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Question on Dish vs. DVD Quality

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Old 12-16-2005, 08:14 PM   #1  
JCM
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Default Question on Dish vs. DVD Quality

Before I get to the question, here's some background: I have a Hitachi 51F510 HDTV, a Dish 811 receiver, and a Sony DVP-NS300 DVD player. The Sony is several years old. Now as I understand it, this DVD player puts out 480 interlaced lines, which my Hitachi upconverts to 1080 interlaced lines. I also understand that the 811 will put out 480p, 720p or 1080i signals. I have tried the 811 on all these settings without a noticeable difference in the Hitachi's picture. (I apologize for spelling out the basics, but I want to be clear about where I'm coming from with this question.)

My Hitachi does a terrific job of upconversion on the DVD signal. I find many (but not all) movies to be virtually indistinguishable from either an OTA or a Dish high definition program. For example, I watched "The Island" on DVD yesterday and was blown away by the quality of the picture -- and this from a relatively primitive player.

On the other hand, the standard def signal from OTA and Dish is usually pretty bad. Although some channels seem to be better than others, none approach the quality of my DVD player. I find the picture on most SD channels to be "fuzzy."

Now here's the question: is there any technical reason the quality of the broadcast can't be as good as that of my aging DVD player, considering that the vertical resolutions of both are the same? Or does the problem lie with the quality of the original program and not with the broadcast medium?

I've seen a lot of discussion on this forum dealing with upconversion and quality of standard definition broadcasts on large-screen TVs, but I haven't seen this specific question about the reason for the difference in quality between standard definition DVDs and standard definition broadcasts addressed.
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Old 12-17-2005, 12:28 PM   #2  
JCM
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Default The Reason Why?

I think jergenf nailed it in a reply to a different post. He says cable and satellite broadcast at 400X480 lines and OTA digital at 640X480 (or sometimes even 704X480) -- while DVD is at 720X480. So the reason for the better DVD picture quality lies with the horizontal resolution. I didn't know that. Thanks, jergenf!

Considering the investment that Dish must have in SD equipment, I doubt that we'll see an improvement in their SD signal quality anytime soon. If they follow this forum -- and I'll bet they do -- they should be aware that there is considerable customer interest in better SD. And I'm sure they know it's possible. It's just a matter of spending the money.

Here's the full quote of jergenf's post (hope he doesn't mind):

>The quality of digital OTA in SD is likely to be better than a typical sat >SD channel for two reasons.

>One the bit stream is genarally smaller for sat and cable channels >than for the average OTA channel. For example in a 6 Mhz >bandwidth of analog station the entire bandwidth is used, with digital >OTA station about 4 SD channels fit in that same space. And with >satellite and cable 6 SD channels fit in that same bandwidth. >Obviously sat and cable want to compress more to maximize the >number of channels where OTA doesn't need to. You get the full >640x480 (or even 704x480) pixels with OTA digital. Cable and sat >are arround 400x480 because they just need to compete with >analog quality levels. Now that people have HD sets they are now >noticing the difference in quality.
>FYI: OTA analog would equate to 320x480 (color TVs not B&W) in >quality so cable and sat are still quite an improvement. Also DVD is >720x480 same as broadcast quality in the studio.

>Two some stations are sending HD 24 by 7 so when they show SD >quality programs it up converted to HD. This means smaller pixel >sizes and more pixels in all are displayed which ensures that SD >remains at studio quality levels.
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Old 12-17-2005, 04:29 PM   #3  
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The quality of a DVD vs OTA broadcast is better because the signal is completely noise free, digital, and should be progressive 480p rather than 480i interlaced broadcast.

Comcast is carrying HD at 18 Mbits/sec, which doesn't degrade the OTA 19.3 Mbits/sec quality because cable strips out all the subchannels and PSIP info.
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Old 12-19-2005, 10:28 AM   #4  
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Quote:
Originally Posted by JCM
Now as I understand it, this DVD player puts out 480 interlaced lines, which my Hitachi upconverts to 1080 interlaced lines..
I don't believe you Hitachi upconverts the DVD to 1080i but rather to 480i or perhaps 480p. The reason is the Hitachi is CRT based and produces the vertical scan frequency it given. There are some DVD players that upconvert their 480p to 1080i because of its own scan converter. The 811 is sending 1080i all the time and upconverts lower formats (assuming you're using the component/DVI outputs).

But to answer your question, you'll find with all video sources (HD/SD/DVD) the PQ varies because of the original quality of the source material. This is beyond your control and your equiment is not to blame. I have some DVDs that have lousy picture and sound while other are superior and appear closer to HD. It's all from where the manufacturer or broadcaster obtained the source material. The best recommendation is choose movies that are newer releases, also recommend buying DVDs that are in the widescreen format as they're more likely truely displayed in 720x480 (without upconversion). Also movies that have very long playing times (on a given DVD) may apply more compression than normal length movies. Greater compression may display more digital artifacts, less color range or lower resolution in some cases.
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Old 12-20-2005, 08:44 PM   #5  
JCM
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Quote:
Originally Posted by jergenf
I don't believe you Hitachi upconverts the DVD to 1080i but rather to 480i or perhaps 480p.
Good reply on all but the Hitachi upconversion. It does indeed convert everything to 1080i. If you don't believe me, check out the specs here:

http://www.hitachi.us/tv/browse/proj...n/51F510.shtml

Many other posts on this site and others have said the same. I did my research before buying. Hitachi also has some marketing hype about a "VirtualHD 1080p Video Processor." I read a technical description about that feature on an independent site; it doesn't actually works like true progressive scan. I will say, however, that I rarely notice interlacing artifacts. (Of course, I'm easily distracted by plot and sound effects, so maybe it's just me.)

I agree completely with you about the varying quality of DVDs. I place the Chinese flick "Heroes" at the low end and the recent "The Island" at the high end of the picture quality scale. And I appreciate your clarification of the reasons for varying picture quality from broadcast and DVD sources.

I rather supect that some program material on the Dish HD channels -- especially movies -- is really upconverted DVD quality. Some programs have the HD tag at the end of their description, and others don't. Any insights there?
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