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Comcast downgrading all 1080i HD channels to 720p

Expert

Re: Comcast downgrading all 1080i HD channels to 720p

1080i and 720p are the current ATSC transmission formats. the 'i' is interlaced and has the approximate detail of 1/2 * 1080 or 540 'p' (but still has the motion artifcacts). all source video is in mpeg 2/4/HEVC. Comcast gets your local broadcast signals from the local studios as an mpeg stream delivered over fiber optics to a comcast headend in the cloud location. No commerical broadcast station in usa broadcasts in 1080p.  the Networks are still converting to mpeg HVEC.  digital deliver of streamed content is in SD mpeg2 or HD 720p for Comcast channels. 



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Re: Comcast downgrading all 1080i HD channels to 720p

Another obfuscative reply by Rustyben quoteunquote expert (!).

 

Comcast absolutely had the option to switch from "i" to "p" (their announced plan) by delivering 1080i content as 1080p.(1)   That would have saved subscribers from the major picture quality degredation which results from TWO scaling operations.   First downscaling from 1080 lines to 720 (to deliver to customers), then upscaling back from 720 to 1080 (or even 2160, shudder, by the customer's settop box or HDTV).

 

(1) By instead of alternating as "i" does, delivering every line every frame as "p" does.

 

The bet they made that most subscribers wouldn't even notice might sadly be correct.  But they lost me.  Their customer service didn't even understand what I explained above, and wouldn't let me out of my contract when I explained that they did this to us.  They did though in response to my FCC Complaint about it.

Regular Visitor

Re: Comcast downgrading all 1080i HD channels to 720p

Re: RustyBen,

 

All the "explanation" in the world can't bring back my lost resolution, because I'm here to tell you my picture now looks like ____. The artifacts in the image have greatly increased due to Comcast's decision to, without notice, or option to me, screw me over. Am I supposed to be happy now that it's been explained? By the way, it's nonsense since the signal is obviously now degraded. My only reply to your explanation would be: well then they must have the crappiest upscalers in the boxes that are bringing it back up to 1080p. Bottom line: degraded signal.

Contributor

Re: Comcast downgrading all 1080i HD channels to 720p

Yes, the lack of notice was shameful. I don't think that converting 1080i to 1080p involves scaling; it seems to me it would simply duplicate every other frame.

 

Theoretically settop boxes could be made to do the same thing and not cost any bandwidth.

Expert

Re: Comcast downgrading all 1080i HD channels to 720p


@coyote2 wrote:

Yes, the lack of notice was shameful. I don't think that converting 1080i to 1080p involves scaling; it seems to me it would simply duplicate every other frame.

 

Theoretically settop boxes could be made to do the same thing and not cost any bandwidth.


the 'quality' (720 vs 1080 vs 4k) at comcast is all digital. only 'broadcast' by a tower to a TV set antenna then to TV is in 1080i.  numbered channels on cable are just the mpeg2/4 streams delivered by QAM channels and IPTV for some 4 digit comcast channels (like 1115 newsmax).  

 

To visualize '4k' TV screens,  imagine you are watching a 16:9 HD (1K) TV.  when watching a Comcast channel, it fills the full screen. to 'make' a 4k TV screen take 4 1k TV screens and make a rectagle of the screens two across by two high. Without scaling the screen space used by a 1K channel would fill only 1/4 of the screen. the ouput of the set top box can be set to 4K or the output can remain 720p or 1080p and then the circuitry in the 4k TV will have to zoom the image 4 times. you can quickly see that with a 4x zoom it will not be as clear as the same size TV that is only 1K native.  The next technology jump for broadcasters is changing to ATSC 3.0 which will require new TV tuners (or converter boxes) to watch off the air. ATSC 3.0 will allow the 4k/8k/16k of the future.   



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Regular Contributor

Re: Comcast downgrading all 1080i HD channels to 720p

The biggest issue isn’t that Comcast is converting 1080i to 720p as 720p can look good.  It’s that Comcast is bit-starving channels so there’s not enough channel bandwidth for a good looking picture.  This is most noticeable when there are a lot of small moving objects in the picture at which the picture turns into a blocky mess. 

 

When HBO Go looks a lot better than HBO on Comcast, there’s an issue. 

Contributor

Re: Comcast downgrading all 1080i HD channels to 720p


@Morac2 wrote:

The biggest issue isn’t that Comcast is converting 1080i to 720p as 720p can look good.  It’s that Comcast is bit-starving channels so there’s not enough channel bandwidth for a good looking picture.  This is most noticeable when there are a lot of small moving objects in the picture at which the picture turns into a blocky mess. 

 

When HBO Go looks a lot better than HBO on Comcast, there’s an issue. 


I don't disagree that the "bit-starving" (I believe aka lossy compression) is also a problem.  (Is that what drives me crazy when the camera moves over a scene with a lot of detail [and all one sees is blur]?)

 

I think that the pair of scaling operations bothers me more since it's impact is constant and I want more than for it to "look good", I want all possible resolution.

 

Perhaps most customers don't care, but it still puzzles me that Comcast doesn't do more to retain customers now that customers have quite a range of alternatives.

Regular Visitor

Re: Comcast downgrading all 1080i HD channels to 720p

I concur with all of the complaints about Comcast / Xfinity downscaling from 1080i to 720p.  My wife and I watched Game of Thrones season 8 episode 3 through Xfinity and it was dark and visibly low resolution - my wife called it "muddy".  I connected my full HD HP laptop to my TV, using Windows 10 / Microsoft Edge / HBO GO:  the HD result was quite satisfying - clearer and brighter.  This result also occured when we used the HBO GO app on my wife's iPhone 6 Plus.  We'll watch the rest of GOT through HBO GO.  Unless Comcast restores 1080i, we will also start looking for an alternative to Comcast / Xfinity for our TV service.  I concur with another comment - Comcast should be providing better service, not giving current customers reasons to change.

Expert

Re: Comcast downgrading all 1080i HD channels to 720p


@mlf1 wrote:

I concur with all of the complaints about Comcast / Xfinity downscaling from 1080i to 720p.  My wife and I watched Game of Thrones season 8 episode 3 through Xfinity and it was dark and visibly low resolution - my wife called it "muddy".  I connected my full HD HP laptop to my TV, using Windows 10 / Microsoft Edge / HBO GO:  the HD result was quite satisfying - clearer and brighter.  This result also occured when we used the HBO GO app on my wife's iPhone 6 Plus.  We'll watch the rest of GOT through HBO GO.  Unless Comcast restores 1080i, we will also start looking for an alternative to Comcast / Xfinity for our TV service.  I concur with another comment - Comcast should be providing better service, not giving current customers reasons to change.


HBO is a cable feed not a broadcast channel - there is no 'broadcast format' . the video is HEVC delivered to Comcast who then puts it out in 720p. It sounds like your TV needs to be set up on the HDMI port to give you the best image reproduction possible. The feed from the HBO site may be in a different format (1080p? 4k? UHD?) 

 

what type of TV screen are you using? the 'i' (interlaced) format is a format made for old glass CRT type picture tubes. 1080i is equivalent to roughly 540p but handles motion quite badly in reroduction. you can search youtuve for any number of demonstration videos using 720p vs 1080i as a search term.



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Re: Comcast downgrading all 1080i HD channels to 720p


@Rustyben wrote:

@mlf1 wrote:

I concur with all of the complaints about Comcast / Xfinity downscaling from 1080i to 720p.  My wife and I watched Game of Thrones season 8 episode 3 through Xfinity and it was dark and visibly low resolution - my wife called it "muddy".  I connected my full HD HP laptop to my TV, using Windows 10 / Microsoft Edge / HBO GO:  the HD result was quite satisfying - clearer and brighter.  This result also occured when we used the HBO GO app on my wife's iPhone 6 Plus.  We'll watch the rest of GOT through HBO GO.  Unless Comcast restores 1080i, we will also start looking for an alternative to Comcast / Xfinity for our TV service.  I concur with another comment - Comcast should be providing better service, not giving current customers reasons to change.


HBO is a cable feed not a broadcast channel - there is no 'broadcast format' . the video is HEVC delivered to Comcast who then puts it out in 720p. It sounds like your TV needs to be set up on the HDMI port to give you the best image reproduction possible. The feed from the HBO site may be in a different format (1080p? 4k? UHD?) 

 

what type of TV screen are you using? the 'i' (interlaced) format is a format made for old glass CRT type picture tubes. 1080i is equivalent to roughly 540p but handles motion quite badly in reroduction. you can search youtuve for any number of demonstration videos using 720p vs 1080i as a search term.


It’s not his TV, it’s Comcast.  I have a Sony 4K TV and ever since Comcast switched to a highly compressed 720p H.264, the lack of quality on channels, including HBO is noticeable.  That’s why I always watch HBO via HBOGo now, which I believe is 1080p H.264.  For example with Game Of Thrones on Comcast you can’t see the individual hairs in characters’ beards.  On HBOGo you can. 

Regular Visitor

Re: Comcast downgrading all 1080i HD channels to 720p


@Rustyben wrote:

@mlf1 wrote:

I concur with all of the complaints about Comcast / Xfinity downscaling from 1080i to 720p.  My wife and I watched Game of Thrones season 8 episode 3 through Xfinity and it was dark and visibly low resolution - my wife called it "muddy".  I connected my full HD HP laptop to my TV, using Windows 10 / Microsoft Edge / HBO GO:  the HD result was quite satisfying - clearer and brighter.  This result also occured when we used the HBO GO app on my wife's iPhone 6 Plus.  We'll watch the rest of GOT through HBO GO.  Unless Comcast restores 1080i, we will also start looking for an alternative to Comcast / Xfinity for our TV service.  I concur with another comment - Comcast should be providing better service, not giving current customers reasons to change.


HBO is a cable feed not a broadcast channel - there is no 'broadcast format' . the video is HEVC delivered to Comcast who then puts it out in 720p. It sounds like your TV needs to be set up on the HDMI port to give you the best image reproduction possible. The feed from the HBO site may be in a different format (1080p? 4k? UHD?) 

 

what type of TV screen are you using? the 'i' (interlaced) format is a format made for old glass CRT type picture tubes. 1080i is equivalent to roughly 540p but handles motion quite badly in reroduction. you can search youtuve for any number of demonstration videos using 720p vs 1080i as a search term.


Why didn't Comcast go to 1080p instead of 720p? This is 2019. Since the change has obviously saved them money, why wasn't this passed on to the customers?  If it had been the other way around, what do you think would have happened? I'll answer that: it would have gone up substantially.

Regular Contributor

Re: Comcast downgrading all 1080i HD channels to 720p

 

Why didn't Comcast go to 1080p instead of 720p? This is 2019. Since the change has obviously saved them money, why wasn't this passed on to the customers? If it had been the other way around, what do you think would have happened? I'll answer that: it would have gone up substantially.

Comcast did this solely to free up QAM bandwidth so they could role out Gigspeed Internent.   They can then charge a lot more for that than they do for TV. 

 

Comcast’s ultimate goal is to eliminate all QAM TV channels and switch entirely to IPTV.  Theoretically at that point Comcast could switch to 1080p since only channels being actively watched would use bandwidth.  I doubt they will though. 

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Regular Visitor

Re: Comcast downgrading all 1080i HD channels to 720p


@Morac2 wrote:

 

Why didn't Comcast go to 1080p instead of 720p? This is 2019. Since the change has obviously saved them money, why wasn't this passed on to the customers? If it had been the other way around, what do you think would have happened? I'll answer that: it would have gone up substantially.

Comcast did this solely to free up QAM bandwidth so they could role out Gigspeed Internent.   They can then charge a lot more for that than they do for TV. 

 

Comcast’s ultimate goal is to eliminate all QAM TV channels and switch entirely to IPTV.  Theoretically at that point Comcast could switch to 1080p since only channels being actively watched would use bandwidth.  I doubt they will though. 


I have read that the change also allowed them to fit an additional channel in their data delivery containers (was the term I believe), is there any truth to this?

Contributor

Re: Comcast downgrading all 1080i HD channels to 720p

I also found it quite frustrating that almost no one I ended up speaking to at Comcast knew that this downgrade had occurred.

 

And I spoke to many during the process of getting out of my contract* because of this downgrade; none knew, neither the front line Customer Service reps, or the Comcast Corporate rep I talked to after filing an FCC complaint. They all suggested I simply had to set my DVR to output 1080p.  None of them admitted to understanding that my issue was with the downgraded delivery to my residence of 720p instead of 1080i, and the major loss of resolution due to the resulting two lossy scaling operations: from 1080i (as they recieve from content producers) to 720p (which they switched to delivering to my residence), and then from that 720p to 1080p (by my DVR or HDTV, at my option).

 

Thankfully, though the Corporate rep didn't understand, they did let me out of my contract (and fixed my monthly rate = the contract rate for a year to give me time to switch to a competitor).

 

*1-year contract which, 'coincidentally' Comcast had never before asked me to enter into until not not long before the downgrade.

Frequent Visitor

Re: Comcast downgrading all 1080i HD channels to 720p

And the hits just keep on coming!   Here in City of Atlanta, Xfinity finally killed its remaining 1080i broadcast of local channels.   Last week on September 10, 2019 NBC and CBS switched from 1080i to 720p.   I have a few weeks of recorded shows on both channels and was able to confirm that date.

Contributor

Re: Comcast downgrading all 1080i HD channels to 720p


@kupe wrote:

And the hits just keep on coming!   Here in City of Atlanta, Xfinity finally killed its remaining 1080i broadcast of local channels.   Last week on September 10, 2019 NBC and CBS switched from 1080i to 720p.   I have a few weeks of recorded shows on both channels and was able to confirm that date.


Local 1080i channels are still 1080i here in the San Francisco Bay area market. No doubt that will change in the near future though.

Expert

Re: Comcast downgrading all 1080i HD channels to 720p


@kupe wrote:

And the hits just keep on coming!   Here in City of Atlanta, Xfinity finally killed its remaining 1080i broadcast of local channels.   Last week on September 10, 2019 NBC and CBS switched from 1080i to 720p.   I have a few weeks of recorded shows on both channels and was able to confirm that date.


You state: " Last week on September 10, 2019 NBC and CBS switched from 1080i to 720p. "

 

Have you checked these local channel's "over the air" signals? I still get 1080i signals when using the antenna. I still read the signal from Comcast on my Cisco RNG 150N (HD cable box) as: 1920 x 1080 / 60i.

 

No different from when we first pointed this out over two years ago. I live in the Twin City metro area of Minnesota.

 


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Re: Comcast downgrading all 1080i HD channels to 720p

local channels are not 'taken off the air' they are sent by fiber optic cable to comcast's servers to encode. the 1080i broadcast is approx equivalent to 1/2 of that say 540p due to how the image is made and the 'frames' show much motion artificacts.  720p is quite good for cable. point is that it isn't a downgrade.



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Re: Comcast downgrading all 1080i HD channels to 720p


@Rustyben wrote:

local channels are not 'taken off the air' they are sent by fiber optic cable to comcast's servers to encode. the 1080i broadcast is approx equivalent to 1/2 of that say 540p due to how the image is made and the 'frames' show much motion artificacts.  720p is quite good for cable. point is that it isn't a downgrade.


Equating 1080i to 540p is misleading.  A 1080i picture will look much better than 520p even if the overall bitrate is the same because of the resolution.  Saying a 1080i video that’s converted to 720p is somehow an upgrade is just wrong. 

Expert

Re: Comcast downgrading all 1080i HD channels to 720p


@Morac2 wrote:

@Rustyben wrote:

local channels are not 'taken off the air' they are sent by fiber optic cable to comcast's servers to encode. the 1080i broadcast is approx equivalent to 1/2 of that say 540p due to how the image is made and the 'frames' show much motion artificacts.  720p is quite good for cable. point is that it isn't a downgrade.


Equating 1080i to 540p is misleading.  A 1080i picture will look much better than 520p even if the overall bitrate is the same because of the resolution.  Saying a 1080i video that’s converted to 720p is somehow an upgrade is just wrong. 


https://www.youtube.com/watch?v=Avvh0iH2xSg



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Re: Comcast downgrading all 1080i HD channels to 720p


@Rustyben wrote:

@Morac2 wrote:

@Rustyben wrote:

local channels are not 'taken off the air' they are sent by fiber optic cable to comcast's servers to encode. the 1080i broadcast is approx equivalent to 1/2 of that say 540p due to how the image is made and the 'frames' show much motion artificacts.  720p is quite good for cable. point is that it isn't a downgrade.


Equating 1080i to 540p is misleading.  A 1080i picture will look much better than 520p even if the overall bitrate is the same because of the resolution.  Saying a 1080i video that’s converted to 720p is somehow an upgrade is just wrong. 


https://www.youtube.com/watch?v=Avvh0iH2xSg


While that’s a nice video describing the differences between interlaced and progressive video, it’s also irrelevant as the source video was never 720p to begin with. 

 

Modern TV’s do a very good job a deinterlacing video because the “missing” frames can easily be reconstructed  so a 1080i will look nearly as good as a 1080p.  

 

Converting a 1080i video to 720p requires transcoding the video which Comcast does in real time.  In order to do so they use a constant bit rate no matter what the scene.  This is why scenes with motion of a lot of small things (like confetti) look like a blurry mess on Comcast.  

 

Now after the video is 720p your TV has to scale it to its native resolution.  I don’t know anyone who has a 720p set anymore so the video will need to be scaled back to 1080 or 2160 (double 1080). That’s an additional change to the video. 

 

So basically with Comcast’s current setup video goes from 1080i to 720p to 1080p/4K rather than 1080i -> 1080p/4K.   That’s an extra real time transcoding and scaling step that adds degradation.  

 

That’s before you take into account that the bitrate given to the 720p channels isn’t nearly high enough to play pre-compressed 720p video, let alone real time transcoded 720p video which means Comcast has to run the video through a smoothing filter to lower the details so it doesn’t look like a pixelated mess. 

 

TLDR it’s a degradation.

Expert

Re: Comcast downgrading all 1080i HD channels to 720p


@Morac2 wrote:

@Rustyben wrote:

@Morac2 wrote:

@Rustyben wrote:

local channels are not 'taken off the air' they are sent by fiber optic cable to comcast's servers to encode. the 1080i broadcast is approx equivalent to 1/2 of that say 540p due to how the image is made and the 'frames' show much motion artificacts.  720p is quite good for cable. point is that it isn't a downgrade.


Equating 1080i to 540p is misleading.  A 1080i picture will look much better than 520p even if the overall bitrate is the same because of the resolution.  Saying a 1080i video that’s converted to 720p is somehow an upgrade is just wrong. 


https://www.youtube.com/watch?v=Avvh0iH2xSg


While that’s a nice video describing the differences between interlaced and progressive video, it’s also irrelevant as the source video was never 720p to begin with. 

 

Modern TV’s do a very good job a deinterlacing video because the “missing” frames can easily be reconstructed  so a 1080i will look nearly as good as a 1080p.  

 

Converting a 1080i video to 720p requires transcoding the video which Comcast does in real time.  In order to do so they use a constant bit rate no matter what the scene.  This is why scenes with motion of a lot of small things (like confetti) look like a blurry mess on Comcast.  

 

Now after the video is 720p your TV has to scale it to its native resolution.  I don’t know anyone who has a 720p set anymore so the video will need to be scaled back to 1080 or 2160 (double 1080). That’s an additional change to the video. 

 

So basically with Comcast’s current setup video goes from 1080i to 720p to 1080p/4K rather than 1080i -> 1080p/4K.   That’s an extra real time transcoding and scaling step that adds degradation.  

 

That’s before you take into account that the bitrate given to the 720p channels isn’t nearly high enough to play pre-compressed 720p video, let alone real time transcoded 720p video which means Comcast has to run the video through a smoothing filter to lower the details so it doesn’t look like a pixelated mess. 

 

TLDR it’s a degradation.


the fiber-fed signal is sent in HEVC (wrongly called mpeg5) video stream. 1080i is not received nor used by comcast. Comcast takes the progressive video stream from the fiber and transcodes it in real time as needed for cable (720p) and SD digital as well as various resolutions for streaming clients. nothing is 'degraded' we are just discussing off the air vs fiber fed progressive (digital) video delivery. 



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