What r codecs?

Answer 1

Codec is an shortened acronym for encoder-decoder.

On a very high level it means converting one for of data to another (coding) - to get coded data, and then converting this coded data back to the origianl data (decoding) - to get decoded data.

So often the codec responsibility is not converting the data into coded form but also to decode it too.

Now what codec are we talking about depends on the kind of data we are working upon e.g.
There are codecs which are used for converting the Audio signals to the digital signals so that they can be stored or transported on digital medium e.g. G711 codec does that.


If we are talking about videos, then we can have a codec which can take a string of images and convert into Video e.g MPEG.

These codecs define a standard behaviour of how to code and decode data.
So a phone working on G711 codec means that the voice of person speaking on the phone would be coded on a standard as recommended by G711 codec. When the voice reaches the other end, it would be decoded on a standard as recommended by G711 codec. If the other end is using a G726 codec then it would decode the data in a wrong way.

Codecs are also categorised on their characterstics such as compression or filtering. We would need to have one video codec which can compress data so that it can be transported quickly over Internet.

Then there can be some lossy codecs which means that they lose some information during coding. e.g. consider a audio codec for a phone. We would not want the background noise to be coded because it is irritating and also because it would mean unecessary data to be transferred. So a lossy codec would strip the noise signals which are not within the range of human voice and thus not code it. However this is not always desirable. For instance sending fax over a telephone line. In such a scenario audio signals for a fax document would be created which would not fall in the human voice range. So for transmitting a fax such a codec would be used which is lossless.

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" is a portmanteau of any of the following: 'Compressor-Decompressor', 'Coder-Decoder', or 'Compression/Decompression algorithm'.

Codecs 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 solutions. 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.

An audio compressor converts analog audio signals into digital signals for transmission or storage. A receiving device then converts the digital signals back to analog using an audio decompressor, for playback.

The raw encoded form of audio and video data is often called essence, to distinguish it from the metadata information that together make up the information content of the stream and any "wrapper" data that is then added to aid access to or improve the robustness of the stream.

Most codecs are lossy, in order to get a reasonably small file size. There are lossless codecs as well, but for most purposes the almost imperceptible increase in quality is not worth the considerable increase in data size. The main exception is if the data will undergo more processing, especially editing, in the future, in which case the repeated lossy encoding could degrade the quality of the eventual file too much. Using more than one codec or encoding scheme throughout processing can also degrade quality but there are many situations where this cannot be avoided.

Many codecs are designed to emphasize certain aspects of the media to be encoded. For example, a digital video (using a DV codec) of a sports event, such as baseball or soccer, needs to encode motion well but not necessarily exact colors, while a video of an art exhibit needs to perform well encoding color and surface texture. There are hundreds or even thousands of codecs ranging from free ones to ones costing hundreds of dollars or more.

Many multimedia data streams need to contain both audio and video data, and often some form of metadata that permits synchronization of the audio and video. Each of these three streams may be handled by different programs, processes, or hardware; but for the multimedia data stream to be useful in stored or transmitted form, they must be encapsulated together in a container format.

An endec is a similar (but not identical) concept for hardware.

While many people explain that AVI is a codec, they are incorrect. AVI (nowadays) is a container format, which many codecs might use (although not to ISO). There are other well known alternative containers such as Ogg, ASF, QuickTime, RealMedia and MP4.

Answer 3

A device that converts analog signals to digital form for transmission and converts signals traveling in the opposite direction from digital to analog form. Derived from coder-decoder
MPEG-2, H.264 (AVC), H.263, MJPEG, WMV
these r the few codec formats

Answer 4

This is like a driver for a type of sound file. There are a million ways to make a file, a million ways to set it up. This file helps the application that uses it interperet the file so it can be played back.

Answer 5

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