| 摘要 |
In a digital coder of the type in which a signal is formed and subject to a transform, for example, a discrete cosine transform 12, the signal is applied to a quantizer 14 with variable coarseness of quantization. The quantization coarseness is controlled by control circuit 32 in response to the occupancy of a buffer 26 following the quantizer so as to prevent buffer overflow or underflow. The control circuit 32 is responsive to the buffer occupancy to generate a quantizing step size control signal which varies relatively slowly with buffer occupancy over a central range of buffer occupancies and varies relatively rapidly with buffer occupancy in top and bottom ranges respectively above and below the central range. <IMAGE> |
