Method and apparatus for adaptive entropy encoding/decoding of quantized transform coefficients in a video compression system

A apparatus for adaptive entropy encoding/decoding of a plurality of quantized transform coefficients in a video compression system, wherein the plurality of quantized transform coefficients are scanned in a predetermined scanning order giving a generally decreasing average power and the plurality of quantized transform coefficients are stored in a memory unit, the apparatus comprising at least one of:

• A) an encoding apparatus comprising:
• A1) a first memory unit, operably coupled to receive the plurality of quantized transform coefficients and to a parameter set determiner, for storing the quantized transform coefficients;
• A2) the parameter set determiner, operably coupled to the first memory unit, for parsing a predetermined number of quantized transform coefficients into a plurality of coefficient groups and converting the coefficient groups into a plurality of parameter sets according to a predetermined scheme and storing the parameter sets in the first memory unit, wherein each parameter set includes a level parameter which is a value of a non zero quantized transform coefficient, wherein, where a last coefficient group comprises all zero quantized transform coefficients, the last coefficient group is discarded;
• A3) an order reverser, operably coupled to the first memory unit, for accessing each parameter set of the plurality of parameter sets in reverse order of the predetermined scanning order and providing the parameter sets to an encoder controller and a plurality of entropy encoders;
• A4) the encoder controller, operably coupled to the order reverser, for choosing a current entropy encoder of the plurality of entropy encoders based on a previous level parameter of a previous parameter set;
• and
• A5) the plurality of entropy encoders, operably coupled to the encoder controller and the order reverser, for encoding a current parameter set to provide entropy encoded information bits;
• and
• B) a decoding apparatus comprising:
• B1) a plurality of entropy decoders, operably coupled to receive the entropy encoded information bits from the plurality of entropy encoders, for decoding the entropy encoded information bits to provide a decoded current parameter set;
• B2) a decoder controller, operably coupled to the plurality of entropy decoders, for adaptively selecting a next entropy decoder of the plurality of entropy decoders based on a decoded current level parameter of the decoded current parameter set and a previously selected entropy decoder;
• B3) a second memory unit, operably coupled to the plurality of entropy decoders, for storing each parameter set of a plurality of decoded parameter sets in the reverse of the predetermined scanning order;
• and
• B4) a parameter set converter, operably coupled to the second memory unit, for converting the decoded parameter sets into a number of decoded quantized transform coefficients according to the predetermined scheme in the predetermined scanning order and storing the decoded quantized transform coefficients in the second memory unit, wherein, where the number of decoded quantized transform coefficients is less than the predetermined number of quantized transform coefficients, zero-valued decoded quantized transform coefficients will be appended.