Willi Studer Ag

Guy W McNally

Roger Lagadec

Philip S Gaskell

Daniele P Pelloni

For both recording and replay, a digital audio tape (14) is accelerated very rapidly by a motor servo (9), motor (8) and capstan (7) so that the tape speed overshoots nominal speed range before settling back to this range in an oscillatory manner. The digital samples are recorded and replayed via a head (15), a random access memory (16) and input/output electronics (19). During recording, the store (17) is precharged by starting to write in as soon as acceleration is initiated. Read-out to the tape is initiated as soon as the tape first reaches the nominal speed range. Uniformity of samples as recorded on the tape is preserved by clocking a read address generator (21) at a rate proportional to tape speed, signaled by a tachometer (7). The write address generator is clocked at the constant sampling rate. For replay the write address generator is clocked at the tape speed rate while the read address generator (21) is clocked at the constant sample rate. Write in and read out are both initiated when the tape speed first reaches the nominal range. The addresses provided by the generators (20 and 21) are compared by a comparator (22) which provides a reference signal to the servo (9) in an arrangement such as to adjust the tape speed always in the sense to maintain a constant degree of filling of the store (17).

Method and apparatus for recording and replay of digital audio data

In producing an edited tape (31) the lead-in material up to a first edit point is separated from the lead-out material running from a second edit point by a space containing unwanted material and accommodating the actual or notional splice. The unwanted material ensures correct operation of error protection for all of the wanted material on replay. The first and second edit points are marked by codes placed on the tape (31) by a code processor (43) and supplementary head (42). During replay the digital data recovered from the tape by a head (32) is entered into a random access buffer store (34) under control of a write address generator (38) and read out to output electronics (37) under control of a read address generator (39) running at the audio sampling rate. The write address generator (38) normally runs at a rate corresponding to tape speed but the code processor detects the codes for first and second edit points and a control unit (51) stops the write address generator (38) between such points so as to discard the unwanted material. The store is then replenished by speeding up the tape by a comparator (40) and speed control unit (10) in an arrangement which preserves a constant relationship between the read and write addresses, i.e. a constant degree of filling of the memory (34).

Technique for editing interleaved digital audio data

Equidistant timing pulses are counted during the time between the arrival of a first pulse edge of a first signal sequence and the arrival of a following second pulse edge of another signal sequence and are averaged to a mean value with equidistant timing pulses of an immediately preceding count between two pulse edges of the two signal sequences. The continuously formed mean values are accumulated with mean values of preceding cycles and in each case the least significant bit is further processed.

Method and apparatus for measuring the time difference between two

A multitrack tape recorder records and replays digital data on a plurality of data tracks (15) by way of record/replay electronics (7), a record head (5) and a replay head (6). Channels (8) corresponding to the tape track (15) are provided for input to and output from the electronics (7). An additional channel (11) carries auxiliary data related to the signals in the channels (8). This data is formatted during recording by the electronics (7) into a block format compatible with the data format on channels (15) and is recorded on a separate dedicated track (16). The auxiliary information may be formatted in labels each of which has an instruction field and a parameter field. The labels can carry a wide variety of information relating to operation of the system. As one example, a label may contain in the instruction field an instruction to increase the playback gain by an amount contained in the parameter field.

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Shere, United Kingdom

Guy W McNally