Picture Quality Issue

[whatchel1]

I actually recorded some HD feeds via firewire from an SA cable box on network stations (almost everything else had HDCP encryption copy once turned on) back when I had Comcast. They were MPEG-2, and exactly the same size as from over the air. MPEG-4 to me, on Dish anyways, look distinctly different than MPEG-2. Its softer but doesn't have giant blocks every during fast motion scenes.

I didn't know any cable systems used MPEG-4, however I'm sure that Comcast does not here. We are however still in the stone age here in NM they have maybe 30-35 HD channels on cable.

Cable uses QAM and Digital QAM standards:
Like all modulation schemes, QAM conveys data by changing some aspect of a carrier signal, or the carrier wave, (usually a sinusoid) in response to a data signal. In the case of QAM, the amplitude of two waves, 90 degrees out-of-phase with each other (in quadrature) are changed (modulated or keyed) to represent the data signal. Amplitude modulating two carriers in quadrature can be equivalently viewed as both amplitude modulating and phase modulating a single carrier.

Phase modulation (analog PM) and phase-shift keying (digital PSK) can be regarded as a special case of QAM, where the magnitude of the modulating signal is a constant, with only the phase varying. This can also be extended to frequency modulation (FM) and frequency-shift keying (FSK), for these can be regarded as a special case of phase modulation.

 

[lobosrul]

Eh? QAM is a digital modulation scheme. Its a means of conveying a digital data stream, of any type. QAM-256 can conveniently carry 2 full ATSC streams.

MPEG-2 and MPEG-4 are compression standards, something completely separate.

I'm not saying no cable systems re-compress the local affiliates HD channels, but Comcast here does not.

This is getting off topic.

 

[DishSubLA]

Hmm. I was always told by one of my distributors it was the some of the best PQ available on an HDTV.

Let me tell you that because of ABC and NBC stuffing Live Well HD (yes, a sub-channel in HD) and Universal Sports HD, in many cities, there are cringing artifacts on the main HD channels of KNBC and especially KABC, but not limited to those 2 channels, although they have improved both the main and even the HD sub-channel, but I see more artifacts on just about every main HD channel than I have ever seen, and it is sad.

Now, getting to the greed of other local stations that stuff This TV and up to 8 or 9 (yes, NINE as in 9) sub-channels, you can get main channel HD that looks worse than even cable or sat provide. Sorry, but these aren't the experimental days of HD anymore and aesthetic slow or still video of a flower in stunning HD just can't be found anymore. Instead it the mega-fast motion and flickery-flash of all the current trend in TV (CSI's and other crime shows) and movies that now play havoc with even the best encoders. Our only hope is the ever improving encoders coming to market.

 

[TheKrell]

I would rather the frame freezes for a half second than to see macroblocking. Ugh. Why can't the stat muxes do that? Done the freeze frame way, you could even do this exclusively to the subchannels so that the main HD channel always has adequate bandwidth.

 

[redelephants]

So I have been told that the encoders are setup to produce the best picture for 42" or smaller sets. Based upon a study it was found that most people had a 42" set or smaller in the surveyed households. Is this really true? It would definately explain why not everyone is complaining about the crappy 1/2 HD picture.

 

[Pakbackr]

Not sure if my issue relates or not, but I welcome the comments. I just bought a new 58 Samsung plasma, and most of the time the picture looks awesome. But sometimes, it seems that we see pulses and distortion (pixelation, macroblocking...I don't know), especially noticeable on people's faces. And tonight, we have a scrolling message regarding flash flooding running at the bottom of the screen on our local CBS station tonight, and the words go back and forth from crystal clear to shaky and well, not crystal clear. I have HDMI feed from my VIP 622, and have never had that issue with my old 50 inch Panasonic DLP.

So, is this an issue with my new TV or something normal for DISH PQ (and noticeable only now on a huge 1080p set)?