what are the video codes for? do they have anything to do with downloading?

Answer 1

video codecs are used for compression of digital video

http://en.wikipedia.org/wiki/Video_codecs

they way they deal with downloading, is that they reduce the file size and make it so that video can be downloading and replayed in a reasonable amount of time, which is what makes streaming possible. even with the average high-speed connection, video, in it's pure form, still isn't able to be downloaded quickly enough to be replayed without lag. typically codecs will employ some type of lossy data compression that is good enough to be played back, yet poor enough to show degredation. this is why video played back on google video or you tube appears grainy. even high-definition television uses some form of lossy compression, as the computers that interpret the data aren't quick enough to process the video without it being compressed.

your video player needs to have the correct codec in order to interpret the video that is being unpackaged from the source. on you tube and google video this is already done for you, but if you're using quicktime or windows media player it has to be set up to play certain video, other than avi or wma. downloading the video in it's entirely, then playing it back, offers better performance than streaming because you can take advantage of a higher bit rate as you aren't forced to unpackage the file as it's sent, but then you have the inconvience of having to wait for it to download to begin with, so it's a bit of a tradeoff.

Answer 2

A codec is a device or program capable of performing encoding and decoding on a digital data stream or signal. The word codec may be a combination of any of the following: 'Compressor-Decompressor', 'Coder-Decoder', or 'Compression/Decompression algorithm'.

An endec is a similar (but not identical) concept for hardware. In the middle 20th Century a "codec" was hardware that coded analog signals into PCM and decoded it back. Late in the century the name came to be applied to a class of software for converting among digital signal formats, and including compander functions.

Codecs (in the modern, software sense) encode a stream or signal for transmission, storage or encryption and decode it for viewing or editing. Codecs are often used in videoconferencing and streaming media applications. A video camera's ADC converts its analog signals into digital signals, which are then passed through a video compressor for digital transmission or storage. A receiving device then runs the signal through a video decompressor, then a DAC for analog display. A "codec" is a generic name for a video conferencing unit.