Processing wherein a measurement signal and an erasure signal are recorded on adjacent tracks of a recordable tape 10 by one recording head HWi of n (i=1 to n) recording heads is effected on n recording heads, and measurement signals are recorded on n tracks substantially simultaneously by n recording heads HW1 to HWn in standard operation state. Then, reproducing heads with respect to thus obtained two kinds of tracks are displaced in track width directions, characteristic curves of reproduced signal waveform amplitudes of measurement signals displacement (off-track) amounts of tracks are obtained, half widths of these characteristic curves are assumed to be expedient track width and a variable Ri optimum and a variable Ri now corresponding to track widths of two kinds of tracks are obtained. Then, deviation between the variable Ri optimum and the variable Ri now is adjusted to become smaller than a desired value.

The object of the present invention is to reduce the load and specification requirements on the network and the video server. The buffer usage rate is counted and supplied to the tape driving controller 7. In the reproduction mode, the tape driving controller 7 decreases the running speed of a video tape when the buffer usage rate is larger than the proper value. And when the buffer usage rate is smaller than the proper value, the tape driving controller 7 increases the running speed of the video tape. Moreover, in the recording mode, the tape driving controller 7 stops the tape motion temporarily if the transmission speed of the network is slow and the buffer usage rate declines lower than the proper value. And if the buffer usage rate increases over the proper value, the tape driving controller 7 resumes the tape driving to record signals. Thus, the reproduction speed or the recording speed by the tape driving device 3 can be coincided with the transmission speed of the network.

A scanner (3-85, 8-85, 9-85) for use in a helical scan magnetic transducing apparatus has a periphery upon which plural read tranducing elements (3-82) and plural write transducing elements (3-80) are mounted non-symmetrically. The plural write transducing elements are physically situated on the periphery of the scanner in M number of local groups (3-81), wherein the plural read transducing elements are physically situated on the periphery of the scanner in N number of local moveable groups (3-83.sub.1, 3-83.sub.2), and wherein M<N. Each of the moveable groups has a separate actuator (89) for adjusting position of the group.

To assure good data playback characteristics even when reading data from a magnetic tape having recording tracks at a narrow pitch, a data recording and/or reproducing apparatus is provided which includes a tape feeder 7 to feed a magnetic tape 100 in which data is recorded on recording tracks formed obliquely to the moving direction of the magnetic tape 100, a magnetic head 4 including a playback head having a width smaller than the recording width of the recording tracks to read data from the magnetic tape 100 and a record head to write data to the magnetic tape 100, a rotating drum 5 on which the magnetic tape 100 is scanned by the magnetic head 4, a rotating drum controller 6 to allow the playback head to scan the recording tracks at least two times in order to detect data recorded in the magnetic tape 100, and a read signal processor 3 to reproduce data recorded in the magnetic tape 100 from the data detected by the playback head having been allowed by the rotating drum controller 6 to scan the recording tracks the plurality of times.