Question

Explain the meaning of the following terms relating to compression:

1. source encoders and destination decoders,

2. lossless and lossy compression,

3. entropy encoding,

4. source encoding.

Answer 1

1) Source encoders convert the continuous analog waveforms of data to digital discrete data.

Destination decoders do the opposite of source encoders, i.e convert the digital data to analog data.

2) Lossless compression is data compression algorithms wherein the original data can be perfectly constructed from the compressef form. Example: ZIP file format.

Lossy compression is when the reconstructed data is approximately correct to the original data. It uses partial data discarding methods to reproduce the data. Example: mostly used in multimedia compression

3) Entropy encoding is a medium independent, lossless data compression technique. Most commonly used Entropy coding techniques are Hoffmann encoding and Arithmetic encoding.

4) Source encoding converts the data waveform into bits which are used to transfer data. It includes:

• Sampling - convert continuous analog data to discrete digital data.

• Quantization - convert continuous symbols to discrete representations

• Data compression - remove data redundancy and distribute bits uniformly.