147 replies to this topic

[Erik Slagter]

SD's are extreme examples, however HD's are also better on the mentioned boxes.

(lots of slightly offending text removed)
The best picture quality (to use your beloved word once again) is achieved when a device outputs a representation exactly the same, or at least closest to the representation put into the device. That's the definition of quality. The broadcom's do exactly that and achieve crystal clear picture when all picture mangling on the SoC and on the television has been turned off. In case the native resolution of your panel is equal to the source material (which, as a videophile you at least try to achieve...), there is no postprocessing necessary of the picture whatsoever for highest quality, because no degradation (!) takes place.

If you think postprocessing is necessary on HD material, then I think you should start wondering yourself... Then apparently you don't like the "quality" the material is recorded and sent to your box. In that case "picture quality" would mean processing the material to something you like from something you don't like... I don't think that has ANYTHING to do with picture quality.

Once again, picture quality is measured in PSNR, dB, which describes to what extend a picture matches before and after it has gone through a device, piece of software, etc. Little difference is GOOD, good quality, so the SoC really perform well.

And once again, if you stop calling what you want "picture quality" and start calling it "postprocessing level" then we can talk. But then still for me best viewable picture means highest quality, is lowest degradation, so no post processing. And I am really not the only one that shares this opinion.

Edited by Erik Slagter, 27 May 2012 - 09:29.

[gorski]

From a lay person's perspective...

The picture is processed a number of times before we see it on our TV screens, is it not? Every time it happens, it is "interpreted", meaning re-created.

In the end, what I see is what counts. The great big tons of explanations is neither here, nor there, really...

All else is dogma, it seems to me...

How do you view 3D now?

Cheers!

P.S. I remember the story around the vinyl audio records and their "warmth", with all the scratches etc. - and CD industry coming strong, being opposed as strongly... Sounds familiar, hehe?

[WanWizard]

@gorski,

That is exactly what I've been trying to say.

Both SD and HD are a digital signal. If your STB, and your scaler, and your TV don't touch the signal, you see it exactly as it is broadcasted. This is from a signal point of view the best picture quality. It might be that you don't like that, or you're stuck with a provider that sends a lousy signal, and you want to add all kinds of optical tricks on the signal to make it look better to you in your specific setup. I don't think anyone has anything against that.

But that is personal preference in combination with a specific hardware setup you have.

Which has nothing to do with "quality" (which is something you can measure) but with "experience" (which is an extremely subjective definition).

[malakudi]

@Erik: Not all content received by an STB can be displayed without proccessing in a TV set.
First of all, it is the SD content. You need deinterlacing (in STB or in TV - since the TV set features a progressive display) and upscale, in STB or TV or both.
The it is the HD 720p content. This doesn't need deinterlacing, but may need upscale.
Finally there is HD 1080i content. This might need downscale and it needs deinterlacing.

So, you always have some postprocessing. Being an owner of an STi chipset box (IPBOX 9000) I must say that the big difference is in the SD content. SD content is perceived better with an STi chipset box. Whatever the reason is, it does happen. For example, on my broadcom boxes i have noticed many times in fast scrolling text the fields to be reversed (thus jerky movement) and after 500-1000ms, the fields are reversed and text scrolling is smooth again. However, I've never seen that in STI boxes. I run the boxes in 720p mode when displaying SD content, so interlaced to non-interlaced transfom is happening to the STB. Same box (IPBOX 9000) with non-Sti dvbapi drivers performs much worse than Broadcom, which I assume is happening because of incorrect drivers.

Then, there is the color problem. You say that Broadcom does not change anything and I am not the one to tell you otherwise. However, what I perceive from Broadcom chipset boxes is saturated red, especially in human flesh. Colors seem better in STi boxes. I don't know why but that is what I see, and many people have the same experience, so I don't think there is something wrong with all those people.

Edited by malakudi, 27 May 2012 - 13:50.

[WanWizard]

I don't think anybody is debating that.

From the three scalers I have (the STB, my external scaler, and my TV), the STB is definately the worst. So I have it switched off, and have the box pass the signal on as-is.

[malakudi]

I don't think anybody is debating that.

From the three scalers I have (the STB, my external scaler, and my TV), the STB is definately the worst. So I have it switched off, and have the box pass the signal on as-is.

I would do the same. Unfortunately, when the broadcom STB is set to output 576i native, then the HD skin looks jaggy (since graphics and text designed for 1280*720 are scaled down)

Edited by malakudi, 27 May 2012 - 13:59.

[gorski]

@gorski,

That is exactly what I've been trying to say.

Both SD and HD are a digital signal. If your STB, and your scaler, and your TV don't touch the signal, you see it exactly as it is broadcasted. This is from a signal point of view the best picture quality. It might be that you don't like that, or you're stuck with a provider that sends a lousy signal, and you want to add all kinds of optical tricks on the signal to make it look better to you in your specific setup. I don't think anyone has anything against that.

But that is personal preference in combination with a specific hardware setup you have.

Which has nothing to do with "quality" (which is something you can measure) but with "experience" (which is an extremely subjective definition).

Agreed! Except the bit about quality being (always) measurable... It depends what we mean by that, I suppose...

But it is a wider debate, probably...

P.S. Still waiting for experts to show us the docs regarding the PQ and measuring...

[WanWizard]

@malakudi,

Hmm... That might be caused by something else in the chain too.

Even if I connect the box (either VU+Duo or ET9000, I don't have any DMM box connected anymore) directly to the TV, the PLi-HD skin looks sharp on all SD channels... So I can't say I have than same experience (which sort of proves by point. ).

[Erik Slagter]

Agreed! Except the bit about quality being (always) measurable... It depends what we mean by that, I suppose...

No, that is what I am trying to say all of the time. There is NO debate possible about picture quality. The quality of something, in this case a picture, is defined bij being true to nature. Every deviation from the input is quality degredation.

And so, if we start talking of "types of post processing" and "level of post processing" and what is most pleasing to the eye, then we can talk. It's just like debating whether 2 * 3 = 6 or if you like 5.8 over 6.2...

[buyukbang]

What me and malakudi (above) are trying to say is it is impossible to get 6 when we need an upscaling to transform SD and 720p material to the tv screen with 1080x1920 resolution. Scaling mechanism and of course "post processing" always modifies the output image. May be you are happy with 4.0 (just an example, this is our perception) on broadcom, while we are expecting 6,2. We see this huge difference with out eyes, as I said before I accept the word "perception" for that. But you also have a perception with broadcom since the output image is always modified.

Agreed! Except the bit about quality being (always) measurable... It depends what we mean by that, I suppose...

No, that is what I am trying to say all of the time. There is NO debate possible about picture quality. The quality of something, in this case a picture, is defined bij being true to nature. Every deviation from the input is quality degredation.

And so, if we start talking of "types of post processing" and "level of post processing" and what is most pleasing to the eye, then we can talk. It's just like debating whether 2 * 3 = 6 or if you like 5.8 over 6.2...

[malakudi]

@malakudi,

Hmm... That might be caused by something else in the chain too.

Even if I connect the box (either VU+Duo or ET9000, I don't have any DMM box connected anymore) directly to the TV, the PLi-HD skin looks sharp on all SD channels... So I can't say I have than same experience (which sort of proves by point. ).

Just tested with PLi-HD skin. Indeed, the problem I mentoned above does not show with PLi-HD. However, it is well shown with a skin I am using that has thin fonts. Then these fonts look ugly when scaled down. I wonder if that could be solved with a multi-resolution skin.

I also don't understand the deinterlacing options on my ET9000. I undestand bob, but what auto, on and off are actually doing?

[gorski]

Agreed! Except the bit about quality being (always) measurable... It depends what we mean by that, I suppose...

No, that is what I am trying to say all of the time. There is NO debate possible about picture quality.

Oh, there is, it's just a broader/deeper debate than some spectral analysis etc. But it is going on in philosophy etc. for a long time, in a variety of ways... Quantity v. quality and how one can become the other, a more dialectical perspective... Hard to figure out, I suppose, without any previous education in that regard, like, for instance, you trying to explain to me SHA in cryptology or some such phenomenon...

The quality of something, in this case a picture, is defined bij being true to nature. Every deviation from the input is quality degredation.

Ermmm, not in all things human, nope, thanx a bunch! We are much more than just nature in us... And Gawd help us if we try to simply root ourselves in 'nature'. In fact, we are essentially different, as we are all about culture over nature, in a manner of speaking...

(See, I told you it's a bit tricky... )

And so, if we start talking of "types of post processing" and "level of post processing" and what is most pleasing to the eye, then we can talk. It's just like debating whether 2 * 3 = 6 or if you like 5.8 over 6.2...

I believe you have been told already that these things are not exactly black or white and I agree with that. At the end of the day, if you can not come up with anything measurable, anything universally obliging, any proof from a scientific stance, then all we have, really, is our eyes and then no amount of technical explanations are any good because we MUST rely only on our eyes, never mind how much we read about various aspects of the story, from the technical side...

[Erik Slagter]

If what you say is true, then you'd need some sort of post processing in your eyes as well, when you're watching something NOT on tv LOL...

The concept is so simple... quality is a measurement of in what degree the "copy" resembles the "original". And with original I mean the physical object/scene/etc. that is being captured with a camera. If someone says quality cannot be defined this way, then I'd be tempted to draw the conclusion that this person doesn't like the "original" to begin with! That would be a bit strange, wouldn't it?

This in combination with the 1:1 straight-through character of digital video, I'd say: a true "videophile" avoids all kinds of tampering/modification to have the picture as close to the original just before the final step: within the television itself.

If we look at the complete chain from camera to pixel:
- camera: introduces (relatively) A LOT of distortion, but I trust the manufacturer and the broadcaster to correct for that as much as possible
- studio: none distortion (if working 100% digital) or a bit (if working analogue)
- broadcast street: introduces some to a lot of distortion because of the lossy character of the encoding, let's assume a decent level here, if the bitrate is set too low, there is no way to recover from that anyway
- remote feed, satellite itself (transponder), your dish, your tuner: no distortion is added because of the all-digital nature
- the decoder (in the stb) itself does not add any distortion, but it reveals the lossy nature of the compression
- a scaler, if necessary, can introduce some to a lot of distortion, but that's not the point here, it won't alter colors anyway, as proposed earlier
- if you are using a deinterlacer in your stb/soc, then your definitly not a "videophile", "deinterlacing" should be done in the tv set, where it can be done in a smart way, where it can done without loss of temporal information
- digital "video enhancement" inside the soc will introduce additional distortion if enabled
- the hdmi/dvi encoder inserts no distortion at all, it's all digital
- then inside the television, the pixels are run through various lookup-tables and calculations, depending on various settings and "enhancements", also the phosphors/filters can never be 100% equal to those used in the camera and also they can never have the same characteristics of the sensitivy of the eye.

So I'd say, the major causes of the distortion in the chain are not in the stb, but in the camera and in the television set, actually. Both should be corrected (as far as possible) at the point they're occuring and not somewhere at a random point in the chain. Each part of the chain should always be as transparant as possible.

In very short, if there is something wrong with the picture, and all artificial distortions ("enhancements") are disabled, then the most logical place to look for problems, is where they are most likely to occur, and that's in the television set...

Edited by Erik Slagter, 27 May 2012 - 18:50.

[gorski]

It sounds to me like we need a lot of "corrections" or "post processing" with all those "distortions" coming our way, so it seems you're missing the wood for the trees...

Moreover, all of them know they are working with human eyes... except maybe you... not even beginning to consider the most important part in all of this...

And yet, with all that alleged complete objectivity - we have nothing to really hang on to, something measurable - so you're stuck with "quality"...

Go figure...

[Roodkapke]

Seems like nobody wants to listen to the other.
And since it's no longer going anywhere i think it's wise to stop arguing.

Surely it's not black and not white either, but somewhere in between.

[malakudi]

So I'd say, the major causes of the distortion in the chain are not in the stb, but in the camera and in the television set, actually. Both should be corrected (as far as possible) at the point they're occuring and not somewhere at a random point in the chain. Each part of the chain should always be as transparant as possible.

In very short, if there is something wrong with the picture, and all artificial distortions ("enhancements") are disabled, then the most logical place to look for problems, is where they are most likely to occur, and that's in the television set...

Although I agree with you, you are missing the point here. There are many reasons someone would want to have deinterlacing and upscaling in the STB and not in the TV set. Maybe TV set sucks at deinterlacing or upscaling. I've seen TVs that can't handle 576i as input from HDMI. It's good that an STB has an option to pass the original signal without touching it, but it is also good to have a great scaler with vector antialiasing and a great deinterlacer like adaptive bob+weave with motion compensation. So, you are defending Broadcom for it's ability to pass the original untouched signal (and this is good) but you are hiding the problem of the Broadcom chip that WHEN deinterlace and scaling is used, the quality is greatly degraded - or at least it is degraded more that other SoCs of other manufacturers.

So, instead of praising Broadcom for its passthrough untouched capability, we (as customers) should demand improved performance when it comes to deinterlacing and scaling. When you pay 650 or 900 euros for an STB (Vu+ Ultimo / DM8000) you demand the best.

The color problem (saturated reds) does exist, even if you deny it. I have configured my TV set and my projector for correct color representation (as much as it can be done) with a help of professional. Then, comparing playback of an MKV in Popcorn Hour (Sigma chip) and an MKV in ET9000 (Broadcom) and an MKV in IPBOX 9000 (STi chip), shows saturated red only in Broadcom. I would also like to find an explanation, but I can't.

Edited by malakudi, 28 May 2012 - 09:54.

[Erik Slagter]

Anyway, I don't have these "problems", and I know if there actually is an issue, it's in hardware, so I leave it here .

I only want to add that what most people call "deinterlacing" (in the stb) is actually bob+weave, the frame rate is doubled and no temperal information is lost. You can actually choose real deinterlacing as well, and you don't want that, that's why I mention it.

Edited by Erik Slagter, 28 May 2012 - 10:01.

[malakudi]

@Erik: my ET9000 has options: auto, on, off and bob. What happens in all those options?

[Erik Slagter]

IIRC "on" does actual deinterlacing (what you don't want, unless you've connected a monitor that cannot handle interlaced content). What works for sure is set the output to 1080p in the /proc/video directory. Normally you should set the "deinterlacing" option to "auto" which will make it "off" or "bob" depending on the situation, which is good .

[MartiniB]

my few cents
SD signals over HDMI(DVI) allmoust never are sent in native(received) resolution
cause through cable goes 720x576, but we receive many different like 704x576; 560x576; 480x576; 320x576; ..
and during rescale(no matter up or down) some pixels becomes as halfcolor of two near pixels

from my point of vision we miss some user changeable option to able choose diffrernt upscaling methods
like vertical pixels x2 or x3
horisontal x2; x3; keepAspectratio

another way to destroy SD quality is send received 4:3 SD through HDMI SD mode with added side blackbars,
picture then downscaled with pixels lose ~20%
this war i have won DMM Board » Enigma 2 - Feature Requests » [SOLVED 99%] DVI(HDMI) can't handle most used aspectratio