Advanced arithmetic coder

An apparatus for entropy coding of video data, the apparatus comprising:

• a memory configured to store a plurality of contexts used in a context-adaptive entropy coding process to entropy code a value for a syntax element in a slice of the video data;
• and
• one or more processors configured to:
• obtain a pre-defined initialization value for a context of the plurality of contexts, wherein the pre-defined initialization value is stored with N-bit precision;
• determine, based on the pre-defined initialization value, an initial probability state of the context for the slice of the video data, wherein a number of possible probability states for the context is greater than two raised to the power of N;
• and
• entropy code, based on the initial probability state of the context, a bin of the value for the syntax element.

An apparatus for entropy coding of video data, the apparatus comprising:

• means for obtaining a pre-defined initialization value for a context of a plurality of contexts used in a context-adaptive entropy coding process to entropy code a value for a syntax element in a slice of the video data, wherein the pre-defined initialization value is stored with N-bit precision;
• means for determining, based on the pre-defined initialization value, an initial probability state of the context for the slice of the video data, wherein a number of possible probability states for the context is greater than two raised to the power of N;
• and
• means for entropy coding, based on the initial probability state of the context, a bin of the value for the syntax element.

A non-transitory computer-readable storage medium storing instructions that, when executed, cause one or more processors of a video coding device to:

• obtain a pre-defined initialization value for a context of a plurality of contexts used in a context-adaptive binary arithmetic coding (CABAC) process to entropy code a value for a syntax element in a slice of the video data, wherein the pre-defined initialization value is stored with N-bit precision;
• determine, based on the pre-defined initialization value, an initial probability state of the context for the slice of the video data, wherein a number of possible probability states for the context is greater than two raised to the power of N;
• and
• entropy code, based on the initial probability state of the context, a bin of the value for the syntax element.