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Does your HDTV support 1:1 pixel mapping?

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Old 09-07-2007, 09:31 AM   #46  
What's all this, then?...
 
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Come on, you're playing semantics. Who's being rude now?

What you've done is changed the bandwidth of the signal processing--it has nothing to do with the bandwidth of the *cable*, it has to do with the rate of data coming down that cable.

I could generate an MP3 file at either rate and use up the same amount of memory--no data loss in the sense of less data stored (as in comparing the amount of storage of HD DVD to BD).

At the lower MP3 rate, you reduce the quality of the signal as a result of reducing the DSP bandwidth used in encoding/decoding the signal. This would be analogous to reducing the bit rate in a video codec and if Hi-Def discs were running at their maximum bit rate all the time, you *would* see better video quality with Blu-Ray than with HD DVD.

But neither format runs anywhere near maximum bit rate the overwhelming majority of the time, as the video codecs don't need to except under special circumstances.

As for your example in regard to Blu-Ray and HD DVD, I already stated you could certainly *engineer* an example that would look fine on BD-50 and not look as good on HD DVD-30, but that's not going to happen in real life. If it looks fine on BD it will look fine on HD DVD and if it overloads HD DVD, it will overload BD, too. Statistically, the likelihood a movie will come out *just the right length* that it overloads HD DVD and doesn't overload BD is very small and since no studio wants their movie to look bad just to add special features, they will simply cut back on the special features until they get the space they need (which BD has done often in the past).

There is no evidence there is any movie that won't fit on HD DVD-30 and not look good because of it's length. Some of the best PQ can be found on the longest HD DVD movies.

Last edited by BobY; 09-07-2007 at 09:41 AM..
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Old 09-10-2007, 12:15 PM   #47  
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Your MP3 example is not an example of data loss, it's an example of bandwidth loss.....
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Come on, you're playing semantics. Who's being rude now?
Ding, ding, ding. You tell yourself off BobY. You were being quite rude with your nitpicking.




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I could generate an MP3 file at either rate and use up the same amount of memory--
Uh. No. You can not use the same identical song, encoded (1) at 15 kbit/sec and (2) 25 kbit/sec, and have identical file sizes. Take as example this three minute song:

15 kbps == 337 kilobytes
25 kbps == 563 kilobytes

The change in bitstream speed ALSO changes the size of the datafile.
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Old 09-10-2007, 05:47 PM   #48  
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Let's see, so if I point out your example is *wrong*, I'm nitpicking.

Right.

If you said 2+2=5 and I corrected you, would I be nitpicking? What do your professors say?

Where did I say encoding the *same* song at two different rates? I just said I could create two files of the same size at two different sample rates, just to demonstrate your example has nothing to do with storage capacity. It's not the fact that the file takes up less space that makes it sound worse, it's that it is encoded at a lower bit rate which translates to lower bandwidth processing and results in a smaller file size.

Your analogy doesn't work when comparing Blu-Ray and HD DVD capacity because neither format runs at maximum bit rate the vast majority of the time (unlike your MP3 encoding example which runs at a constant bit rate, not a variable bit rate approach like these video codecs).
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Old 09-11-2007, 09:08 AM   #49  
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Here is my ORIGINAL ARGUMENT:
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Good point. Nevertheless a 4-hour movie is going to look better on a 25 Mbps bluray than on a 15 Mbps hd dvd, since the bluray preserves more of the original data. (Same way that a 25kbps MP3 sounds better than a 15kbps MP3.)
We're talking about the SAME content, encoded at differing bitrates. Naturally the slower rate is going to look/sound worse.

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Then, of course, neither the survey, nor the results presented meet the requirements of the "scientific" viewpoint
Yes true, but you can't copy a 50 gig file (from bluray) onto a 30 gig HD-DVD. It won't fit unless you slow down the bitrate. And when you slow down the bitrate, you're going to get a worse-looking picture.

Last edited by electrictroy; 09-11-2007 at 09:11 AM..
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Old 09-11-2007, 07:54 PM   #50  
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Well we're certainly going around in circles and now we're back to where we started.

I already said you can "engineer" a large video file that will look good on 50GB Blu-Ray and not look as good on 30GB HD DVD due to having to use a lower bit rate to make it fit, but that's not going to happen in real-life. Statistically, with the codecs they are using, if a movie looks good on Blu-Ray it will look good on HD DVD and if it looks bad on HD DVD, it will look bad on Blu-Ray.

The difference isn't significant enough. In both cases, the vast majority of the film will not be running anywhere near the maximum bit rate and it would be foolish to up the average bit rate unless there was an appreciable improvement in PQ. The high bit rates are only really necessary on fast-moving, complex scenes.

Realistically, Blu-Ray films aren't going to use a higher bit rate just for the fun of it--they would need to see a significant improvement in PQ for it to be worth wasting valuable disc space that could be used for special features--or worth moving from BD-25 to BD-50.

The Blu-Ray exclusive studios have had the opportunity to "blow HD DVD away" for a long time if it was a realistic option--they have no reason *not* to run their films at a higher bit rate and use all 50GB in the process, since they don't have to worry about maintaining file compatibility with HD DVD like the "neutral" studios. They haven't done it because they have concluded the minor improvements in PQ simply aren't worth wasting the extra storage space.
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Old 09-12-2007, 07:51 AM   #51  
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I already said you can "engineer" a large video file that will look good on 50GB Blu-Ray and not look as good on 30GB HD DVD due to having to use a lower bit rate to make it fit,
(1) In what post number did you say that?

(2) At least we agree.
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but that's not going to happen in real-life. Statistically, with the codecs they are using, if a movie looks good on Blu-Ray it will look good on HD DVD
I disagree. 50-30 == 20 gigabytes of lost data. That's a lot and the difference in quality will be visible on extra-long videos (like 4 hour movies).


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Blu-Ray films aren't going to use a higher bit rate just for the fun of it--they would need to see a significant improvement in PQ for it to be worth wasting valuable disc space that could be used for special features--
Perhaps. Hopefully somebody will give the "Superbit" treatment to Bluray that they did for DVD..... eliminating all special features so as to get the highest bitrate & quality out of the disc.

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The Blu-Ray exclusive studios have had the opportunity to "blow HD DVD away" for a long time if it was a realistic option--they have no reason *not* to run their films at a higher bit rate and use all 50GB in the process, since they don't have to worry about maintaining file compatibility with HD DVD like the "neutral" studios.
Um. Okay. How do you know they have not used all 50 gigs? There are a number of BD-50 releases. Any one of them could have maxes out the disc.
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Old 09-12-2007, 07:24 PM   #52  
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(1) In what post number did you say that?
That would be post #37 *and* post #46 of this thread.

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Originally Posted by electrictroy View Post
(2) At least we agree.
We agree, provided you accept that such a situation would have to be engineered and would be extremely unlikely to happen under normal circumstances.

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Originally Posted by electrictroy View Post
I disagree. 50-30 == 20 gigabytes of lost data. That's a lot and the difference in quality will be visible on extra-long videos (like 4 hour movies).
Well, we've been through this before as well. Both formats are throwing away huge amounts of data. There's certainly no objective evidence that what your saying is true--some of the best looking HD DVD's are the longest films.

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Perhaps. Hopefully somebody will give the "Superbit" treatment to Bluray that they did for DVD..... eliminating all special features so as to get the highest bitrate & quality out of the disc.
There's no real point with the high-efficiency, variable bit rate codecs in use, all it will do for most of the film is waste disc space with no appreciable difference in quality. If the bit rate is sufficient to produce excellent quality on average, it's just a waste to increase the bit rate under most circumstances. This is not MPEG2 at 10Mbs with 4.7GB of storage.

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Um. Okay. How do you know they have not used all 50 gigs? There are a number of BD-50 releases. Any one of them could have maxes out the disc.
If that's the case, then it proves my point since not even the most ardent Blu-Ray fanboys have suggested that *any* Blu-Ray films look significantly better than the *best* HD DVD's (which, as I previously indicated, include some of the longest movies available on either format).
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Old 09-13-2007, 06:50 AM   #53  
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You didn't answer my question. So let me be more specific: Please list the BD-50 discs which have "maxed out" the disc with 50 gig VLC-codec files. To date, I'm aware of none. They've all used 30 gig files ported-over from HD-DVD.
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That would be post #37
Okay. Got me; I forgot about that. ----- I still say it's possible for a movie to look good on a 50 gig disc, and lousy on a 30 gig disc, in a similar way that a dual-layer ~8 gig DVD can look great while the single-layer ~5 gig version looks watchable but inferior.

Less data == less picture == lower image quality.

At this point, since neither of us is going to change his mind, it's probably better to just agree to disagree about this topic.


Oh, and yes "superbit" would make a difference. The extra space gained by eliminating extra audios/videos from DVD *does* make a better picture... (I've seen it with my own eyes)... and the same would be true with HD DVD or Blu-ray.

Last edited by electrictroy; 09-13-2007 at 06:58 AM..
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Old 09-13-2007, 09:03 AM   #54  
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I didn't answer your question as I did not perceive it as a question. I have no idea which, if any, Blu-Ray discs are using all 50GB just for the movie.

That wasn't my point. My point was, Blu-Ray exclusive studios (who have no reason to maintain file compatibility with HD DVD) are perfectly free to use the entire disc space to make a better picture.

Either they *have* done that, or they *haven't". If they have, it obviously made no significant improvement over HD DVD's picture quality--the best Blu-Ray titles don't look obviously better than the best HD DVD titles. If they haven't, it's most likely because they realized it wasn't worth it.

The idea that 50GB is somehow enough to insure a great picture, but 30GB isn't makes no sense to me. In that sense, both formats have enough to insure an acceptable picture and neither format has enough to be superb.

If your argument is that more is always better--well, get a few years of real-world engineering under your belt and then see what you think.

You really need to get out of the DVD world for reference. MPEG2 at 10Mbs is starved for resources a lot of the time. It has little bearing on Hi-Def formats which use much more efficient codecs, much higher bit rates and much more storage.
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Old 09-14-2007, 09:34 AM   #55  
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Some quick math: DVD == around 8.0 gigabytes maximum (with the other 0.5 gig used by sound files). At 720x480 resolution.

HD == 1920x1080. 6 times as many pixels, and 6 times more data to be stored. In order to maintain the *same ratio* of loss as a DVD movie, you need storage space == 8.0 * 6 == 48 gigabytes. (For 1080p, at twice as many video fields, you'd need 96 gigabytes!!!)

You'd need a either a 48 or 96 gigabyte MPEG2-encoded DVD to maintain the same quality/ratio of loss for high-definition video (as its 8 gig standard-def counterpart). ----- Now you are correct the VC-1 is more efficient than MPEG2, but even VC-1 can't perform miracles. Loss is loss.
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My point was, Blu-Ray exclusive studios (who have no reason to maintain file compatibility with HD DVD) are perfectly free to use the entire disc space to make a better picture.
I know. And my point was there are no Bluray exclusive studios using BD-50s (that I know of).
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If your argument is that more is always better--well, get a few years of real-world engineering under your belt and then see what you think.
Uh huh. Whatever. I've got ten years; I think that's plenty.



I was listening to a distant radio station (via internet) at 16 kbit/second. Then I noticed they had a 24 kbit/second feed, so I switched.

Even though both had the same frequency width (upto 44kHz), there was a noticeable difference. You would argue that the difference is so small as to be unnoticeable (since "Delta 8 compressed / 1400 uncompressed" is only a ~1/2% loss of the original CD data).

But that doesn't change the fact that I could hear a difference in the quality.

Last edited by electrictroy; 09-14-2007 at 10:01 AM..
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Old 09-14-2007, 11:58 AM   #56  
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A pic of Troys supersensitive ears....

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Old 09-14-2007, 12:22 PM   #57  
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Uh huh. Whatever. I've got ten years (of engineering experience); I think that's plenty.
this from the same guy who recently posted: "I don't know about dryers, but I used to sell energy-efficient washers. The combined savings of less electricity, less water, and less detergent pays back the "surcharge" in just 1-2 years."

Good lord, we ARE dealing with a real RENAISSANCE MAN here!!
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Old 09-14-2007, 02:36 PM   #58  
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Some quick math: DVD == around 8.0 gigabytes maximum (with the other 0.5 gig used by sound files). At 720x480 resolution.

HD == 1920x1080. 6 times as many pixels, and 6 times more data to be stored. In order to maintain the *same ratio* of loss as a DVD movie, you need storage space == 8.0 * 6 == 48 gigabytes. (For 1080p, at twice as many video fields, you'd need 96 gigabytes!!!)

You'd need a either a 48 or 96 gigabyte MPEG2-encoded DVD to maintain the same quality/ratio of loss for high-definition video (as its 8 gig standard-def counterpart). ----- Now you are correct the VC-1 is more efficient than MPEG2, but even VC-1 can't perform miracles. Loss is loss.
VC-1 doesn't have to perform miracles--MicroSoft's tests show it to be 2-3 times more efficient than MPEG2--you would need to run MPEG2 at a 2-3 times higher bit rate to equal the quality of VC-1. If you don't believe that, take it up with them.

You do realize these video codecs are non-linear and use interframe compression? They don't store every frame, they store key frames at full resolution, then they store macroblock descriptors with motion vectors, or some other high-order transform to describe the changes from frame-to-frame. That means just because your key frames have 6 times as many pixels, you don't need to store 6 times as much information for the entire film--it's not linear.

BTW, the data is already stored as 1080p on Hi-Def discs--1080p doesn't require any more data storage than 1080i--they are both 1920 x 1080. The reason SD DVD's are stored as 480i is they were trying to offload some of the work, as the signal processors weren't fast enough at the time to do real-time MPEG2 decoding and the interlacing as well.

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I know. And my point was there are no Bluray exclusive studios using BD-50s (that I know of).
Then you should be wondering why that is. Of all the studios, they are the ones who should be trying to show Blu-Ray at it's best. The obvious conclusion is they don't think whatever improvement (if any) is worth it.

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Uh huh. Whatever. I've got ten years; I think that's plenty.
Apparently not. I guess you don't work in the consumer arena.

Try asking some of your older, more experienced colleagues whether in their experience "more is always better". Ask them about the point of diminishing returns.

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I was listening to a distant radio station (via internet) at 16 kbit/second. Then I noticed they had a 24 kbit/second feed, so I switched.

Even though both had the same frequency width (upto 44kHz), there was a noticeable difference. You would argue that the difference is so small as to be unnoticeable (since "Delta 8 compressed / 1400 uncompressed" is only a ~1/2% loss of the original CD data).

But that doesn't change the fact that I could hear a difference in the quality.
I'm not saying you didn't, I'm just saying it has little bearing on what we're talking about. The ear is more sensitive than the eye (particularly when it comes to changes over time), the compression algorithms aren't comparable and your talking about a factor of 1.5 for the bit rate difference, while the factor is only 1.3 for the *maximum* (which is rarely used) bit rate difference from Blu-Ray to HD DVD.

This is a good presentation regarding the differences in auditory and visual perception. It's a PowerPoint presentation, but this link is to a HTML version:

http://64.233.169.104/search?q=cache...diovsvideo.ppt
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Old 09-20-2007, 08:18 AM   #59  
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BILL PRINCE: I was not aware that being a salesperson precluded being an engineer. I didn't realize we still live in a class-based society & it's forbidden to cross from the "salesman class" to the "engineer class". How positively Middle Ages & feudal.
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VC-1 doesn't have to perform miracles--MicroSoft's tests show it to be 2-3 times more efficient than MPEG2--you would need to run MPEG2 at a 2-3 times higher bit rate to equal the quality of VC-1.
Can you provide a weblink? I'd like to review that study. ----- Assuming those numbers to be correct, a 48 gig MPEG2 DVD high-definition video could be squeezed to a 24 gig VC1 disc, without any detriment.
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That means just because your key frames have 6 times as many pixels, you don't need to store 6 times as much information for the entire film--it's not linear.
That doesn't really make sense. Although I-frames only record the "area" that changes from frame to frame, because its high-def, they still have 6 times as many pixels in that "area" that need to be updated.

(Aside - This reminds me of how videos (like Dragons Lair/Space Ace) were stored on old Amiga computers using 1 megabyte floppies. It used the same concept of only describing the changes from frame-to-frame. The technique dates back at least twenty years.)
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BTW, the data is already stored as 1080p on Hi-Def discs--1080p doesn't require any more data storage than 1080i--they are both 1920 x 1080.
Yes but I was thinking of 1080p/60 which has twice as many frames than 1080i/30. I guess at this point, nothing exists at 1080p/60.
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The reason SD DVD's are stored as 480i is they were trying to offload some of the work, as the signal processors weren't fast enough at the time to do real-time MPEG2 decoding and the interlacing as well.
I thought it was because DVD was based upon NTSC-III (digitally stored video), including the resolution, timing, and interlacing.



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Then you should be wondering why that is. Of all the studios, they are the ones who should be trying to show Blu-Ray at it's best. The obvious conclusion is they don't think whatever improvement (if any) is worth it.
Perhaps. I'll concede that point, although I don't understand it. (If I was using BD50s, I'd certainly use the extra 25 gigs for something, like a better picture or exclusive extras not available elsewhere.)
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The ear is more sensitive than the eye (particularly when it comes to changes over time)
Ahhh.... didn't know that.

I'll review the PowerPoint later today.

Last edited by electrictroy; 09-20-2007 at 08:30 AM..
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Old 09-20-2007, 10:46 AM   #60  
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reviewed this presentation. It makes a good point about how the Ear is more sensitive to Time changes than the Eye is.

There was one part I was confused about. It reads, "Video cameras have a Gamma curve applied to the sensing element. Originally this was to pre-compensate for non-linearities in the camera. The opposite gamma curve is applied in a TV set to restore the linear levels." ... "Gamma correction in audio? That would introduce a great deal of nonlinear distortion to an audio signal. The frequency domain components would be audible (the ear is a frequency analyzer). A varying noise floor would be exposed by the 90+dB mechanical filtering mechanisms in the ear."

Well. Isn't that exactly how Dolby Noise Reduction and Phonograph Equalization works? It seems to have been applied with great success & no ill effects to the Ear's experience.
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