Pure Audio Visual Research #3 ! ! ! (TEXT) Flashcards
Why do we have IP Addresses?
(1) Best Answer: IP addresses are hierarchical. To greatly simply things imagine your IP address is 10.20.30.40. Any random host on the Internet that you want to contact does not need to know specifically where 10.20.30.40 is. Instead it contacts its router, which knows how to get to all the networks beginning with 10. Once it has reached a router for those network it is sent to another router that deals specifically with 10.20 addresses, and so on to one that deals with 10.20.30 addresses which forwards it on to your computer. This is why you can’t simply change your IP address to anything you like - the coordination is needed so that one machine knows in what direction to send data even if it does not know about the specific machine in question. In this way the amount of data that routers need to handle to keep track of where data should be sent is kept to a manageable size.
(5) MAC addresses in contrast are essentially random by the time you receive your computer - one MAC address has no relationship to the MAC of a machine it is only feet away from. To route by MAC addresses routers would have to account for every machine on the network individually which is a complete impossibility for a network the size of the Internet.
Finally not all machines have MAC addresses. MAC addresses are a feature of ethernet which is not the only networking standard. In particular WAN links such as between the different sites your ISP operates from do not have MAC addresses. If you were routing by MAC address how would you send data between these devices that do not have MAC addresses?
Foot Candles vs. Lumens
(1) Foot-Candles Vs. Lumens
By Craig Colin Smith
eHow Contributor
Lumens measure the light radiated by the bulb. Foot-candles measure the illuminance of the ring around the bulb.
Image by Flickr.com, courtesy of hobvias sudoneighm
A “foot-candle” is a unit of measure for quantifying the intensity of light falling on an object. A “lumen” is a unit of measure for quantifying the amount of light energy emitted by a light source. In other words, foot-candles measure the brightness of the light at the illuminated object, while lumens measure the power of the light radiated by the light source.
Lumens to Foot Candles Calculations How to Convert Candle Power to Lumens
(3) Function
Both foot-candles and lumens are units of photometry, that is, measurements of electromagnetic radiation detectable by the human eye. Foot-candles are used to measure photometric “illuminance,” the density of light energy reaching a reference surface at a given distance from one or more light sources. Lumens are used to measure photometric “luminous flux,” the amount and rate of light energy radiated by a particular light source.
Identification
A foot-candle is a traditional unit of photometry based on the English system of measurements. A foot-candle equals 1 lumen per square foot. The international standard (SI) counterpart of the foot-candle is the “lux.” A lux equals 1 lumen per square meter. The equation used to convert foot-candles to lux is: 1 foot-candle = 10.76 lux.
(5) Significance
Lighting designers for residential, commercial and industrial must calculate the total number of lumens of various light sources and their distances from living spaces and work areas to ensure adequate illumination. Foot-candles are calculated using the formula: Foot-candles (fc) = Total Lumens (lm) ÷ Area in Square Feet. Lux are calculated using the formula: Lux = Total Lumens ÷ Area in Square Meters. Indoor light fixtures typically provide light outputs ranging from 50 to 10,000 lumens.
Misconceptions
People sometimes confuse the wattage rating of a light bulb with the amount of light that the bulb will produce. In fact, it is the lumen rating which indicates the amount of light energy produced. The wattage rating indicates the amount of electrical energy that the bulb consumes. Because a bulb does not convert all of the electricity consumed into light energy—for example, heat is also generated—the lumen rating should be used to determine a bulb’s light output capability.
Fun Fact
The foot-candle continues to be commonly used by American and British lighting designers and photographers because many light meters used to measure illuminance are still calibrated in foot-candles instead of lux.
EX FAT FILE FORMAT
(1) Can Microsoft’s exFAT file system bridge the gap between OSes?
Aurich Lawson / Thinkstock
With Apple’s licensing of Microsoft’s exFAT file system, it seems like we finally have a good option for OS X and Windows disk swapping. Dave Girard spent some time investigating the appeal, the limitations, and the alternatives to exFAT.
One of the more painful areas of cross-platform computing is data sharing. While networking between Mac OS X, Windows, and Linux has gotten a lot easier thanks to SAMBA, disk sharing still feels like it’s in its infancy thanks to proprietary file systems and the unique legacy needs of the respective operating systems they run on. There are options for cross-platform file sharing—plenty actually—it’s just that each one presents its own limitations and appeals. With Apple’s licensing of Microsoft’s exFAT file system, it seemed like the main problem with FAT32—the 4GB file size limit—was put to rest, and many people are probably now using it to swap video libraries between their MacBooks and HTPCs or share downloads between OS X and Boot Camped Windows. But exFAT has its own issues and limitations that few people are probably aware of—and considering how few people even know about exFAT, we thought this was a good opportunity to cover it, along with the various alternatives.
exFAT: The savior of cross-platform file sharing?
(2) First, a brief history of exFAT for those unfamiliar with it. exFAT is a proprietary Microsoft file system that was designed to bridge the gap between the NTFS file system and the more dated FAT32 file system. Its main advantages are that it can store files over 4GB since it is a 64-bit file system. Its max file size limitation is 16 EiB (Exbibyte) and its theoretical max capacity is 64 ZiB (Zebibyte), which our people in the lab have called “stupidly huge.” You won’t have any issues with hitting file size or capacity ceilings with exFAT. Since exFAT is a closed format, Apple had to license it to integrate it into OS X 10.6.5 and later. You can format a volume as exFAT within Disk Utility. I’ve read about people having issues with exFAT disks that were formatted using Snow Leopard’s (10.6.x) Disk Utility showing up in Windows. Apparently, Apple’s block size was correct according to the standard, but different enough from Windows’ default to cause it not to be recognized on the Windows side. So Snow Leopard users were forced to use Windows to format the drive as exFAT, and then it would show up fine in OS X. This seems to be fixed in Mountain Lion (10.8) since I didn’t have any issues getting the Mountain Lion-formatted exFAT partitions to show up in Windows 7. On the Windows side, native exFAT support is built into Windows as of Vista SP1, and exFAT drivers are available for older builds like XP. Since it’s a relatively new and proprietary format, Linux exFAT support is definitely lackluster, but there is an implementation of exFAT as a FUSE user-space level file system. I haven’t personally tried it.
(5) exFAT limitations and things to keep in mind
Before you run out and format everything as exFAT, you should understand its limitations—and they aren’t insignificant. exFAT has no file system-level encryption or compression support, and, like FAT32 before it, there is no journaling built into the exFAT file system. This means it has a much higher probability of data loss than with NTFS or HFS+. Since FAT32 and exFAT are common USB stick file systems, TFAT and TexFAT are driver-level additions to FAT32 and exFAT volumes that address the lack of journaling in much the same way that Apple has with HFS+ in OS X. But those are currently only implemented in mobile OSes. That’s not it. exFAT also isn’t supported by Time Machine in OS X, which requires an HFS+ volume. Another odd limitation of exFAT support in OS X is that you can’t create a software RAID array in exFAT format, but you can do it with the FAT32 format. It also has very limited permission and ACL support for those who need to isolate different users from certain files. If you’re just planning on sharing a video or music library, this isn’t a problem. Still, the lack of journaling could be problematic. In the limited testing I did, bundled OS X applications launched fine from an exFAT volume. I wouldn’t recommend installing apps to a non-HFS+ volume, though, since the lack of permissions support could probably cause issues with larger applications. For content developers and designers looking to share files between Macs and PCs, you should have no issues using exFAT as a bridge format. You should be careful when copying older Mac fonts to an exFAT-formatted disk, though. Older Mac PostScript font suitcases have resource fork data that is not retained when copied to non-HFS or HFS+ volumes (HFS is the older pre-OS X file system, for those wondering). So if you’re using anything other than HFS+ disks, it’s best practice to use the Finder to zip your fonts if you’re transferring older suitcase-based PostScript fonts. The OS X Finder’s zip supports resource forks—that’s one of the reasons it creates the __MACOSX folder in zip archives. Newer font formats like OpenType don’t use resource forks, so newly purchased fonts won’t be an issue on non-HFS+ volumes.
Differnces Between LED and Plasma TV’s
(1) For years, the question of which type of HDTV to get was one of the most important to consider. You could get a plasma HDTV, a CCFL-backlit LCD, or if you had the money, you could buy an LED-backlit HDTV. Now that Panasonic is out of the plasma field and CCFL LCDs are nearly extinct, LED is the obvious choice. LEDs are available in any size and price range, and now approach the performance once only seen with plasmas. There is a new technology on the horizon that might give LED a run for its money, though: OLED has the potential to overwhelmingly exceed even plasma in picture quality.
The History and Technology
In the early days of HDTVs, plasma, with its inky blacks and top-notch picture quality, was the prevalent flat-panel technology among videophiles. Gradually, thinner, more energy-efficient LCDs with CCFL backlighting, and later LED backlighting became less expensive and more capable, and started gaining ground. The difference between plasma and LCD wavered for some time, with each offering different economic and visual benefits depending on the model, price, and time in the life cycle of HDTVs. LED screens have steadily produced improved pictures, with some high-end models comparable to high-end plasmas. They’ve also become steadily more affordable and accessible, with LED backlighting now standard in all high-end, midrange, and even most budget screens.
(2) These technologies are vastly different, particularly with respect to how each display is lit. Non-LED screens, often just called LCDs, use cold cathode fluorescent, or CCFL lights to illuminate the panel. LED uses arrays of light-emitting diodes (LEDs) arranged either along the edges of the panel or along the back to light it up. Edge-lit LEDs can be thinner and lighter than backlit LEDs, but backlit arrays can sometimes individually control different sections of the screen and how they’re lit to make darks look darker.
CCFL-lit LCDs were common as budget and midrange screens, but many companies have moved almost completely to LED backlighting. Now you can get even budget screens that are LED-backlit, thinner, lighter, and more energy efficient than they would have been a few years ago.
In plasma HDTVs, the phosphors that create the image on the screen light up themselves, and don’t require backlighting. This doesn’t mean it’s more efficient than backlit LCD screens, though. On the contrary, plasma panels are much heavier than both CCFL- and LED-backlit LCDs, and consume much more power.
Then there’s organic light emitting diode, or OLED, technology. This new display type has barely hit HDTVs yet, but the few screens using it have been very impressive. OLEDs are, electronically, light-emitting diodes like the backlights of LED HDTVs (though in the case of OLEDs, it’s a thin film of electroluminescent organic material instead of an inorganic, often gallium-based chemical), but function more like plasma cells. Each OLED generates its own color and light, meaning it can completely shut off to produce black. They can potentially produce a superior picture to plasma HDTVs while staying energy efficient like LED HDTVs. They’re just extremely rare and expensive, and will remain so for a few years.
(3) The Present: LED
I have some bad news: Plasma is dying. Panasonic has left the plasma market, leaving only Samsung and LG producing plasma HDTVs. Some of the best HDTVs we’ve tested in the past have been plasmas, but they’re fewer and farther between with each year. The technology is still clinging to life as the choice for home theater enthusiasts, but we could see plasmas completely abandoned by HDTV makers by 2016. It’s a bit of a shame. Historically, plasma HDTVs have produced the best black levels, specifically the discontinued Pioneer Kuro HDTV brand. The Kuro’s screen got so satisfyingly dark that it remained a popular HDTV for enthusiasts long after Pioneer stopped making the sets.
The domination of plasma in this field, however, is over. While Panasonic’s 2013 high-end plasmas, the VT60 and the ZT60 series, have produced black levels of 0.005 cd/m2 in our tests, some LED HDTVs can produce comparable results. The Vizio E550i-B2 LED-backlit LCD HDTV, for example, produces an 0.01 cd/m2 black level and a contrast ratio of 11,997:1. There’s also the issue that the E550i-B2 is available, while the VT60 and ZT60 series have been discontinued and Panasonic won’t make any more plasmas.
LCD HDTVs used to literally pale in comparison to plasmas, but that’s just not necessarily the case anymore. Generally, a black level of 0.02 cd/m2 is considered excellent, and until a few years ago LCD HDTVs couldn’t come close. Now there are LED-backlit LCD screens that can get that dark, all while consuming less power and often having a lower price than comparable (and increasingly rare) plasma screens. This isn’t always the case, but the technology is capable of it. That doesn’t mean it will always be the best choice, though, especially for sheer picture quality.
(5) The Future: OLED
For the deepest of blacks, OLED will almost certainly become the new standard for high-end HDTVs once they stop being astronomically expensive. The LG 55EA9800, a curved OLED screen with a sticker price of $8,000, produced something we’ve never seen before in testing: perfect black. Even with other parts of the screen illuminated, black produced no light. This is sometimes referred to as an infinite contrast ratio, though it’s more of a mathematically impossible contrast ratio. To calculate it, you divide the peak brightness by the black level; a black level of zero would require dividing by zero.
If other OLED HDTVs can deliver similar performance, and if HDTV manufacturers can produce OLED HDTVs that cost less than a used Ford Focus, they will replace plasma screens as cinephiles’ favored displays in a few years.
The Verdict
At this point, you have three choices: buy an LED-lit LCD, plasma, or OLED HDTV. Of those choices, only two (plasma and LED) are realistic, and one of those choices is dying out. Plasma screens are much more rare and expensive than most LCD screens at this point, but if you can spend over $2,000 on an HDTV and don’t mind being limited to just Samsung and LG, you can pick up one that offers some of the best picture quality available. If you can spend closer to $10,000, you could get an OLED HDTV with a potentially even better picture, but that’s a much less realistic option for most users. That leaves us with LED HDTVs, the most numerous and easy-to-find HDTV type, and one that can produce a great picture.
For more HDTV shopping advice, check out How to Buy an HDTV. And for a look at the top-rated HDTVs we’ve tested, read The 10 Best HDTVs.
Robe Point
*prefered over the clay paky sharpy.
(1) Product Description
The Pointe® is very bright and super-fast with a sharp parallel beam that cuts through the air and across video with ease. It can project a static or rotating glass gobo to produce precision in-air and surface images with an even focal plane. Tight or at full 20° zoom, the output is crystal clear and brilliant. Add in either rotating, 6 way linear or 8 way circular, prisms to create wide reaching effects across any set.
Drop in the frost filter and use any of the 13 rich colours to create a smooth even wash. The Pointe® has an output far greater in size, quality and power than seems possible from it’s small, lightweight body – due to the efficient short arc 280 W discharge source and the Robe optical configuration. This new technology fixture even travels efficiently in a case of 4 and will cover all your needs – Beam, Spot, Wash, FX - there is no point in using any other fixture.
(2) Source
• Lamp: Discharge short arc lamp with integrated reflector
• Approved model: Osram Sirius HRI 280 W
• Lamp Life Expectancy: Standard mode (280 W) - 2.000 hrs, Eco mode (230 W) - 3.000 hrs
• Control: Automatic and remote on/off
• Ballast: Electronic
Optical System
• Light Output:
o Beam mode: 75,250 lx @ 20 m distance
o Spot mode: 82,400 lx @ 5m distance
• Dichroic glass reflector integrated with the lamp for maximizing the light efficiency
• Zoom range: 2.5°-10° beam application; 5° – 20° spot application
(3) Electrical Specification
• Power supply: Electronic auto-ranging
• Input voltage range: 100–240 V, 50/60 Hz
• Power consumption: 470 W at 230 V / 50 Hz
• cETLus compliant
• CE compliant
Mechanical Specification
• Height: 22.6” – head in vertical position
• Width: 14.3”
• Depth: 9.8”
• Weight: 33 lbs
• Fixation option: Pan/Tilt-lock mechanism
Thermal Specification
• Maximum ambient temperature: 104°F
• Maximum surface temperature: 212°F
Rotating Gobos
• Glass gobos - outside diameter: 15.9 mm, image diameter: 12.5 mm, thickness: 1.1 mm, high temperature borofloat or better glass
Static - Beam Gobos
• Aluminium gobo wheel - thickness: 0.5 mm, gobo image diameter: 6 mm
(4) Control and Programming
• Setting & Addressing: ROBE Navigation System 2 (RNS2)
• Protocols: USITT DMX-512, RDM, ArtNet, MA Net, MA Net2
• Optional wireless version available: CRMX™ technology from Lumen Radio
• Control channels: 16, 24
• 2 DMX protocol modes
• 3-editable programs, each up to 100 steps
• Stand-alone operation
• QVGA Robe touch screen with battery backup gravitation sensor for auto screen positioning operation memory service log with RTC
• Pan/Tilt resolution: 8 or 16 bit
• Movement control: Tracking and vector
• Colour wheel positioning: 8 or 16bit
• Rotating gobo wheel positioning: 8 bit
• Gobo indexing & rotation: 8 or 16bit
• Static gobo wheel positioning: 8 bit
• Prism indexing & rotation: 8 bit
• Frost: 8 bit
• Zoom: 8 or 16bit
• Focus: 8 or 16bit
• Dimmer: 8 or 16bit
• Ethernet port: Art-Net, MA Net, MA Net 2 protocols, ready for ACN
• Data in/out: Locking 3-pin & 5-pin XLR
• Power input: Neutrik PowerCon
• Built-in analyzer for easy fault finding
(5) Electromechanical Effects
• Colour wheel: 13 dichroic filters + white
• Rotating Gobo wheel: 9 rotating, indexable and replaceable “SLOT&LOCK” glass gobos + open
• Static Gobo wheel: 14 gobos + open
• Prism 1: 8-facet circular prism rotating in both directions at different speeds
• Prism 2: 6-facet linear prism rotating in both directions at different speeds
• Frost effect: Separate, variable
• Dimmer/Shutter: Full range dimming and variable strobe effect
• Motorized zoom and focus
• Pan: 450°
• Tilt: 270°
Rigging
• Mounting points: 2 pairs of ¼-turn locks
• 2 x Omega bracket with ¼-turn quick locks
• 1 x Safety attachment point
IRE
1)With film, its amount of exposure to light, and how we process it with chemicals, helps determine how bright a frame will be. With video, voltage determines the luminance of the image.
Instead of being a physical object, like film, video is a signal of binary code – tiny ones and zeros marching into your television, or monitor, telling all those little pixels what to do. The Institute of Radio Engineers came up with a unit of measurement – ingeniously called IRE units – to define the range from white to black in composite video signals. 100 IRE = white, and 7.5 IRE = black. (I’m oversimplifying so you don’t flee at the sight of a little math.) In essence the range of 7.5 – 100 IREs are the minimum and maximum levels that can be recorded. Normal skin tones appear between 50-80 IREs.
2)What do IREs have to do with filmmaking? Why are we talking about this? And where did I leave my keys? I can answer two of your three questions. IREs translated to exposure levels when you’re shooting anything on video. But you’re not used to measuring exposure in IREs, are you? No, you’re more familiar with film’s good friend the F-stop.
F-stop, whatever happened to F-go?! (Who could resist?) If you have no idea what an F-stop is, we’ll talk about that more as we get into Cinematography. But in brief, f-stops are the little numbers on the side of your lens. Setting your f-stop controls the size of the aperture inside the lens, determining the amount of light allowed through for exposure. But there isn’t any film to expose in my camera? Yep, this is a key example of how the concepts and terminology of film have carried over into the world of video. Understanding more about one will help you understand more about the other. So pay attention.
3)So back to IREs for a second, each f-stop = 15 IRE units. This is what’s happening under the hood as you’re playing with your video’s exposure. So why is this important to know? There’s one specific feature on your camera that measures things specifically in IREs. That’s right I’m talking about your Zebra settings. They’re not just indecisive horses. Now we’re learning something practical!
Follow along for your pro-tip of the week:
For most of you the zebra button is going to be buried somewhere within your vast menu set. (Turn to the appendix of your camera manual. If you don’t have your manual, consult the Google.) Once you find it, you should find that you have access to two zebra settings. Go to zebra-1, and set it for 70 IREs – sometimes displayed as 70%. Now go to zebra-2, and set it to 100 IREs – yep, pure white.
4) You should be able to these zebras off and on in your display settings. When you film with them on, you’ll see where they get their name. Zebra-1, will display a series of striped, diagonal lines over any part of the image at or above it’s threshold. In this case, anything exposing above 70 IREs, which as you may recall is the median range for natural skin tones. (See where this is going yet?) Zebra-2 will display a cross-hatching of diagonal lines over any part of the image at or above 100 IREs, or pure white. To be sure, these lines won’t record onto your video, they simply act as visual warnings. If you see cross-hatching on a white sheet of paper, you’re fine. If you see cross-hatching all over your friend’s face, you might be a little overexposed.
5) Overall you can play with the levels of your zebra settings to figure out how much “warning” you’d like to see. Maybe you want to know before a part of your frame hits pure white? Try setting zebra-2 to 95 IREs. Overall, when filming with your zebra setting on, you’ll have a better chance of maintaining more accurate exposure levels on the fly. When you see that zebra-2 hit, you know you might need to turn your f-stop up.
