Communications Toolbox

arithdeco

Decode binary code using arithmetic decoding

Syntax

• dseq = arithdeco(code,counts,len)
  

Description

dseq = arithdeco(code,counts,len) decodes the binary arithmetic code in the vector code to recover the corresponding sequence of len symbols. The vector counts represents the source's statistics by listing the number of times each symbol of the source's alphabet occurs in a test data set. This function assumes that the data in code was produced by the arithenco function.

Examples

This example is similar to the example on the arithenco reference page, except that it uses arithdeco to recover the original sequence.

• counts = [99 1]; % A one occurs 99% of the time.
  len = 1000;
  seq = randsrc(1,len,[1 2; .99 .01],19069); % Random sequence
  code = arithenco(seq,counts);
  dseq = arithdeco(code,counts,length(seq)); % Decode.
  isequal(seq,dseq) % Check that dseq matches the original seq.
  

The output is

• ans =
  
       1
  

Algorithm

This function uses the algorithm described in [1].

See Also

arithenco

References

[1]  Sayood, Khalid, Introduction to Data Compression, San Francisco, Morgan Kaufmann, 2000.

apkconst

arithenco