This is topic Film-Tech Digital? in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.
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Posted by Mitchell Dvoskin (Member # 751) on 08-05-2002, 07:30 AM:
1) My eyes see things analog. Therefore, I wish to see films they way they are supposed to be seen, analog.2) There is no such thing as digital projection. There is digital media storage, there is digital transmission (moving the information from the storage device to the projector), but in order to get something visable on the screen, it eventually needs to be converted to analog.
3) When digital audio came out in the early 1980's, it offered superior storage capabilities than the analog devices it replaced, so that when it was finally converted to analog for your speakers, it sounded better. Digital video does not offer this advantage, being still inferior to it's analog predecessor.
4) Does Film-Tech Digital mean that we now have to refer to film grain as film pixals?
/Mitchell
Posted by Steve Kraus (Member # 476) on 08-05-2002, 07:38 AM:
It's not true that there is no such thing as digital projection. A DLP projector is flashing individual pixels on and off varying amounts of time in accordance with the need to effect gray scale values. A pixel is either on or off with no inherent in-between levels. In fact, the way it works is to load the micromirror array with the Least Significant Bits (and all the mirrors flip on or off as needed), hold it for a tiny interval, then load the array with the 2nd Least Significant Bits, hold it for twice the tiny interval, then the 3rd LSB and hold it for 4X the tiny interval etc. Or they can start with the Most Significant Bit and cut the intervals in half each time. The sum of all intervals = 1/24 sec. And all of this times 3 for RGB. The discrete values involved do indeed meet the definition of "digital."
Posted by Mitchell Dvoskin (Member # 751) on 08-05-2002, 09:07 AM:
Yes Steve, you are indeed correct. My point was not that there are no digital projectors, but there is no digital projection. What I was trying to say is that the information has to be coverted to analog (which is what the DLP array is doing) for us to view it. We see the resultant analog light output passed though the DLP array. Converting to analog at the last step before the lens is definately the best place to do it, but IMO, at present time not better than keeping the whole process analog (film projection).Technically, all television is "digital", in that a CRT phosphor is either on (energized) or off (dark). The fact that the source for a conventional TV is not binary, or the fact that a CRT phosphor turns off at a hard preset number of milliseconds from the time it is entergized, does not alter the fact that the set has to "digitize" (in a primitive way) the signal so that the scanning beam knows which pixals to energize. We see the resultant analog light output from the phosphors.
/Mitchell 
Posted by John Anastasio (Member # 607) on 08-05-2002, 09:26 AM:
Mitchell, your idea that the phosphor on a CRT is either "on" or "off" with no values in between is erroneous. The brightness of the phosphor at any given moment is determined by the power of the electron beam. That beam current represents an analog value that is determined by the video waveform, which can be anywhere from 0 to 1.5v. (actually, -40 to +100 IRE, with 0 IRE units seen as black on the screen) Only at zero volts does the current to the face of the tube reach its maximum value and drive the phosphor to its brightest level. At any other level, the brightness will be less. Of course, the beam consists of individual electrons, but I don't think we need to push the argument down to the level of quantum physics to make the point.
Posted by Darryl Spicer (Member # 711) on 08-05-2002, 09:34 AM:
3) When digital audio came out in the early 1980's, it offered superior storage capabilities than the analog devices it replaced, so that when it was finally converted to analog for your speakers, it sounded better. Digital video does not offer this advantage, being still inferior to it's analog predecessor.
I have to disagree partly to this. When analog recordings were transfered to digital they cut out the information that supposedly the human ear couldn't hear to allow more information to fit on the disks. In some cases they over did this causing loss of audible bass and highs. Thus if a rcord was well maintained it could sound better than the digital media.
Posted by Steve Kraus (Member # 476) on 08-05-2002, 09:48 AM:
Mitchell, DLP projection is still digital as there is no conversion to analog--what is coming out of the lens is still discrete pixels being flashed on and off at discrete intervals---that is digital. It's not like there is some sort of "optical capacitor" that smooths the flashes into gray scale values. Your eye does that. Conventional television on the other hand IS analog. The only division is into scan lines and these vary in brightness and color continuously on along their length. Even the screen which seems to be broken into dots is this way only because the color phosphors must be kept separate. B&W television or color done with three projection CRT's doesn't have this. It's true that virtually all signals nowadays are digitized at some point or other (including within some tv's) but the system itself analog.
Posted by Mitchell Dvoskin (Member # 751) on 08-05-2002, 10:28 AM:
I stand corrected. Thanks everyone for furthering my understanding of how the technology works./Mitchell
Posted by John Moriarty (Member # 1153) on 08-05-2002, 12:33 PM:
Given that in conventional (film) projection, the moving image is created by "discrete [frames] being flashed on and off at dicrete intervals" could it be siad to be digital. Or does the fact that each of frames is individually analogue make the system a hybrid of anologue and digital.John
Posted by Bernie Anderson Jr (Member # 410) on 08-05-2002, 04:59 PM:
You people all fell on your head with this digital crap! What was it that brought us to work in this field? For me the whole magic of the movies starts with the FILM Projector. There is no Magic in digital. It's boreing and sterile like everything else that has the digital stamp on it. You all gotta agree that there is something about film running through the projector to achieve a moving picture that still amazes me everytime I see and work with Film. With Digital, it's not a moving picture, it's moving pixels. Where's the fun in that. This concept of new is better is pure crap. You tell me, would you prefer a battery operated car to a mint 57 chevy Bel-aire? I wouldn't. And I have this feeling that Brad changed the header of this forum to Digital (becuase it's better) is his own little joke to get people in a uproar. I can go on and on about the problems with Digital, but I will reserve that for another time when film once again, (the scapegoat for what's wrong with our industry) needs to be defended. In a nut shell what's wrong with this industry is that the magic of movies is gone and has been replace with the importance of how much can we charge at the concession stand.
Posted by Ken Lackner (Member # 1002) on 08-06-2002, 06:58 PM:
A-friggen-men to Bernie!!!
Posted by David Stambaugh (Member # 1102) on 08-06-2002, 07:22 PM:
Darryl said: "When analog recordings were transfered to digital they cut out the information that supposedly the human ear couldn't hear to allow more information to fit on the disks. In some cases they over did this causing loss of audible bass and highs. Thus if a rcord was well maintained it could sound better than the digital media."You got that right. Sony's initial ads for CD technology promised "Perfect Sound Forever". What a laugh! I bought the very first Sony CD player released in the US: Model CDP-101 I think. It sounded like crap. CD players and recordings have improved dramatically over the years, but analog can still beat CD. Don't even get me started on the quality of MP3 or MiniDisc sound.
Posted by Brad Miller (Member # 2) on 08-06-2002, 07:25 PM:
"Perfect sound forever"Some of my original cds that I purchased in the mid 80's have already deteriorated to the point they have trouble playing too.
See how wonderful everything digital is? 
Posted by David Stambaugh (Member # 1102) on 08-06-2002, 09:18 PM:
Early laserdiscs (video) suffered from a high rate of "laser rot" problems. I think the explanation was poor lamination of the disc's layers of materials would allow oxygen in and cause corrosion of the inner metallic layer. CDs that are poorly manufactured can be vulnerable to the same problem. When I bought that Sony CD player mentioned above, I had my choice of 1 of 2 CD titles available at the time: Bruce Springsteen's "Born To Run", and some other one I don't remember. I chose Springsteen. It still plays OK but the "sound" has always been kind of harsh and metallic.
Posted by Bobby Henderson (Member # 840) on 08-06-2002, 10:31 PM:
I have DVDs that have rotted. I have to go buy a new copy of "American Beauty" because my copy has this weird milky fluid-like stuff spread around the edges of the disc where it seems the glue holding the two data layers together has lost its bond. My copy of "Three Kings" strangely will no longer play in my DVD player into the third act regardless of there being no visible blemishes, dirt or scratches on the disc. It won't even load in my DVD-ROM drive; my computer totally locks up with it.Dolby SR mag has more dynamic range and headroom capability than any 16-bit digital audio format, and can fool listeners thinking it is 20/48 or 24/48. Maybe that is one reason why so many DVD-A recordings are coming from 20+ year old analog tape masters.
Digital may be digital, but the bits still have to be recorded to some kind of medium that is just as prone (if not much more so) to problems as any analog sound tape or film print.
Posted by Joe Redifer (Member # 3) on 08-07-2002, 02:18 AM:
quote:
Don't even get me started on the quality of MP3 or MiniDisc sound
You definitely have a point with MP3, especially those at 128kbps. But to me MiniDisc sounds DAMN good... virtually indistinguishable from the CD. I have a very hard time hearing compression artifacts on MD. Maybe I have magical MD hardware. However it's still only 16-bit 44.1khz. I wish one of the high resolution audio formats would take off for the mass market, which will NEVER happen as long as they keep charging super high prices for the hardware and for the software.
Posted by William Hooper (Member # 71) on 08-07-2002, 04:36 AM:
A lot of things which seem to be continuous aren't really.
Two points in the process of watching movies are actually discrete processes.For the first, photographic movies clattering through the projectors are discrete images sampled 24 times per second.
It's always been acknowledged that it's due to the "persistence of vision" that we run them together to perceive continuous movement, as we perceive movements that are continuous around us in wherever the real world is.
But it turns out that the mechanism which gives us the effect of persistence of vision is actually a process of discrete stages; thus, when we see continuous, real-world things, we perceive them in a sort of sampled manner.
Light energy (photons) entering the eye strikes a molecule of the chemical rhodopsin, the energy breaks a bond, & the molecule changes its shape. When the shape changes, it then releases the protein opsin, which then goes banging around in the neurochemical chain of events (mostly dependent on the *shape* of a molecule, like gears & woodruff keys) which make up vision. The rhodopsin somewhat slowly returns to its original configuration, & that period of slow return is where you get the persistence.
You see that it is discrete: either the molecule is in state A or B.
There's a lot of rhodopsin in our eyes, increasing the "population" of our "sample". We are acclimated to smear these samples together into our perception movement that we know is continuous, and that's why as frame rates go up, things get closer to our visual "sampling" rate.
I think you mean by your reference to analog events things like people walking, grass swaying, needles reproducing audio in grooves of records, which are continuous, & can be sampled to any rate to get whatever rate is needed for Your Particular Sampling Needs.
There are other photochemical receptors in the eye, they tend to have the same mechanism; rhodopsin is the dim light, monochromatic, baseline one. At some point, it seems like everything comes down to mechanisms that don't look or work too different from the transmission in a 1971 Triumph GT6.