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"Slowdown" on PAL TV broadcasts

529 Views 11 Replies 5 Participants Last post by  3lions

Does anyone know what the cause of the slowdown is on PAL broadcasts? I have an original Lumagen vision, and have supplied some material which displays the problem to Lumagen Tech Support. They are looking into a fix.

I was wondering if anyone know's what the broadcaster's are doing to cause the slowdown to happen? I have noticed the Lumagen is more susceptible to it, than my previous Iscan Ultra.

I've read a few threads that mention this problem is corrected on the Iscan HD and HD+. Can anyone advise as to what was done to correct the problem?

Just really trying to find out the cause and a potential fix.

Thanks in advance

Cheers, Lee
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Are you sure you're not describing judder?

I'm not really sure what you're referring to - I've never seen it on any of my scalers and I watch a LOT of PAL content.
I see the slow down on the IScan Ultra. Not sure how to describe it other than motion looks unnaturally slow on occasion. This only occurs on some PAL programs that have been converted to NTSC and rebroadcast. I watch a lot of British shows on satellite and some of them show this. Other British show are perfect. I have two different satellite systems and they both exhibit the problem so its not the satellite provider. I have tried two different Ultras (Thanks DVDO) and they are both the same. Am at a loss at the moment

One other thing to note is that the menu system on the DirecTivo does tend to judder slightly going through the ISCAN when compared to composite. The menus sweep in right to left on the screen and this is smooth on composite and ever so slightly jerky on the ISCAN. Using the twin feature on the plasma has allowed me to verify this side by side

I'm aware of the problem with iScan ULTRA (I think it's losing frames due to a problem with film/video detection or continually switching from video to film).

Converted TV shows can be a really big problem. Usually, content gets converted from the source (24fps film) directly to PAL and NTSC. However, on some occasions when the source is not 24fps, but 60Hz or 50Hz (PAL content), some companies utilize cheaper methods to do the frame rate conversions.

In such instances, you get very strange cadence combinations. Both Silicon Optix and DVDO have demonstrated (at least privately) algorithms capable of processing all sorts of crazy cadence combinations that are a result of bad edits or such awful conversions.

However, in the meantime, most companies simply try to make due by moving to video mode when this occurs. If it continues, strong judder can ensue (which might also show up as a "slow motion" effect).
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The aretefact is not so much a slow down as missing fields or frames. So you get a slo mo effect but it's really normal motion with limited temporal resolution (if that's the correct term)


Thanks for the reply. It good to know that I am not going mad and that this is real.

Do you know if the HD has this same problem. It might be the final reason to upgrade
Hi, 3lions,

You are not going mad, and I can relate! This is driving me round the bend...

I have three options as far as I can see it....

1) Wait for Lumagen to offer a firmware update, although this is looking unlikely on my original model.

2) Run a bypass around the Lumagen just for PAL TV.

3) Change to another type of scaler, that already has this sorted.

At the minute I have stopped watching TV, as it is too irritating.

Someone must know if this has been corrected in the HD/HD+

Cheers, Lee
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I'm actually seeing it too on the Lumagen now too. I've reported it to Lumagen. It occasionally misses a frame or two (it also happens when you operate the OSD).

I have not seen this type of issue on the iScan HD or HD+.
Hi Ofer,

Got a response back from Patrick at Lumagen to say he has received my disc and was able to see some of the problems I reported.

He is working on a solution...

I'll keep you guys posted.

Cheers, Lee
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Any of you guys know if the Ultra is upgradeable? I know it is not field programmable by the customer but are the algorithms coded in a DSP or maybe a FPGA? If it is an ASIC implementation then there wouldn't be any. I am wondering if it worth pushing this issue with DVDO. Of course the easiest thing would be to upgrade to HD but that does not have great WAF
3lions (Terry) - The iScan Ultra is not designed to be reprogrammed as you suggest.
Thanks for the the info Josh and all your help with this in the past

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