Many parameter set fields are encoded in a form that is modified I am
guessing for the purpose of maximizing the range of possible encoded
values but are probably more useful for the encoding of frames in their
unmodified forms. For example, both the VPS and SPS have a field called
m_maxSubLayersMinus1 but m_maxSubLayers may be more useful for analyzing
and encoding of frames.
When the unmodified form is more useful, I think it would be less
confusing to use the unmodified form with the variable name without the
modification and then modify the field at the time of encoding. That is,
use m_maxSubLayers, then at the time of encoding in TEncSbac, encode
m_maxSubLayers - 1.
This would break from naming h265 fields after the names used in the
specification but removes any thought of "Do I need to add one to
m_maxSubLayersMinus1 before using it.." or "do I need to subtract 1
before encoding it.." I don't think removing MinusX or PlusX from a
field name is going to hurt too much, especially if it's documented in
comments at it's declaration.
Of course some fields may be more useful in their modified form. Either
way, I prefer to have the name of the field match the state of the value
it holds. If anyone knows of any particular field that should be
treated one way or the other please let me know.
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