HD Cable skipping/stuttering

spaceywilly · 01-10-07, 07:05 PM

I'm sorry I'm sure this has been discussed before but I can't seem to find it. I have Charter Cable with a SA Explorer 3250HD box, and since we've signed up for HD cable it skips and stutters quite often, enough to make me switch to the SD version of shows sometimes. I thought it was the signal strength, which was at -10dB at the time, so we bought a signal amp. Then it was at 12dB and still skipped. I plugged the cable box into another port that is after a splitter and now it is 9dB, and still skips, although it isn't as bad. Should I try to get the signal strength closer to 0 or is the skipping problem coming from somewhere else?

walford · 01-10-07, 07:33 PM

What resolution are you outputting the "HD" channels in over what interface to what kind of TV/Display?
Have you asked Charter to come out and fix the problem? Is the problem more apparent when there is a lot of motion in the program being watched?
Does it appear to be worse on some channels then on others?
What if you bypass the splitter entirely as a test?

spaceywilly · 01-10-07, 07:48 PM

1080i over HDMI, it did the same thing on component before we got the HDMI cable. It's a samsung LCD.

We haven't talked to Charter yet, it usually takes them at least a week to get someone out here, so when we have problems we try to fix them ourselves. I'll try bypassing the splitters when I get chance.

The only channel that seems to be more prone to skipping than the others is FOX. It also is the only channel that loses audio sync when it skips (changing the channel and then coming back fixes it). Right now it's at 6dB and FOX is still skipping (on an SD show) but all the others seem ok.

spaceywilly · 04-02-07, 11:00 PM

This problem had gone away for a long time but now it has come back. The only thing I can think of that is different is they've added another HD channel to our lineup (ESPN2HD). Now the signal levels are at about +9 or 10 and there is noticeable skipping. Also I noticed that in the status pages of the cable box there is an "errs" Avg/Inst section and the Errs goes up whenever the show skips.

I found some info on this thread but it wasn't too helpful:
http://www.avsforum.com/avs-vb/archi.../t-471859.html

Quote:

Errs Avg/Inst: Average and Instantaneous Bit (byte? block?) Error Rates.

Anything else I can do to smooth this out or should I call Charter again? They weren't too helpful last time, just switched out the box and made sure the crimps on the connections were good, but they didn't look at the signal at all.

I also found a somewhat better description of Errs Avg/Inst at a website for a cable modem:

Quote:

Errs Avg/Inst is two numbers. The first number indicates the total number of data errors encountered averaged over the time the frequency has been locked (Seconds, above). The second number indicates the number of errors that have been encountered since the las time the screen was refreshed (every 3 seconds).

walford · 04-03-07, 11:25 AM

Since your problem only happens with channels that broadcast in 720p instead of 1080i. It appears that you STB is having a problem upscaling the 720p to 1080i. Do you have a passthrough option on your STB so all programs will be forwarded to your HDTV in the resoluiton that they are recieved in and then the TV will do any required scaling?
Do you have a 1080p LCD? If not have you tried sending it 720p instead of 1080i?

spaceywilly · 04-03-07, 10:00 PM

Our tv is 720p but I've always left it at 1080i because the tv does a much better job of downscaling the 1080i shows than the cable box, and there didn't seem to be any loss of quality when the 720p shows were upscaled by the cable box, then downscaled by the tv. But I did switch it to 720p output for Idol and House tonight, and the skipping was much much better. It's still not 100% perfect, but it's watchable again now. Thanks for the tip.

bfdtv · 04-03-07, 10:51 PM

Quote:

Originally Posted by spaceywilly

Our tv is 720p but I've always left it at 1080i because the tv does a much better job of downscaling the 1080i shows than the cable box, and there didn't seem to be any loss of quality when the 720p shows were upscaled by the cable box, then downscaled by the tv.

The most significant loss in quality on 720p channels would be actual 60p video content, such as sports, where you lose half the framerate. Shows like House are just 24p with repeat frames, so you don't lose half the framerate on those programs.

Nmlobo · 04-03-07, 11:06 PM

Quote:

Originally Posted by bfdtv

The most significant loss in quality on 720p channels would be actual 60p video content, such as sports, where you lose half the framerate. Shows like House are just 24p with repeat frames, so you don't lose half the framerate on those programs.

This is why you would want to select pass through mode. This way a 720/60p input is upscaled and displayed as 1080/60p. No loss of frames. And a 1080/60i input would display as 1080/30p - "if" the tv properly deinterlaces and 3:2 pull down.

If the stb does not allow direct pass through, I would agree with spaceywilly and leave the box set to 1080i.

spaceywilly · 04-04-07, 10:41 AM

It does seem like there would be a loss of frames when converting 720/60p to 1080i and back again, but if it was happening I never noticed it.

Since I'm using HDMI, I get an "Auto DVI" option instead of pass-through. What this does apparently is uses the information coming over the HDMI cable to select the best resolution to output at. With my TV, when I use Auto DVI it just outputs everything at 1080i, since it is the best option available according to the TV. I'd rather have a pass-through mode, but for now I'm fine with manually changing the output resolution to match the show I'm watching, since it seems to have gotten rid of the data errors.

01-10-07, 07:05 PM	#1 \| Link	<a href='http://rev.avsforum.com/phpAdsNew/adclick.php?n=a4ac4393' target='_blank'><img src='http://rev.avsforum.com/phpAdsNew/adview.php?what=zone:30&n=a4ac4393' border='0' alt=''></a>
spaceywilly Member Join Date: Dec 2005 Location: Waltham/Boston, MA Posts: 39	HD Cable skipping/stuttering I'm sorry I'm sure this has been discussed before but I can't seem to find it. I have Charter Cable with a SA Explorer 3250HD box, and since we've signed up for HD cable it skips and stutters quite often, enough to make me switch to the SD version of shows sometimes. I thought it was the signal strength, which was at -10dB at the time, so we bought a signal amp. Then it was at 12dB and still skipped. I plugged the cable box into another port that is after a splitter and now it is 9dB, and still skips, although it isn't as bad. Should I try to get the signal strength closer to 0 or is the skipping problem coming from somewhere else?

04-03-07, 11:25 AM	#5 \| Link	<a href='http://rev.avsforum.com/phpAdsNew/adclick.php?n=a591f81a' target='_blank'><img src='http://rev.avsforum.com/phpAdsNew/adview.php?what=zone:36&n=a591f81a' border='0' alt=''></a>
walford AVS Special Member Join Date: May 2003 Location: Orange County, CA Posts: 9,974	Since your problem only happens with channels that broadcast in 720p instead of 1080i. It appears that you STB is having a problem upscaling the 720p to 1080i. Do you have a passthrough option on your STB so all programs will be forwarded to your HDTV in the resoluiton that they are recieved in and then the TV will do any required scaling? Do you have a 1080p LCD? If not have you tried sending it 720p instead of 1080i?

01-10-07, 07:33 PM	#2 \| Link
walford AVS Special Member Join Date: May 2003 Location: Orange County, CA Posts: 9,974	What resolution are you outputting the "HD" channels in over what interface to what kind of TV/Display? Have you asked Charter to come out and fix the problem? Is the problem more apparent when there is a lot of motion in the program being watched? Does it appear to be worse on some channels then on others? What if you bypass the splitter entirely as a test?

01-10-07, 07:48 PM	#3 \| Link
spaceywilly Member Join Date: Dec 2005 Location: Waltham/Boston, MA Posts: 39	1080i over HDMI, it did the same thing on component before we got the HDMI cable. It's a samsung LCD. We haven't talked to Charter yet, it usually takes them at least a week to get someone out here, so when we have problems we try to fix them ourselves. I'll try bypassing the splitters when I get chance. The only channel that seems to be more prone to skipping than the others is FOX. It also is the only channel that loses audio sync when it skips (changing the channel and then coming back fixes it). Right now it's at 6dB and FOX is still skipping (on an SD show) but all the others seem ok.

04-03-07, 10:00 PM	#6 \| Link
spaceywilly Member Join Date: Dec 2005 Location: Waltham/Boston, MA Posts: 39	Our tv is 720p but I've always left it at 1080i because the tv does a much better job of downscaling the 1080i shows than the cable box, and there didn't seem to be any loss of quality when the 720p shows were upscaled by the cable box, then downscaled by the tv. But I did switch it to 720p output for Idol and House tonight, and the skipping was much much better. It's still not 100% perfect, but it's watchable again now. Thanks for the tip.

04-04-07, 10:41 AM	#9 \| Link
spaceywilly Member Join Date: Dec 2005 Location: Waltham/Boston, MA Posts: 39	It does seem like there would be a loss of frames when converting 720/60p to 1080i and back again, but if it was happening I never noticed it. Since I'm using HDMI, I get an "Auto DVI" option instead of pass-through. What this does apparently is uses the information coming over the HDMI cable to select the best resolution to output at. With my TV, when I use Auto DVI it just outputs everything at 1080i, since it is the best option available according to the TV. I'd rather have a pass-through mode, but for now I'm fine with manually changing the output resolution to match the show I'm watching, since it seems to have gotten rid of the data errors.