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Guest Message by DevFuse

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Skip causing pixelation on HR 24


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21 replies to this topic

#1 OFFLINE   shendley

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Posted 11 April 2013 - 09:08 PM

I recently received a refurbished HR 24 (500 I think) and have noticed something curious. When I skip through commercials there is occasional significant pixilation at random places during the skips. Since I'm skipping through commercials, this is absolutely no problem. I'm just curious about it since I never saw this on my old 24 (100 I think). Anyone else seen this?

AU9, SWM8
Panasonic TH-58PX60U, HDMI to HR44-100, Native, DD, HDMI to Pioneer VSX-1123-k Receiver, Harmony One, Networked with Ethernet Cable, 35/4 Mbps DSL.
Panasonic TH-42PD50U, Component to HR 24-100, Antec MX-1 w. WD10EVDS ESata, Native, DD, DTV Remote.
Panasonic TC-L32X2, HDMI to C41-100, DTV Remote.
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#2 OFFLINE   dpeters11

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Posted 11 April 2013 - 09:11 PM

The big difference on the 500 is it uses a different colorspace, but haven't heard of that causing this type of issue before.

#3 OFFLINE   Diana C

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Posted 12 April 2013 - 09:07 AM

I've noticed this starting to happen on all our DVRs. I think it is just a difference in the way the software grabs frames during skip (I also notice it when coming out of a slip). The way MPEG compression works is that most of the time each frame only contains the pixels that are different from the previous frame. After a specified number of frames, or when the differences become big enough (whichever comes first), a full frame is transmitted. So, when slipping or skipping, if the software doesn't go to the nearest full frame you'll see a pixelated image. Since it only happens in conjunction with trick play, I don't think it is an issue.

Dish Network Customer from 9/1998-11/2001
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Current setup:
DirecTV: HR34-700 (1TB) / HR24-100 (1TB) / HR24-500 (1TB) / HR21-700 (320GB) / HR21-100 (1TB) / 2 H25s / C41-500 / SWiM16 / Nomad / CCK

FiOS: 2 Tivo Roamio Pros (6 TB total) / 5 Tivo Minis attached via MOCA


#4 OFFLINE   shendley

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Posted 12 April 2013 - 09:27 AM

Thanks. A sensible explanation. And, of course, it's not an issue since it only happens when I skip. Just curious.

I've noticed this starting to happen on all our DVRs. I think it is just a difference in the way the software grabs frames during skip (I also notice it when coming out of a slip). The way MPEG compression works is that most of the time each frame only contains the pixels that are different from the previous frame. After a specified number of frames, or when the differences become big enough (whichever comes first), a full frame is transmitted. So, when slipping or skipping, if the software doesn't go to the nearest full frame you'll see a pixelated image. Since it only happens in conjunction with trick play, I don't think it is an issue.


AU9, SWM8
Panasonic TH-58PX60U, HDMI to HR44-100, Native, DD, HDMI to Pioneer VSX-1123-k Receiver, Harmony One, Networked with Ethernet Cable, 35/4 Mbps DSL.
Panasonic TH-42PD50U, Component to HR 24-100, Antec MX-1 w. WD10EVDS ESata, Native, DD, DTV Remote.
Panasonic TC-L32X2, HDMI to C41-100, DTV Remote.
Whole Home.


#5 OFFLINE   jdspencer

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Posted 12 April 2013 - 09:41 AM

My HR24-500 has been doing this for quite awhile. Not a problem since everything is fine after the 30s skip is done.
DirecTV since '96, Waivers for ABC, CBS, NBC, & Fox, HR23-700 & HR24-500/AM21, using ethernet based MRV.

#6 OFFLINE   Sea bass

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Posted 12 April 2013 - 10:19 AM

+ 1.

#7 OFFLINE   makaiguy

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Posted 13 April 2013 - 07:51 AM

That was one of the first differences I noticed when my venerable HR20-700 was replaced by a new HR24-500.
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HR24-500, HR22-100
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#8 OFFLINE   RACJ2

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Posted 13 April 2013 - 01:59 PM

You can always eliminate that pixilation, which is probably macroblocking, by switching from Skip to Slip.
HR34-700, HR22-100

#9 OFFLINE   jdspencer

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Posted 13 April 2013 - 05:52 PM

Yeah, I went to 30s slip but was so used to 30s skip I couldn't stand it.
I'll put up with the pixelation.
DirecTV since '96, Waivers for ABC, CBS, NBC, & Fox, HR23-700 & HR24-500/AM21, using ethernet based MRV.

#10 OFFLINE   makaiguy

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Posted 14 April 2013 - 10:32 AM

Yeah, I went to 30s slip but was so used to 30s skip I couldn't stand it.
I'll put up with the pixelation.

^^^ +1


DirecTV customer since 1997
HR24-500, HR22-100
I don't do buddy/friends lists, don't ask.

#11 OFFLINE   shendley

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Posted 14 April 2013 - 12:41 PM

In Diana C's post above, she said she saw the pixilation coming out of a slip as well as the skip. But even if it did fix it, I'm too used to the skip to switch to the slip. The pixilation doesn't really bother me anyway. I was just curious since I'd never seen it before.

You can always eliminate that pixilation, which is probably macroblocking, by switching from Skip to Slip.


Edited by shendley, 14 April 2013 - 12:41 PM.

AU9, SWM8
Panasonic TH-58PX60U, HDMI to HR44-100, Native, DD, HDMI to Pioneer VSX-1123-k Receiver, Harmony One, Networked with Ethernet Cable, 35/4 Mbps DSL.
Panasonic TH-42PD50U, Component to HR 24-100, Antec MX-1 w. WD10EVDS ESata, Native, DD, DTV Remote.
Panasonic TC-L32X2, HDMI to C41-100, DTV Remote.
Whole Home.


#12 OFFLINE   Rtm

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Posted 15 April 2013 - 02:21 AM

Same issue for split second on HR24-100 and I'm using 30Skip


Edited by Rtm, 15 April 2013 - 02:21 AM.


#13 OFFLINE   TomCat

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Posted 15 April 2013 - 06:28 PM

...The way MPEG compression works is that most of the time each frame only contains the pixels that are different from the previous frame. After a specified number of frames, or when the differences become big enough (whichever comes first), a full frame is transmitted. So, when slipping or skipping, if the software doesn't go to the nearest full frame you'll see a pixelated image...

That is a very simplified idea of how this works. AVC part 10 can use a GOP that is up to 200 frames long (200 differential frames between full I-frames), but in the interests of faster channel acquisition time extra I-frames are inserted every second or so.

 

But none of that matters either, because any digital consumer system that uses any method of jumping non-linearly from one place to another or shuttling from one place to another within media already takes that into account, by only jumping to the nearest I-frame rather than an exact distance (exact number of frames) which might land on a B or P frame, and it does this precisely to prevent the problem of pixillation due to an unreferenced B or P frame which creates a broken or orphaned partial GOP, as well as to make shuttling smoother. Frame-accurate editing systems reprocess B and P frames at the desired edit point as new I-frames, but they do that off line, and a consumer DVR does not have the horsepower to do that on the fly. So if you are seeing this issue, that is not the reason why. It is broken in some other way. HRs jump GOP to GOP, I-frame to I-frame.

 

I could understand this issue on a server/client setup like Genie because there is an intermediate bandwidth-related task of moving the content from server to client, but there really should be no reason why an HR24 would do this, short of it being broken or the input content having some issue.


Edited by TomCat, 15 April 2013 - 06:30 PM.

It's usually safe to talk honestly and openly with people because they typically are not really listening anyway.

#14 OFFLINE   Steve

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Posted 12 May 2013 - 01:52 PM

The way MPEG compression works is that most of the time each frame only contains the pixels that are different from the previous frame. After a specified number of frames, or when the differences become big enough (whichever comes first), a full frame is transmitted.

 

 

That is a very simplified idea of how this works. AVC part 10 can use a GOP that is up to 200 frames long (200 differential frames between full I-frames), but in the interests of faster channel acquisition time extra I-frames are inserted every second or so.

 

IOW, what Diana already explained to us in plain English.


/steve

#15 OFFLINE   Rich

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Posted 13 May 2013 - 11:02 AM

I've noticed this starting to happen on all our DVRs. I think it is just a difference in the way the software grabs frames during skip (I also notice it when coming out of a slip). The way MPEG compression works is that most of the time each frame only contains the pixels that are different from the previous frame. After a specified number of frames, or when the differences become big enough (whichever comes first), a full frame is transmitted. So, when slipping or skipping, if the software doesn't go to the nearest full frame you'll see a pixelated image. Since it only happens in conjunction with trick play, I don't think it is an issue.

 

Been happening to me for awhile.  Minor annoyance.

 

Rich



#16 OFFLINE   Rich

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Posted 13 May 2013 - 11:03 AM

Same issue for split second on HR24-100 and I'm using 30Skip

 

Yup, I'm seeing it with my 24-100s too.  

 

Rich



#17 OFFLINE   Rich

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Posted 13 May 2013 - 11:05 AM

IOW, what Diana already explained to us in plain English.

 

And used brevity to make her point.

 

Rich



#18 OFFLINE   Diana C

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Posted 13 May 2013 - 12:10 PM

And used brevity to make her point.

 

Rich

Gee...thanks...I don't think I've ever been accused of brevity before. ;)


Dish Network Customer from 9/1998-11/2001
DirecTV Customer 10/2001 - 7/2014

FiOS TV/TiVo Customer since 6/2014
Moderator, DBSDish.com 1999-2000
Co-Founder and Administrator, DBSForums.com 2000-2006

Current setup:
DirecTV: HR34-700 (1TB) / HR24-100 (1TB) / HR24-500 (1TB) / HR21-700 (320GB) / HR21-100 (1TB) / 2 H25s / C41-500 / SWiM16 / Nomad / CCK

FiOS: 2 Tivo Roamio Pros (6 TB total) / 5 Tivo Minis attached via MOCA


#19 OFFLINE   jimmie57

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Posted 14 May 2013 - 07:11 AM

Diana

LOL
All your explanations that I have read are very good. Keep them coming.

DirecTV customer since 1996 - Current :Slimline 3 SWM,   HR24-100 HDMI to 32" Sharp LED,
HR24-100 Component cables to 46" Samsung LCD & Optical Cable to Yamaha AVR, H21-200 HDMI to Yamaha AVR & HDMI to 52" Mitsubishi LCD


#20 OFFLINE   bobcamp1

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Posted 14 May 2013 - 07:27 AM

I could understand this issue on a server/client setup like Genie because there is an intermediate bandwidth-related task of moving the content from server to client, but there really should be no reason why an HR24 would do this, short of it being broken or the input content having some issue.

 +1   No other DVR I've seen (Tivo, FIOS, even the crappy TWC box) does this with MPEG2 or MPEG4.  I think it's a small bug that's just low on the priority list for now.






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