PQ on U-verse -- 720p vs 1080i

PQ on U-verse -- 720p vs 1080i

I recall reading a post somewhere that someone mentioned the 720p sourced broadcasts look better than the 1080i sourced broadcasts on U-verse.  I think the theory was the extra overhead of the 1080i resolution and that progressive sources compress better.  I was wonderig if this was perhaps true?  

 

I've made the observation that HLN HD has issues the pixelation with sudden graphic and camera fade in/outs.  In watching similar things happen on ESPN I did not see  the pixelation bursts that were happening on HLN.  

 

A little wiki research shows that HLN is 1080i and ESPN is 720P. 

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Message 1 of 28

Re: PQ on U-verse -- 720p vs 1080i

Well, not too many opinions yet but I found this article.

 

http://www.bluesky-web.com/numbers-mean-little.htm

 

The basic premise is that compressing 1080i results in more artifacts compared to 720p.  Unfortunately, most HD networks are 1080i and the U-verse compression is rather aggressive.  

Message 2 of 28

Re: PQ on U-verse -- 720p vs 1080i

So far I've watched a few of the 720p networks and I really think this is the case. They do seem to have better picture quality on U-verse compared to the 1080i source.

 

So if 720p is a much better format for delivery of compressed sources why are so many networks delivered over compressed providers 1080i?

Message 3 of 28
ACE - Expert

Re: PQ on U-verse -- 720p vs 1080i

That was me that mentioned it here in regard to football, have to say the Michigan/Michigan State game onABC HD (720p) looked absolutely great yesterday, even hardly any weird grass look (compressionartifact). 


Now I won't totally agree w/regular programming on that, the 2 best looking HD programs I watch IMHO are The Mentalist and Criminal Minds, on CBS (1080i).  In many other cases 1080i channels have good HD and is really dependent on the quality of the source material.  I've seen some real stinker quality HD on ESPN/ABCs (720p) in addition to real good HD.


Actually everything is shot in 1080p, then downconverted to 1080i or 720p.  At this point they are pretty comparable.  It's when ATT puts the H.264 algorhythm on the stream and 1080i needs about 20% more bandwidth for the extra info in the signal.Smiley Wink


Chris

 


Please NO SD stretch-o-vision or 480 SD HD Channels
1-866-465-1496 for direct TS to avoid Mr. Voice recognition
Your Results May Vary, In My Humble Opinion
I Call It Like I See It, Simply a U-verse user, nothing more

 

*The views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.
Message 4 of 28

Re: PQ on U-verse -- 720p vs 1080i

I guess I'm nit picking on pixelation but on DirecTV I see less (not none) artifacts on 1080i sources compared to U-verse.  The experimental watching I've done seems to indicate 720p sources don't seem to suffer as much if at all.

 

With HLN HD (1080i) the graphics and fast source cuts are driving me crazy.  The compression just can't handle it.  It might be HLN but I think it's the compression not being able to deal with the quick changes. DTV doesn't have HLN in HD so I can't make that comparison.  ESPN does similar graphics and camera cuts and I haven't seen that make pixel fireworks.

 

Most of these non-OTA channels are delivered over networks with a bit of compression, unless I've heard your on Verizon's fios.  So if 720P is better at being compressed it seems logical they'd be in that format.

 

Message 5 of 28
ACE - Expert

Re: PQ on U-verse -- 720p vs 1080i

As to HLN, 1203, I don't see anything going on like you are reporting, everything looks just fine on my 42" Panasonic plasma. Smiley Wink


Chris

 


Please NO SD stretch-o-vision or 480 SD HD Channels
1-866-465-1496 for direct TS to avoid Mr. Voice recognition
Your Results May Vary, In My Humble Opinion
I Call It Like I See It, Simply a U-verse user, nothing more

 

*The views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.
Message 6 of 28

Re: PQ on U-verse -- 720p vs 1080i

I suppose I should stop looking for artifacts.  I see them on DirecTV now as well where I didn't notice them before.

Message 7 of 28
ACE - Expert

Re: PQ on U-verse -- 720p vs 1080i

Well, you were comparing the two services, it's inevitable that you are seeing these things. Smiley Very Happy


Chris


Please NO SD stretch-o-vision or 480 SD HD Channels
1-866-465-1496 for direct TS to avoid Mr. Voice recognition
Your Results May Vary, In My Humble Opinion
I Call It Like I See It, Simply a U-verse user, nothing more

 

*The views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.
Message 8 of 28
Teacher

Re: PQ on U-verse -- 720p vs 1080i

That's been my observation based on nothing but the eyeball test. 720p content looks pretty good and high motion scenes remain mostly sharp. 1080i looks mostly the same except when theirs a lot of motion. At that point it becomes a pixelated mess. 

 

I'm on a 65" 1080p Mitsu set, new to Uverse coming from DirecTV.  Uverse picture quality definitely suffers comparatively from high compression. 

Message 9 of 28

Re: PQ on U-verse -- 720p vs 1080i

I think the differences between 720p and 1080i are why we see so many conflicting reports on the PQ.  

 

I'm also careful to note that the source into AT&T's encoders could be bad to begin with.  However, I'm thinking the 1080i sources don't make it out of the encoder without suffering some. Which, unfortunately, is the bulk of what the broadcasters are using.  

 

Notice cut scenes and fast motion on ESPN and the History channels (720p).  Then do the same with the 1080i stations, such as the various Discovery channels.

 

It seems it's common practice for cable and satellite operators to re-encode 1920x1080i to 1440x1080i in order to reduce artifacts.  I'm not sure if U-verse does this or if even they should. However, the more I read up on it the more it sounds like broadcasters should stick to 720p.  

 

Perhaps one of the engineers will chime in Smiley Happy.

Message 10 of 28
ACE - Expert

Re: PQ on U-verse -- 720p vs 1080i

Here're some SomeJoe (he authors and edits HD material) posts on the subject:


http://forums.att.com/t5/TV-Programming/World-Cup-HD-picture-quality-just-as-poor-as-superbowl-and-o...


http://forums.att.com/t5/Equipment/720-or-1080-Installer-told-me-that-720-is-more-reliable/m-p/22037... Smiley Wink


Chris

 


Please NO SD stretch-o-vision or 480 SD HD Channels
1-866-465-1496 for direct TS to avoid Mr. Voice recognition
Your Results May Vary, In My Humble Opinion
I Call It Like I See It, Simply a U-verse user, nothing more

 

*The views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.
Message 11 of 28

Re: PQ on U-verse -- 720p vs 1080i

I gave those a read over but I don't think that addresses what's going on at encoding time.  

 

I see numerous comments about Dish's PQ being so much better than U-verse.  The interesting thing is Dish supposedly down converts 1080i to avoid compression issues within the allocated bandwidth.  The theory being reduced compression issues are better than a messy higher resolution picture.

Message 12 of 28
Expert

Re: PQ on U-verse -- 720p vs 1080i

Maybe he'll pop in here later to give you his detailed take on the subject. Smiley Wink


michail77 wrote:

I gave those a read over but I don't think that addresses what's going on at encoding time.  

 

I see numerous comments about Dish's PQ being so much better than U-verse.  The interesting thing is Dish supposedly down converts 1080i to avoid compression issues within the allocated bandwidth.  The theory being reduced compression issues are better than a messy higher resolution picture.


 

Message 13 of 28
Expert

Re: PQ on U-verse -- 720p vs 1080i

The picture quality (i.e. artifact level) is dependent on the bitrate and the complexity of the source material.

 

A 1080i source is more complex than a 720p source, both because there are more pixels to encode (62.2 Mpixels/sec for 1080i vs. 55.3 Mpixels/sec for 720p), and because interlaced video is inherently more difficult to encode than progressive material (there are less opportunities to use accurate motion prediction).  To get the same artifact level (picture quality) for 1080i, you need about 20% more bitrate (about 10% for the additional pixels and another 10% to make up for the difficulty of interlaced video).

 

But, most providers, U-Verse included, do not make special consideration for 1080i material.  On U-Verse, both 720p and 1080i material are encoded and transmitted at 5.7 Mbps.  This is why the 1080i material doesn't look as good as it could.

 

If the bitrate for 1080i were upped to 6.8 Mbps, it would look (artifact-wise) as good as the 720p material.

 

The encoders that AT&T are using for U-Verse are the Motorola SE-5100 units, and they're using the constrained fidelity (capped VBR) mode.  The H.264 output from these units isn't the best MPEG-4 you can get, because these encoders don't implement all features of the codec, but they perform quite well anyway.

 

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Message 14 of 28
Expert

Re: PQ on U-verse -- 720p vs 1080i

Thanks, SJ, for popping in with your wisdom. Smiley Happy

Message 15 of 28
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