U.S. Philips Corporation

Reinier B Klein Gunnewiek

Gerrit J Keesman

Imran A Shah

A device comprising an MPEG encoder (2) is provided with a preanalyser (8) which encodes each picture with a fixed step size (Q.sub.2). The preanalyser is coupled to a computing circuit (9) which computes, for each type of (I, P, B) picture, a target value (T) for the number of bits for encoding said picture, as well as a suitable distribution of the target value among the macroblocks of the picture. A proportionally integrating control circuit (7) controls the quantization step size (Q.sub.1). Since the PI control circuit does not introduce any residual errors, the desired number of bits per picture or per group of pictures is achieved within narrow limits. The output signal is eminently suitable for recording and subsequent editing.

Motion-compensated predictive encoder in which groups of pictures are

A device for encoding a video signal comprises a picture transformer (22), a quantizer (23) and a variable-length encoder (24), as well as distribution device (6) for distributing a global target value (T) for the number of bits per picture or group of pictures in local target values (T.sub.n) for separate macroblocks of each picture. The device for encoding is provided with proportionally integrating control device for for controlling the quantization step size (Q.sub.1) in such a way that the buffer contents (b) of an output buffer (4) are in conformity with the target value. Since the PI control circuit does not introduce any residual errors, the desired number of bits per picture or group of pictures is achieved within narrow limits. The output signal is eminently suitable for recording and subsequent editing.

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Eindhoven, Netherlands

Reinier B Klein Gunnewiek