# HD picture quality



## koralis (Aug 10, 2005)

HD shows decoded via the OTA tuner in the 921 are apparently inferior in quality/detail to the internal OTA tuner in my television. 

Watching the Dallas football game on ABC I noticed that there was some oddly-shaded blocks on the field further away from the viewer. Switching my TV input to the internal viewer (also connected to the antenna) this wasn't evident. I went back and forth between the inputs for 15 minutes or so looking at and comparing the various scenes as best I could. Basically in non-detailed areas the 921 tuner seems to get some weird coloration going that isn't evident when going directly to the TV.

For the record, the 921 is outputting a 1080i signal over DVI/HDMI.

Does anyone else notice this problem? Is there any tweaking that I can do? Can it be solved with a software update? It's not a huge deal, but it's a bit annoying to have spent this much money on the 921 and basically have to decide whether I want a better picture or the ability to pause.


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## lujan (Feb 10, 2004)

koralis said:


> HD shows decoded via the OTA tuner in the 921 are apparently inferior in quality/detail to the internal OTA tuner in my television.
> 
> Watching the Dallas football game on ABC I noticed that there was some oddly-shaded blocks on the field further away from the viewer. Switching my TV input to the internal viewer (also connected to the antenna) this wasn't evident. I went back and forth between the inputs for 15 minutes or so looking at and comparing the various scenes as best I could. Basically in non-detailed areas the 921 tuner seems to get some weird coloration going that isn't evident when going directly to the TV.
> 
> ...


I mentioned this subject about a year ago. I've had the 921 since February of 2004 and I noticed that the picture quality coming directly from the antenna to the TV's digital tuner is much better than the one going through the 921 to the TV especially with regards to HD picture quality. I know that many others have mentioned having the 921 do a pass-through so that the signal broadcast is the signal received on the 921 rather than doing it's conversions. Anyone with more technical knowledge, please chime in...


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## jergenf (Mar 31, 2005)

I believe the difference you are observing is due to the signals going thru different inputs. For example component input may differ from DVI/HDMI in color, overscan and even some degree of artifacts or noise. For those that have digital tuners built-in to their TV are totally avoiding any chance of noise that cables might present. 

All OTA digital stations are transmitting 19.4Mbits of data. Regardless which digital tuner you use it produces the same exact sequence of zeros and ones meaning there shouldn't be any PQ issues at least as far as the tuner is concerned.


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## dishbacker (Jun 15, 2004)

koralis said:


> HD shows decoded via the OTA tuner in the 921 are apparently inferior in quality/detail to the internal OTA tuner in my television.
> 
> Watching the Dallas football game on ABC I noticed that there was some oddly-shaded blocks on the field further away from the viewer. Switching my TV input to the internal viewer (also connected to the antenna) this wasn't evident. I went back and forth between the inputs for 15 minutes or so looking at and comparing the various scenes as best I could. Basically in non-detailed areas the 921 tuner seems to get some weird coloration going that isn't evident when going directly to the TV.
> 
> ...


One guess would be... set the 921 to 720p output as that is generally what ABC stations broadcast OTA (I say generally because Belo here in DFW sends out ABC broadcasts in 1080i for some reason). By doing this, there is less scaling going on within the 921 and forces your TV to do the needed conversion like its doing with the built-in TV signal.


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## dishbacker (Jun 15, 2004)

jergenf said:


> ....
> All OTA digital stations are transmitting 19.4Mbits of data. Regardless which digital tuner you use it produces the same exact sequence of zeros and ones meaning there shouldn't be any PQ issues at least as far as the tuner is concerned.


Your assuming an OTA station doesn't have any sub-channels... otherwise that 19.4Mbits gets carved up a little bit.


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## BarryO (Dec 16, 2003)

I think that's it. When tuning an ABC station, with the 921 output set to 1080i, he's forcing it to do 720p->1080i transcoding.


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## koralis (Aug 10, 2005)

Ahhhhh. So basically the 921 is scaling the image and doing a so-so job at it. Presumably if I had the 921 just output the native signal then it'd be up to the TV to do the scaling, and apparently it's better at it.

Is there any good way to determine what format each station broadcasts in?


Could we get a 921 option that is uses the channel input format as the output format when tuning an OTA HD signal so that this could be avoided? If not, I don't suppose there are any discrete codes to set the output format?


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## Ron Barry (Dec 10, 2002)

Native Pass through is a requested feature on the 811, 921 and 942. If you do a search on "native pass through" you should get some hits on the thread. There currently is not a way to accomplish this. As to discrete codes for native format, I am not aware of any.


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## DonLandis (Dec 17, 2003)

It is generally more important to set your output to match your display device, not your channel you tune to. 
the rule of thumb is to set your output to 720Px 1280 if your display is digital using a 720p x 1280 imager. Use 1080i x 1920 if your display is an analog CRT based using scanline imager. The most important factor is the vertical scan part of the signal, not the horizontal pixel count as that often varies with each individual program source, not to mention limiting factors that some program providers will do for bandwidth reasons. If your imager is a digital display such as an LCD that is less than 720 native then use 720 as opposed to 1080i setting. While it is best to use native resolution on your display device, conversion whether it is at the receiver or at the display device is an individual choice. On the other hand, thinking you will get more resolution and PQ from an upconversion of cross conversion when you also have a choice of running in native mode is a myth. Chose native in all cases, or trust your eyes in a blind test procedure (no pun intended)


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## AVJohnnie (Jul 27, 2004)

DonLandis said:


> ...trust your eyes in a blind test procedure...


I love it Don!:goodjob:
And I think this is undoubtedly the procedure used for some time now by certain (a-hmm unmentionable) software developers whom as I stated, cannot be mentioned, other than for an occasional&#8230;Hail Britannia! :rolling:


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