Method for controlling the filling of the buffer memory of a picture coder, and controlling device for carrying out the method

Abstract

Abstract The invention relates to a method for controlling the filling of the buffer memory of a picture coder in which the digital values representing the pictures are quantised according to a quantisation scale defined by a controlling parameter Par (R,n,j) which is a function of the filling value (R). The method consists in making the value of the controlling parameter progress over a family of graphs (GR1,...,GR6), each graph comprising a horizontal plateau for all the filling values lying between 0 and 80% of the capacity of the buffer memory, and comprising an exponential part for the filling values lying between 80 and 100%. One graph is selected for the duration of an entire picture. The value of the parameter moves over this graph in the course of the coding of this picture. Each graph is defined by its plateau value, and the method consists in choosing a plateau value such that the current picture, if it is very similar to the preceding picture, will cause a filling of the buffer memory which will remain between 20% and 80%, this allowing the controlling parameter to be kept absolutely constant during at least the duration of an entire picture. For a sequence of virtually stationary pictures, the controlling parameter remains almost constant. This is a significant advantage, since the eye is very sensitive to temporal noise in the pictures. Application to the coding of television pictures. <IMAGE>

Inventors

• 👤 Philippe Tourtier
• 👤 Claude Perron
• 👤 Jean-Yves Babonneau

Bibliographic Details