Picture data coding apparatus

A picture data coding apparatus for predictive coding a series of inputted frames, each of the frames being composed of picture data, and for displaying said frames on a display of a receiver at an end of a predetermined smoothing time period, said smoothing time period following a sampling operation of each frame and being provided for smoothing dispersion in time required for coding, transmitting, and decoding each sampled frame, said picture data coding apparatus comprising:

• a reference frame storage means having a capacity to store at least one frame for storing a predetermined frame;
• a coding means for sampling every predetermined number of inputted frames and for predictive coding sampled frames by using, as reference frames, at least a latest-transmitted frame stored in said reference frame storage means and a frame under transmission;
• a coded data storage means having storage areas to store at least two coded frames for storing predictive coded frames;
• a transmission means for transmitting each coded frame to the receiver via a transmission path;
• a first judging means for judging every predetermined point of time whether or not a frame under transmission can be displayed on the display of the receiver, from a remaining time before a displaying operation of the frame from a current time point, amount of coded data of the frame, and a decode time of the frame;
• a second judging means for judging whether or not each frame stored in said coded data storage means can be displayed on the display of the receiver, from a remaining time before a displaying operation of the frame from a current time point, amount of coded data of the frame, and a decode time of the frame;
• and
• a system control means for, when said first judging means has judged that the frame under transmission cannot be displayed, directing said coded data storage means to read a frame which uses a predetermined frame as a reference frame among frames stored in said storage area and to transfer the read frame to said second judging means, and for, when said second judging means has judged that the frame stored in said coded data storage means can be displayed, directing said coded data storage means to transfer said frame that has been judged to be capable of being displayed, to said coding means.

A picture data coding apparatus for predictive coding a series of inputted frames, each of the frames being composed of picture data, and for displaying said frames on a display of a receiver at an end of a predetermined smoothing time period, said smoothing time period following a sampling operation of each frame and being provided for smoothing dispersion in time required for coding, transmitting, and decoding each sampled frame, said picture data coding apparatus comprising:

• a coding means for predictive coding each inputted frame from a smallest numbered frame;
• a transmission means having a transmission buffer for storing coded frames to be transmitted, for storing coded frames coded by said coding means to said transmission buffer and transferring each coded frame from a smallest numbered frame from said transmission buffer to the receiver via a transmission path;
• a first judging means for judging whether or not a frame under transmission can be displayed on the display of the receiver at the end of said smoothing time period;
• a picture data reproduction means for applying a process opposite to the coding operation to coded frames coded by said coding means until said first judging means has been judged that a frame under transmission cannot be displayed, and for substantially reproducing picture data before the coding operation;
• and when said first judging means has been judged that a frame under transmission cannot be displayed, applying said process opposite to the coding operation to all remaining frames in said transmission buffer at that time and for substantially reproducing picture data before the coding operation;
• a reproduced data storage means having a storage area for storing at least four reproduced frames, two of said four reproduced frames being a latest-transmitted frame and a latest-coded frame among frames reproduced by said picture data reproduction means;
• a second judging means for judging whether or not every remaining frame in said transmission buffer can be displayed on the display of the receiver at the end of said smoothing time period;
• and
• a system control means for controlling said coding means to code a reproduced frame which has been first judged to be capable of being displayed, by using, as a reference frame, a latest-transmitted frame whose receipt has been informed from the receiver and further to code a next inputted frame in a same manner as a newly inputted frame by using, as a reference frame, a frame which has been coded immediately before said next inputted frame and to transfer the coded frame to said transmission means.