JPH0676470A - Recording and reproducing device - Google Patents

Abstract

PURPOSE:To record a variable length encoding signal and to execute reproduction with a fixed tranfer rate by controlling the transfer of a recording signal in accordance with the storing quantity of a buffer. CONSTITUTION:At the time of recording, an input picture signal 1 is variable- length-encoded in accordance with the information quantity of a picture by a frame unit and stored in the buffer 3. When the storing quantity of the buffer 3 exceeds a prescribed value, a control circuit 10 transfers the signal to a recording processing circuit 4, permits an optical system to stand-by when quantity is below the prescribed value and does not transfer the signal from the buffer 3. At the time of reproducing, the signal from a reproduction processing circuit 8 is stored in the buffer 3. When the storing quantity of the buffer 3 is below the prescribed value, the control circuit 10 reproduces the signal from an optical disk 16 for a fixed period, permits the optical system 6 to stand-by when quantity exdeeds the prescribed value, transfers the signal from the buffer 3 to a decoder 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording / reproducing apparatus such as an optical disk or a magnetic disk for recording / reproducing a variable length coded signal.

[0002]

2. Description of the Related Art Conventionally, there are many known devices for recording a video signal on a recording medium by performing fixed length coding. This is because when recording a fixed-length encoded signal, if the number of revolutions of the recording medium is kept constant, the synchronization signals are aligned in a straight line in the radial direction, so during reproduction, the disc rotation and the signal cycle are synchronized. This is because it is easy to take

On the other hand, there is already an apparatus for variable-length coding a video signal and recording it on a recording medium, but it is necessary to control the rotation speed of the recording medium according to the code amount, and this control is difficult. .

[0004]

From the viewpoint of the image compression rate, the variable length coding is more efficient than the fixed length coding, and from the viewpoint of the recording / reproducing apparatus, the fixed length coding is performed. This signal is advantageous in that the disc rotation control is easier than the variable length coded signal.

The present invention solves this drawback and provides a recording / reproducing apparatus for recording a variable-length coded signal on a recording medium and reproducing the reproduced signal with a constant instantaneous and instantaneous transfer rate. The purpose is to

[0006]

SUMMARY OF THE INVENTION The present invention is an apparatus for recording / reproducing a variable-length coded signal on a recording medium, wherein during recording, information to be recorded is temporarily stored in a buffer, Is less than a predetermined value, recording of a signal on the next track is interrupted and the system waits. When the storage amount in the buffer exceeds a predetermined value, the signal is recorded on the recording medium for a certain period. During reproduction, the relative speed between the recording medium and the reproducing head, or the number of revolutions of the recording medium is kept constant, the transfer rate of the instantaneous reproduction signal is constant, or reproduction is performed in proportion to the position of the reproducing head from the center of the recording medium. , The reproduced signal is once stored in the buffer, and if the storage amount of the buffer is less than the predetermined value, the signal is reproduced from the recording medium for a certain period, and if the storage amount of the buffer exceeds the predetermined value, It is configured such that the reproduction of the signal from the track is interrupted and the waiting is performed.

[0007]

As a result, it becomes possible to record / reproduce a variable-length coded signal with a constant instantaneous transfer rate at the time of recording or reproducing, and to perform efficient encoding in accordance with the amount of information of an image. Becomes Further, since the recording / reproducing is performed at a constant instantaneous transfer rate during recording or reproduction, the rotation of the disk can be easily controlled.

Further, even in the case of different kinds of video signals and signals of a plurality of compression modes in which the bit rate per pixel is significantly different, the instantaneous or instantaneous transfer rate of the signal to be recorded or reproduced is fixed to the same recording medium. It becomes possible to do.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. In the following embodiments, an example will be described in which a video signal is used as a recording signal, an optical disk is used as a recording medium, and the video signal is variable length coded in frame units and recorded and reproduced.

In the following description, the CLV method is a method of recording or reproducing with a constant relative speed between the recording medium and the recording or reproducing head, and the CAV method is a method of recording or reproducing with the rotation speed of the recording medium being constant. I will call it.

FIG. 1 shows a block diagram of a recording / reproducing apparatus of the present invention. First, the operation during recording will be described. The input image signal 1 from the outside enters the encoder 2 and is variable length coded in frame units according to the information amount of the image. The encoded signal enters the buffer 3 and is stored therein. The control circuit 10 monitors the storage amount of the buffer 3, and when it exceeds a predetermined value, controls the buffer 3 to send a signal to the recording processing circuit 4 for a certain period, and when it does not reach the predetermined value. First, a control signal is sent to the sending control circuit 11 so that the optical system 6 stands by in the still state, and control is performed so that no signal is sent from the buffer 3 to the recording processing circuit 4.

The signal that has entered the recording processing circuit 4 is added with data such as a time code, and then enters the laser modulation circuit 5, and the output thereof modulates the semiconductor laser light source which is a component of the optical system 6. To convert electrical changes into optical changes. A signal is recorded on the disk 16 by the modulated laser light.

Next, the operation during reproduction will be described. The signal recorded on the optical disc 16 is reproduced by the optical system 6, amplified by the amplifier 7, and enters the reproduction processing circuit 8.
The signal processed by the reproduction processing circuit 8 enters the buffer 3,
Accumulated. The control circuit 10 monitors the storage amount of the buffer 3 and reproduces a signal from the optical disc 16 for a certain period when the value is less than a predetermined value, and when the value exceeds the predetermined value, the optical system 6 is stopped. The control signal is sent to the sending control circuit 11 so that the decoder 9 is put in the state of waiting in the state.
Control to send a signal to. The signal that has entered the decoder 9 is decoded and output for each frame.

The CAV control during reproduction is performed by the rotation control circuit 14
A signal from the oscillator 13 and a signal corresponding to the rotation of the optical disc 16 output from the spindle motor 15 are input to the spindle motor 1 and the rotation control circuit 14 uses the signals.
A control signal is sent to 5.

In the case of CLV control, the position detector 12 detects the position of the optical system 6, and the rotation control circuit 14 causes the spindle motor 1 to rotate at a rotation speed corresponding to the position.
A control signal is sent to 5.

As a second embodiment, control of the buffer during recording will be described with reference to FIGS.

FIG. 2 shows the flow of signals during recording. The variable length coded signal 17 is temporarily stored in the buffer 3, and the recording signal 18 is recorded on the optical disc 16 according to the storage amount. FIG. 3 shows recording according to the accumulated amount in the buffer. 3A shows a variable-length coded signal in units of frames, FIG. 3B shows the amount of data stored in the buffer, and FIG. 3C shows the operation of the printhead. The control circuit monitors the accumulated amount of variable-length coded signals input to the buffer, and if the accumulated amount exceeds half the capacity of the buffer, only half the information of the buffer capacity is transferred for a certain period at a predetermined transfer rate. Record on disc. If the buffer is less than half,
Stop recording and wait in the still state.

FIG. 4 is a diagram showing changes in transfer rate with time. FIG. 4A shows a case where the instantaneous transfer rate during recording is constant in the CAV method or the CLV method.
(B) shows the change when the instantaneous transfer rate at the time of recording in the CAV method is changed according to the position from the center of the disc. That is, as shown in FIG. 4, since the instantaneous instantaneous transfer rate is constant, the transfer rate is always constant during the information transfer period at the time of recording and reproduction.
It does not mean that the so-called average transfer rate in the period including the still period is constant.

In the CAV method, as shown in FIG. 4A, when recording is performed with a constant instantaneous transfer rate, the amount of information that can be recorded on one track of the disk is constant, so a fixed period of recording is set to one track. It may be rotated or an integral multiple thereof. At this time, the required buffer capacity is at least twice the amount of information recorded in a certain period, and at least twice the maximum value of the information amount of the variable-length coded signal.

In the CLV method, or when recording is performed by changing the instantaneous and instantaneous transfer rate according to the position from the center of the disk as shown in FIG. 4B, recording can be performed by controlling the same buffer. However, in the case of recording by the CAV method, the fixed period of recording is one rotation of the disc, but in this case, the information amount of one rotation of the disc varies depending on the track position, and therefore the fixed period of recording is set to a predetermined time. Good.

Although the control of the buffer at the time of recording has been described in the present embodiment, the operation of the buffer is exactly the same at the time of reproduction, and when the capacity of the buffer is less than half, the signal is reproduced from the disc. , When the number exceeds half, the reproduction from the disc is interrupted and the still state is waited. Further, in the present embodiment, the standard of control of recording or reproduction is half the capacity of the buffer, but the present invention is not limited to this. Further, although the recording / reproducing apparatus has been described in the present embodiment, a recording apparatus capable of performing recording control and reproduction control individually,
It goes without saying that the structure of the reproducing apparatus may be used.

When a disc recorded by the CAV system is reproduced by the CLV system, or when a disc recorded by the CLV system is reproduced by the CAV system, the signal transfer rate at the moment of reproduction is the center of the disc. It changes in proportion to the position from and the control of the buffer is exactly the same. However, the required buffer amount is twice or more the information amount of the outermost track in either case. Also, C
The same applies to the case of reproducing a disc recorded by the CAV system or the CLV system by changing the instantaneous transfer rate of the recording signal according to the position from the center of the disc in the AV system.

In the above-mentioned embodiment, the optical disk is taken as an example of the recording medium, but the same applies to the magnetic disk. Further, although the video signal is taken as an example in the above-mentioned embodiment, the same applies to the audio signal.

Further, although the above embodiment has described the case where the input signal is variable length coded, the case of the fixed length coding is considered to be a special case of the variable length coding, and therefore it is exactly the same.

In the above embodiment, the case of only one type of signal is described, but when different types of video signals or signals of a plurality of compression modes having different bit rates per pixel are recorded on the same recording medium. However, recording / reproduction can be performed in exactly the same manner by changing the instantaneous transfer rate and the buffer amount during recording or reproduction.

[0026]

The present invention is an apparatus for recording / reproducing a variable-length coded signal on a recording medium, and at the time of recording, information to be recorded is temporarily stored in a buffer, and the storage amount of the buffer is a predetermined value. If it does not satisfy the condition, the recording of the signal on the next track is interrupted and the system waits. If the accumulated amount in the buffer exceeds a predetermined value, the signal is recorded on the recording medium at a predetermined transfer rate for a certain period.

During reproduction, the relative speed between the recording medium and the reproducing head or the number of revolutions of the recording medium is constant, the instantaneous and instantaneous transfer rate of the reproduced signal is constant, and the reproduced signal is temporarily stored in the buffer. If the amount of storage in the buffer is less than the predetermined value, the signal is reproduced from the recording medium for a certain period,
When the accumulated amount of the buffer exceeds a predetermined value, the reproduction of the signal from the next track is interrupted and the device stands by.

As a result, it becomes possible to record / reproduce the variable-length coded signal at a constant transfer rate, and to efficiently code the signal in accordance with the information amount of the image. Further, since the recording and reproducing are performed at the constant transfer rate, the rotation control of the disc can be easily performed.

Furthermore, it is possible to record and reproduce different kinds of video signals and signals of a plurality of compression modes having significantly different bit rates per pixel on the same medium with a constant signal transfer rate.

[Brief description of drawings]

FIG. 1 is a block diagram of a recording / reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is a signal flow chart according to a second embodiment of the present invention.

FIG. 3A is a diagram showing a variable-length coded signal in a buffer control method. FIG. 3B is a diagram showing an accumulated amount in the buffer. FIG. 3C is a diagram showing an operation of a recording head.

FIG. 4A is a characteristic diagram when recording is performed with the instantaneous and instantaneous transfer rate being constant, and FIG. 4B is a characteristic diagram when recording is performed by changing the instantaneous and instantaneous transfer rate according to the position from the center of the disc.

[Explanation of symbols]

 1 Input signal 2 Encoder 3 Buffer 4 Recording processing circuit 5 Laser modulation circuit 6 Optical system 7 Amplifier 8 Reproduction processing circuit 9 Decoder 10 Control circuit 11 Feed control circuit 12 Position detector 13 Oscillator 14 Rotation control circuit 15 Spindle motor 16 Optical disc 17 Variable length coded signal 18 Recording signal

Claims (4)

[Claims] 1. An apparatus for recording a variable-length coded signal in a recording medium, wherein the signal to be recorded is temporarily accumulated in a buffer, and the signal is recorded in the recording medium according to the amount of accumulation in the buffer. A recording / reproducing apparatus, which controls whether recording is performed intermittently with an instantaneous transfer rate as a predetermined value, or whether recording is interrupted and waiting. 2. An apparatus for reproducing a variable-length coded signal from a recording medium, wherein the reproduced signal is temporarily accumulated in a buffer, and the signal is reproduced from the recording medium according to the accumulated amount of the buffer. A recording / reproducing apparatus, which controls whether the instantaneous transfer rate is set to a predetermined value for intermittent reproduction, or whether reproduction is interrupted and waiting. 3. Different types of video signals, or signals of a plurality of compression modes having significantly different bit rates per pixel, are recorded on the same recording medium with the instantaneous and instantaneous transfer rates at the time of recording or reproduction as predetermined values. The recording / reproducing apparatus according to claim 1, wherein recording / reproducing is performed. 4. The instantaneous transfer rate of a signal to be recorded or reproduced is constant when recording or reproducing is performed with the relative speed between the recording medium and the recording or reproducing head being constant, and the rotational speed of the recording medium is constant. 4. The recording / reproducing apparatus according to claim 1, wherein the recording / reproducing is constant or changes depending on the position from the center of the recording medium.