Official AVS TiVo HD Topic! - Page 95

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We appreciate your participation, but get your facts right. 720p is as much HD as 1080i.

If you read the posts subsequent to the one you cite, you will see they put things in context.

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I read them. You are entitled to think what ever you want, but 720p is HD. End of story.

3 days worth, to be exact.

I've found that in the consumer marketplace, nothing is ever exact.

Only by definition

On OTA, several broadcast stations here transmit 720p and the HD shows PQ from these look no different from the HD PQ from the 1080i broadcasts as seen on a Vizio 52 inch 1080p LCD.

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IMO there is no comparison between 720p and 1080i on my 46" or even 32" HDTV, even though my 32" is only 768 native 1080i still looks noticeably better, although true 720p HD still looks a far site better than SD 480. YMMV

From how far? That's the determining factor in 720 v 1080. If you are sitting very close you can easily tell the difference; if you sit far from a 52" you might not see any difference.

I come down somewhere in the middle on this debate. First, as I have already observed, 720p images are included in the HD standard and are "true HD" just as are 1080i and 1080p images. Thus, I disagree that any difference between the PQ of a 720p transmission and a 1080i transmission received via cable or satellite is going to be any more than marginal. The problem gets complicated, though, when a comparison is made between a high bitrate 1080p BD displayed on a modern 1080p HDTV, on one hand, and a bitrate starved cable or satellite transmission with a resolution of either 720p or 1080i, on the other. Under those circumstances, the difference is clearly noticeable, if not dramatic.

5 to 6 feet viewing distance. Have reviewed many seating distance vs resolution charts in the past. For the 52 inch panel at 1080p 5 to 6 feet allows normal visual acuity to resolve the full 1080p pixels displayed.

The Vizio has PIP and can be set to side by side equal size images. Setting the TV to show a 720p OTA from antenna and a 1080p OTA from the TivoHD is an interesting experiment but this involves viewing different programs and cannot allow a fair comparison.

Still, comparing the Mentalist with Boston legal I cannot discern any real difference. True, one can argue that there are uncontrollable variables involved, but the bottom line is that if the viewer cannot fault the PQ in either one, that is all that matters.

720p vs. 1080i has been rehashed endlessly, and it doesn't need to be done again here. They are both HD, and the quality of both depend on the source material and compression used for delivery. That's it.

Correct,
This is why my comparisons are made on broadcasts which do not have subchannels and are checked with TSReader to see the active bitrate.

Argh . . . sometimes sparks just hit tinder and poof. I guess if the TiVo had more problems we would have something else to talk about.

Look, I'm not saying 720 is not "HD". It is "HD" by definition so if that is all the argument with me is about, then done. 720 is HD. My contention is that there are levels of HD.

I am a numbers guy so here it is: a 720x1280 frame is comprised of 921,600 pixels; a 1080x1920 frame is comprised of 2,073,600 pixels -- that's 2.25X the number of pixels. I have a 50" 1080p plasma and I sit about 7' away from the screen. When I watch ABC or Fox (I'm OTA), my display has to upconvert the 720 signal to fill the 1080 screen. It has to fabricate over 1/2 of the picture -- so please don't tell me 720 is just as good as 1080. I know what I see; that's what I base my opinion on; hence my branding of 720 as "HD-lite". It is HD and it looks terrific, hand-down, compared to 480x720 SD, but it's on the low end of the HD scale.

Anybody got a problem with their TiVo?

It's really hit or miss. We just got another five HD channels a week ago, and the TiVo just filled in the guide data late yesterday (so about one week). But earlier this year, it took almost two months for us to get some program/guide data for one HD channel. It also depends on the cooperation of your local cabelco.

Be proactive. Don't wait for others to call TiVo and report the changes.

Call TiVo and report these lineup changes yourself. Be sure to give them the local phone number for your cable office so they can call and verify.

In addition, you may want to submit a TiVo lineup change form. On the lineup change form, I wouldn't bother listing every channel (that would take forever); just list a few prominent channels and mention the mass lineup change in the notes. As before, include the local phone number for your cable office.

I do. I records too much! I can't keep up with all the stuff that it is recording. Since I upgraded to a 1TB drive, my NPL is getting huge. Tivo needs to add a feature to pause the rest of the world so I can watch more TV.

I feel your pain, it's unavoidable. Once you get the hang of setting a season pass you're done for it. Fortunately, with a large primary drive and network transfers to a PC disk farm I'm able to stock-pile regular season series for the summer. But by necessity I've become very selective in what I watch. If a new series looks like it is going nowhere, I cancel the pass and move on.

[quote=Kelson;17005199]



Well said.

It all comes down to this:

http://carltonbale.com/2006/11/1080p-does-matter/

My Tivo works great, by the way

Since you're a numbers guy, I suppose I should mention your calculation only applies to Blu-Ray disks. For broadcast HDTV your calculations are a bit off. The resolution of 2,073,600 pixels is for your 1080p screen. 1080i only broadcasts 1036800 pixels per frame, and two or more of these frames are electronically joined to to forge a 1080p image. The result is you do not get 2.25 times the detail of a 1280x720p broadcast [from a 1080i broadcast]. The result is actually closer to 1.1 times the detail.

I do not doubt you can see a difference between 720p and 1080i on your TV, but suggest that the source of the difference is that either your TV or the Tivo does a worse job converting 720p to 1080p than it does going from 1080i to 1080p. A quality 720p source should look much the same as a quality 1080i source when they both been scaled and deinterlaced properly.

To bring the discussion back to Tivo...does the Tivo scale HDTV well? I use an external scaler and I believe it does a much better job of scaling than the Tivo. Have others been happy with Tivo scaling?

This chart has little to do with comparing the visual quality of 720p program material to 1080i program material. I believe few will argue that a Blu-Ray disk looks better than a bit-starved 720p HDTV sports broadcast. The question for Tivo users is if a bit-starved 720p HDTV broadcast looks worse than a 1080i bit-starved broadcast. If it does look worse, then I believe that there are scaling issues that need to be addressed.

That said, it is pretty obvious that the distance from your screen is extremely important, and the chart shows that nicely.

Thanks, I love the chart. But it doesn't apply to what I have posted. That chart deals with the physical resolution of the display, not the resolution of the source.

Still, a great chart. Thanks for the link.

No, I believe you are off. Broadcast 1080i is interlaced as you have stated. That means the original 1080x1920 image is transmitted as 2x1,036,800 pixel frames of complimentary information (not identical) at I believe 60Hz. The pixels of the two frames are interleaved. A 1080p display simply collects both frames and deinterlaces them to construct a 1080p image comprised of the 2,073,600 original pixels (full 1080x1920 detail, not interpolated) it displays at I believe 30Hz.


I've tried both ways and like the 720p --> 1080p scaling my Panasonic plasma does better than the TiVo so I have the TiVo transmit in native format. What I really like is the 1080p scaling of DVDs provided by my Oppo 981HD with Faroudja DCDi.

I was more so referring to the discussions about how the picture looked from a distance. There are several posts regarding this. If you read my original post on this, you'll see that I mention that there are other reasons why PQ can look better or worse. Resolution is only part of what we see. Contrast, color saturation, etc. are very important, too.

My point in providing the article and chart link is to say that since seating distance and screen size affect how we view (or perceive) resolution, it is important to make sure one is within the "benefit becomes visible" sections of the given resolution. Otherwise, it would be impossible to perceive the difference between a 1080p and a 720p source.

As for the physical resolution of the display versus resolution of the source, the "resolution of the source" is exactly what the article and chart are discussing - namely at a given distance, with a given screen size, one's eyes are able to perceive a given "source resolution," right, or am I missing something?

In any event, I think we've all covered this well.

Yup. Bottom line is this is all so subjective, but looks great either way. I think everybody knows that and the discussion has been pretty low-key. If I had a different display that was not as sharp as the plasma, I probably would never notice the difference. I think I'm done with this.

And to think, a few years ago we were so happy just to have 480p and anamorphic widescreen. We're so fortunate to even be able to discuss HD - whether it be 720p, 1080i, or 1080p.

It would only work that way if the original source content was 1080p/30, and I think that is rare. For content that is recorded in 1080i, the 2 fields of a frame are not captured at the same point in time, so if there is any motion between the fields then it is not possible to reconstruct a perfect 1080p frame from the 2 fields. This is where deinterlacing gets complicated.

I don't want to propagate the off-topic 720p vs 1080i discussion in this thread, so I'll just say that the answer depends on many factors such as the source material, bit rate, etc. Neither format is inherently superior to the other in all cases, that's why they both exist. 720p should not be discounted as "HD Lite", since there are cases where it is preferable to 1080i.

Of course 1080p at high bit rate is the undisputed king, but the only way to get that today is HD DVD or Blu Ray so that does not apply to this Tivo discussion.

Back on topic, I'm also interested in Hyrax's question about how well the Tivo handles scaling and/or deinterlacing. I currently have my Tivo set to output 1080i fixed to avoid resolution switching delays in my TV. In this config, the Tivo handles scaling and the TV handles deinterlacing. The main downside to this approach is that for 720p material, the Tivo has to convert it to 1080i, and the TV then converts it to 1080p. Technically I don't think the 720p-->1080i converison can be lossless. Either resolution or motion must be lost. In reality though, I have a hard time seeing a difference between that and native 720p. Switching delays make it difficult to compare though. It would be very interesting to see 2 identical Tivos and TVs side-by-side for comparison. Ideally, future Tivo boxes will offer a 1080p fixed output mode which would allow max quality for all source resolutions.

I did some testing here and I don't see a difference in xfer rates between Standby and awake. This is on a THD with software 11.0d. It is talking via the ethernet port to a wireless bridge. My throughput seems to always be in the 800-850KB/s range according to TivoPlaylist. Note that I don't know how to tune low power analog broadcasts, but I did set my Tivo to channels that I don't receive.

Transfers using kmttg (uses curl) at 1600KB/s + on wired 100Mbs ethernet here. Maybe that's why I noticed a difference.