VS useless for SD broadcast ?

[old man]

I have a very basic set up with a panny PH9 that i use almost exclusively to watch Sky and SkyHD, very rarely SD DVD (Pioneer 400 dvd player with HDMI) and was sufficiently satisfied with the performance in Standard Definition after upscaling by the Pio.

However, recently i noted that Pio 428 received high praise for its SD performance from some members of AVF and began getting some info of an external video scaler in order to improve the SD performance of the PH9 because when watching Sky TV sometime program quality is acceptable, but often the quality of broadcast is really objectionable.

Now a few days ago have been told that really video scalers are not able to improve the quality of normal SDTV transmission, but rather they act to worsen their defects.

Is this true ? Or perhaps this is only true if we consider medium to low quality(and price...) scalers?

Should be very interested to know the opinion of some knowledgeable member.


om

[Gordon @ Convergent AV]

In a way the person who commented to you is possibly correct in that any video enhancement should, hopefully, reduce artefacts (defects) in the image. However to say this means a scaler is worthless for SD I would argue is nonsense.

I would use a technical term for the description of the reduction of artefacts in an image...I'd call that AN IMPROVEMENT.

Your Panasonic plasma is incapable of detecting whether the content of an SD broadcast is video or film based. It treats everything as video (it can do this trick for 60Hz sources but not 50Hz ones). A decent external video processor would, just for a start, be able to detect the Film sources broadcast and weave fields together that came from the same frame. This will immediately reduce artefacts on screen and give you a HIGHER RESOLUTION image.

If it was a clever scaler it could also employ much better algorithms to deal with the video source material, giving it reduced artefacts and a higher perceived resolution.

We haven't even got on to upscaling, gamma and greyscale adjustment, colour management......even the 428 would be improved with a high quality scaler...on HD and SD.....

So I'd avoidj speaking to whoeer told you that nonsense again....
Gordon

[NicolasB]

Originally Posted by old man

Now a few days ago have been told that really video scalers are not able to improve the quality of normal SDTV transmission, but rather they act to worsen their defects.

Is this true ? Or perhaps this is only true if we consider medium to low quality(and price...) scalers?

I think it is correct to say that video scaling (or, more precisely, upscaling) worsens SD quality. This is why, when I'm watching an SD programme on my 1920x1080 resolution rear projection TV I shrink the picture down to a little 1024x576 window in the middle of the screen.

However, I am probably the only person in the world who would watch TV like this.

Normal, healthy, not-insane people always want to watch with the picture scaled up so that it fills the whole TV screen.

This means that your SD picture will always be upscaled. The question is not "should I upscale or not?" the question is "should I use the scaling electronics in the TV to do the upscaling, or should I use an external scaler to do it instead?" You therefore shouldn't be thinking about whether scaling causes a loss of quality, you should be thinking about which approach to scaling causes the smallest loss of quality.

Judged by that criterion, a dedicated scaler may well do a significantly better job than the TV can do by itself. Some scaling algorithms tend to exaggerate compression artefacts more than others. A good scaler will exaggerate them quite a bit less than the average built-in-to-the-TV scaler does. Therefore, it is not valid to say that "using a scaler will worsen SD video" - it is actually likely to improve it when compared with what the TV can do by itself.

And, as Gordon says, actual "scaler" devices do a lot of things besides just scaling - good deinterlacing, grey-scale and colour correction, etc.

(I could also add that actually the only way I can watch SD at 1024x576 on my 1080p TV is to use an external scaler! )

[Barcoing Mad]

Of course if the original SD picture quality is a pile of you know what, then no amount of polishing can help it.

I use a good external scaler to make the best of decent quality SD and just moan at the rest.

N.B's suggestion to reduce SD down to a window embedded within a high res display is interesting - for ITV, I suggest something around 16:9...16 pixels by 9 pixels that is.

[hornydragon]

Scaling is generally a bad idea, but with fixed pixel displays its a necassary evil. As scaling is unfortunately necassary you should employ the best scaler to do the job, this may be internal or external (normally external, but some displays cant accept the superior output of the external units without messing them about) it really depends on what you find disappointing with current sD material as to the benfit of a Video processor. VP's can do some interewsting things with SKy HD boxes to inprove the PQ of SD channels

[JohnWH]

I strongly disagree with the comment that scaling is a bad thing, if done properly it is most definitely a good thing (just look at how much upscaling DVD players help with PQ). But, at the end of the day you can't polish a turd, if you have a poor SD signal brimming with compression artifacts in the first place and you blow it up to fit a large screen its going to look rubbish irrespective of how its scaled (that includes large screen CRT's).

John.

[hornydragon]

Originally Posted by JohnWH

I strongly disagree with the comment that scaling is a bad thing, if done properly it is most definitely a good thing (just look at how much upscaling DVD players help with PQ).

Rubbish they just do a better job than than the internal scale rin a fixed pixel display, ideally everything should be native RES so no scaling for the best image at a specific resolution. all no native sources displayed on a fixed pixel device are scaled