Adaptive coding: Difference between revisions

Revision as of 19:51, 15 November 2004

Revision as of 21:49, 16 November 2004

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In adaptive coding, the encoder and decoder are instead equipped with identical rules about how they will alter their models in response to the actual content of the data, and otherwise start with a blank slate, meaning that no initial model needs to be transmitted. As the data is transmitted, both encoder and decoder adapt their models, so that unless the character of the data changes radically, the model becomes better-adapted to the data it's handling and compresses it more efficiently.

'''''==Adaptive Method'''''<br>==

'''===Encoder'''===

# Initialize the data model as per agreement.

# While there is more data to send

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## Modify the data model based on the last symbol.

'''===Decoder'''===

# Initialize the data model as per agreement.

# While there is more data to receive

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Any adaptive coding method has a corresponding ''static model'' method, in which the data model is precalculated and then transmitted with the data.

'''''==Static Method'''''<br>==

'''===Encoder'''===

# Initialize the data model based on a first pass over the data.

# Transmit the data model.

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## Encode the next symbol using the data model and send it.

'''===Decoder'''===

# Receive the data model.

# While there is more data to receive

## Decode the next symbol using the data model and output it.

[[Category:Data compression]]