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Category: Video Lingo

Streaming


Streaming – The process of sending audio and/or video information over the internet or other digital connection, such as Bluetooth. Basically, this is how things like YouTube and Netflix work. Basically, it’s sending digital files that can be read as it is received without the entire file being sent. So, rather than having to download an entire movie, you can watch it as it’s downloading. Streaming will hold or “buffer” a certain amount of information to deal with internet connections speeding up and slowing down or drop outs. The advantage is that it is an efficient way to broadcast information over the internet. The bad news is that it is completely reliant on the internet connection. This can happen at the source or the receive end.

Contrast


Contrast – The ratio between how bright and how dark a projector (or other display device) can produce and image. Projectors with high light output typically do not have good contrast ratios. Contrast can affect the perceived resolution of an image (for example, black letters stand out better and are easier to read on a white background than grey or off-white letters would, even if the resolution is exactly the same).

Tech Head Note – A projector or display device will have a contrast rating, based on how it performs in a dark room with no ambient light. Ambient light greatly effect contrast! A flat panel display will handle ambient light much differently than a projector and screen.

Component Video


Component Video – Video signal that is separated out by its color components. Most often when someone refers to component video they are talking about an analog video signal. Analog component video uses three cables, usually red, green, and blue (although, the signals are NOT actually red, green, and blue but rather complex signals that determine what red, green, and blue will be). By keeping them separate they maintain better quality than if they are all encoded into one signal (composite). Component video can be used with both standard definition or high definition video.

Progressive Scan


Progressive Scan (also see “Interlaced Video) – A method of displaying a video or computer image where every row of pixels (or “lines”) are drawn in order, or progressively, from top to bottom. A video image is made much like typing a page: one line is drawn from left to right and when it gets to the end of the line it goes back to the left to start a new line. When it gets to the bottom right corner the image is complete and the next page or “frame” is started in the top left. This happens at least 60 times a second, sometimes more. Since progressive scan video displays all of the rows (or “lines”) at a time rather than half like interlaced, it is usually better quality than interlaced. Most computer displays are progressive scan.

Tech Head Note – With the advent of HDTV you see a lot of commercials for 1080p displays. The “1080” part is the number of lines from top to bottom that make up an image and the “p” is for Progressive Scan. Interlaced scan would have an “i”.

HDSDI – High Definition Serial Digital Interface


HDSDI – High Definition Serial Digital Interface (see also “SDI”) – A professional type of video transport that sends uncompressed HD digital video information down a single cable, usually a BNC cable. SDI and HDSDI are the same except for the amount of information per second that can be transported. SDI is also a generic term referring the type of interface, whereas HDSDI refers to an SDI interface that carries HD video signals.

Tech Head Note – These days SDI is generally labeled by the bit rate of the interface (the amount of digital information transported per second). The original SDI interface transferred video signals at 270Mbps (megabits per second). HDSDI transfers video signals at 1.5 Gbps (gigabits per second). Now, terms such as 3G, 6G, and 12G are used (note, this has NOTHING to do with cell phone carriers 3G & 4G). HD video using 1080P resolution uses 3G SDI. Ultra HD (also known as 4K) uses 6G and 12G SDI. Also, the higher the bit rate, the shorter the distance in can travel down a cable and longer runs may require conversion to a fiber-optic cable.

Codec (Compressor/Decompressor)


Codec – Short for Compressor/Decompressor (or Coder/Decoder). A codec is a means of converting AV signals into digital code and then converting them back into AV signals. This allows AV signals to be transmitted over the internet or stored on digital devices. There are many types of codecs and can be set for various levels of quality.

Here are some common codecs:

  • MP3 (MPEG, Layer 3)
  • AAC (Advanced Audio Coding) Used by iPods
  • MPEG 2 (Motion Pictures Expert Group, Version 2) The codec used on DVD’s
  • MP4 (Motion Pictures Expert Group, Version 4)
  • H.264 (MPEG 4, Part 10), also known as AVC (Advanced Video Coding) which is found on BluRay discs, and many internet streaming programs.

 

Firewire


Firewire – A digital transport interface similar to USB. Firewire was largely used to transfer digital video signals as it was much faster than USB. With the advent of USB3 and Thunderbolt, Firewire is not seen as much these days. Like USB, Firewire underwent changes over the years. The data rates got faster and the connectors changed. The original Firewire used a 4-pin connector, then was upgraded to a 6-pin connector. Firewire-800 uses a 9-pin connector. You can use adapters to go from 4-pin to 6-pic to 9-pin, but the speed will always default to the lowest version connector.

Aspect Ratio


Aspect Ratio – The ratio of width to height of any screen or display device, regardless of resolution. Older TVs have an aspect ratio of 4:3 (4 parts wide by 3 parts tall), Most new TV’s and High Definition displays use a 16:9 ratio. Standard Definition video can also be 16:9. Note that “widescreen” can refer to may  aspect ratios. The most common widescreen ratios are 16:9 (TVs) and 16:10 (computers).

Blended Image


Blended Image – A switching and display technology where a single image is divided among multiple projectors which are then “blended” together to create one projected image that is larger than any one projector can make. These images are usually very wide (like a movie screen) or tall. These images can also have multiple PiPs (Picture in Picture, or “windows”) that can display anything from camera shots to PowerPoint presentations. Advantages are that screens can be used for scenery and can display a lot of content in many ways. Plus, they are just plain cool to look at! Disadvantages are costs – switching packages are expensive and graphics must be custom designed.

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