disks (made from 24fps film-source material) are sped up by fractionally over 4%. The audio increases in pitch as a consequence. The pitch change is not half an octave actually, it is approximately a quarter of a tone (i.e. less than a semitone). 99% of people cannot notice this unless doing an A-B comparison with a non-pitch changed source (i.e. R1 DVD or CD soundtrack).


Exceptionally, the people who make the PAL DVD may decide to 'pitch correct' it which involves tweaking the sound digitally so as effectively to lose 4% of it. This was done for LOTR:FOTR and also for the Two Towers, allegedly at the director's own request (I'm not sure if it was done for both the DD and the DTS track, on the EE - it would be worth checking). Obviously the mass market does not typically notice such things, but some purists mind a lot.
 

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Discussion Starter · #6 ·
I never said the Sony refreshes its LCD panel at 50hz - Im just saying those are the inputs it accepts - its in the manual and its show it in its OSD when inputting those frequencies. So yes - it most probably is upconverting to 60hz for the LCD panel. But, and I dont claim to understand this, if I feed it 50hz material at 50HZ (hope that makes sense) playback is perfect (until the major stutter kicks in).


The video card is set to 50hz - the disc is 50hz. So I am outputting 50hz. However, I get major (I dont mean microstutter) stutter. Some discs are worse than others.


If I use Dscaler using a 50hz feed and outputting to my projector at 50hz I get no problems.


So - in theory we can forget its the projector at fault and even rule out the graphics card as it can show a 50hz input succesfully with anything but dvd software.



As for the speed half an octave thing - I am sure to are quite correct - I couldnt remember if its an octave or semitone or whatever without looking it up (lazy I know). I, unfortunately, am one of these people that notice the speed increase and so have to buy R1 music DVD's. Are you sure it's only recently that they have done this audio process. I was led to beleive it had been going on since mid 90's and was almost standard on most discs.
 

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Drummerjohn


It is NOT the DVD software - well not entirely anyway. I play 99% PAL disks and it's as smooth as silk on my CRT projector at 50hz. Using Reclock gives you that last ounce of smoothness, but I don't think it will help you. With a true multisync projector smooth playback is possible.


Your problem is with the digital projector - I think it internally scales to 56hz - a very odd number. There have been a few threads by LeonardisVourdis (I think the spelling is right) on this topic. I think it is the same projector he has.


The only PAL disks that are pitch corrected are the LOTR disks AFAIK, but I could be wrong.

Fellowship has clearly audible blips all the way through it, drives me nuts. However the picture is much better than NTSC. Two Towers does not seem to suffer, thank god!


Mark
 

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Discussion Starter · #8 ·
Thank you for that Mark.


Ive just watched 2 hours of 50hz TV on my Sony10HT fed through my PC using Dscaler outputting at 50hz without a hitch.


Can you post yor setup please so I can compare.


Thank you.
 

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Drummerjohn

10HT, and HS10 are very similar in terms of electronics, with HT10 having the same 1366*768 resolution on a greater LCD panel (1,35' HS10=0.87) Sony steadily uses 56Hz refresh rate for WIDE SCREEN 1366*768 COMPUTER MODE to every model I know (with the exception of HS20 which seem to have an extra 1280*720 60Hz but not 50Hz). So for 50Hz Drummerjohn must be using the video GBR mode 720p (or a computer 1184*666 50hz). In both cases due to resolution/panel mismatch the internal scaler is ON but his picture should be steady with no stuttering. I think something else is going wrong there especially if stuttering appears 5-10 minutes later...

Maybe some background task (Some have reported as one the windowsXP messenger...), I had same problems with DVDidle(older version). DVD disc problems (especially if stutter appears at the same minute of play..) or ... some other resource hungry application!

Drummerjohn keep on top the CPU/Memory/Application usage window and try to see what happens 5-10min later.

Now if Dscaler/TV works ok then monitor/9200Ati /background tasks/50hz are ruled out and we are left with DVD/DVD disc/ IDE related /Audio problems..... By the way which DVD player are you using?

Many users also report problems with their revo cards

You can change the latency of both 9200 and M audio(usually 32 but 64 is good) through powerstrip (adapter info..)
 

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Discussion Starter · #10 ·
THankyou Leonidas...


Now we may be getting somewhere.


Yes - i am using [email protected] into Video GBR mode.


Background tasks - got them down to 7. Sometimes this stuttering kicks in from the outset so I don't think its a background task.


DVD player is Pioneer 106s


Adjusted the latency of video card and audio card with a lot of success - ie stuttering was horrendous now its every few seconds. After working through combinations of latencies I found 128 was best for both.


I'm still convinced this is a software issue and will try my other PC.
 

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Drummerjohn

Intervideo gives high priority to PAL viewers/customers so WinDVD seems to play better PAL Region 2 DVDs than let's say PowerDVd. It seems highly improbable that WinDVD (especially 4.5.xxx, don't use 5.xx) would be incompatible with 50Hz. As you mentioned yours problems must be due to audio sync. Try disabling audio in WinDVD, use SPDIF out instead of REVO output, use latest audio drivers, latest Intel drivers USE intel's ACC program!! (By the way in powerstrip under ATI 9200 info is DMA enabled?)
 
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