JPH0528641A - Variable speed disk playback device - Google Patents

Abstract

(57) [Summary] [Purpose] The playback time can be varied according to the playback speed specified by the user without changing the pitch of the playback voice. [Structure] A time axis correction memory-9, an input device 6 for designating a reproduction speed, and a signal writing control circuit 1 for the memory.
0 and a read control circuit 1 for controlling the read of signals from the memory according to the reproduction speed designated by the input device.
1, a control signal indicating that writing to the memory is possible, a control device 5 for controlling the reproduction state of the disc according to the state of the control signal, and a pitch correction control device 16 for audio signals.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for reproducing a digital audio signal recorded on a recording medium such as a digital disk.

[0002]

2. Description of the Related Art A conventional variable speed disc reproducing apparatus is disclosed in, for example, Japanese Unexamined Patent Publication No. 2-252173. For example, when the reproducing speed is 1/2 times, the memory is written at the same clock as when the writing speed is 1 times. At the time of writing and reading, the reproduction speed is made variable by reading from the memory with 1/2 clock and performing digital interpolation to compensate the cutoff frequency after D / A conversion. Similarly, it is also possible to correspond to reproduction speeds of 1/4 speed, 1/8 speed, 1/16 speed, and 1/32 speed.

[0003]

However, the above-mentioned conventional method has a problem that a variable speed of 1 × speed or more cannot be achieved. Further, there is a problem in that it is impossible to correct the change in the pitch of the reproduced voice caused by changing the reproduction time. An object of the present invention is to solve the above-mentioned problems, and a variable speed disc that can be played back faster or slower than at 1 × speed and that can change the playback time without changing the pitch of the reproduced voice. It is to provide a reproducing apparatus.

[0004]

In order to achieve the above object, a variable speed disc reproducing apparatus according to the present invention has a memory for storing a digital audio signal, an input device for specifying a reproducing speed, and a memory. A signal write control circuit,
A read control circuit that controls the reading of signals from the memory according to the playback speed specified by the input device that specifies the playback speed, a control signal indicating that writing to the memory is possible, and writing to the memory is possible. A control device for controlling the reproduction state of the disc according to the state of the control signal and a control device for correcting the pitch of the sound of the audio signal reproduced at the specified reproduction speed.

[0005]

According to the present invention, with the above configuration, the audio signal written in the memory is read from the memory at a speed corresponding to the reproduction speed designated by the input device, and the pitch of the reproduced audio signal is adjusted. The correction enables variable speed reproduction without changing the pitch of the voice. In addition, by a control device that controls whether the disc is reproduced or paused by a signal indicating that writing to the memory is possible,
Variable speed reproduction can be performed without interruption of sound.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a block diagram of an embodiment of the present invention. Reference numeral 1 is a digital disk, and 2 is an optical pickup having a disk rotating means and a disk radial moving means. An amplifier 3 includes a servo control circuit for an optical pickup. 4 is a signal processing IC, 5 is a controller, 6
Is an input device, 7 is a video signal processing circuit, and 8 is a three-stage.
Element, 9 is a time axis correction memory, 10 is a write controller, 11 is a read controller, 12 is a timing generation circuit, 13 is a crystal oscillator, 14 is a voltage controlled oscillator, 15
Is a voice expansion circuit, 16 is a pitch correction control device, 17 is a digital-analog converter, and 18 is an audio output.
Data is recorded on the digital disk 1 in the format shown in FIG. In this embodiment, one block is 2352
In order to identify the type of data at the beginning of the data area, a total of 4 bytes including 12 bytes as a synchronization signal, 3 bytes as time information, 1 byte as recording information and 1 byte as recording format information are recorded as management information. Record the identification signal. As data, a video signal or an audio signal compressed to 8 bits is recorded. The audio signal block and the video signal block are alternately arranged in order to reproduce the audio signal without interruption. First, the signal recorded on the digital disk 1 is converted into an electric signal by the optical pickup 2, amplified by the amplifier 3, binarized, and then by the signal processing IC 4.
14-8 conversion, interleave demodulation, error correction detection,
Scramble demodulation and synchronization signal processing are performed. The control of the servo system at the time of reproducing the disc is performed by the control device 5 through the amplifier 3 and the signal processing IC 4. Signal processing IC
2 is transferred to the video signal processing circuit 7 in the case of a video signal according to the state of the identification signal in FIG. 2 and demodulated according to the recording format. On the other hand, in the case of a voice signal, it is written in the time axis correction memory 9 via the three-state element 8. The write address of the time axis correction memory-9 is generated by the write control circuit 10, and the reference clock of the write control circuit 10 is a clock generated by the crystal oscillator 13 which is also the reference clock of the signal processing IC 4,
The timing generation circuit 12 divides and generates the frequency. On the other hand, the read address of the time axis correction memory-9 is generated by the read control circuit 11, and the reference clock of the read control circuit 11 is output by the control device 5 according to the information of the reproduction speed designated by the input device 6. The clock generated by the voltage controlled oscillator 14 according to the reference voltage is supplied to the timing generation circuit 12
It is divided by and generated. The data read out from the time base correction memory-9 is displayed by the voice expansion circuit 15 in the 2's complement display.
And is input to the pitch correction control device 16. In the pitch correction control device 16, in order to correct the change in the pitch of the reproduced voice caused by the time base correction by the read clock specified by the input device 6, the reproduction speed information input from the control device 5 Correct the pitch of the reproduced voice. The output of the pitch correction control device 16 is converted into an analog signal by the digital-analog converter 17 and output from the audio output 18.

In the present embodiment, when the reproduction speed is increased, the reproduction speed is set to less than twice the normal reproduction speed, and the optical pickup 2 is included so that the data in the time base correction memory 9 exists exactly. The rotating means of the disk is usually 2
The disc is reproduced at twice the number of rotations, and the data is transferred to the time base correction memory 9 while repeating the reproduction and the temporary stop by the control signal of the timing generation circuit 12.

FIG. 3 shows a waveform when the reproduction speed is increased. A waveform A indicated by time T1 is a waveform during normal reproduction. The waveform B read from the time base correction memory-9 by the read control circuit 11 is time-compressed to T2 / T1 = 3/4, while the frequency of the reproduced sound is increased by 4/3. The pitch correction circuit 16 lowers the frequency of the reproduced sound by 3/4 as shown by the waveform C, so that the reproduction time can be compressed to 3/4 times as much as the normal reproduction without changing the pitch. it can. FIG. 4 shows a waveform when the reproduction speed is lowered. A waveform A indicated by time T1 is a waveform during normal reproduction. The waveform B read by the control circuit 11 from the time base correction memory-9 is T2 / T1 = 5/4.
However, the frequency of the reproduced sound is lowered by 4/5. In the pitch correction circuit 16, the frequency of the reproduced sound is increased by 5/4 as shown by the waveform C, so that the reproduction time can be extended to 5/4 times without changing the pitch as compared with the normal reproduction. it can.

FIG. 5 shows the generation timing of the data write control signal to the time base correction memory-9. In the state A, the read address and the write address are at the positions shown in the figure, and the data writing is possible. In state B, the speed of updating the write address is higher than that of updating the read address, so both addresses approach a position where the write address may overtake the read address. At this time, the timing generation circuit 12 sends write prohibition information to the control device 5, and the control device 5
Disc reproduction is temporarily stopped for the signal processing IC 4 and the amplifier 3. In state C, the update of the write address is stopped, whereas the update of the read address is performed regularly, so both addresses reach the position where there is no possibility that the write address will overtake the read address. Leave. At this time, the timing generation circuit 12 sends information to the control device 5 to release the write inhibition, and the control device 5 restarts the disc reproduction to the signal processing IC 4 and the amplifier 3. Thereafter, by repeating the state ABC, the control is performed so that the data in the time base correction memory 9 exists without excess or deficiency.

As described above, according to the present embodiment, the number of revolutions of the disk is doubled during the normal reproduction, and the time axis correction memory is
By performing the reproduction and the pause depending on the state, the reproduction can be performed at the reproduction speed designated by the input device, and the reproduction time can be changed without changing the pitch of the reproduced voice.

[0012]

As described above, according to the present invention, the read address for changing the time axis is controlled according to the reproduction speed designated by the input device, and according to the states of the write address and the read address. Since the disc can be reproduced and paused, the disc reproduction time can be varied according to the reproduction speed designated by the user. Also, because the circuit that corrects the pitch can correct the change in the pitch of the playback sound that is caused by varying the playback time, the playback time of the disc can be changed at the playback speed specified by the user without changing the pitch of the playback sound. It can be changed.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention,

FIG. 2 is a diagram showing a recording format of data used in this embodiment,

FIG. 3 is a waveform diagram when time compression is performed according to the present invention,

FIG. 4 is a waveform diagram when time extension is performed according to the present invention,

FIG. 5 is a state diagram showing generation conditions of a data write control signal of a time correction memory.

[Explanation of symbols]

1 ... Digital disc, 2 ... Optical pickup, 3 ... amplifier, 4 ... Signal processing IC, 5 ... Control device, 6 ... input device, 7 ... Video signal processing circuit, 8 ... Three-state element, 9 ... Time axis correction memory, 10 ... Writing control device, 11 ... Read-out control device, 12 ... Timing generation circuit, 13 ... Crystal oscillator, 14 ... Voltage controlled oscillator, 15 ... voice decompression circuit, 16 ... Pitch correction control device, 17 ... Digital-analog converter, 18 ... Audio output.

Claims (2)

[Claims] 1. A device for reproducing a digital audio signal recorded on a recording medium, a memory for storing the digital audio signal, an input device for designating a reproduction speed, and a signal writing control circuit for the memory. A read control circuit for controlling the reading of a signal from the memory according to the reproduction speed designated by the input device for designating the reproduction speed, and a control signal indicating that writing to the memory is possible, A variable speed disc reproducing apparatus comprising a control device for controlling a reproducing state of a disc according to a state of a control signal indicating that the memory is writable. 2. The variable speed disc reproducing apparatus according to claim 1, further comprising a control device for compensating the pitch of the sound of the audio signal reproduced at the specified reproducing speed.