Pixelization only when images have movement

[sattati]

Hi,

One funny thing that I don't understand is pixelization only when pictures have action or movement. I mean for example, pictures iare very bad on a soccer game or people dancing or any moving object. These moving things are always highly pixelized. Otherwise the picture is crystal clear when no movement is involved (news anchors, still pictures and so on). The sound is always good in both instances. FYI I have a fortec classic and a 90cm dish with a 0.4 dB LNB. The strenght of my signal is always above 70% (I don't have a quality bar). Also, I have not experienced any rain or snow faids.
So is my receiver signal processing not up to the task or ....?


Thanks

[elgemcdlf]

Sounds like your dish is off just a bit. Try moving east to west a tiny bit. If that does not resolve the issue. Try up or down a tiny bit on elevation. Is this consistant with all sats or only one? Is this a consistant problem or intermittant? I have found signal strength seems to waver a bit.

[vj9999]

It can also be that the channel you are watchin is in avery populated MUX and has little bandwidth assigned to it and/or is over compressed.

[pmb1010]

I get the same thing (Lifetime Ultra). Many channels are like that for me too. When I used to watch U-ON-TV, it became unbearable at times with the shakey camera movements of user's poor video movie skills (fast pans etc).

I considered moving to newer generation box (thinking that faster processors might help) but if you have one of the "new" Fortec's, well Sadoun claims this is the best thing going and if this thing pixels out, well then that's just the way it is with FTA I guess too overly compressed signals as VJ says.

[pictureon]

I do not think it's a signal problem. I would check the RCA or S video cable. It could also be receiver problem.

[wejones]

I agree with VJ. I see this all the time with any receiver and any digital format it there is significant compression, lack of bandwidth, etc. You'll even see the same thing with an analog signal fed into a TIVO, if you put the TIVO in low quality mode. Also, if the original signal is PAL, and has been converted to NTSC, you'll often see problems with moving objects even with the best equipment. Back 10-12 years ago, before there was much in the way of digital TV, I used to watch the British Open golf on ABC, and the ball would jump forward and backward after it was hit, when the camera view was from overhead, and this was attributed to the PAL->NTSC conversion process.
Also, any signal in an interlaced mode will give you problems with moving objects. During the NFL playoffs, I recorded two games, one in 1080i, and one in 720p, and there was no comparison. The 1080i video had all sorts of problems whenever there was any motion, but the 720p video was fine with moving objects. Same would be true with the SD interlaced video.
Moving objects are just a problem whenever you have interlacing, low bandwidth/compression, or PAL-->NTSC conversion.

[Sadoun]

Yes, VJ's assesmnet is correct. If you look at the PBS stations for example, you will not see the pixalation issue. They don't compress the signal as much as the other stations do.

[pmb1010]

Hmmm....

Just watching a live feed channel for CNN on AMC5, for the immigration rallies they are having in LA. (12038V/3.979)

I have cable TV and went to CNN to compare. The picture on the fortec is noticably crappier than what comes over the Adelphia cable.

If the satellite up/downlink is compressing the signal, why wouldn't CNN's real channel suffer the same effect when they cut to their live reporter?

[bobkat]

Originally Posted by pmb1010

If the satellite up/downlink is compressing the signal, why wouldn't CNN's real channel suffer the same effect when they cut to their live reporter?

That's an interesting question. Once I watched CNN on a C-band and a DirecTv dish at the same time. The picture quality on the C-band was way better. The funny thing was there was a 3 second delay on the DirecTv signal. Kinda neat.

kat

[DruzeTito]

Originally Posted by sattati

Hi,

One funny thing that I don't understand is pixelization only when pictures have action or movement. I mean for example, pictures iare very bad on a soccer game or people dancing or any moving object. These moving things are always highly pixelized. Otherwise the picture is crystal clear when no movement is involved (news anchors, still pictures and so on). The sound is always good in both instances. FYI I have a fortec classic and a 90cm dish with a 0.4 dB LNB. The strenght of my signal is always above 70% (I don't have a quality bar). Also, I have not experienced any rain or snow faids.
So is my receiver signal processing not up to the task or ....?


Thanks

this is how MPEG 2 compression is supposed to work. It basically "guesses" or predicts that the current frame will also be the next frame with little change. When there is BIG frame change (ie high speed camera movement) then it is surprised and attempts to map out the movement and compress at the same time yielding to pixelization.

This is a sign that the satellite channel you are watching is saving on bandwidth and has a lower resolution and compression bitrate.. this translates to saved money for the provider. Compression on pay channels is much much less and it has higher resolution and this kind of problem is not as prominent.

[wejones]

Originally Posted by pmb1010

Hmmm....

Just watching a live feed channel for CNN on AMC5, for the immigration rallies they are having in LA. (12038V/3.979)

I have cable TV and went to CNN to compare. The picture on the fortec is noticably crappier than what comes over the Adelphia cable.

If the satellite up/downlink is compressing the signal, why wouldn't CNN's real channel suffer the same effect when they cut to their live reporter?

You don't say whether the lack of quality here is the pixilation on motion thing discussed earlier, or some other more general lack of quality. If it's the motion problem, then I'd agree that it is interesting. If it is some other measure of quality, then I'd think that it may just be related to the quality of the receiver/lnb. I've noticed that the Fortec receivers in general don't give very high quality video compared to my other receivers, plus on narrow signals like that, there might be problems due to lnbf drift/noise found in consumer equipment. However I've never noticed any motion induced pixelation in the Fortec video, except in very compressed signals. I think the worst example of this was the Utah PBS channel on AMC5. The OETA DCII signal on the same sat is very high quality for me, but the Utah channel is terrible, at least it used to be, as I haven't tuned that signal in for about 3 years because it was so bad.
If, however, it's pixelation you're seeing in the live feed, but not in the broadcast, then it's interesting. I wonder if it means they are doing something different with the mpeg encoding or something?

Re the other comment saying the 3 second delay was neat.... if you run your signal through a TIVO, you can see some really BIG delays. I typically see delays of around 9 seconds between a C-band feed and what I see on DTV broadcasts, and when it comes to LIVE events where they might have an additional delay, I've seen delays of nearly 20 seconds. But despite the delays, the DTV video is still delayed less than the audio on those Sirius radio broadcasts. This past season, I watched a lot of NFL football, and I like to listen to the "home audio" over Sirius, rather than the network people. I was expecting to have to delay the Sirius because of the known delays in the DTV video in order to sync audio and video, so I ran the Sirius audio through a second TIVO so I could delay it. However it was the other way around, in that I had to delay the video even more to get them in sync. But during a couple of these games, I was feeding raw video into my laptop computer that wasn't delayed by TIVO, from another receiver, and often would be confusing my wife as to why I was yelling at the screen 10 or 15 seconds before the play happened. She made me turn off the laptop.

[bobkat]

Originally Posted by wejones

... I was feeding raw video into my laptop computer that wasn't delayed by TIVO, from another receiver, and often would be confusing my wife as to why I was yelling at the screen 10 or 15 seconds before the play happened. She made me turn off the laptop.

LOL !! Yeah, wives don't dig the technology like we do. That's why I only have 1 TV in the house...

kat

[pmb1010]

Originally Posted by wejones

You don't say whether the lack of quality here is the pixilation on motion thing discussed earlier,

Sorry, it was motion. I was watching the reporters hand moving the microphone around.
Signal reception at my location for this transponder was very good.

And I'll add simply to mention, I have video connected via S-video cable.
Receiver is Fortec Ultra, lnbf is Invacom SNH-031.

What receiver do you consider superior in picture decoding over a fortec?
Just as computer video has progressed over the years, I would sort of expect faster processors be used in these receivers, also.

[wejones]

Originally Posted by pmb1010

Sorry, it was motion. I was watching the reporters hand moving the microphone around.
Signal reception at my location for this transponder was very good.

And I'll add simply to mention, I have video connected via S-video cable.
Receiver is Fortec Ultra, lnbf is Invacom SNH-031.

What receiver do you consider superior in picture decoding over a fortec?
Just as computer video has progressed over the years, I would sort of expect faster processors be used in these receivers, also.

Strange re the motion problem. Makes you wonder if they were using some non-standard mpeg or something.
Re the "superior" receivers, I wasn't talking about a DVB settop box, and it may not have been a fair comparison. I was comparing it to analog, DCII, and/or my Twinhan feeding a Roku. It's just that the Fortec picture sometimes, but not always looks just a bit washed out or something, like lacking a bit in contrast or video level or something. However, I may not have been doing a fair comparison of identical signals, it's just that several times I noticed the washed out video with the Lifetimes, but don't generally notice that with the other receivers. It may just have been the signals I was watching.

[elgemcdlf]

I have a Coship Irdeto receiver and find the picture quality far superior to the Fortec. Connection to the TV same and utilizing the same dish and LNB. Cost is comparable to the Fortec Platinum NA. Plus or minus 10% depending on where you shop. The Fortec blows the Coship away with features. The Coship is DiSeqC 1.0 so no motor but great for a big dish. No blind search. Sat setup is comparable to the Fortec.

[pmb1010]

Nah, won't have a receiver that doesn't come with USALS.