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A comment on A working entropy encoder with output below the Shannon limit. Parent comment

Re:A working entropy encoder with output below the Shannon l... by gliptic on Monday June 24, 2024 @04:52PM (#40780615)
With arithmetic coding this requires 1 bit to store: the value of the first bit. The other is known with 100% probability. This is very simple to implement, especially with bit-wise arithmetic coding.

The problem is that the Shannon limit doesn't apply to your example. A fixed 1:1 ratio bit string is not I.I.D.

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Re:A working entropy encoder with output below the Shannon l... by ajb on Monday June 24, 2024 @05:24PM (#40780985)
This. Optimal use of an arithmetic encoder is with P(symbol | all previous symbols), not just P(symbol). Obviously there are practical problems with storing all possible contingency tables, so for something like HEVC there is quite a lot of effort in identifying where this matters.
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