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Post by JayUtah on Jun 28, 2005 23:45:51 GMT -4
You might have a defective disc. Pixelation occurs in MPEG rendering if some bits go awry. And believe it or not, that can affect video for up to 30 seconds. But Mark is exceptionally attentive to his customers. Hit him up.
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Post by turbonium on Jun 29, 2005 0:25:03 GMT -4
You might have a defective disc. Pixelation occurs in MPEG rendering if some bits go awry. And believe it or not, that can affect video for up to 30 seconds. But Mark is exceptionally attentive to his customers. Hit him up. Thx, jay, I will - he sounds approachable on this - you bring up a valid point. Would it be of interest to anyone if I were to present the anomalous stills and video clips? I'd like honest opinions and you aren't a group that would just throw out insults for my presenting this stuff, but would have replies that are thought out and worthwhile to consider. Let me know....
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Post by turbonium on Jun 29, 2005 0:29:38 GMT -4
Almost forgot - I'm out of town until Tuesday after tomorrow so I may not have time to post much if anything until then - just to let you guys know. If I can find some time before then I will post.
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Post by Kiwi on Jun 29, 2005 5:38:54 GMT -4
While I have the Spacecraft Films' Apollo 11 DVDs here (kindly lent to me by another Kiwi member of this board), can someone please tell me exactly where to view the footage concerned, and which part of it was shown by Sibrel. I have the original version of the Spacecraft Films Apollo 11 DVD, so it might be slightly different (as far as menus and chapters are concerned) than the version distributed by FOX. The footage that Sibrel used (a tiny part of) starts at Title 22, Chapter 5 on my DVD, and it takes place at about 34:00 GET. It shows the Earth out one of the windows for about 10 minutes and then the Capcom (Charlie Duke, I believe) requests that they turn on the lights so everyone can see the astronauts. They turn on the lights and remove some blinds from the windows. Sibrel only shows about 5 seconds of it and has his narrator speaking over most of it. Thanks, LunarOrbit. The things we do... It's probably reinventing the wheel, but in the hope of making the facts easily accessible, I have transcribed the dialogue from the two Apollo 11 TV transmissions at 10:32 and 30:28 GET. They can be found here, in "The Reality of Apollo": apollohoax.proboards21.com/index.cgi?board=apollo&action=display&thread=1120036997Some parts I couldn't understand so have shown [garbled] in those places. There are probably some errors and it is sometimes difficult to identify exactly who is speaking, so any help in getting the transcriptions accurate would be appreciated. Each new piece of dialogue starts with the times on the Spacecraft Films Apollo 11 DVDs, Disc 1, with three asterisks showing gaps in the dialogue, so it is easy to race through the DVD to find everything said. Maybe I am indeed a thicko, but I can't see where Bart Sibrel gets the idea that there is some sort of smoking gun or a hoax being perpetrated in these transmissions. Please, anyone, feel free to use the text to show others the true nature of his claim. Much of the dialogue sounds pretty routine to me (if flying to the moon can be routine), and it's worth noting the unhurried and free-of-frustration nature of it. Just professionals doing their job as efficiently as they can and tossing in the odd joke. Nothing mysterious at all, except perhaps to those people who might take a pimple to be a sign that they're getting the bubonic plague.
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Post by Data Cable on Jun 29, 2005 7:44:45 GMT -4
I hope you don't find any errors of fact or logic in what I write [...] What's even worse, "not" is a word I frequently omit. Well, technically, that's an error in (boolian) logic in and of itself, isn't it?
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Post by sts60 on Jun 29, 2005 8:30:57 GMT -4
Would it be of interest to anyone if I were to present the anomalous stills and video clips? I'd like honest opinions and you aren't a group that would just throw out insults for my presenting this stuff, but would have replies that are thought out and worthwhile to consider. Let me know....
turbonium: What do you think of this photo? See, this looks anomalous right here... Other AHers: Don't give us that, you snotty-faced heap of parrot droppings! turbonium: What? Other AHers: Shut your festering gob, you tit! Your type really makes us puke, you vacuous, toffee-nosed (fixed - thanks Al!), malodorous, pervert!!! turbonium: Look, I came here to argue about Apollo, I'm not going to just stand...!! Other AHers: Ah! We' sorry, but this is abuse. turbonium: Oh, I see, well, that explains it.
Monty Python sketches aside, this is the right place, so fire away.
Just be aware that many, many such "anomalous" bits have been waved by some pretty obnoxious HBers, who went on and on about how one odd-looking shadow conclusively proved Apollo to be a fake, only to be thoroughly dismantled by some of the resident experts here.
You have been quite civil so far, I hasten to add, and welcome to the board. It's just that a lot of the people we've seen have made up for their complete lack of relevant knowledge with an enormous amount of arrogance, and have been impervious to all attempts at educating them. If the latter sounds kind of snooty, consider that a number of regulars here have put a great deal of time into understanding the Apollo record, and into reconstructing scenarios in some detail. Also, some are engineers, electronics wizards, or thoroughly competent photographers.
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Al Johnston
"Cheer up!" they said, "It could be worse!" So I did, and it was.
Posts: 1,453
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Post by Al Johnston on Jun 29, 2005 9:31:23 GMT -4
"toffee-nosed malodorous pervert" surely? ;D
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Post by Joe Durnavich on Jun 29, 2005 10:09:49 GMT -4
Turbo, what was the size of the online image you are comparing the DVD image to? Was it something small like 240 x 180 pixels or something? If you had to enlarge it to 640 x 480, the rescaler may have smoothed out some of the details of the image, making it appear "clearer".
The DVD image on the right of your four captures shows the herringbone interference pattern (the faint dark and light crosshatch stripes) that plagued some of the Apollo video. (This was interference from the voice and telemetry signals, which were difficult to filter out completely.) This detail is missing from the online version of image.
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Post by Joe Durnavich on Jun 29, 2005 14:40:31 GMT -4
You might have a defective disc. Pixelation occurs in MPEG rendering if some bits go awry. And believe it or not, that can affect video for up to 30 seconds.
My DVD looks the same. The Apollo 12 video shows severe compression artifacts whenever there is a lot of motion. The frame captures turbo posted are during the time Al was taking the camera off the MESA and, um, pointing it into the Sun. The camera pans across what I take to be the S-band erectable antenna, but which turbo says looks like a bare arm holding a pole.
I have noticed in the past that the surface video sequences in Spacecraft Film's DVDs tended to show more compression artifacts than the sequences taken from film. Jay, you were demonstrating recently how mostly-flat JPEG backgrounds often have such compression artifacts. I wonder if the MPEG compressors have trouble with the very low bandwidth Apollo video?
To put some numbers on it, DVD can have up to a 5.4 MHz video bandwidth, as I remember, but the Apollo video tops out at around 0.9 MHz. Does DCT compression count on having enough image detail to hide the macroblocks?
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Post by JayUtah on Jun 29, 2005 16:21:57 GMT -4
With MPEG it's the bitrate that counts.
In addition to DCT artifacts, MPEG streams can exhibit MPEG compression artifacts. DCT is how to compress images in space over the field of view. MPEG compression is how to compress frames in time.
MPEG sequential encoding produces three types of frame: I-frames, B-frames, and P-frames. They differ in appearance by how big they are and therefore how many bits it takes to send them. The differ functionally in how much of an individual motion picture frame they represent.
An I-frame is a DCT-encoded image representing the entire frame. A P-frame is a complex data type that contains descriptors telling how one particular motion picture frame differs from the preceding I-frame. It generally contains only the blocks that change between frames. It can also contain instructions that simply move a block from one place to another on the screen, or transform existing blocks in some particular way. A P-frame refers to a motion-picture frame several frames ahead of the I-frame. The intervening frames are encoded as B-frames, which contain the same type of information as a P-frame, but can use the I-frame as the initial state and the P-frame as the final state, and interpolates between them.
You get I-frames every 12 seconds or so, or when the picture changes so dramatically that interpolative or extrapolative means are not reductive. You get P-frames every second or half-second, so in the ideal world one I-frame can "feed" a couple dozen P-frames. And of course the B-frames happen every 1/30 second or 1/25 second, corresponding to the original or remapped frame rate.
But in order to decode the stream, the P-frame must be delivered before the B-frames that refer to it. So the frames are delivered out of order in the MPEG stream. You may encode a set of 20 frames as follows:
IBBBBPBBBBPIBBPBBBBP
but it has to be delivered as
IPBBBBPBBBBIPBBPBBBB
It therefore follows that the encoder has to keep several seconds of video in memory in order to encode the frames properly. The magic of MPEG encoding is knowing what type of frame to create for any given situation. B-frames and P-frames are both considerably smaller than I-frames. Lots of I-frames give high-quality video, but require a very high bitrate. Lots of P- and B-frames lead to image "tear" and other interoplation artifacts, but consume low bitrate
Some delivery systems such as satellite transponders deliver data at a fixed bitrate. The Boeing 601HP can transmit about 30 Mbps per transponder, with 16-24 transponders per chassis. DVDs can deliver much higher bitrates, and even variable bitrates. But the real problem comes in the complexity of the encoder. Real-time encoders that can optimize an MPEG bitstream are very expensive since they have to consume a rolling window of several seconds' worth of video and work through various options for encoding it. They typically run in the hundreds of thousands of dollars.
Less expensive approaches either don't work in real time, or else they adopt some standard simplifications to the frame designation algorithms. This usually results in poor encoding at some point in the program.
At any rate, when a flurry of closely spaced I-frames is suggested, such as when motion occurs too rapidly to be efficiently done as intermediate frames, a common strategy for staying under your bitrate involves encoding each block with fewer DCT basis functions -- i.e., a lower JPEG quality for those frames.
That seems to be what has happened here.
DCT compression actually does very well on macroblocks of a single color. A first-order basis function covers it. But the initial bias for each macroblock is itself dictated by a DCT compression from an original constant value for the entire image. So if that high-level DCT compression is also done with a minimum of basis functions, the expansion through that level and the intra-macroblock level results in discontinuity at the macroblock boundaries.
I hadn't seen the frames in question until just now, and I'm reasonably certain they are simply resolution-deprived I-frames. The compression for those particular frames is excessive, and the pixelation you are seeing is highly characteristic of what happens when you get an I-frame bottleneck in an MPEG stream. It's "intentional" in the sense of being an accepted tradeoff for stream size and bitrate limitations, but not intentional necessarily in the sense of wanting to hide something.
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Post by Sticks on Jun 29, 2005 18:24:05 GMT -4
JayUtah never fails to amaze at his breadth of knowledge [Off Tangent]Jay, have you ever thought abouty teaching at a University? You would probably know more than some university professors, but I suspect you could make oodles more as a private consultant[/Off Tangent]
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Post by turbonium on Jun 29, 2005 19:57:22 GMT -4
Would it be of interest to anyone if I were to present the anomalous stills and video clips? I'd like honest opinions and you aren't a group that would just throw out insults for my presenting this stuff, but would have replies that are thought out and worthwhile to consider. Let me know....turbonium: What do you think of this photo? See, this looks anomalous right here... Other AHers: Don't give us that, you snotty-faced heap of parrot droppings! turbonium: What? Other AHers: Shut your festering gob, you tit! Your type really makes us puke, you vacuous, toffee-nosed (fixed - thanks Al!), malodorous, pervert!!! turbonium: Look, I came here to argue about Apollo, I'm not going to just stand...!! Other AHers: Ah! We' sorry, but this is abuse. turbonium: Oh, I see, well, that explains it. Monty Python sketches aside, this is the right place, so fire away. Just be aware that many, many such "anomalous" bits have been waved by some pretty obnoxious HBers, who went on and on about how one odd-looking shadow conclusively proved Apollo to be a fake, only to be thoroughly dismantled by some of the resident experts here. You have been quite civil so far, I hasten to add, and welcome to the board. It's just that a lot of the people we've seen have made up for their complete lack of relevant knowledge with an enormous amount of arrogance, and have been impervious to all attempts at educating them. If the latter sounds kind of snooty, consider that a number of regulars here have put a great deal of time into understanding the Apollo record, and into reconstructing scenarios in some detail. Also, some are engineers, electronics wizards, or thoroughly competent photographers. LMAO!! "That parrot's not dead! He's pining for the fjords!" As far as informative replies, that is exactly what I'm looking for - I have my own business that involves electro-pneumatic medical devices, so I'm not averse to engaging in technical discussions with engineers. Some of my best friends are engineers - somebody has to be!!
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Post by turbonium on Jun 29, 2005 20:23:28 GMT -4
Turbo, what was the size of the online image you are comparing the DVD image to? Was it something small like 240 x 180 pixels or something? If you had to enlarge it to 640 x 480, the rescaler may have smoothed out some of the details of the image, making it appear "clearer". The DVD image on the right of your four captures shows the herringbone interference pattern (the faint dark and light crosshatch stripes) that plagued some of the Apollo video. (This was interference from the voice and telemetry signals, which were difficult to filter out completely.) This detail is missing from the online version of image. The original online video still frames are all 320 x 240 pixels, and I have enlarged them to 640 x 480. The enlargements really have not made the images any "clearer" - the originals have certainly as much clarity as the enlargements, maybe slightly more so. Why would the online version not have the herringbone interference pattern on it?
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Post by jaydeehess on Jun 29, 2005 20:48:00 GMT -4
Hi turbonium , I see you took my advice. As you have discovered these guys have much better answers than I could have offered you
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Post by Joe Durnavich on Jun 29, 2005 20:57:11 GMT -4
Why would the online version not have the herringbone interference pattern on it?
Because image detail was lost somewhere along the way. The online version might be a taken from a kinescope, for example, which is a recording of the original video from a TV screen onto film. I was asking about the original size because another way that detail can be filtered out is to shrink the image to a small size (which would have been done with the online video was produced) and then scale it back up to a larger size. The better algorithms will scale the image without pixelating it.
Filtering detail often makes an image look better. This is why photographers happily throw away resolution when they enlarge or contact print an image from a sharp, but grainy negative onto much lower resolution photographic print paper. Image detail is lost, but so is much of the graininess.
I pointed out the herringbone pattern to show that even with the compression artifacts, the DVD image contains more of the original video detail. The online version is not necessarily a technically better reproduction of the original, even though is it aesthetically more pleasing.
By the way, I am pretty sure the "bare arm holding a pole" is just the erectable dish antenna that Pete Conrad was setting up at that time. He hasn't unfolded the "umbrella" or dish part yet, which happens to be flesh or brown/organgish in color.
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