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post #1 of 78 Old 02-21-2008, 08:17 PM - Thread Starter
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I wanted to get a thread started about choppy and jerky HD video content on ABC primarily during primetime. I've done some researching here and elsewhere, and have gathered some common issues:

I have the jerky and choppy video on Dish Network in Chicago, Illinois for both LOST and Eli Stone. Commercials and other programming looked fine. And oddly, these shows on OTA are fine.

One individual here confirms that he has also experienced the same problem - and he is on DTV. Not sure where he lives.

Another individual at dbstalk that is located in Chicago who is having the same problem. Not sure what feed he has.

There are about 5 other individuals from Chicago, Texas, and Denver that have all also experienced the same problem. One indicated he was on Comcast, and two indicated that they were on OTA.

Is there anyone else out there that is having this issue?
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post #2 of 78 Old 02-22-2008, 08:15 PM
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ABC uses equipment which drops frames to speed up playback to allow more commercials to be inserted. This can be confirmed by comparing the broadcast on ABC to one on a Canadian network such as CTV. Once commercials are removed, the CTV broadcast of an hour-long show is usually about 30 seconds longer than ABC's. This isn't related to any specific station or distribution method, and isn't present on every show; it's most common on the late primetime show when they add more commercials to the middle show to make it last till 2 past the hour.
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post #3 of 78 Old 02-23-2008, 05:33 PM
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I have also experienced this judder effect during LOST over the last two weeks. I have Dish Network DVR and am in the Chicago suburbs. I DVRed the first two episodes of Lost season and did not have this problem.
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post #4 of 78 Old 02-28-2008, 06:52 PM - Thread Starter
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coyoteaz - I'm not sure I understand. ABC is intentionally making the video unwatchably juddery/choppy? Or is this a result of an error related to what you are describing?

I'm at my wits end. I can't watch this.
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post #5 of 78 Old 02-28-2008, 07:15 PM
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I don't notice the choppy video but the overall PQ on Eli Stone on WABC-DT is not good.

The video looks soft on the HD and SD feed. I'm also getting more artifacting during medium camera movement then I notice on the other HD shows.
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post #6 of 78 Old 02-28-2008, 11:17 PM
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It is intentional, though I wouldn't call it unwatchable. Like other processes such as telecine that alter the frames of a video to adjust framerate or runtime, most people won't notice it but there will be a small number who are sensitive.
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post #7 of 78 Old 03-01-2008, 09:13 PM
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I am also in the Chicago area and Lost is irritating to watch because of the juddering. At first I thought it was the DVR, but my other standard HD receiver does the same thing. It is beyond something only a few people will notice, it is like the framerate drops into the teens. The sound is fine, but the video is ridiculous.

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post #8 of 78 Old 03-02-2008, 02:59 PM
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Quote:
Originally Posted by coyoteaz View Post

ABC uses equipment which drops frames to speed up playback to allow more commercials to be inserted. This can be confirmed by comparing the broadcast on ABC to one on a Canadian network such as CTV. Once commercials are removed, the CTV broadcast of an hour-long show is usually about 30 seconds longer than ABC's. This isn't related to any specific station or distribution method, and isn't present on every show; it's most common on the late primetime show when they add more commercials to the middle show to make it last till 2 past the hour.

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post #9 of 78 Old 03-03-2008, 01:03 PM
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Quote:
Originally Posted by bool View Post

I am also in the Chicago area and Lost is irritating to watch because of the juddering. At first I thought it was the DVR, but my other standard HD receiver does the same thing. It is beyond something only a few people will notice, it is like the framerate drops into the teens. The sound is fine, but the video is ridiculous.

I totally agree that this is something way more noticeable than only by a few people. I am also in the Chicago subs and have a Dish 622. I noticed this on the last 3 episodes of Lost. It was also on Eli Stone (I don't watch Eli - I just noticed it while flipping through the dial).

I'm not sure this is a compression issue... I also recorded the SD feed of Lost and it does not have the judder and the SD vs. HD shows did not appear to have a significant time shift - I did not time them with a stop watch or anything, just that the recording stopped at very similar places after recording ended (interesting happenstance to be discussing a potential time shift and the broadcast of Lost ). The SD PQ left a lot to be desired compared to the HD feed, however, I found that the HD judder was something that I could not watch and settled for the SD image.

It does seem interesting that several of the people experiencing this are in the Chicago area???

Anyone have additional info on this?

E
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post #10 of 78 Old 03-03-2008, 01:34 PM
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Interesting info about dropping frames. The TivoHD has an issue where after a few weeks it begins stuttering on 720p stations and I thought it was weird that LOST in 1080i stuttered at the same time. The purposeful frame dropping explains it. A TivoHD reboot fixes the 720p station problem but LOST still stutters, just not as much.

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post #11 of 78 Old 03-03-2008, 07:07 PM
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Sounds like WLS might be having an issue since the rest of the country isn't seeing the level of problems being described in this thread by those watching on that station. ABC's temporal compression drops a frame every few seconds so it wouldn't cause the issues being seen here. It also applies to the SD broadcast since they are synced. All of you in the Chicago area should email the station since they might not even know of the problem, and even if they do, they probably blame it on viewer equipment since they haven't heard enough complaints.
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post #12 of 78 Old 03-04-2008, 06:09 AM
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I'm in the Phila burbs using a Direct TV DVR and the ABC feed is horrible.The picture locks up and I get green blocks.It's almost unwatchable.I suspect the blocking originates with my display when it looses data.(samsung HLT6187) All other channels are perfect.so it has to be the ABC feed.Wifey had a fit watching the royal family 20/20 show.
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post #13 of 78 Old 03-04-2008, 07:08 AM
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I have emailed the engineering department at WLS twice about the stuttering video on many of their HD shows, and of course have not received any replies.

R. B.
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post #14 of 78 Old 03-04-2008, 08:53 AM
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Quote:
Originally Posted by retromzc View Post

I have emailed the engineering department at WLS twice about the stuttering video on many of their HD shows, and of course have not received any replies.

I just emailed WLS as well. We will see if anyone gets a response. Maybe we should get Pam Zeckman on the case
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post #15 of 78 Old 03-04-2008, 01:47 PM
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Quote:
Originally Posted by coyoteaz View Post

ABC uses equipment which drops frames to speed up playback to allow more commercials to be inserted. This can be confirmed by comparing the broadcast on ABC to one on a Canadian network such as CTV. Once commercials are removed, the CTV broadcast of an hour-long show is usually about 30 seconds longer than ABC's. This isn't related to any specific station or distribution method, and isn't present on every show; it's most common on the late primetime show when they add more commercials to the middle show to make it last till 2 past the hour.

I believe this is a separate issue. I have seen reports of juddering with 720p on Mpeg4 DBS feeds. Has anyone who has seen this problem on ABC also noticed it on FOX?

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Originally Posted by PooperScooper View Post

Interesting info about dropping frames. The TivoHD has an issue where after a few weeks it begins stuttering on 720p stations and I thought it was weird that LOST in 1080i stuttered at the same time. The purposeful frame dropping explains it. A TivoHD reboot fixes the 720p station problem but LOST still stutters, just not as much.

larry

Unless your local affiliate is changing the format, Lost is 720p as are all ABC programs.
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post #16 of 78 Old 03-04-2008, 02:18 PM
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So far ABC primetime HD shows are the only ones that are exhibiting the judder for me. No problems during the day barring the occasional hiccup.

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post #17 of 78 Old 03-04-2008, 02:36 PM
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Unless your local affiliate is changing the format, Lost is 720p as are all ABC programs.

That's what I thought too. But I looked more than once at my TivoHD resolution output and it says 1080i. It says 720p for ESPN, Fox and the other 720p stations. I need to remember to look when it's recording LOST and look at the resolution and compare to other shows on ABC.

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post #18 of 78 Old 03-04-2008, 06:52 PM
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Dunno if this is applicable or useful or not, but just in case ... One issue I have run into with one of my decoders here (Zenith HDV420 ATSC receiver specifically) involving "seemingly" dropped frames(stuttering video/etc - this is all with OTA) has occured when local broadcasters sending 720p have their encoders set so that setting on the encoder such as "repeat field detection"(note: I think that one "specifically" is the "term" used for the setting for certian Harmonic encoders) is turned on .... This is supposed to allow repeated fields to be flagged so that they are drawn by the decoder rather than encoded, but apparently some decoders can't do it properly ... In any case When engineers turned off "repeat field detection" settings on their encoder, the problem went away .. Note that the decoder in the Zenith is the ONLY decoder I have which exhibited this issue ...

Note that the issue only happened during programming sourced from 24fps sources (film, 24p HD video/etc) ... And, it wasn't just network (such as ABC) programming which was effected .... From one Fox affiliate for example, the problem never occured during Fox programming since that is encoded at network level and the splicer "allows it" to effectively bypass the local encoder, but, during syndicated programming sourced from film from that station, the issue occured until they turned off the "repeat field detection" setting on their encoder ... But, from a ABC affiliate, it occured both during Network, syndicated or local programming sourced from 24fps sources ....

BTW, The time compression "issue" previously mentioned is a PITA if you are IVTC'ing and decimiating(or just decimating) frames to return material to 24fps (such as with various AVIsynth filters/scripts which I do for processes such as reencoding using AVC or VC1)....

Jeff
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post #19 of 78 Old 03-04-2008, 06:59 PM
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Quote:
Originally Posted by PooperScooper View Post

That's what I thought too. But I looked more than once at my TivoHD resolution output and it says 1080i. It says 720p for ESPN, Fox and the other 720p stations. I need to remember to look when it's recording LOST and look at the resolution and compare to other shows on ABC.

larry

WCVB in Boston is converting ABC network programming to 1080i. They claim this was done to be in sync with the internal standard used by owner Hearst.
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post #20 of 78 Old 03-04-2008, 08:30 PM
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I thought I was the only one with an HDV420. It's still kicking but I get horizontal pink and green lines occasionally on any channel.
Just about stopped watching ABC except for Lost. At least ABC doesn't have the snap, crackle, pop of NBC switching to commercials and back. Nascar races on ABC look fabulous. For Lost I record it with an MDP-130 while watching with the same tuner but have not noticed any stuttering recently even during playback.
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post #21 of 78 Old 03-05-2008, 02:50 PM
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This is pretty clearly on an affiliate by affiliate basis. I was noticing this frame-rate speed up during some summer re-runs last year. However I am 100% sure that last weeks episode of Lost was shown @ 24/1001 on KOAT-Albuquerque, since I decimated and re-encoded with mencoder x264.
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post #22 of 78 Old 03-05-2008, 02:54 PM
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I'm not seeing any stuttering OTA here. Since Lin Productions doesn't have an HD deal with D*, I can't compare it via D* MPEG4.

At any rate, it can't be an issue from the network since I'm not seeing it on my affiliate.


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post #23 of 78 Old 03-05-2008, 03:01 PM
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Quote:
Originally Posted by lobosrul View Post

However I am 100% sure that last weeks episode of Lost was shown @ 24/1001 on KOAT-Albuquerque, since I decimated and re-encoded with mencoder x264.

mencoder will output any frame rate you specify regardless of what the frame rate of the source is.

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post #24 of 78 Old 03-05-2008, 06:09 PM
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The framerate coming out of ABC's encoder (and from standard ABC stations) is still 60000/1001. Figure there are 75500 frames in a 21 minute broadcast. ABC drops 1800 of those and they can now show an extra 30 seconds worth of commercials. The total number of frames in a 30 minute timeslot hasn't changed from ~108000 and the framerate hasn't changed from 60000/1001, but ABC gets to charge for an extra 30 second slot with little noticeable effect for most viewers.
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post #25 of 78 Old 03-06-2008, 03:45 AM
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Quote:
Originally Posted by coyoteaz View Post

The framerate coming out of ABC's encoder (and from standard ABC stations) is still 60000/1001. Figure there are 75500 frames in a 21 minute broadcast. ABC drops 1800 of those and they can now show an extra 30 seconds worth of commercials. The total number of frames in a 30 minute timeslot hasn't changed from ~108000 and the framerate hasn't changed from 60000/1001, but ABC gets to charge for an extra 30 second slot with little noticeable effect for most viewers.

Yep - I think the speed-up is noticable with people trying to convert 3:2 60p content to 1:1 24p by removing the 3:2 pulldown pattern. AIUI the "squeeze an extra ad in" speed-up breaks the 3:2 cadence (as some frames will be dropped in a 30 minute period, giving you a source frame pair encoded as 3:1, 2:2 etc. rather than 3:2 occasionally?)

The number of 60p frames broadcast in the 30 minute period hasn't changed, but the number of frames that are used to contain the programme broadcast has been reduced as the show has been sped up. Rather than edit out a single 30 second chunk, 30 seconds worth of frames are discarded throughout the show. (I assume without interpolation though I may be wrong)
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post #26 of 78 Old 03-06-2008, 10:15 AM
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So what's the remedy for getting rid of the judder during Lost?

The 3:2 pulldown on my TV is automatically disabled with 720p @ 60 hz. I could try the "Smooth" setting, but this applies some sort of fakey frame interpolation to the signal -- I'd prefer to stay away from that. The only other setting available is "Advance", which is specifically for 1080p 24fps sources (i.e., Blu-Ray).

Or is this something WLS has to address on their end? Do they need to set their decoder's "repeat field detection" to "off" as Nitewatchman suggests?

Thanks.
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post #27 of 78 Old 03-06-2008, 10:52 AM
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Quote:
Originally Posted by Eric_RP View Post

I just emailed WLS as well. We will see if anyone gets a response. Maybe we should get Pam Zeckman on the case

e-mail sent to WLS....doubt it will amount to anything

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post #28 of 78 Old 03-06-2008, 11:44 AM
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Quote:
Originally Posted by coyoteaz View Post

WCVB in Boston is converting ABC network programming to 1080i. They claim this was done to be in sync with the internal standard used by owner Hearst.

Thanks for the reason. I did check and Boston ABC is coming in at 1080i and New Hampshire ABC is 720p.

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post #29 of 78 Old 03-06-2008, 11:54 AM
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Quote:
Originally Posted by Backlight View Post

So what's the remedy for getting rid of the judder during Lost?

If frames are missing, there's no way to fix it. I convert Lost to 24 fps every week and missing frames would print a big error message during the conversion so I'm not convinced that the network is stealing frames for more commercials.

True 24 fps will sometimes have more judder than the 720p we watch. If you step through the 3:2 pattern in 720p, you may find that you're not really seeing three perfect duplicates followed by two perfect duplicates. The first frame will sometimes be soft and the second one will be sharper. This actually makes motion look smoother than if the first frame were sharp and second frame were a perfect duplicate of it.

I don't know if this is how the frames are being sent from the network or if is a side effect of my affiliate's encoder trying to encode a higher bit rate network feed into a lower bit rate ATSC stream.

Quote:


The 3:2 pulldown on my TV is automatically disabled with 720p @ 60 hz.

Yes, the network is already doing that for you.

Quote:


Or is this something WLS has to address on their end? Do they need to set their decoder's "repeat field detection" to "off" as Nitewatchman suggests?

I thought that was only for interlaced sources.

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post #30 of 78 Old 03-06-2008, 12:20 PM
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Quote:
Originally Posted by sneals2000 View Post

Yep - I think the speed-up is noticable with people trying to convert 3:2 60p content to 1:1 24p by removing the 3:2 pulldown pattern. AIUI the "squeeze an extra ad in" speed-up breaks the 3:2 cadence (as some frames will be dropped in a 30 minute period, giving you a source frame pair encoded as 3:1, 2:2 etc. rather than 3:2 occasionally?)

The number of 60p frames broadcast in the 30 minute period hasn't changed, but the number of frames that are used to contain the programme broadcast has been reduced as the show has been sped up. Rather than edit out a single 30 second chunk, 30 seconds worth of frames are discarded throughout the show. (I assume without interpolation though I may be wrong)

Correct on all counts.
Quote:
Originally Posted by Backlight View Post

So what's the remedy for getting rid of the judder during Lost?

The 3:2 pulldown on my TV is automatically disabled with 720p @ 60 hz. I could try the "Smooth" setting, but this applies some sort of fakey frame interpolation to the signal -- I'd prefer to stay away from that. The only other setting available is "Advance", which is specifically for 1080p 24fps sources (i.e., Blu-Ray).

Or is this something WLS has to address on their end? Do they need to set their decoder's "repeat field detection" to "off" as Nitewatchman suggests?

Thanks.

WLS definitely has something wrong on their end because the rest of us don't see any major problems with Lost. Also, from what I've seen, ABC rarely drops frames on the 9pm show since it usually goes over by 1-2 minutes anyway and that gives them more room for commercials as it is.
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If frames are missing, there's no way to fix it. I convert Lost to 24 fps every week and missing frames would print a big error message during the conversion so I'm not convinced that the network is stealing frames for more commercials.

True 24 fps will sometimes have more judder than the 720p we watch. If you step through the 3:2 pattern in 720p, you may find that you're not really seeing three perfect duplicates followed by two perfect duplicates. The first frame will sometimes be soft and the second one will be sharper. This actually makes motion look smoother than if the first frame were sharp and second frame were a perfect duplicate of it.

I don't know if this is how the frames are being sent from the network or if is a side effect of my affiliate's encoder trying to encode a higher bit rate network feed into a lower bit rate ATSC stream.


Yes, the network is already doing that for you.


I thought that was only for interlaced sources.

It's not like there are frames missing from the broadcast and replaced with nothing. When frames are intentionally dropped, everything after that is shifted ahead in time to fill the gap. Your encoder doesn't notice the difference, but like sneals2000 pointed out, the cadence is broken and your eyes might notice a skip if there happens to be a lot of motion happening at that time.
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