Arithmetic coding for transforming video and picture data units

A method for decoding a transform data unit or a sub-unit thereof from a coded bit stream, the transform data unit being a precoded version of a predetermined transform coefficient of transform coefficients which are the result of a transformation of data corresponding to a predetermined portion of portions of a video frame or picture, the portions being either a portion of a first type being associated with a first scanning pattern or a portion of a second type being associated with a second scanning pattern, the method comprising the following steps:

• choosing one of a first and a second set of context models, depending on as to whether the predetermined portion is a portion of a type being associated with the first or the second scanning pattern, the first and the second set being different to each other;
• assigning one context model of the chosen one of the first and the second set of context models to the transform data unit or the sub-unit thereof based on the scanning position assigned to the predetermined transform coefficient, wherein each context model is associated with a different probability estimation;
• and
• arithmetically decoding the transform data unit or the sub-unit thereof from the coded bit stream based on the probability estimation with which the assigned context model is associated.

A computer readable medium storing a computer program product having instructions for performing, when running on a computer, a method for encoding a video frame or picture, the method comprising:

• dividing up the video frame or the picture in portions of a first type and portions of a second type, wherein the portions of the first type are associated with a first scanning pattern, and the portions of the second type are associated with a second scanning pattern that is different from the first scanning pattern;
• transforming data corresponding to a predetermined of the portions of the video frame or picture into a two-dimensional array of transform coefficients, wherein a scanning order is defined among the transform coefficients by the scanning pattern of the predetermined portion, the scanning order assigning each transform coefficient a unique scanning position;
• precoding a predetermined of the transform coefficients in order to obtain a transform data unit;
• choosing one of a first and a second set of context models, depending on as to whether the predetermined portion is a portion of a type being associated with the first or the second scanning pattern, the first and the second set being different to each other;
• assigning one context model of the chosen one of the first and the second set of context models to the transform data unit based on the scanning position assigned to the predetermined transform coefficient, wherein each context model is associated with a different probability estimation;
• and
• arithmetically encoding the transform data unit or a sub-unit thereof into a coded bit stream based on the probability estimation with which the assigned context model is associated.

A computer readable medium storing a computer program product having instructions for performing, when running on a computer, a method for decoding a transform data unit or a sub-unit thereof from a coded bit stream, the transform data unit being a precoded version of a predetermined transform coefficient of transform coefficients which are the result of a transformation of data corresponding to a predetermined portion of portions of a video frame or picture, the portions being either a portion of a first type being associated with a first scanning pattern or a portion of a second type being associated with a second scanning pattern, the method comprising the following steps:

• choosing one of a first and a second set of context models, depending on as to whether the predetermined portion is a portion of a type being associated with the first or the second scanning pattern, the first and the second set being different to each other;
• assigning one context model of the chosen one of the first and the second set of context models to the transform data unit or the sub-unit thereof based on the scanning position assigned to the predetermined transform coefficient, wherein each context model is associated with a different probability estimation;
• and
• arithmetically decoding the transform data unit or the sub-unit thereof from the coded bit stream based on the probability estimation with which the assigned context model is associated.

An apparatus for encoding a video frame or picture, the method comprising:

• means for dividing up the video frame or the picture in portions of a first type and portions of a second type, wherein the portions of the first type are associated with a first scanning pattern, and the portions of the second type are associated with a second scanning pattern that is different from the first scanning pattern;
• means for transforming data corresponding to a predetermined of the portions of the video frame or picture into a two-dimensional array of transform coefficients, wherein a scanning order is defined among the transform coefficients by the scanning pattern of the predetermined portion, the scanning order assigning each transform coefficient a unique scanning position;
• means for precoding a predetermined of the transform coefficients in order to obtain a transform data unit;
• means for choosing one of a first and a second set of context models, depending on as to whether the predetermined portion is a portion of a type being associated with the first or the second scanning pattern, the first and the second set being different to each other;
• means for assigning one context model of the chosen one of the first and the second set of context models to the transform data unit based on the scanning position assigned to the predetermined transform coefficient, wherein each context model is associated with a different probability estimation;
• and
• means for arithmetically encoding the transform data unit or a sub-unit thereof into a coded bit stream based on the probability estimation with which the assigned context model is associated.

An apparatus for decoding a transform data unit or a sub-unit thereof from a coded bit stream, the transform data unit being a precoded version of a predetermined transform coefficient of transform coefficients which are the result of a transformation of data corresponding to a predetermined portion of portions of a video frame or picture, the portions being either a portion of a first type being associated with a first scanning pattern or a portion of a second type being associated with a second scanning pattern, the method comprising the following steps:

• means for choosing one of a first and a second set of context models, depending on as to whether the predetermined portion is a portion of a type being associated with the first or the second scanning pattern, the first and the second set being different to each other;
• means for assigning one context model of the chosen one of the first and the second set of context models to the transform data unit or the sub-unit thereof based on the scanning position assigned to the predetermined transform coefficient, wherein each context model is associated with a different probability estimation;
• and
• means for arithmetically decoding the transform data unit or the sub-unit thereof from the coded bit stream based on the probability estimation with which the assigned context model is associated.