Floating point type digital signal reversible encoding method, decoding method, devices for them, and programs for them

A decoding method for a digital signal in a floating-point format, comprising:

• (a) a step of decoding and expanding a first code sequence to produce a first digital signal sample in an integer format;
• (b) a step of producing a difference signal based on difference information;
• (c) a step of converting said first digital signal sample in the integer format into a second digital signal sample in the floating-point format;
• and
• (d) a step of combining said second digital signal sample in the floating-point format and said difference signal to produce a third digital signal sample in the floating-point format.

A lossless coder for a digital signal in a floating-point format, comprising:

• an integer formatting part that converts an input first digital signal sample in a floating-point format into a second digital signal sample in an integer format;
• a first compressing part that losslessly compresses a sequence of second digital signal samples in the integer format to produce a first code sequence;
• and
• a difference producing part that produces a difference signal corresponding to the difference between said second digital signal sample in the integer format and said first digital signal sample in the floating-point format,
• in which said first code sequence and difference information corresponding to said difference signal are output as a coding result.