Objective PQ thread - is it possible to "measure" for an end user?

[Flummox]

Lots of various threads over time on the comparitve picture quality of the various canadian providers but most of it seems pretty subjective.

Curious to hear from the experts here: Is it possible for an end user (without access to the actual source material I presume) to make objective measurements on the relative PQ of the various providers? If so - how should it be done?

[hugh]

Well how can a professional "measure" PQ? The only real measuring tool for PQ is the human eye.

Your testing should be done on properly a calibrated test bed but once your display device is properly tweaked, you change sources and let the eye decide.

[jvincent]

As hugh points out, you cannot objectively measure something which is based on human perception.

The best you can do is a sample of viewer opinions and use that to create ratings.

[57]

The PQ you see on your TV varies a lot even with the same service provider on various channels. This is due mostly to the "production values" that go into the original material which often has the most dramatic effect on what you see.

The only "measureable" difference is really the bitrate, where there is more compression on certain channels and certain providers. A proper setup of the STB and TV is also most important.

The bitrate for the providers is approximately as follows, but depends on the channel since there is no compression on certain channels for certain cable service providers for example: Here's my list from lowest bitrate to highest. Bitrate is not the most important factor, but it is one factor.

Bell Sat,
Shaw Direct,
Shaw/Cogeco/Eastlink/Videotron,
Rogers,
OTA (assumes good channel lock)

I have seen most of these providers during my optimization tours, including OTA and can say that the original material and the proper setup of the STB and TV are far more important than the bitrate.

[Flummox]

I was thinking that with access to the source material you could do a bit by bit comparison (assuming it was digital) and measure the overall variation or some such. Obviously this still won't necessarily reflect the perceived PQ in reality but might be a good proxy.

Or do a real-time side by side and compare "noticeable" artefacts (I know - this is subjective too - noticeable to one is not noticeable to another)

Thanks 57 - the bitrate is probably a good proxy. Assuming they are all using roughly equivalent quality compression gear it should be a good guideline. Have you seen differences between SD and HD in the relative bit rates? (ie does the bitrate ranking order change at all?)

[hugh]

But even bitrate is meaningless. IPTV providers have lower bitrates but use superior (MPEG4) compression algorithms. In addition, most providers alter the bitrate by channel so you would have to compare the bitrates on every channel.

My belief is that quality of the television, set up of the television, and source material are far greater factors in PQ.

The only real issues you could measure are things like quantity of audio dropouts, amount of digital artifacts etc.

[stampeder]

I would say don't focus on objective comparisons because there are just too many variables along the chain from the source material on the broadcast network all the way to the ambient light in your viewing area.

To make your own subjective comparison in your premises under equal conditions use the split-screen feature on a high end display. This is very effective in assessing which of your broadcast providers/sources gives the best HD PQ for your exact location and viewing conditions. For example, watch CSI in split screen from a couple of different sources while sitting in your typical viewing spot. If you don't have split-screen you can just cycle through the display's inputs to compare each source. Nothing like a good A-B test.

I've always found that to be OTA, and you'll see many such realizations at this site.

[hugh]

I did an ABC comparison. Same display, three sources, Bell / Rogers and OTA tuned to multiple stations and multiple shows.

[Arthur Dent]

I agree with all posts so far. There are just too many variables and too much subjectivity involved in picture quality perception.
My experience shows that some people have no clue what PQ is supposed to mean and give very vocal misguided opinions that contradict a lot with others. To sort those out, you need to know if those people watch Blu-ray on regular basis on a 50''+ 1080p screen using HDMI. If not, with all due respect, thier PQ opinions should be disqualified as misinformed.
It may come out a bit harsh, but I just can't stand hearing from someone that he prefers SD for one reason or another, or waste time reading their opinion, and at the end be slapped with a "confession" that they most prefer "Dynamic" picture mode.

[stampeder]

As 57 has mentioned many times in his posts and FAQs it is astonishing how many consumers simply leave their HDTVs in "torch mode" and complain about the PQ when they could easily have professional PQ results with some changed settings and/or a calibration.

Sadly, those HDTVs won't display what the broadcasters are trying to pump out until the proper setup is done.

[pappcam]

I went to a buddy's house to watch a football game game on his new 46" Samsung and he had left it in "torch mode". The reds were brighter a w****'s lipstick and once I showed him how to adjust he agreed was a much better picture.

[JoeFigueiredo]

Bell has a lower bit rate than Cogeco? But my experience has been (based on an HD image on my 106" projection screen), that Cogeco is not as crisp and clear as Bell sat.

Any thoughts?

[57]

What's your make/model of FP? Are you feeding it 720P or 1080i from each STB? What's the native format of the FP? Assume you're using the same channel - like HDNet or CBC for example. If you're using a native 720P channel (like Oasis or Fox), then that may also make a difference because then BTV would not be changing the format. A lot goes into these various permutations and combinations.

[JoeFigueiredo]

Epson 1080UB projector (1080p). I feed it 1080i from the stb.

I'm about to signup with Cogeco.