The Arithmetic Decoding Engine
The arithmetic decoder is described in some detail in the Standard. It has three distinct properties:
1. Probability estimation is performed by a transition process between 64 separate probability states for “Least Probable Symbol” (LPS, the least probable of the two binary decisions “0” or “1”).
2. The range R representing the current state of the arithmetic coder is quantized to a small range of pre-set values before calculating the new range at each step, making it possible to calculate the new range using a look-up table (i.e. multiplication-free).
3. A simplified encoding and decoding process is defined for data symbols with a nearuniform probability distribution. The definition of the decoding process is designed to facilitate low-complexity implementations of arithmetic encoding and decoding. Overall, CABAC provides improved coding efficiency compared with VLC at the expense of greater computational complexity.
Read more about this topic: Context-adaptive Binary Arithmetic Coding
Famous quotes containing the words arithmetic and/or engine:
“Your discovery of the contradiction caused me the greatest surprise and, I would almost say, consternation, since it has shaken the basis on which I intended to build my arithmetic.... It is all the more serious since, with the loss of my rule V, not only the foundations of my arithmetic, but also the sole possible foundations of arithmetic seem to vanish.”
—Gottlob Frege (1848–1925)
“Industrial man—a sentient reciprocating engine having a fluctuating output, coupled to an iron wheel revolving with uniform velocity. And then we wonder why this should be the golden age of revolution and mental derangement.”
—Aldous Huxley (1894–1963)