| 摘要 |
<p>PURPOSE:To utilize effectively a data transmission period by coding a digital video signal at a high compression rate and controlling adaptively bit allocation to two frame data when the data quantity of a coded output is made constant for each prescribed period. CONSTITUTION:The difference between an input frame P and a frame I generated by a local decoder is detected by a subtractor circuit 23, its absolute value is integrated for each block and an integrated output Ef is compared with two threshold levels Th1, Th2 at a comparator circuit 26. Data transmission of a block having a relation of Ef<=Th1 is omitted, and difference data of blocks having a relation of Th1<Ef<Th2 are subjected to DC transformation and processing of variable length coding. Blocks having the relation of Ef>=Th2 are subjected to in-frame coding processing. Since three modes are in existence as coding results of the frame P, the quantity of data generated from the frame P is fluctuated. Since the quantity of data generated from the frame P is less, data of excess blocks are added to data from the frame I and then bit allocation data T-B and B to the two frames are generated.</p> |
