GB2222718A

GB2222718A - Digital tape recorders

Info

Publication number: GB2222718A
Application number: GB8919178A
Authority: GB
Inventors: Il-Young Noh
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 1988-08-23
Filing date: 1989-08-23
Publication date: 1990-03-14
Also published as: DE3927661A1; KR950009382B1; KR900003864A; GB8919178D0; JPH02105302A

Abstract

There is disclosed an apparatus and method capable of reducing the size of a cylinder for use in a digital audio tape recorder (R-DAT) system and miniaturizing the R-DAT system by using a drum 24 with a small diameter, by which a portable, compact R-DAT system can be realized easily and employing time expansion on recording and compression on playback. The head-drum 24 of the R-DAT system includes: an upper drum 22 whose a first head 20 and second head 21 for recording and playing audio information are symmetrically attached in a direction of a core thereof at the lower side of the cylinder surface in which the diameter of the cylinder is smaller than that of a standard cylinder by a given factor; the entire drum 24 including the upper drum 22 and a lower drum 23, said lower drum having a cylinder of the same diameter with that of the upper drum and supporting said upper drum; and a small-sized motor 25 for rotating said entire drum 24. <IMAGE>

Description

DIGITAL TAPE RECORDERS This invention relates to digital tape recorders and is concerned particularly although not exclusively with digital audio tape recorders (hereinafter referred to as R-DAT).

Generally, an R-DAT system has a drum of 30mm diameter, on which two heads are mounted, and records audio information on the tape or plays back recorded audio information by helically scanning each track of the tape. However, in a known R-DAT system, as shown in Figure 1, of the accompanying drawings, the distance from a cassette to the top of the drum reaches at least 3Om or more when the tape is inserted into the deck.

This causes a major problem when trying to miniaturize an R-DAT system.

Preferred embodiments of the present invention aim to provide an apparatus and method capable of reducing the size of a drum (cylinder) for use in a digital audio tape recorder (R-DAT) system and miniaturizing the R-DAT system by using a drum with a small diameter, by means of which a portable, compact R DAT system can be made.

According to one aspect of the present invention, a method of reducing the size of a digital magnetic tape recorder includes reducing the diameter of a drum by a given factor, the method including expanding and compressing data to be recorded and played back on and from a magnetic tape.

During recording on the tape, data may be expanded and during playback of the tape data may be read, compressed and played back.

The method may comprise making the period of a receive clock shorter than that of a transmit clock by a specified factor.

According to a second aspect of the present invention, a cylinder reducing method in a digital tape recorder includes expanding audio data to record on a tape, by reducing a diameter of a drum by a given factor, said method being able to read, compress the audio data to be recorded on the tape, and then play back recorded data on the tape.

According to a further aspect of the present invention a head-drum includes an upper drum of which a first head and second head for recording and playing audio information are symmetrically attached in a direction of a core thereof at the lower side of the cylinder surface in which the diameter of the cylinder is smaller than that of a standard cylinder by a given factor, an entire drum including the upper drum and the lower drum, said lower drum having a cylinder of the same diameter as that of the upper drum and supporting said upper drum, and a small-sized motor for rotating said entire drum.

According to a still further aspect of the present invention, apparatus for reducing a cylinder in a digital audio tape recorder/player comprises: an upper drum whose a first head and second head for recording and playing audio information are symmetrically attached in a direction of a core thereof at the lower side of the cylinder surface in which the diameter of the cylinder is smaller than that of a standard cylinder by a given factor; the entire drum including the upper drum and a lower drum, said lower drum having a cylinder of the same diameter with that of the upper drum and supporting said upper drum; a small-sized motor for rotating said entire drum; a recording/playing amplifier which amplifies recording audio data and outputs the data to a first and a second head to record the audio data on a tape, or amplifies the audio data read from the first and the second head;; a phase-locked loop which generates a play data clock from reproduced audio data which are applied from said recording/playing amplifier, and outputs the clock with said reproduced audio data; a time base controller which receives the compressed audio data to be recorded with the record data clock, expands said audio data on the basis of said record data clock, and then outputs the data to said recording/playing amplifier, or receives the reproduced audio data from said phase-locked loop and the play data clock together, compresses said reproduced audio data on the basis of said play data clock, and then outputs the audio data;; a digital signal processor which receives and processes the reproduced and compressed audio data from said time base controller, and then outputs the data to a digital-analog converter, or receives and processes the audio data to be recorded from an analog-digital converter, and then generates the compressed audio data to be recorded and the record data clock in order to output to said time base controller; and a memory which receives the recorded or reproduced audio data from said time base controller and then temporarily stores the data.

The time base controller may comprise: a multiplexer which receives the compressed audio data from the digital signal processor during recording via the first input terminal or receives the audio data that are read and reproduced by the second head from the second output terminal of the phase-locked loop during playing; a second serial-parallel circuit which converts a serial form audio data output from said multiplexer into a parallel form audio data; a first serial-parallel circuit which receives the serial form audio data reproduced by the first head from the first output terminal of said phase-locked loop and then converts the audio data into the parallel form audio data; a first buffer circuit which transfers the parallel form audio data from said first serial-parallel circuit to the memory;; a second buffer circuit which transfers the parallel form audio data from said second serial-parallel circuit to the memory; a first parallel-serial circuit which receives the parallel form audio data that are input from the memory during recording, converts the audio data into the serial form, and then outputs to the first input terminal of the recording/playing amplifier; a second parallel-serial circuit which receives the serial form audio data that are read from the memory, and then converts the audio data into the serial form; a third buffer circuit, connected between said first parallel-serial circuit and the memory, transfers the audio data that are read from the memory to the first parallel-serial circuit;; a fourth buffer circuit, connected between said second parallel-serial circuit and the memory, transfers the audio data that are read from the memory to said second parallel-serial circuit; a demultiplexer which transfers the serial form audio data that are applied from said second parallelserial circuit to a second input terminal of the recording/playing amplifier during recording or to the digital signal processor during playing; and a control circuit which, during recording, accesses the memory, controls said multiplexer and demultiplexer, the first and the second serial-parallel circuit, the first and the second parallel-serial circuit, and a first through the fourth buffer circuit, expands the compressed audio data that are applied from the digital signal processor, and outputs the expanded data to the recording/playing amplifier, or which, during playing, compresses the reproduced audio data that are applied from the phase-locked loop and then outputs the reproduced data to the digital signal processor by controlling on the basis of the play data clock that are input from the phase-locked loop and by accessing the memory.

The invention also includes apparatus substantially as herein described with reference to the accompanying Figures 2 to 6.

The invention also includes a method substantially as herein described with reference to the accompanying Figures 2 to 6.

The invention also includes a magnetic tape recorder when used with apparatus or a method substantially as herein described.

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings, in which: Figure 1 illustrates a winding arrangement of a tape on a drum of a deck of the prior art, as mentioned above; Figure 2 shows, in both plan and side views, a diagrammatic construction of a drum according to an embodiment of the present invention; Figure 3 illustrates a winding arrangement of the tape on the drum of an embodiment of the present invention; Figure 4 is a circuit diagram of an embodiment of the present invention; Figure 5 is a detailed circuit diagram of one example of a Time Base Controller of the circuit of Fig 4; and Figure 6 is an operational timing diagram illustrating an example of operation of the circuit of Figure 5.

Referring now to Figure 2, there is shown a drum assembly which comprises an upper drum 22 having a first head 20 and a second head 21 for recording and playing audio information. The first and second heads 20, 21 are symmetrically mounted in the direction of the drum core at a lower side of the drum surface, and the diameter of the drum is smaller than that of a standard drum by a given factor. The entire drum assembly 24 consists of a lower drum 23 and the upper drum 22, said lower drum 23 having a cylinder of the same diameter as that of the upper drum 22 to support said upper drum 22.

Moreover, a miniature motor 25, attached to the entire drum assembly 24, rotates said entire drum assembly 24.

Referring now to Figure 3, illustrating one example of the winding situation of the tape on the drum shown in Figure 2, and the circuit diagram of Figure 4, a recording/playing amplifier 40 amplifies audio data for recording and outputs the data to the first and second heads 20, 21 to record the audio data on the tape, or amplifies the audio data read from the first and the second heads 20, 21. A phase-locked loop 41 (hereinafter referred to as PLL) generates a play data clock from the reproduced audio data which are applied from said recording/playing amplifier 40, and outputs said clock with said reproduced audio data.A time base controller 42 (hereinafter referred to as TBC) receives compressed audio data to be recorded with a record data clock, expands said audio data on the basis of said record data clock, and then outputs the data to said recording/playing amplifier 40, or receives the reproduced audio data from the PLL 41 together with the play data clock, compresses said reconstructed audio data on the basis of said play data clock, and then outputs the audio data.A digital signal processor 43 (hereinafter referred to as DSP) receives and processes the reproduced and compressed audio data from said TBC 42, and then outputs the data to a digital-analog (hereinafter referred to as D-A) converter, or receives and processes the audio data to be recorded from an analog-digital (hereinafter referred to as A-D) converter, and then generates the compressed audio data to be recorded and the record data clock which are output to said TBC 24. Further, a memory 44 receives the audio data to be recorded or the reproduced audio data from said TBC 42 and then temporarily stores the data.

Figure 5 is a detailed circuit diagram of oneexample of the TBC 42 shown in Figure 4. A multiplexer 50 is used to receive the compressed audio data from the DSP 43 during recording via a first input terminal or to receive the audio data that are read and reproduced by the second head 21 from a second output terminal of the PLL 41 during playing. A second serial-parallel circuit 52 converts serial form audio data delivered from said multiplexer 50 into parallel form audio data. In addition, a first serial-parallel circuit 51 receives serial form audio data reproduced by the first head 20 from a first output terminal of said PLL 41, and then converts the audio data into parallel form audio data.

A first buffer circuit 53 transfers the parallel form audio data from said first serial-parallel circuit 51 to the memory 44. A second buffer circuit 54 transfers the parallel form audio data from said second serial-parallel circuit 52 to the memory 44.

A first parallel-serial circuit 57 receives parallel form audio data that are input from the memory 44 during recording, converts the audio data into serial form, and then outputs the data to the first input terminal of the record play amplifier 40. A second parallel-serial circuit 58 receives parallel form audio data that are read from the memory 44, and then converts the audio data into serial form. A third buffer circuit 55, connected between said first parallel-serial circuit 57 and the memory 44 transfers the audio data that are read from the memory 44 to the first parallel-serial circuit 57. A fourth buffer circuit 56, connected between said second parallel-serial circuit 58 and the memory 44, transfers the audio data that are read from the memory 44 to said second parallel-serial circuit 58.

A demultiplexer 59 transfers the serial form audio data that are supplied from said second parallelserial circuit 58 to the second input terminal of the recording/playing amplifier 40 during recording or to the DSP 43 during playing. A control circuit 60, during recording, accesses the memory 44, controls said multiplexer 50 and demultiplexer 59, the first and the second serial-parallel circuits 51, 52, the first and the second parallel-serial circuits 57, 58, and the first to the fourth buffer circuits 53 to 56, expands the compressed audio data that are supplied from the DSP 43, and outputs the expanded data to the recording/playing amplifier 40, or, during playing, compresses the reproduced audio data that are supplied from the PLL 41 and then outputs the reproduced data to the DSP 43 by controlling on the basis of the play data clock that are applied from the PLL 41 and by accessing the memory 44.

In Figure 6 showing one example of an operational timing diagram, PHS indicates a head switching signal during playing, a PFD the reproduced audio data which are applied to the first serial-parallel circuit 51 during playing, PSD the reproduced audio data which are applied to the second serial-parallel circuit 52 during playing, PPD the reproduced and compressed audio data which the second parallel-serial circuit 58 outputs, WHS the head switching signal during recording, WPA the compressed audio data which are applied to the second serialparallel circuit 52 during recording, WFD the expanded audio data which the first parallel-serial circuit 57 outputs during recording, and WSD indicates the expanded audio data which the second parallel-serial circuit 58 outputs during recording.

The effects and features of the illustrated arrangements will now be described in more detail with reference to Figs. 2 to 6 Firstly, in Figure 2, the diameter of the drum 24 is reduced as compared with that of a known drum.

Otherwise, the structure may be the same as that of a conventional drum. The first and the second heads 20, 21 helically scan each track of the tape by rotating as much as the azimuth degree on the basis of the rotating speed and the rotation axes. Figure 3 shows the contacting situation of the drum 24 with the tape, and the tape is wound around the cylinder wall of the drum to about 360 degrees.

Referring to Figure 4, during playing, the record play amplifier 40 amplifies the audio data, which is reproduced by the first and the second heads 20, 21, by a prescribed amplification ratio according to the rotation of the drum assembly 24 as shown in Figure 2, and outputs the reproduced data to the PLL 41 via first and the second output terminals.

Then the PLL 41 detects the rising edge and the falling edge of the reproduced audio data, which are applied from the first and the second output terminal of said recording/playing amplifier 40 to the first and the second input terminal, to generate the play data clock, and then outputs the clock and the reproduced audio data, which are applied at said first and second input terminal, to said TBC 42 via first to third output terminals.

Then, the TBC 42, which receives the reproduced audio data and the play data clock from the first to third output terminal of said PLL 41, via first to third input terminals, stores and writes the reproduced audio data into said memory 44 by accessing the memory 44 on the basis of said play data clock, and then outputs the data to the DSP 43. Next, the DSP 43 processes the compressed audio data which are applied from said TBC 42, and outputs the compressed data to the D-A converter.

Contrary to said playing procedure, during recording operation, the DSP 43 generates the compressed audio data and the data clock which are used to process and record the audio data input from the A-D converter, and then outputs them to fourth and fifth input terminals of the TBC 42 via first and second output terminals.

The TBC 42, which receives the compressed audio data and the record data clock from the first and the second output terminals of said DSP 43 via the fourth and the fifth input terminals, expands the compressed audio data by storing or reading said compressed audio data into or from said memory 44 by accessing the memory 44 on the basis of said record data clock, and then outputs the expanded audio data to the first and the second input terminals of the recording/playing amplifier 40 via the first and the second output terminals.

Then the recording/playing amplifier 40, which receives the expanded audio data from said TBC 42, outputs said audio data to the first and the second heads 20, 21, which helically scan each track of the tape according to the rotation of drum, to store the audio data on the tape.

Referring now to Figs. 5 and 6, there follows a more detailed explanation of the TBC 42 of Figure 4, which expands the compressed audio data and compresses the reproduced audio data.

The description of an operation during playback such as PHS now follows. The first reproduced audio data such as PFD in Figure 6, which the first head 20 reads and reproduces from the tape according to the head switching signal, are applied to the first parallelserial circuit 51; and the second reproduced audio data such as PSD in Figure 6, which the second head 21 reads and reproduces from the tape, are applied to the second input terminal of the multiplexer 50, and the play data clock is applied to the second input terminal of the control circuit 60.

Then the system generates first to fourth latch signals, a mode control signal, and a transmit/receive clock as the play data clock, outputs them to the second input terminal via the line 9, and supplies the sequential address and the Read/Write (R/WR) signal to the memory 44 in order to access the memory 44.

Accordingly, the multiplexer 50, which receives the reproduced audio data from the second output terminal of the PLL 41 on the second input terminal via the line 2, selects the reproduced audio data, which are entered to the second input terminal during playing by the mode control signal that is supplied from the control circuit 60, and outputs the reproduced data to the second serialparallel circuit 52.

The serial form reproduced audio data from said multiplexer 50 such as PSD of Figure 6 are applied by one bit at every moment when the receive clock is supplied from said control circuit 60. When the specified bits of audio data are applied, the specified bits of audio data are output to the second buffer circuit 54 in accordance with the second latch signal which is supplied from said control circuit 60.

The first serial-parallel circuit 51 receives the serial form audio data such as PFD of Figure 6, which are input from the first input terminal of the PLL 41 via the line 1, by one bit at every moment when the receive clock is supplied from said control circuit 60, and outputs the specified bits of the first reproduced audio data to the first buffer circuit 53 in accordance with the first latch signal which is supplied from said control circuit 60.

In this case, the first buffer circuit 53 latches the output of said first serial-parallel circuit 51 to the memory 44 via the bus line 4, and then stores into the memory 44 according to the first latch signal supplied from said control circuit 60. The second buffer circuit 54, which operates in alternating fashion with the first buffer circuit 53, latches the output of the second serial-parallel circuit 52 to the memory 44 via the bus line 4 and stores the second reconstructed audio data into the memory 44 according to the second latch signal supplied from said control circuit unit 60.

On the other hand the fourth buffer circuit 56 outputs the reproduced audio data, which are read from the memory 44 and output to the bus line 4, to the second parallel-serial circuit 50 according to the latch signal supplied from said control circuit unit 60.

Then the second parallel-serial circuit 58 receives the output of said fourth buffer circuit according to the fourth latch signal supplied from said control circuit unit 60, outputs the data to the demultiplexer 59 by one bit at every moment when the transmit clock from said control circuit 60 is applied, and then compresses the audio data such as PPD in Figure 6.

The demultiplexer 59, which selects the first output terminal in accordance with the mode control signal supplied from said control circuit unit 60, transfers the compressed audio data to the DSP 43 by delivering the output of said second parallel-serial circuit 58 to the input terminal of the DSP 43 through the first output terminal and the line 7.

Since the period of the transmit clock is shorter than that of the receive clock by a specified factor, the data compression can be achieved in which the transmitting time for the reproduced audio data is shorter than the input time of the first and the second reproduced audio data by a factor of two.

Conversely, during recording, the compressed audio data from the DSP 43 and the record data clock are output via the line 3.

Then the control circuit 60, which receives the record data clock from the first input terminal via the line 8, generates the second through the fourth latch signal, the transmit/receive clock, and the mode control signal as said record data clock, and accesses the memory 44. Then, the multiplexer 50 receives the compressed recording audio data on the line 3 and outputs the data to the second serial-parallel circuit 52 by selecting the first input terminal according to the mode control signal supplied from said control circuit 60. Then the second serial-parallel circuit 52 receives the serial form of compressed recording audio data of Figure 6 from said multiplexer 50 by one bit at every moment when the receive clock is supplied from said control unit 60.

When specified bits of recording audio data are input, the specified bits of recording audio data are output to the second buffer circuit 54 according to the second latch signal supplied from said control circuit 60.

Then the second buffer circuit 54 latches the output of said second serial-parallel circuit 52 into the memory 44 through the bus line 4 at every moment when the second latch signal is supplied from said control circuit unit 60, and then stores the output into the memory 44.

The third buffer circuit 55 receives the recording audio data, which are read from the memory 44 by the third latch signal applied from said control circuit unit 60, through the bus line 4, and then latches the data into the first parallel-serial circuit 57. The fourth buffer circuit 56, which operates in alternating fashion with said third buffer circuit 55, also receives the recording audio data, which are read from the memory 44 by the fourth latch signal applied from said control circuit 60, through the bus line 4, and then latches the data into the second parallel-serial circuit 58.

Therefore, the first parallel-serial circuit 57 receives the recording audio data output from said third buffer circuit 55 using the third latch signal applied from said control circuit unit 60. And then, the recording audio data are output to the first input terminal of the recording/playing amplifier 40 through the line 5 by one bit at every moment when the transmit clock is applied from said control circuit 60, and the first recording audio data such as WFD in Figure 6 are generated.

However, the second parallel-serial circuit 58 also receives the recording audio data output from said fourth buffer circuit 56 by the fourth latch signal applied from said control circuit 60. And then, the recording audio data are output to the demultiplexer 59 by one bit, and the second recording audio data such as WSD in Figure 6 are generated. Therefore, the demultiplexer 59, which receives the second recording audio data from said second parallel-serial circuit 58, outputs the data to the second input terminal of the recording/playing amplifier 40 through the second output terminal and the line 6 according to the mode control signal applied from said control circuit 60 during recording.

The method of expanding said compressed recording audio data is accomplished by making the period of the receive clock shorter than that of the transmit clock by the specified factor and by also making the period of the second latch signal shorter than that of the third and the fourth latch signal by the specified factors.

Since the above described embodiment reduces the diameter of the drum to miniaturize the mechanism of a deck, the advantages of implementing a handy and pocketsized R-DAT system can be obtained.

It will be understood by those skilled in the art that modifications in detail may be made to the preferred embodiment which has been shown and described above, purely by way of example, without departing from the spirit and scope of the invention.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. A method of reducing the size of a digital magnetic tape recorder by reducing the diameter of a drum by a given factor, the method including expanding and compressing data to be recorded and played back on and from a magnetic tape.

2. A method according to Claim 1, wherein during recording on the tape, data is expanded and during playback of the tape data is read, compressed and played back.

3. A method according to Claim 1 or Claim 2, comprising making the period of a receive clock shorter than that of a transmit clock by a specified factor.

4. A method substantially as hereinbefore described with reference to the accompanying Figures 2 to 6.

5. A cylinder reducing method in a digital audio tape recorder which expands audio data to record on a tape, by reducing a diameter of a drum by a given factor, said method being able to read, compress the audio data to be recorded on the tape, and then play back recorded data on the tape.

6. A head-drum including an upper drum of which a first head and second head for recording an playing audio information are symmetrically attached in a direction of a core thereof at the lower side of the cylinder surface in which the diameter of the cylinder is smaller than that of a standard cylinder by a given factor; an entire drum including the upper drum and the lower drum, said lower drum having a cylinder of the same diameter as that of the upper drum and supporting said upper drum; and a small-sized motor for rotating said entire drum.

7. An apparatus for reducing a cylinder in a digital audio tape recorder/player, said apparatus comprising: an upper drum whose a first head and second head for recording and playing audio information are symmetrically attached in a direction of a core thereof at the lower side of the cylinder surface in which the diameter of the cylinder is smaller than that of a standard cylinder by a given factor; the entire drum including the upper drum and a lower drum, said lower drum having a cylinder of the same diameter with that of the upper drum and supporting said upper drum; a small-sized motor for rotating said entire drum; a recording/playing amplifier which amplifies recording audio data and outputs the data to a first and a second head to record the audio data on a tape, or amplifies the audio data read from the first and the second head;; a phase-locked loop which generates a play data clock from reproduced audio data which are applied from said recording/playing amplifier, and outputs the clock with said reproduced audio data; a time base controller which receives the compressed audio data to be recorded with the record data clock, expands said audio data on the basis of said record data clock, and then outputs the data to said recording/playing amplifier, or receives the reproduced audio data from said phase-locked loop and the play data clock together, compresses said reproduced audio data' on the basis of said play data clock, and then outputs the audio data;; a digital signal processor which receives and processes the reproduced and compressed audio data from said time base controller, and then outputs the data to a digital-analog converter, or receives and processes the audio data to be recorded from an analog-digital converter, and then generates the compressed audio data to be recorded and the record data clock in order to output to said time base controller; and a memory which receives the recorded or reproduced audio data from said time base controller and then temporarily stores the data.

8. Apparatus for reducing a cylinder in a digital audio tape recorder/player, wherein said time base controller comprises: a multiplexer which receives the compressed audio data from the digital signal processor during recording via the first input terminal or receives the audio data that are read and reproduced by the second head from the second output terminal of the phase-locked loop during playing; a second serial-parallel circuit which converts a serial form audio data output from said multiplexer into a parallel form audio data; a first serial-parallel circuit which receives the serial form audio data reproduced by the first head from the first output terminal of said phase-locked loop and then converts the audio data into the parallel form audio data; a first buffer circuit which transfers the parallel form audio data from said first serial-parallel circuit to the memory;; a second buffer circuit which transfers the parallel form audio data from said second serial-parallel circuit to the memory; a first parallel-serial circuit which receives the parallel form audio data that are input from the memory during recording, converts the audio data into the serial form, and then outputs to the first input terminal of the recording/playing amplifier; a second parallel-serial circuit which receives the serial form audio data that are read from the memory, and then converts the audio data into the serial form; a third buffer circuit, connected between said first parallel-serial circuit and the memory, transfers.

the audio data that are read from the memory to the first parallel-serial circuit; a fourth buffer circuit, connected between said second parallel-serial circuit and the memory, transfers the audio data that are read from the memory to said second parallel-serial circuit; a demultiplexer which transfers the serial form audio data that are applied from said second parallel serial circuit to a second input terminal of the recording/playing amplifier during recording or to the digital signal processor during playing; and a control circuit which, during recording, accesses the memory, controls said multiplexer and demultiplexer, the first and the second serial-parallel circuit, the first and the second parallel-serial circuit, and a first through the fcurth buffer circuit, expands the compressed audio data that are applied from the digital signal processor, and outputs the expanded data to the recording/playing amplifier, or which, during playing, compresses the reproduced audio data that are applied from the phase-locked loop and then outputs the reproduced data to the digital signal processor by controlling on the basis of the play data clock that are input from the phase-locked loop and by accessing the memory.

9. Apparatus substantially as herein described with reference to the accompanying Figures 2 to 6.

10. A method substantially as herein described with reference to the accompanying Figures 2 to 6.

11. A magnetic tape recorder when used with apparatus or a method as claimed in any of the preceding claims.