Video signal coding systems and processes using adaptive quantization

An adaptive quantization method in a coding process for coding data values corresponding to each picture element (pel) of a portion of a video frame, the method comprising the steps of:

• selecting, for each portion of a video frame, a quantizer set Rx of quantizer values from a group of quantizer sets R0-Rn where each quantizer set differs from each other quantizer set;
• determining the distortion and bit rate characteristics provided by each quantizer set in the group R0-Rn;
• and
• selecting the quantizer set Rx based on the distortion and bit rate characteristics provided by each quantizer set in the group;
• and
• correlating each data value with a quantizer value from the selected quantizer set Rx to provide a quantized set of values corresponding to the pel data values, wherein each quantizer value in each quantizer set within the group R0-Rn is a multiple of a quantization coefficient QP.

A method of coding video signal data, comprising the steps of:

• sampling a video signal to obtain data values corresponding to picture elements (pel) of at least a portion of a video frame;
• providing a set Rx of predefined quantizer values from a group of quantizer sets R0-Rn where each quantizer set differs from each other quantizer sets;
• correlating each data value obtained in the sampling step to a value within the set Rx of predefined quantizer values;
• said correlating step further comprising the steps of:
• determining the distortion and bit rate characteristics of a quantized portion of said video frame provided by each quantizer set in the group R0-Rn;
• selecting the quantizer set Rx based on the distortion and bit rate characteristics of said quantized portion of said video frame;
• determining a quantified distortion and bit rate value for each quantizer value in the set Rx for each pel of the portion of the video frame;
• and
• selecting the quantizer value based on the quantified distortion and bit rate value for each quantizer value in the set Rx;
• and
• coding the quantizer values derived in the correlating step using a variable length coding system.

A system for coding sampled video signal data corresponding to a portion of a video frame comprising:

• a storage means for storing a group of quantizer sets R0-Rn where each quantizer set differs from each other quantizer set;
• wherein each quantizer set in the group R0-Rn is a set of quantizer values;
• processor means for determining, for each video portion of the video frame, a quantified distortion and bit rate value provided by each quantizer set in the group R0-Rn;
• said processing means further including:
• means for selecting, for each portion of the video frame being coded, a quantizer set Rx based on the quantified distortion and bit rate value for each quantizer set in the group R0-Rn;
• means for correlating each video signal data value for each frame portion being coded with a quantizer value from the quantizer set Rx selected for that frame portion;
• and
• means for encoding the quantizer values using a variable length encoding scheme.

An adaptive quantization method in a coding process for coding data values corresponding to each picture element (pel) of a portion of a video frame, the method comprising the steps of:

• selecting, for each portion of a video frame, a quantizer set Rx of quantizer values from a group of quantizer sets R0-Rn, wherein each quantizer set differs from each other quantizer set and each quantizer set includes a different combination of at least two quantizer values from a set consisting of:
• {0,±1QP,±2QP,±3QP,±4QP,±5QP,±6QP};
• and
• correlating each data value with a quantizer value from the selected quantizer set Rx to provide a quantized set of values corresponding to the pel data values.