An idea used herein is to use the same function for the dependency of the context and the dependency of the symbolization parameter on previously coded/decoded transform coefficients. Using the same function—with varying function parameter—may even be used with respect to different transform block sizes and/or frequency portions of the transform blocks in case of the transform coefficients being spatially arranged in transform blocks. A further variant of this idea is to use the same function for the dependency of a symbolization parameter on previously coded/decoded transform coefficients for different sizes of the current transform coefficient's transform block, different information component types of the current transform coefficient's transform block and/or different frequency portions the current transform coefficient is located within the transform block.

This application is a national stage application of International Patent Application PCT/JP2019/018292, filed May 7, 2019, now published as WO/2019216324. International Patent Application PCT/JP2019/018292 claims the benefit of U.S. Provisional Patent Application 62/669,928, filed May 10, 2018 and U.S. Provisional Patent Application 62/692,327, filed Jun. 29, 2018. U.S. Provisional Patent Application 62/669,928, U.S. Provisional Patent Application 62/692,327 and International Patent Application PCT/JP2019/018292, now published as WO/2019216324, are incorporated herein by reference.

Some embodiments provide a method for subdividing an interval during entropy coding for a bitstream representing a set of video pictures. The method performs a bit-shifting operation on a probability estimator value. The method computes a sub-interval value by multiplying a range value representing the interval by the bit-shifted probability estimator value. The method uses the sub-interval value to update the interval.

The invention provides an information preserving coding method based on possibility distribution of value of a sample. The possibility distribution of value of a sample refers to evaluation of the possibility of various values of the sample. The information preserving coding method provided is more in line with the non-stationary probability property of an actual source, and a coding code length is the overhead caused by a prediction error of the possibility distribution of value of the sample. The invention further provides multiple coding methods based on possibility distribution of value of a sample. Through improving the prediction accuracy of the possibility distribution of value of the sample, the coding efficiency is greatly improved.

The image decoding method includes: determining a context for use in a current block to be processed, from among a plurality of contexts; and performing arithmetic decoding on a bit sequence corresponding to the current block, using the determined context, wherein in the determining: the context is determined under a condition that control parameters of neighboring blocks of the current block are used, when the signal type is a first type, the neighboring blocks being a left block and an upper block of the current block; and the context is determined under a condition that the control parameter of the upper block is not used, when the signal type is a second type, and the second type is one of cbf_luma, cbf_cb, and cbf_cr.

Video coding systems or apparatus utilizing context-based adaptive binary arithmetic coding (CABAC) during encoding and/or decoding, are configured according to the invention with an enhanced binarization of non-zero Delta-QP (dQP). During binarization the value of dQP and the sign are separately encoded using unary coding and then combined into a binary string which also contains the dQP non-zero flag. This invention capitalizes on the statistical symmetry of positive and negative values of dQP and results in saving bits and thus a higher coding efficiency.

A binary arithmetic device includes an LPS/MPS determining unit that determines, using a context variable, a range length, and an offset, whether a code is an inferior probability code or a superior probability code, a renormalization processing unit that performs renormalization processing on the range length and the offset, and a context-variable calculating unit that derives the binary data of the code using a determination result and updates the context variable according to the determination result. The renormalization processing unit 15 includes a first renormalizing unit and a second renormalizing unit and a selecting unit that selects, according to the determination result, an output of the first renormalizing unit or an output of the second renormalizing unit.

An idea used herein is to use the same function for the dependency of the context and the dependency of the symbolization parameter on previously coded/decoded transform coefficients. Using the same functionwith varying function parametermay even be used with respect to different transform block sizes and/or frequency portions of the transform blocks in case of the transform coefficients being spatially arranged in transform blocks. A further variant of this idea is to use the same function for the dependency of a symbolization parameter on previously coded/decoded transform coefficients for different sizes of the current transform coefficient's transform block, different information component types of the current transform coefficient's transform block and/or different frequency portions the current transform coefficient is located within the transform block.

Methods and apparatus are provided for improved entropy encoding and decoding. An apparatus includes a video encoder (200) for encoding at least a block in a picture by transforming a residue of the block to obtain transform coefficients, quantizing the transform coefficients to obtain quantized transform coefficients, and entropy coding the quantized transform coefficients. The quantized transform coefficients are encoded using a flag to indicate that a current one of the quantized transform coefficients being processed is a last non-zero coefficient for the block having a value greater than or equal to a specified value.

Video coding systems or apparatus utilizing context-based adaptive binary arithmetic coding (CABAC) during encoding and/or decoding, are configured according to the invention with an enhanced binarization of non-zero Delta-QP (dQP). During binarization the value of dQP and the sign are separately encoded using unary coding and then combined into a binary string which also contains the dQP non-zero flag. This invention capitalizes on the statistical symmetry of positive and negative values of dQP and results in saving bits and thus a higher coding efficiency.

An audio encoder for encoding segments of coefficients, the segments of coefficients representing different time or frequency resolutions of a sampled audio signal, the audio encoder including a processor for deriving a coding context for a currently encoded coefficient of a current segment based on a previously encoded coefficient of a previous segment, the previously encoded coefficient representing a different time or frequency resolution than the currently encoded coefficient. The audio encoder further includes an entropy encoder for entropy encoding the current coefficient based on the coding context to obtain an encoded audio stream.