| 摘要 |
The pictures of a video signal (a1) are coded and quantized in data blocks by a hybrid coder (4). A quantizer (404) is controlled in dependence upon the filling level of a buffer memory. To improve the bit rate reduction without any loss of picture quality in a standardized hybrid coder, circuitry is provided with which in special cases the usual control of the quantizer (404) is replaced by another type of control. There is such a special case when a data block is recognized as being associated with the background of a scene. This data block is then transmitted with high accuracy (very fine quantization), whereas the data blocks of the subsequent video pictures associated with the same background are not transmitted at all (coarsest quantization).
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