Buffer capacity change monitoring method and apparatus

A buffer capacity change monitoring apparatus for monitoring change in buffer capacity extent of a variable capacity buffer having a usable region, when the usable region has been reduced to a required threshold value for expansion, comprising:

• a reference value calculation means to calculate, using said threshold value and buffer capacity extent at an arbitrary point in time, a reference value which corresponds to said buffer capacity extent at said arbitrary point in time;
• and
• a display means for displaying change of said buffer capacity extent according to said reference value calculated by said reference value calculation means;
• a usage ratio calculation means for determining a current usage ratio as
• current buffer usage amount / buffer capacity extent * 100;
• a current expandable amount calculation means for determining and displaying a current amount of possible buffer expansion as initial buffer capacity extent times a required expansion unit times a number of expansions possible;
• a cumulative expansion amount calculation means for determining a cumulative expansion amount by multiplying a required expansion unit by a cumulative number for the number of expansions;
• and
• a numerical value display means for displaying a type and value of said reference value determined by said reference value calculation means, and displaying a value determined by said calculation means for each buffer.