Robert Boschgmbh

Rudolf Wilhelm

Jurgen Heitmann

Hans-Peter Maly

This invention concerns a method of reproducing, at a selectable magnetic tape speed different from that used during the recording, a video signal stored in a plurality of separate tracks inclined to the center line of the magnetic tape by means of a head wheel carrying peripherally arranged magnetic heads, wherein the addresses of reproduced lines of picture information are derived solely from the composite signal reproduced from the magnetic tape, wherein useful lines are read into respective locations of a picture store in accordance with these line addresses, and wherein the stored lines are read out from the store in a predetermined sequence. In the embodiment described the line addresses are derived by a counter to the counting input of which are delivered pulses which correspond to that of the horizontal synchronizing pulses taken from the magnetic tape, to the resetting input of which are delivered pulses which correspond to the vertical synchronizing pulses taken from the magnetic tape, and to a third input of which are delivered pulses the frequency of which corresponds to the frequency of cross modulation disturbances and each of which causes a change in the registered count by an amount which is determined by the registered count itself and whether the tape reproduction speed is greater or less than the recording speed.

Method and apparatus for the variable speed reproduction of a video

A head wheel is rotated at a predetermined, essentially constant speed within a tape cylinder over which a tape is guided in a spiral path, on which video signal tracks are recorded in inclined track portions. The instantaneous position of the head wheel is determined, for example by a tacho generator applying signals to a counter, phase-synchronized by the outputs from the head wheel tacho generator. The instantaneous position of the tape is determined, for example from sensing the cross modulation of signals derived from the head as the head crosses from one track portion to another, or by sensing the phase jump of the pulse sequence of the horizontal synchronization signals; the two position signals are combined in a logic stage so that a line address can be derived of a signal transduced at any one instant by said head from an incremental area of the tape, the signal being associated with the line address for storage, for example in a memory for subsequent re-recording or reproduction at a time relation (slow motion or fast motion) differing from the original recording speed.

Method and system for speed-modified reproduction of video signals

The invention provides an apparatus for producing video frequency color value signals which correspond to a desired arrangement of vertical or horizontal color bars on a television screen. In the case of vertical color bars the apparatus derives during each line period an identical series of pulses having a multiple of the line frequency. Each series of pulses is applied to a binary counter which provides as output a sequence of sets of binary signals. This sequence of sets of binary signals is translated by a pre-programmed store into a further sequence of sets of binary signals, these latter sets of signals being applied to a digital-to-analogue converter adapted to derive therefrom corresponding sets of color value signals. Each set of color value signals defines a differently colored line segment. The effect of this operation over a plurality of successive line periods is to build up a number of vertical color bars each composed of vertically adjacent line segments of the same color derived from identical sets of color value signals occurring in successive line periods. In the case of horizontal color bars the apparatus operates in a similar manner except that the series of pulses initially produced is at a fraction of the line frequency and is derived once for each field period rather than once for each line period.

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Klein-Gerau, Germany

Rudolf Wilhelm