Decoder, Encoder And Method For Supporting Adaptive Dependent Quantization Of Transform Coefficient Levels

Abstract: A decoder configured to decode residual levels, which represent a prediction residual, from a data stream, and sequentially dequantize the residual levels by selecting a quantizer out of a set of default quantizers depending on a current transition state, dequantizing a current residual level using the quantizer to obtain a dequantized residual value, and updating the current transition state depending on a current residual level's characteristic obtained by an application of a binary function onto the current residual level, and depending on a quantization mode information contained in the data stream. The decoder is configured to reconstruct a media signal using the dequantized residual values. The current transition state transitions, according to a surjective mapping which depends on the quantization mode information, from a domain of combinations of a set of one or more transition states with the current residual level's characteristic onto the set of one or more transition states, wherein a cardinality of the set of one or more transition states differs depending on the quantization mode information. Additionally, the decoder is configured to perform, whatever the quantization mode information is, the selection of the quantizer by mapping, using a first mapping, a predetermined number of bits of the current transition state onto the default quantizers, the predetermined number and the first mapping being equal whatever the quantization mode information is.

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