Methods and apparatus for unified significance map coding

In a video encoder, a method, comprising:

• encoding transform coefficients for at least a portion of a picture, the transform coefficients obtained using a plurality of transforms
• determining a common rule for creating context sharing maps wherein for each transform coefficient position, a context is mapped according to the common rule for all transforms, regardless of size, and a context sharing map is defined as a map indicative of a probability model for one or more bins of a binary sequence created by uniquely mapping a given non-binary valued syntax element shared among different transform coefficient positions;
• providing bitstream syntax indicative of said determined common rule;
• creating the context sharing maps for the transformed portion of the picture based on said determined common rule,
• wherein one or more context sharing maps are generated for the transform coefficients based on the determined common rule used for the transformed portion of the picture, the one or more context sharing maps for providing at least one context that is shared among at least some of the transform coefficients obtained from at least two different ones of the plurality of transforms.

An apparatus, comprising:

• a video decoder for decoding transform coefficients for at least a portion of a picture, the transform coefficients obtained using a plurality of transforms,
• a decision generator for determining a common rule for creating context sharing maps wherein for each transform coefficient position, a context is mapped according to the common rule for all transforms, regardless of size, and a context sharing map is defined as a map indicative of a probability model for one or more bins of a binary sequence created by uniquely mapping a given non-binary valued syntax element shared among different transform coefficient positions;
• a bitstream parser for finding bitstream syntax indicative of said determined common rule;
• a map generator to create the context sharing maps for the transformed portion of the picture based on said determined common rule,
• wherein one or more context sharing maps are generated for the transform coefficients based on the determined common rule used for the transformed portion of the picture, the one or more context sharing maps for providing at least one context that is shared among at least some of the transform coefficients obtained from at least two different ones of the plurality of transforms.

In a video decoder, a method, comprising:

• decoding transform coefficients for at least a portion of a picture, the transform coefficients obtained using a plurality of transforms,
• determining a common rule for creating context sharing maps wherein for each transform coefficient position, a context is mapped according to the common rule for all transforms, regardless of size, and a context sharing map is defined as a map indicative of a probability model for one or more bins of a binary sequence created by uniquely mapping a given non-binary valued syntax element shared among different transform coefficient positions;
• finding bitstream syntax indicative of said determined common rule;
• creating the context sharing maps for the transformed portion of the picture based on said determined common rule,
• wherein one or more context sharing maps are generated for the transform coefficients based on the determined common rule used for the transformed portion of the picture, the one or more context sharing maps for providing at least one context that is shared among at least some of the transform coefficients obtained from at least two different ones of the plurality of transforms.