Comcast 5100 image great, 6400 DVR image not

el_duderino · 12-14-2004, 07:38 PM

I own a Toshiba 34HF84 and picked up a Motorola STB model DCT5100 about 10 days ago.

DVI was enabled - ran it into my HDMI port with an adapter. Worked fine. Occasionally lost HDMI authentication if I powered down the TV. I just changed to a non-HD channel and back and that was fine. Pic was great, audio was great, my Sony RM-AV3100 remote controlled the STB just fine.

The DCT5100 would lock up a couple times a day. The remote-signal-received LED on the STB front panel usually would come on during the lockup. During the lockup the remote would not work, but after the lockup all remote commadns pressed would activate. (It was NOT the remote BTW).

According to Comcast the new guide signal on the cable is fouling up the 5100 and 6200 series of HD STBs. Comcast gave me a 6400 HD DVR to "fix" the problem.

Well,after 10 days of watching the 5100, I can tell you the 6400 image is not as good. Brightly colored fast moving images get fuzzy on the edges, with obvious pixilation in the worst cases. Only with static or slowly-changing images is the image as clear.

I called Comcast - they are clueless, but are chasing it down. I called Motorola, and the HD 6400 series uses a compression algorithm that is not used in the 5100 or the 6200 series. According to the person I talked to the algorithm is different enough that the engineers were not surprised to hear that someone saw a difference in the image.

So for now I can get an STB that locks up multiple times a day or a DVR STB that isn't as clear as I know the image from Comcast can be... or I guess I can get DirectTV or VOOM.

Anyone else with this sort of issue? (I HOPE this is not a repost - I looked...)

Cobra · 12-14-2004, 08:30 PM

Frustrating as hell dealing with Comcast sometimes ain't it? I find there are basically two levels of folks there. One's who have a clue about a technical issue your trying to convey and one's who shouldn't operate a child's toy without adult supervision at all times!

I'm wondering why a lower compression algorithm would be utilized by the upgraded box if they are both enabled for DVI signal transmission which should be a direct "compressionless" digital video signal transmission. Are they now intentionally "down rez'ing" the signals for some silly reason? If so that defeats the whole purpose of DVI or HDMI connection cables which are designed to be compressionless!

Right now I have no answer for this and I doubt you'll get an intelligent one out of Comcast anytime soon. Keep us posted on the update on this because if what you're saying is true (and I believe ya) then others will be running into the same issue.

el_duderino · 12-14-2004, 11:10 PM

I agree with your assessment of who answers the phone, and I'd already decided I alternate 50-50 between clued and less.

Guess what? Comcast doesn't have a Customer Service department! They have Sales, Billing, Repair, and Disconnect.

No one seems to be taking effective ownership here.

My assumption is that the TiVo box sends digitized video, post-recording, to the TV - there is a delay in viewing. This allows the "rewinding" of live TV viewing.

If this model of operation is carried over, then I would assume that the 6400 is compressing video somewhat for HDD recording, in a manner that is not needed for 5100/6200 direct viewing.

Of course, there could be a button between direct viewing and DVR viewing, with the associated image quality increase. But I doubt that anyone in Comcast marketing has the balls/ovaries to tell people that DVR viewing is not as good as direct viewing... especially with the disdain they view the public with.

HDTVSam007 · 12-15-2004, 09:17 PM

I believe it is because it is compressed accross the memory buffer which enables you to pause ,rewind live tv.However I fixed this issue by a 2 way splitter before the DVR box a line to the tv and a line back to the DVR.So I use the DVR box for HDTV and shows I wana bare to record and watch,while using the tv tuner for clearing up my more frequently watched channels.This dramticaly improved the PQ although any cable signal on an HDTV is magnified and less flatering to the signal imperfections that comes along with cable.However this is a minor complaint considering benefits of the DVR Box,if it breaks its their problem,which my friend has been through 6 series 1 Tivos and they dont record HD (lucky for him he BOUGHT an extended warranty) but if you do decide to shell out the $999.99 for the DirectHDTivo warranty again is only one year unless you shell out more money on a gamble of an extended warranty.Not blasting Tivo but bringing to light the advantages of the Comcast vs Tivo....

el_duderino · 12-16-2004, 01:24 PM

Quote:

Originally Posted by HDTVSam007

However I fixed this issue by a 2 way splitter before the DVR box a line to the tv and a line back to the DVR.So I use the DVR box for HDTV and shows I wana bare to record and watch,while using the tv tuner for clearing up my more frequently watched channels.

It sounds like you are only getting benefit on non-HD shows... I was mostly concerned about degradation of HD images between the HD STB and the HD DVR STB... even if you have an HDTV tuner (I don't) you couldn't be watching HD without the DVR STB UNLESS you have a CableCard HDTV.

The Comcast guy says they look the same to him, he saw the same image artifacts on both with the problem movie. So I guess they are doing nothing.

With what I read about Directv HD signal compression they probably aren't the solution. I am thinking about checking out VOOM.

Runaround · 12-16-2004, 11:50 PM

From the information that I have been able to get on the DVRs, most of which comes from Moto, they don't re-encode/re-compress any of the digital signals they get. The only time the DVR actually encodes/compresses is for the analog signals. So the box does play back from the cache always just as TiVo does. In theory this shouldn't be the cause for the picture issue. That being said I haven't had a chance to spend any time with their non-DVR HD boxes as we only carried them for about a month or so till the DVRs came out. I wonder if they are using a different signal processor to put the picture on the wire than the other?

bpajax · 01-01-2005, 03:11 PM

I have the Motorola DCT 5100 which had been working fine. Recently, I'm getting the intermittant lockup when using the remote described elsewhere in the forum. I don't want to switch boxes and get poorer HD reception, but the lockups are becoming a real pain. Any suggestions? By the way, my 5100 has an active DVI port that I'm using to connect to my Samsung TX-P2675WH.

Cobra · 01-01-2005, 06:30 PM

Well I know this is going to sound like it definitely should not be a solution but for me it was. I have a 5100 box in one room that would lock up like crazy when I first got it. Just for the heck of it I reprogrammed the infrared signals into my Denon 5700 learning remote. The lock-up issue stopped. I realize this should not have fixed the problem given the fact that all that was transferred were the exact same infrared signals; but for some odd reason the lock-ups did stop. My only conclusion is it is some gremlin within the Motorola remote itself that may be the culprit.

Lanny · 01-02-2005, 09:28 AM

Those with a DCT5100 should consider upgrading to a newer DCT6200 series. Its processor is much faster; see specs on Motorola web site.

Cobra · 01-02-2005, 12:37 PM

Duh . . . have you looked at the "MANY" posts where people are discovering the newer boxes are rendering poor SD?

I have a six series box in another room and I can definitely confirm the 5100 box renders cleaner SD. The six series boxes are using a different compression algorithm for some silly reason. The Comcast techs will confirm this as well. So thank you . . . but anybody lucky enough to still have a five series box and looking for great HD as well as great SD viewing should hold on to them!

Lanny · 01-04-2005, 12:30 PM

Not to dispute your observations, but most agree that SD is not particularly good on any of the Moto boxes. But, if you want the DVR capability, it's the only show in town.

Plus, if you limit yourself to discussion in only this forum, you'll be missing the discussions in other forums, i.e., the AVS Forum, where there are literally hundreds of pages on the DCT-6412 alone. And, in general, they are mostly favorable.

Cobra · 01-04-2005, 02:55 PM

Points well taken. I've been an AVS forum member as well as Home Theater Spot forum member for years, so no I don't think anyone has forgotten those forums. However, I have to disagree about SD not being rendered well on "any" of the Moto boxes. That is kind of an unfair sweeping indictment of the Moto product in general. I have both a five series and a six series box and have been able to directly A/B compare them and the differences are visible.

The Moto boxes are capable of rendering very nice SD transmission. People are simply remarking that for all the advanced features the more recent boxes offer, there appears to have been a sacrifice in SD quality. But I'd never say that Moto has "never" had good SD quality . . . just not so and I have a box that proves it and I'm sure many others do as well.

joe98390 · 01-04-2005, 11:51 PM

I have a Philips 42" Plasma HDTV. (42PF9966). On the top of the screen, there appears a black/white line (seems like some kind of data compression problem) that flickers constantly. It takes up about an eigth of an inch and is present on HDTV channels as well as local broadcast channels. It is not present dor DVDs or other video sources...just TV. Anyone know what this might be. The cable company seems to think it should only appear on HDTV channels and seems to know about it. Does anyone else experience this and was wondering if this TV might be more susceptable than others.

Cobra · 01-05-2005, 12:18 AM

Hi Joe and welcome to the Forum:

Off hand I can't say exactly what that might be. My first impression is to think this is a geometry issue with the set that might be fixed by a trained ISF tech. See the section in this forum on ISF calibration of display devices but I don't think that's what it is.

On the other hand, it is odd it doesn't present itself with DVD's. I do have a question . . . do you see this line on ABC HD broadcasts? I ask this because DVD's are usually rendered in progressive line format and ABC-HD also uses the 720P progressive format. This could be an issue with only "Interlaced" sources. You might try fiddling with your STB (set top box). I know the Motorola boxes with Comcast have a hidden menu to tweak your set for 480I/P, 720P & 1080I/P. You may have similar settings with your plasma as well.

Also, could there be any kind of magnetic source near the top of your screen such as an unshielded center speaker? I don't know how magnetic sources effect plasma display devices but I had a sub woofer magnet screw the hell out of my Toshiba 56" HD rear projection set one time. It rendered similar weird lines near the bottom of the screen where the sub was positioned. But I would think this kind of distortion would also show on DVD's as well.

If none of these are the culprit then I would contact Phillips and see if they have this issue in their database. You could also have a bad connection coming in from the STB or just a bad connecting cable.

Cobra · 01-07-2005, 07:16 PM

Well I told you I'd post back if I had some more news. You won't believe this but I just saw exactly what your seeing on one of my own sets! It seems to come and go intermittently every few seconds. The very top of the screen is a flickering black and white image just as you described.

I have a theory on it. Forget all the aforementioned culprits that I suspected. It very much looks like my cable provider (Comcast) is using that damn "Sweep Generator" again. It is a test signal they send out that monitors something or other on their end. The only problem is it "can" interfere with the end users signal. The last time they pulled this junk on us in this area they had to receive a flood of complaints before they shut if off. I would suggest you call and report it and see if you can get a few others in your area to call as well (whether they see it or not!).

Sometimes you just have to have a little devil in you !

12-14-2004, 07:38 PM	#1
el_duderino My plasma is High Def. Join Date: Dec 2004 Posts: 6	Comcast 5100 image great, 6400 DVR image not I own a Toshiba 34HF84 and picked up a Motorola STB model DCT5100 about 10 days ago. DVI was enabled - ran it into my HDMI port with an adapter. Worked fine. Occasionally lost HDMI authentication if I powered down the TV. I just changed to a non-HD channel and back and that was fine. Pic was great, audio was great, my Sony RM-AV3100 remote controlled the STB just fine. The DCT5100 would lock up a couple times a day. The remote-signal-received LED on the STB front panel usually would come on during the lockup. During the lockup the remote would not work, but after the lockup all remote commadns pressed would activate. (It was NOT the remote BTW). According to Comcast the new guide signal on the cable is fouling up the 5100 and 6200 series of HD STBs. Comcast gave me a 6400 HD DVR to "fix" the problem. Well,after 10 days of watching the 5100, I can tell you the 6400 image is not as good. Brightly colored fast moving images get fuzzy on the edges, with obvious pixilation in the worst cases. Only with static or slowly-changing images is the image as clear. I called Comcast - they are clueless, but are chasing it down. I called Motorola, and the HD 6400 series uses a compression algorithm that is not used in the 5100 or the 6200 series. According to the person I talked to the algorithm is different enough that the engineers were not surprised to hear that someone saw a difference in the image. So for now I can get an STB that locks up multiple times a day or a DVR STB that isn't as clear as I know the image from Comcast can be... or I guess I can get DirectTV or VOOM. Anyone else with this sort of issue? (I HOPE this is not a repost - I looked...)

12-15-2004, 09:17 PM	#4
HDTVSam007 High Definition is the definition of life. Join Date: Dec 2004 Posts: 62	I have noticed this as well. I believe it is because it is compressed accross the memory buffer which enables you to pause ,rewind live tv.However I fixed this issue by a 2 way splitter before the DVR box a line to the tv and a line back to the DVR.So I use the DVR box for HDTV and shows I wana bare to record and watch,while using the tv tuner for clearing up my more frequently watched channels.This dramticaly improved the PQ although any cable signal on an HDTV is magnified and less flatering to the signal imperfections that comes along with cable.However this is a minor complaint considering benefits of the DVR Box,if it breaks its their problem,which my friend has been through 6 series 1 Tivos and they dont record HD (lucky for him he BOUGHT an extended warranty) but if you do decide to shell out the $999.99 for the DirectHDTivo warranty again is only one year unless you shell out more money on a gamble of an extended warranty.Not blasting Tivo but bringing to light the advantages of the Comcast vs Tivo....

12-16-2004, 11:50 PM	#6
Runaround $20 HDTV Join Date: Oct 2004 Location: Tyler, TX Age: 29 Posts: 59	From the information that I have been able to get on the DVRs, most of which comes from Moto, they don't re-encode/re-compress any of the digital signals they get. The only time the DVR actually encodes/compresses is for the analog signals. So the box does play back from the cache always just as TiVo does. In theory this shouldn't be the cause for the picture issue. That being said I haven't had a chance to spend any time with their non-DVR HD boxes as we only carried them for about a month or so till the DVRs came out. I wonder if they are using a different signal processor to put the picture on the wire than the other? __________________ -Daniel Hitachi 57F510, Onkyo TX-SR502 Reciever, Motorola DCT 6412 DVR, LG LGDVB418 DVD Player, Xbox 360, Logitech Harmony Remote 688, Bose Acoustimass 5 Series III Speaker System, Bose VCS-10 Center Speaker, Bose 141 Bookshelf Speakers, Sony SA-WM250 Subwoofer

01-01-2005, 03:11 PM	#7
bpajax Samsung HDTV with Comcast Join Date: Jan 2005 Posts: 1	Which Comcast Motorola STB ? I have the Motorola DCT 5100 which had been working fine. Recently, I'm getting the intermittant lockup when using the remote described elsewhere in the forum. I don't want to switch boxes and get poorer HD reception, but the lockups are becoming a real pain. Any suggestions? By the way, my 5100 has an active DVI port that I'm using to connect to my Samsung TX-P2675WH.

01-04-2005, 11:51 PM	#13
joe98390 What is HD? Join Date: Jan 2005 Posts: 2	Comcast I have a Philips 42" Plasma HDTV. (42PF9966). On the top of the screen, there appears a black/white line (seems like some kind of data compression problem) that flickers constantly. It takes up about an eigth of an inch and is present on HDTV channels as well as local broadcast channels. It is not present dor DVDs or other video sources...just TV. Anyone know what this might be. The cable company seems to think it should only appear on HDTV channels and seems to know about it. Does anyone else experience this and was wondering if this TV might be more susceptable than others.

12-14-2004, 08:30 PM	#2
Cobra Mars-Alpha Quadrant-Base7 Join Date: Nov 2004 Posts: 121	Frustrating as hell dealing with Comcast sometimes ain't it? I find there are basically two levels of folks there. One's who have a clue about a technical issue your trying to convey and one's who shouldn't operate a child's toy without adult supervision at all times! I'm wondering why a lower compression algorithm would be utilized by the upgraded box if they are both enabled for DVI signal transmission which should be a direct "compressionless" digital video signal transmission. Are they now intentionally "down rez'ing" the signals for some silly reason? If so that defeats the whole purpose of DVI or HDMI connection cables which are designed to be compressionless! Right now I have no answer for this and I doubt you'll get an intelligent one out of Comcast anytime soon. Keep us posted on the update on this because if what you're saying is true (and I believe ya) then others will be running into the same issue.

12-14-2004, 11:10 PM	#3
el_duderino My plasma is High Def. Join Date: Dec 2004 Posts: 6	I agree with your assessment of who answers the phone, and I'd already decided I alternate 50-50 between clued and less. Guess what? Comcast doesn't have a Customer Service department! They have Sales, Billing, Repair, and Disconnect. No one seems to be taking effective ownership here. My assumption is that the TiVo box sends digitized video, post-recording, to the TV - there is a delay in viewing. This allows the "rewinding" of live TV viewing. If this model of operation is carried over, then I would assume that the 6400 is compressing video somewhat for HDD recording, in a manner that is not needed for 5100/6200 direct viewing. Of course, there could be a button between direct viewing and DVR viewing, with the associated image quality increase. But I doubt that anyone in Comcast marketing has the balls/ovaries to tell people that DVR viewing is not as good as direct viewing... especially with the disdain they view the public with.

01-01-2005, 06:30 PM	#8
Cobra Mars-Alpha Quadrant-Base7 Join Date: Nov 2004 Posts: 121	Well I know this is going to sound like it definitely should not be a solution but for me it was. I have a 5100 box in one room that would lock up like crazy when I first got it. Just for the heck of it I reprogrammed the infrared signals into my Denon 5700 learning remote. The lock-up issue stopped. I realize this should not have fixed the problem given the fact that all that was transferred were the exact same infrared signals; but for some odd reason the lock-ups did stop. My only conclusion is it is some gremlin within the Motorola remote itself that may be the culprit.

01-02-2005, 09:28 AM	#9
Lanny High Definition is the definition of life. Join Date: Sep 2004 Location: Winthrop, MA Posts: 421	Those with a DCT5100 should consider upgrading to a newer DCT6200 series. Its processor is much faster; see specs on Motorola web site.

01-02-2005, 12:37 PM	#10
Cobra Mars-Alpha Quadrant-Base7 Join Date: Nov 2004 Posts: 121	Duh . . . have you looked at the "MANY" posts where people are discovering the newer boxes are rendering poor SD? I have a six series box in another room and I can definitely confirm the 5100 box renders cleaner SD. The six series boxes are using a different compression algorithm for some silly reason. The Comcast techs will confirm this as well. So thank you . . . but anybody lucky enough to still have a five series box and looking for great HD as well as great SD viewing should hold on to them!

01-04-2005, 12:30 PM	#11
Lanny High Definition is the definition of life. Join Date: Sep 2004 Location: Winthrop, MA Posts: 421	Not to dispute your observations, but most agree that SD is not particularly good on any of the Moto boxes. But, if you want the DVR capability, it's the only show in town. Plus, if you limit yourself to discussion in only this forum, you'll be missing the discussions in other forums, i.e., the AVS Forum, where there are literally hundreds of pages on the DCT-6412 alone. And, in general, they are mostly favorable.

01-04-2005, 02:55 PM	#12
Cobra Mars-Alpha Quadrant-Base7 Join Date: Nov 2004 Posts: 121	Points well taken. I've been an AVS forum member as well as Home Theater Spot forum member for years, so no I don't think anyone has forgotten those forums. However, I have to disagree about SD not being rendered well on "any" of the Moto boxes. That is kind of an unfair sweeping indictment of the Moto product in general. I have both a five series and a six series box and have been able to directly A/B compare them and the differences are visible. The Moto boxes are capable of rendering very nice SD transmission. People are simply remarking that for all the advanced features the more recent boxes offer, there appears to have been a sacrifice in SD quality. But I'd never say that Moto has "never" had good SD quality . . . just not so and I have a box that proves it and I'm sure many others do as well.

01-05-2005, 12:18 AM	#14
Cobra Mars-Alpha Quadrant-Base7 Join Date: Nov 2004 Posts: 121	Hi Joe and welcome to the Forum: Off hand I can't say exactly what that might be. My first impression is to think this is a geometry issue with the set that might be fixed by a trained ISF tech. See the section in this forum on ISF calibration of display devices but I don't think that's what it is. On the other hand, it is odd it doesn't present itself with DVD's. I do have a question . . . do you see this line on ABC HD broadcasts? I ask this because DVD's are usually rendered in progressive line format and ABC-HD also uses the 720P progressive format. This could be an issue with only "Interlaced" sources. You might try fiddling with your STB (set top box). I know the Motorola boxes with Comcast have a hidden menu to tweak your set for 480I/P, 720P & 1080I/P. You may have similar settings with your plasma as well. Also, could there be any kind of magnetic source near the top of your screen such as an unshielded center speaker? I don't know how magnetic sources effect plasma display devices but I had a sub woofer magnet screw the hell out of my Toshiba 56" HD rear projection set one time. It rendered similar weird lines near the bottom of the screen where the sub was positioned. But I would think this kind of distortion would also show on DVD's as well. If none of these are the culprit then I would contact Phillips and see if they have this issue in their database. You could also have a bad connection coming in from the STB or just a bad connecting cable.

01-07-2005, 07:16 PM	#15
Cobra Mars-Alpha Quadrant-Base7 Join Date: Nov 2004 Posts: 121	Well I told you I'd post back if I had some more news. You won't believe this but I just saw exactly what your seeing on one of my own sets! It seems to come and go intermittently every few seconds. The very top of the screen is a flickering black and white image just as you described. I have a theory on it. Forget all the aforementioned culprits that I suspected. It very much looks like my cable provider (Comcast) is using that damn "Sweep Generator" again. It is a test signal they send out that monitors something or other on their end. The only problem is it "can" interfere with the end users signal. The last time they pulled this junk on us in this area they had to receive a flood of complaints before they shut if off. I would suggest you call and report it and see if you can get a few others in your area to call as well (whether they see it or not!). Sometimes you just have to have a little devil in you !