Community Forum

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. 



I am not a Comcast Employee.
I am a Customer Expert volunteering my time to help other customers here in the Forums.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Mark the post as Best Answer!
Contributor

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.   



I am not a Comcast Employee.
I am a Customer Expert volunteering my time to help other customers here in the Forums.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Mark the post as Best Answer!
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.