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FAQ: 

 Miscellanious

In a bit stream, the number of bits occurring per unit time, usually expressed in bits per second

In a bit stream, the number of bits occurring per unit time, usually expressed in bits per second.

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Technology to store large amounts of digital data in a relatively small amount of space. Most videoformats use lossy compression that brings a loss of quality.

Compression uses mathematic algorithms to store large amounts of digital data in a relatively small amount of space. There are two main kinds of compression, lossy, and loss-less. Loss-less compression includes the RAR/ZIP format, where the original data is compressed, and when de-compressed, the data has not changed. Lossy compression includes most video compression formats, such as MPEG-1/2/4, DivX - this means that when the digital data is compresssed and de-compressed, it is no longer the same as the original (usually denoting a loss of quality).

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Content Scrambling System. Prioprietary scrambling system for video DVDs. Designed to stop people from making copies of DVDs.

Content Scrambling System. Prioprietary scrambling system for video DVDs. Designed to stop people from making copies of DVDs, most commercial DVDs are encrypted using CSS. During playback, DVDs are then decrypted on the fly. Only parts of the DVD are encrypted (for instance all IFO and BUP files are not encrypted, and VIDEO_TS.VOB often isn't encrypted either) and the encryption scheme is rather weak and was quickly defeated. If you want to know what CSS does, insert a DVD video disc into your PC, start playing the disc using a software DVD player, then close the player. Now copy a 0.99GB VOB file from the disc to your harddisk and try to play back that VOB file in your software DVD player. You'll see a lot of funny colored blocks all over the picture making the movie unwatchable. But you'll also see parts of the movie (the parts that are not encrypted).

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The process of taking a raw uncompressed file and compressing it to an encoded form while maintaining the quality.

Refers to doing something to a video into a particular format (as in "encoding a video into a particular format). Usually refers to compressing to a particular compression format (as in "encoding video to DivX"). Decoding is the opposite of encoding.

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Like film video, consists of a stream of pictures, called frames.
The number of frames used per second (fps) is the framerate.

One frame represents one image. A movie usually runs at 24 frames per seconds, so it has 24 different images per second. Imagine 24 images with a bird on it, in the first image it's on the left, then it gradually movies somewhat to the right. On the 24th frame the bird is on the right end of the image. Imagine these 24 images being played in sequence fast enough and it looks like a bird would fly from left to right to the human eye.

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A frame that has very little compression, which the other frames compare themselves to. Compression records the change in movement from one frame to the next; the keyframes act as a reference point for the compressor.

An individual image exhibiting the extreme of an action or gesture. Used as a guide for the construction of intermediate frames (In-betweens.) Stops and changes of direction also occur at keyframes. A KeyFrame is used to mark the beginning and end of a motion sequence. Each Key frame contains the position, size and rotation of the Camera Window. The Codec use the start and end Key frame position to calculate all the intervening frames in a motion sequence

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The amount of pixels used in a frame.
DV and NTSC uses 720 x 480, PAL & SECAM 720 x 576 pixels in a frame.

Number of horizontal and vertical pixels that a device or image contains, expressed as: (horizontal dimension)x(vertical dimension), 1024x768. In camcorders this can be applied to the CCD, LCD and viewfinder, as well as the recorded image and a photo if applicable. Each device or feature can have a different resolution. Normally the higher a higher resolution is better than a lower resolution.

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Streaming video can be played over an internet connection, that is simultaneously played and downloaded.

Movies that can be watched over the network before the entire file has downloaded to the user's computer. Provides fast-starting for on-demand movies, and supports live broadcasts (with specialized hardware). Streaming video is usually customized for different bandwidth requirements (modem connections versus high-speed cable modem or DSL connections).

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