bitbang3r's profile

Explorer

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29 Messages

Tuesday, October 2nd, 2012 1:33 PM

Is the receiver truly this crippled?!?

I'm now slightly under a week away from installation, and played with a friend's U-verse box last night for a couple of hours. I'd be lying if I said I wasn't seriously underwhelmed and disappointed.

 

Problem #1: no apparent way to tell the box, "Show me content in its native format" -- ie, leave 1080i60 as 1080i60, and 720p60 as 720p60. The box seemed determined to force everything to one or the other. Is there truly no way to force it to be native?

 

At the very least, do discrete remote codes exist to directly select 720p60/1080i60/480i60, or can you program macros on a thirdparty remote to quickly and deterministically blast through the menus and change? 

 

Problem #2: no apparent way to hide SD shadows of HD channels... or even visually distinguish HD from SD in search results without actually clicking on each result one at a time to see whether it's HD or SD. Can you at least go in and set up a list of favorite channels by hand (to reduce the size of the realtime tv guide), and is there a way to search for programs that limits itself to either channels in that 'favorite' list, or only shows HD channels? 

 

Along the same lines, does the box perhaps cooperate with a Logitech Revue to improve things a bit? I have one that I haven't really bothered with lately (it ended up being more of an annoyance than anything), but if it can shake hands with AT&T''s box and improve it, that would be an option worth considering.

 

On the other hand, does the box and AT&T have an official or reverse-engineered API for searching/grabbing program data in XML format over the internet (or directly from the box over tcp/ip), and/or any way to directly do things like change output resolution/mode via TCP/IP, so that thirdparty Android apps could work around and overcome its limitations?

Accepted Solution

Official Solution

Expert

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9.4K Messages

11 years ago

bitbang3r,

 

I know where you're coming from and what you're thinking.  Yes, it's true, the U-Verse STB boxes do not have any native resolution output option like DirecTV's boxes do.  This is unfortunate because as you've surmised, it means that the STB will handle all resizes as opposed to your TV.  Ordinarily this would be a bad thing.

 

However, in this case, it is not as bad as it might seem.  The scaler/deinterlacer chip in the U-Verse STBs is a chip manufacturered by Sigma Designs.  In most of the STB units that U-Verse uses, it is the 8634 model chip.  This chip's scaler/deinterlacer is actually pretty good.

 

This chip uses the proper methods to do resizes.  It first uses motion-adaptive deinterlacing to convert interlaced content to progressive content at double the frame rate.  The motion-adaptive algorithm separately analyzes areas of the picture, uses motion vectors, and uses the previous and following fields to add detail where appropriate.  The luminance and chrominance information is maintained separately, and the chroma is properly upconverted from the MPEG-subsampled 4:2:0 before processing.

 

The actual resize algorithm used on the now-progressive content is Lanczos or Lanczos4, which can increase sharpness a bit too much on downsizes, but going from only 1080 to 720 it's not too bad, and retains a lot of detail.

 

Sigma Designs did the reference implementation for all the U-Verse STBs, and chose to not offer a native output method for two reasons:

 

1. Native output helps the most with TVs that actually change their scanning format in response to the signal format, i.e. front- and rear-projection CRT sets.  Hardly any of these exist anymore.  Modern TVs are all digital pixel matrix based, thus will always have to involve a resize operation unless the signal matches the native resolution.  In some cases, the TV's native resolution doesn't match any signal format at all, so a resize operation is always required (e.g. 1366x768 sets).

 

2. Some consumer TVs respond poorly to signal format changes.  On these TVs, switching from a native 720p60 channel to a 1080i60 channel would result in a signal format change, and the TV may then take an excessively long period of time to tune the new signal format (e.g. > 2-3 seconds of black screen before a picture reappears).  Since one of U-Verse's selling points is much faster channel changes than cable or satellite, native resolution would defeat this selling point.

 

My suggestion to you would be to try U-Verse if you want, and set the output resolution to 1080i60 (which matches your TV's native spatial resolution).  This will give you native format on 1080i60 channels, and your TV will deinterlace this signal for 1080p60 display.

 

For 720p60 channels, the U-Verse box will upconvert these to 1080i60, which your TV will then detinterlace for 1080p60 display.  This is not ideal, but you will still get most of the spatial resolution and all of the temporal resolution.

 

Here is another thing to consider, however: If you know this much and can see these differences in video, I think a larger issue for you will be the compression artifacts rather than detail lost in resolution processing.  If you're expecting the U-Verse feeds to look like Blu-Ray, you will be disappointed.  U-Verse's HD feeds are only 5.7 Mbps H.264, which is insufficient to carry a high amount of detail.

 

In fact, most cable and satellite services, including U-Verse, will have some visible compression artifacts, so don't expect maximum performance out of your TV with any service other than Blu-Ray.

 

ACE - Expert

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27.6K Messages

11 years ago

I am answering to the best of my knowledge.  If anyone knows better, please jump in!

Problem #1: no apparent way to tell the box, "Show me content in its native format" -- ie, leave 1080i60 as 1080i60, and 720p60 as 720p60. The box seemed determined to force everything to one or the other. Is there truly no way to force it to be native?  Uverse boxes broadcast programming in the native format.  If you've got and HD tv and subscribe to HD, you can set your box (and TV) to either 1080i or 720p.  Opinions vary on which is better

 

At the very least, do discrete remote codes exist to directly select 720p60/1080i60/480i60, or can you program macros on a thirdparty remote to quickly and deterministically blast through the menus and change? 

 

Problem #2: no apparent way to hide SD shadows of HD channels... or even visually distinguish HD from SD in search results without actually clicking on each result one at a time to see whether it's HD or SD. Can you at least go in and set up a list of favorite channels by hand (to reduce the size of the realtime tv guide), and is there a way to search for programs that limits itself to either channels in that 'favorite' list, or only shows HD channels?  You can hide channels on each STB.  You can also set up favorites.  HD channels start with 1*** while SD channels no not.  For example, SD version of Bravo is 181, HD version is 1181.

 

ACE - Expert

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34.7K Messages

11 years ago

#1: Actually, the STB shows the content in the output format you've set, or the TV and the STB have agreed to via HDMI negotiation.  The TV will paint the pixels in its native resolution, either by putting up a black border around them or scaling the pixels up, i.e. a 1080 TV doesn't have an independant overlay of 720 pixels it can use for 720 content. Most people don't want black borders, so most people expect it to be scaled.  What you don't want to have happen is for scaling to be repeated up and down.  Your best bet is for the STB to output at the TV's native resolution and let the STB scale content as appropriate.  Please explain your objections to this if you have any.

 

#2: Menu key, Options>Channel Options>Hide Channels.

 

There is an API for controlling a STB from an iOS device.  I don't believe it includes the ability to change the output resolution, but again I challenge you to explain why the STB shouldn't just output in the TV's native resolution.

 

Master

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4.2K Messages

11 years ago

I wish it was 1080p but as most broadcasters send out 720p or 1080i as was said that is your choice and let your eyes be the judge for me 1080i and let my TV deinterlace to 1080p is acceptable.

Explorer

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29 Messages

11 years ago

Just to make sure I'm being understood, I *want* the box to output everything at the content's native resolution/framerate & allow the TV to deal with it directly.

 

However, I got the impression from both avsforum.com and the menu options on my friend's U-verse DVR that there IS NO "output content at its natively-encoded resolution" option, and that you HAVE to pick 1080i60 or 720p60 as the output format for EVERYTHING. If the box won't volunarily leave the resolution+framerate alone, I'm going to have to program macros for every channel I care about to forcibly set the box to the right mode whenever I change the channel.

 

To my TV (1080p60 native DLP), EVERYTHING is an alien, non-native format. I trust its Faroudja-blessed video processor *way* more than I'll ever trust any mass-market STB whose main design objective was "be as cheap as possible".

Master

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4.2K Messages

11 years ago


@bitbang3r wrote:

Just to make sure I'm being understood, I *want* the box to output everything at the content's native resolution/framerate & allow the TV to deal with it directly.

 

However, I got the impression from both avsforum.com and the menu options on my friend's U-verse DVR that there IS NO "output content at its natively-encoded resolution" option, and that you HAVE to pick 1080i60 or 720p60 as the output format for EVERYTHING. If the box won't volunarily leave the resolution+framerate alone, I'm going to have to program macros for every channel I care about to forcibly set the box to the right mode whenever I change the channel.

 

To my TV (1080p60 native DLP), EVERYTHING is an alien, non-native format. I trust its Faroudja-blessed video processor *way* more than I'll ever trust any mass-market STB whose main design objective was "be as cheap as possible".


I doubt you will notice a difference and you might be a bit overthinking this but the STB does a good job but hey if you can see a difference more power to you.

Explorer

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29 Messages

11 years ago

Please explain your objections to this if you have any.

 

Specifically, my TV is natively 1080p60, so any forced-transcoding done by AT&T's box would create a mangled mess not even Faroudja can repair.

 

When consumer STBs convert 1080i60 to 720p60, they don't buffer multiple adjacent frames, decompose the scene into virtual sprites animating over a panning/zooming/rotating background using motion-vector analasys, and re-render it as a virtual 1080p60 frame before resizing it to 720p60... they just treat it like fake 540p60, butcher and bob it from 1920x540 to 1280x720, blur it slightly, and call it a day.

 

Or, if they recognize it as 24p or 30p film-source content, they might pull out the recognizable frames, resize them, and apply 3:2 or 2:1 telecine to bring the framerate back up to 60.

 

The results of such transcoding are usually "OK" for content that starts out as 24fps or 30fps film (Hollywood movies and NBC Prime Time TV shows, for example), but anything that starts out as true 60fps video is going to look somewhere between "worse" and "totally awful" by the time that mangled 720p60 mess finally gets rendered to 1080p60.

 

For a good example, try watching an episode of "Stormchasers" on a large natively-1080p60 TV (60" or larger DLP) with your box set to force the output to 720p60. Ewwwww. Or, pretty much any live sports event.

 

When people on this site with large TVs post messages saying that movies look OK, but live sports look terrible, 9 times out of 10 they'd get PROFOUNDLY better PQ if they changed the output from 720p60 to 1080i60. Live broadcast TV will *always* be bitrate-starved compared to anything compressed in non-realtime, but 1080i60->720p60->1080p60 is just about the most brutal thing you can do to video content.

 

I can't believe that there's literally no way to make the box output content at source-resolution. At the *very* least, it would almost *have* to be in there on a hidden service menu as a debugging option...

ACE - Master

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6.9K Messages

11 years ago


@bitbang3r wrote:

Please explain your objections to this if you have any.

 

Specifically, my TV is natively 1080p60, so any forced-transcoding done by AT&T's box would create a mangled mess not even Faroudja can repair.

 

When consumer STBs convert 1080i60 to 720p60, they don't buffer multiple adjacent frames, decompose the scene into virtual sprites animating over a panning/zooming/rotating background using motion-vector analasys, and re-render it as a virtual 1080p60 frame before resizing it to 720p60... they just treat it like fake 540p60, butcher and bob it from 1920x540 to 1280x720, blur it slightly, and call it a day.

 

Or, if they recognize it as 24p or 30p film-source content, they might pull out the recognizable frames, resize them, and apply 3:2 or 2:1 telecine to bring the framerate back up to 60.

 

The results of such transcoding are usually "OK" for content that starts out as 24fps or 30fps film (Hollywood movies and NBC Prime Time TV shows, for example), but anything that starts out as true 60fps video is going to look somewhere between "worse" and "totally awful" by the time that mangled 720p60 mess finally gets rendered to 1080p60.

 

For a good example, try watching an episode of "Stormchasers" on a large natively-1080p60 TV (60" or larger DLP) with your box set to force the output to 720p60. Ewwwww. Or, pretty much any live sports event.

 

When people on this site with large TVs post messages saying that movies look OK, but live sports look terrible, 9 times out of 10 they'd get PROFOUNDLY better PQ if they changed the output from 720p60 to 1080i60. Live broadcast TV will *always* be bitrate-starved compared to anything compressed in non-realtime, but 1080i60->720p60->1080p60 is just about the most brutal thing you can do to video content.

 

It just blows my mind that anybody could make a STB that's incapable of leaving the video format alone and outputting it "as-is".


Considering NO network broadcasts in 1080p60 your theory doesn't hold water.  Currently only Direct TV has a few 1080p movies available on demand.

 

Explorer

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29 Messages

11 years ago

Considering NO network broadcasts in 1080p60 your theory doesn't hold water.  

 

Who said anything about having the box output 1080p60? I just want the box to leave the source video format unchanged, so my TV can do its own scaling and deinterlacing.

 

I want content that's delivered to AT&T as 1080i60 to leave the box and arrive at my TV as 1080i60.

 

I want content that's delivered to AT&T as 720p60 to leave the box and arrive at my TV as 720p60.

 

I want content that's delivered to AT&T as 480p60 to leave the box and arrive at my TV as 480p60, and if it's 4:3 aspect ratio, I don't want the box to stretch it, manually pillarbox it, or otherwise screw with the timing. Correct flagging of the aspect ratio via WSS on line 20 would be nice... but ONLY if they can actually get it right.

 

Ditto, for content that's delivered to AT&T as 480i60... I want it to leave the box and arrive at my TV as nice, clean, untainted, unmangled 480i60, for my TV to handle as it sees fit.

ACE - Expert

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34.7K Messages

11 years ago

Okay, so you have this massive wonderful, expensive TV that some sales person has convinced you it could slice bread if only you'd tape a knife in the right place, and only it can scale/deinterlace properly.  I was afrad that was the answer.

 

Okay, well, then you're not going to be happy with the AT&T U-verse STB & DVR.  Or probably any content transmitted to you in real time from outside your home.

 

 

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