TiVo : TiVo Picture Quality

[muppetman11]

Originally Posted by Stephen

Glad you agree about the Samsung :-) However I find TiVo to have just as good PQ.

I still have a Samsung V+ , and the PQ is excellent on it.

[clinteastman]

Originally Posted by Lew

From those pictures it looks like some sort of de-interlacing error.

That looks like a field order problem or an unfiltered resize of the image.

---------- Post added at 14:48 ---------- Previous post was at 14:46 ----------

Originally Posted by muppetman11

I still have a Samsung V+ , and the PQ is excellent on it.

Better than the Sky PQ? Was stopping with my sister the other weekend who has Sky+HD and the PQ was dreadful, thought it was the TV's settings but after much fiddling it looked the same, was quite shocked to tell the truth.

[Lew]

Originally Posted by clinteastman

That looks like a field order problem or an unfiltered resize of the image.

I'd say the first, personally. If that's the case then hopefully it should be an easy fix.

[muppetman11]

Originally Posted by clinteastman

That looks like a field order problem or an unfiltered resize of the image.

---------- Post added at 14:48 ---------- Previous post was at 14:46 ----------



Better than the Sky PQ? Was stopping with my sister the other weekend who has Sky+HD and the PQ was dreadful, thought it was the TV's settings but after much fiddling it looked the same, was quite shocked to tell the truth.

The Sky+HD box produces a softer SD image I think ,however these days i only watch HD and thats equally as good as VM.

[Lew]

Originally Posted by Perfect Choice

Sorry too technical to me, is that a signal feed issue or a software in the box issue if that is the cause of course!

OK. When a TV signal (such as standard SD video) is interlaced, only half the lines of the picture are included in each frame (technically a field, but that'll do for this explanation). On the first frame only the odd lines are scanned, and the second frame has only the even lines (or possibly vice-versa). De-interlacing combines these two images to create a progressive frame (one that contains both the odd and even lines). If it incorrectly detects which lines are which it will display the odd lines where the even lines should be, and the even lines where the odd lines should be. This can result in a problem such as the one shown in the second image in the linked post. As TiVo is providing the de-interlacing and upscaling then it's a software issue.

[DaBoz]

Originally Posted by Lew

OK. When a TV signal (such as standard SD video) is interlaced, only half the lines of the picture are included in each frame (technically a field, but that'll do for this explanation). On the first frame only the odd lines are scanned, and the second frame has only the even lines (or possibly vice-versa). De-interlacing combines these two images to create a progressive frame (one that contains both the odd and even lines). If it incorrectly detects which lines are which it will display the odd lines where the even lines should be, and the even lines where the odd lines should be. This can result in a problem such as the one shown in the second image in the linked post. As TiVo is providing the de-interlacing and upscaling then it's a software issue.

So you think this is fixable with a software update? Next question, are VM aware of this?

Originally Posted by DaBoz

So you think this is fixable with a software update? Next question, are VM aware of this?

I think they do. In the community forum VM staff say they are looking in to why some have this issue.

[Perfect Choice]

Originally Posted by Lew

OK. When a TV signal (such as standard SD video) is interlaced, only half the lines of the picture are included in each frame (technically a field, but that'll do for this explanation). On the first frame only the odd lines are scanned, and the second frame has only the even lines (or possibly vice-versa). De-interlacing combines these two images to create a progressive frame (one that contains both the odd and even lines). If it incorrectly detects which lines are which it will display the odd lines where the even lines should be, and the even lines where the odd lines should be. This can result in a problem such as the one shown in the second image in the linked post. As TiVo is providing the de-interlacing and upscaling then it's a software issue.

Thanks, understand now. Means that if this is an example or one of the causes of PQ then it is fixable at least through software change. That is what I am hoping for, but my SD PQ is not as bad as others and while I still have a difference from what I had before with my SA V+ it is now at a level I can "live with" and hope to see improved over time.

[Lew]

I wonder if the TiVo code is assuming that the odd field is scanned first like it is on SD NTSC video, whereas PAL scans the even field first. That would certainly explain the wrong field order.

---------- Post added at 16:19 ---------- Previous post was at 16:17 ----------

Originally Posted by DaBoz

So you think this is fixable with a software update?

If it is simply a field order error in their de-interlacing code then it could be as simple as changing a flag in the code. The problem with software though, is that it could just as easily be really complicated to fix.

---------- Post added at 16:23 ---------- Previous post was at 16:19 ----------

I've taken some photos of the text on channel 999 to show the differences when using different settings on the TiVo. My camera was mounted on a tripod and set to full manual mode so the settings are exactly the same for all 3 photos.

This is how the text looks when I set the TiVo to 576i only and let my TV handle the conversion to 1080p

[img]Download Failed (1)[/img]

This is how it looks when I set the TiVo to 720p

[img]Download Failed (1)[/img]

This is how it looks when I set the TiVo to 1080i

[img]Download Failed (1)[/img]

Notice how even though the text looks smoother in 720p mode it looks distorted vertically due to the (supposed) wrong field order.

---------- Post added at 17:03 ---------- Previous post was at 16:23 ----------

A few more pics, zoomed in so that the pixels are visible, desaturated and the levels tweaked:

576i (TV de-interlacing and upscaling)



720p



1080i



---------- Post added at 17:40 ---------- Previous post was at 17:03 ----------

Here's an example of what happens to static text when the odd and even lines are swapped.

[img]Download Failed (1)[/img]

Look familiar?

[clinteastman]

Originally Posted by Lew

[/COLOR]Here's an example of what happens to static text when the odd and even lines are swapped.



Look familiar?

All signs point to that being the problem, certainly looks like it.

[devilincarnate]

Originally Posted by Lew

[/COLOR]Here's an example of what happens to static text when the odd and even lines are swapped.


Look familiar?

Stop it it is sending my eyes funny

[DaBoz]

Looking at the text on 999 I can see the picture is flickering at 720p, but stable at 1080i

So despite the interlacing problem described, the effect of the interlacing is to stabilise the picture at 1080i

Help indeed! My brain and eyes hurt.

[Lew]

Someone on the VM forum has also pointed out that this also sounds like the same problem that affects the menus on the SA V+ Box when set to 1080i.

[devilincarnate]

Originally Posted by DaBoz

Looking at the text on 999 I can see the picture is flickering at 720p, but stable at 1080i

So despite the interlacing problem described, the effect of the interlacing is to stabilise the picture at 1080i

Help indeed! My brain and eyes hurt.

Yes I noticed this as well on channel 999 and the picture flickered at 720p, then changed it 1080i and it was stable as well?

[clinteastman]

Originally Posted by devilincarnate

Yes I noticed this as well on channel 999 and the picture flickered at 720p, then changed it 1080i and it was stable as well?

On channel 484 in 720p it's enough to give you a seizure! Not that I watch that channel let me point out.