JP2661541B2 - Optical disk drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk apparatus for reproducing digitally compressed image data, and more particularly to an optical disk apparatus capable of reproducing data at a high speed of about 2.times.

[0002]

2. Description of the Related Art In recent years, in order to efficiently store images on an optical disk such as a CD-ROM, image data to be stored is intra-coded, that is, intra-field or intra-frame encoding, and inter-field or frame encoding. It has been proposed that compression be performed by forward encoding and bidirectional predictive encoding, which are intermediate encodings, before storing. Intra coding is a coding method that uses information only in one image. When the intra-coded image data is decoded, one image can be reconstructed using only the data. Further, forward prediction coding and bidirectional prediction coding are methods for coding a difference from an image positioned forward or backward in time, and decoding only data subjected to forward prediction coding or bidirectional prediction coding. Even though one image cannot be reconstructed, the amount of image data to be encoded can be greatly reduced.

Conventionally, high-speed image reproduction such as cue (fast-forward) and review (reverse fast-forward) involves rotating an optical disk at a speed that is not different from a normal rotation speed, and reading only intra-coded data from the optical disk. It was done by. This is because the intra-coded image data can reconstruct one image from itself.

[0004]

However, usually, the intra-coded image data is included in only one in ten or more frames. For this reason, in the conventional high-speed reproduction in which only the intra-coded image data is reproduced, it is inevitable that the temporal resolution significantly deteriorates.

[0005] In particular, in order to reproduce at double speed and triple speed using only intra-coded image data,
An image obtained from image data corresponding to one image is
Until the next intra-coded image data is decoded and reproduced, it must be reproduced a plurality of times. For this reason, if only the intra-encoded image data is used as in the related art, a smooth reproduced image can be reproduced at 2 × speed.
It is impossible to display at triple speed.

Normally, the time required for reading out one field or one frame of image data that has been intra-coded from the optical disk and decoding the image data is determined by the time required for decoding one field or one frame of image data. Time for outputting to image display unit and reproducing (1 frame = 1/30)
sec) takes longer. Therefore, during the time when one decoded image is being reproduced, the data of the image to be displayed next cannot be decoded. Therefore, one image that has already been reproduced must be repeatedly reproduced until the data of the image to be displayed next is decoded. As described above, the conventional high-speed reproduction technique has a problem that images cannot be reproduced one by one continuously.

[0007] Further, the sound is usually muted not only in high-speed reproduction but also in variable-speed reproduction. This is because even if the audio data is decoded, the obtained audio cannot be reproduced together with the image.

The present invention has been made in view of such circumstances, and has as its object to display a smooth image in reproduction at a speed slightly higher than a normal reproduction speed such as double speed or triple speed, It is still another object of the present invention to provide an optical disk device capable of reproducing sound together with an image.

[0009]

An optical disk apparatus according to the present invention reads image data and audio data from an optical disk and generates an image data signal and an audio data signal in accordance with the read image data and audio data. Signal processing means, image decoder means for receiving the image data signal from the signal processing means and generating a reproduced image signal based on the received image data signal, and high-speed reproduction control for switching from normal reproduction to high-speed reproduction and a control means for generating a signal, the and the normal reproduction even during high-speed reproduction
Like, all data from the optical disk can be
The image data signals by reading the image data of Te, the image decoder means, and the image data decoding means for decoding the image data signals, sometimes received a high-speed reproduction control signal from the control means, the image Of the data signals , only the signals corresponding to the intra-coded image data and the forward prediction-coded image data are decoded and output as the reproduced image signal. During normal reproduction, the image data signal is decoded.
Means for decoding all the signals and outputting the decoded signals as the reproduced image signal, whereby the object is achieved.

[0010] The optical disk apparatus further includes audio decoder means for generating a reproduction audio signal based on the audio data signal from the signal processing means, and the audio decoder means transmits the high-speed reproduction control signal from the control means. When a signal is received, the first of the audio data signals
, And without demodulating the portion generated in the second period following the first period,
Outputting only the demodulated portion generated during the first period as the reproduced audio signal; otherwise, decoding the entire audio data signal and outputting it as the reproduced audio signal;
The first period and the second period may be alternately repeated.

In the optical disk device, the first period corresponds to nGOP (n ≧ 1), and the second period corresponds to mGOP.
It may correspond to P (m ≧ 1).

The optical disk apparatus further includes a motor for rotating the optical disk, and motor driving means for driving the motor, wherein the motor driving means receives the high-speed reproduction control signal from the control means. To
Even if the speed at which the image data and the audio data are read from the optical disc can be increased by increasing the rotation speed of the motor in accordance with the high-speed reproduction control signal to be higher than the minimum rotation speed required for normal reproduction. Good.

[0013] The optical disk apparatus further includes audio decoder means for receiving the audio data signal from the signal processing means and generating a reproduced audio signal based on the received audio data signal. Means for demodulating the audio data signal, and when receiving the high-speed reproduction control signal from the control means, temporally compresses the demodulated audio data signal and outputs it as the reproduced audio signal. And a means for outputting the demodulated audio data signal as the reproduced audio signal without compression.

[0014]

According to the present invention, all image data recorded on an optical disk is read regardless of the speed at which an image is reproduced. At the time of normal reproduction, all of the read image data is decoded and output as a reproduced image signal. At the time of high-speed reproduction, intra-coded image data of the read image data and forward prediction are used. Only the encoded image data is output as a reproduced image signal. Thus, by reading out only the intra-coded image data from the optical disc, decoding the data, and outputting the decoded data, the time resolution is improved and a smoother than the conventional optical disc apparatus that performs high-speed image reproduction. Image reproduction can be performed.

Further, at the time of high-speed reproduction, by changing the number of rotations of the motor to a value equal to or higher than the minimum number of rotations necessary to realize the transfer rate at the time of normal reproduction, all image data can be reproduced even at the time of high-speed reproduction. Can be read.

Further, according to the present invention, the audio data signal generated in the first period is demodulated, and the audio data signal output in the subsequent second period is omitted without being demodulated,
Since the audio data signal generated in the first period is output as a reproduced audio signal until the next first period starts,
The sound is reproduced almost in synchronization with the image.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the principle of a method for encoding image data recorded on an optical disk will be described.

FIG. 1 shows a frame sequence according to an image coding method proposed by MPEG. One frame corresponds to one screen (picture) and is encoded in units of pictures. There are three types of pictures: I picture, P picture, and B picture. An I picture is a picture obtained by intra-frame coding (intra coding). For intra-frame encoding, information closed only in one image is used. Intra-frame coding is generally inefficient. The P picture is the I picture located ahead in time.
This is a picture obtained by encoding using a picture or a P picture as a reference for taking a difference. As the B picture, an interpolated image made of an I picture or a P picture located temporally forward, an I picture or a P picture located temporally backward, and both are used.

In the frame sequence shown in FIG. 1, the first and 13th frames are I pictures, the fourth, seventh and tenth frames are P pictures, and the second, third, fifth, sixth, eighth, ninth and eleventh frames are B pictures. Indicates a picture. The frame sequence from the first frame to the twelfth frame forms one GOP (group of pictures).

Next, an optical disk device according to the present invention will be described with reference to FIG. The optical disk 1 on which the digital image data subjected to the intra coding, the forward prediction coding, and the bidirectional prediction coding is recorded is rotated by a motor 10. The motor 10 is driven by the motor drive circuit 9. Data recorded on the optical disk 1 is optically read by the reproducing head 2 and input to the reproduction signal processing unit 3 as an electric signal. The reproduction signal processing unit 3 includes a signal processing circuit 4 and a decoder circuit 5, performs digital demodulation, error correction, and the like on the electric signal input from the reproduction head 2, and then outputs the electric signal to the output terminal 11. A reproduced image signal is output to the output terminal 12, and a reproduced audio signal is output to the output terminal 12.

A high-speed reproduction control circuit 8 is connected to the decoder circuit 5 and the motor drive circuit 9. The terminal 13 is connected to the high-speed reproduction control circuit 8. When receiving a signal for instructing high-speed reproduction from the terminal 13, the high-speed reproduction control circuit 8 controls the motor drive circuit 9 to increase the rotation speed of the optical disk to a rotation speed required for normal reproduction, and at the same time, Is controlled so that the image decoder circuit 6 and the audio decoder circuit 7 perform predetermined operations.

FIG. 3 is a block diagram showing the configuration of the image decoder circuit 6. The image data signal output from the signal processing circuit 4 is supplied from a terminal 61 to an inverse quantizer 62, an inverse discrete cosine transform circuit (hereinafter simply referred to as an inverse DCT circuit) 6
3 are input in order. The image data signal subjected to inverse quantization and inverse discrete cosine transform is input to the adder 64. The signal output from the adder 64 is input to the predictor 65. The image signal output from the predictor 65 is
6 again to the adder 64. Switch 66
Is open only when the image signal output from the predictor 65 corresponds to an I picture, and is always closed otherwise. The opening and closing of the switch 66 is controlled by the controller 69. The image signal output from the adder 64 in this manner is input to the switch 67. During normal reproduction, the switch 67 is always closed, and all image signals input to the switch 67 are sent to the output buffer 68. The output of the output buffer 68 is connected to the terminal 11, and from the terminal 11, reproduced image signals corresponding to the I picture, the P picture, and the B picture are output one frame at a time. During high-speed playback, the switch 67 is closed when the input image signal corresponds to an I picture and a P picture, and is opened when the input image signal corresponds to a B picture. Therefore, at the time of high-speed reproduction, only the image signals corresponding to the I picture and the P picture are input to the output buffer 68. In this embodiment, the opening and closing of the switch 67
6 is controlled by the controller 69.

FIG. 4 shows a first configuration example of the audio decoder circuit 7. The audio data signal output from the signal processing circuit 4 is input from the terminal 71 to the switch 72. When receiving the control signal from the controller 75, the switch 72 is closed for a predetermined period and becomes conductive. When the switch 72 is closed, the audio data signal is input to the input buffer 73.
Is input to The input buffer 73 outputs the input audio data signal to the DEM 74. When the detection circuit (not shown) detects that the data amount of the audio data signal stored in the input buffer 73 has fallen below a predetermined amount, the controller 75 controls the switch 72 based on the detection result of the detection circuit. To generate a control signal. Thereby, the audio data signal input to the switch 72 when the switch 72 is closed is input to the input buffer 73. The audio data signal input to the DEM 74 is digitally demodulated and output to the terminal 12.

The operation of the optical disk device during normal reproduction and high-speed reproduction will be described below with reference to FIGS. 3, 4, and 5.

FIG. 5A shows an encoding pattern of a signal recorded on the optical disc 1. As described with reference to FIG. 1, the first, thirteenth, twenty-fifth, and thirty-seventh
The image data of the frame is intra-coded, the image data of the fourth, seventh, tenth, and sixteenth frames is forward-predictively encoded, and the image data of the second, third, fifth, and sixth frames is The data is bidirectionally predicted encoded and recorded on the optical disc 1. In the case of normal reproduction, the motor drive circuit 9 controls the motor 10 to rotate the optical disc 1 at a predetermined speed. From the rotating optical disk 1, information including audio data and image data is optically read by the reproducing head 2 and output as an electric signal. FIG.
FIG. 3B shows a data string read by the reproducing head 2 during normal reproduction. The horizontal axis represents the time axis. The output time of one frame is 1/30 sec regardless of the encoding method.
Although it is c, the amount of data per frame differs depending on the encoding method. The data amount of the intra-coded frame is the largest, and the data amount of the bidirectionally predicted-coded frame is the smallest. Therefore, as can be seen from FIG. 5B, the time required to read the image data of the intra-coded frame is longer than the time required to read the image data of the frame subjected to the forward prediction coding or the bidirectional prediction coding. It takes a long time. Immediately before the image data of the intra-coded frame, the GO to which the frame belongs
Audio data corresponding to P is recorded.

The signal output from the reproducing head 2 is input to an image decoder circuit 6 and an audio decoder circuit 7 via a signal processing circuit 4. The image decoder circuit 6 decodes the image data as described above and outputs the decoded image data to the image terminal 11 of one frame in the order recorded on the optical disc 1. FIG. 5C shows a pattern of a reproduced image signal decoded and output from the image decoder circuit 6 to the terminal 11. In the present optical disk apparatus, 1 GOP
The time for reading the data for one minute is set equal to the time for outputting the reproduced image signal for one GOP to the terminal 11. Note that the time for reading data for one GOP may be slightly shorter than the time for outputting a reproduced image signal for one GOP to the terminal 11. The reproduced image signal output to the terminal 11 is supplied from the terminal 11 to an image display unit (not shown). When receiving the reproduced image signal via the terminal 11, the image display unit displays an image of one frame for 1/30 sec.

As shown in FIG. 5B, the audio data is recorded immediately before the GOP image data corresponding to the audio data. The audio data read by the reproducing head 2 is subjected to predetermined processing by a signal processing circuit 4 and is input to an audio decoder circuit 7. The audio decoder circuit 7 decodes the input audio data signal as described above and outputs it to the terminal 12.

More specifically, first, the first 1G
The audio data A1 corresponding to the OP is input to the input buffer 73. The audio data signal A1 input to the input buffer 73 is output to the DEM 74. When the remaining amount of the audio data signal A1 stored in the input buffer 73 decreases, the controller 75 generates a control signal to close the switch 72. The audio data signal first input from the terminal 71 after the switch 72 is closed is input to the input buffer 73 as the audio data signal following the audio data signal A1. The speed at which the audio data signal is output from the input buffer 73 to the DEM 74 is such that the audio data signal input first after the switch 72 is closed during normal playback is A
2 is set. In this way, during normal playback, the playback audio signal is output from the terminal 12 in synchronization with the playback image signal of the corresponding GOP.

Next, the operation of the optical disk apparatus 1 according to the present invention when reproducing at triple speed will be described. The optical disc apparatus of the present invention uses only I-pictures and P-pictures when reproducing an image at 3 × speed. However, when reading image data from the optical disc 1, it is necessary to selectively read out only I-pictures and P-pictures. Have difficulty. This is because the B picture and the P picture are recorded in a mixed manner as shown in FIG. In addition, even if the I picture and the P picture can be selectively read, this may complicate the device. Therefore, the optical disk device of the present invention stores all data in the optical disk 1
From the read image data and omit the image data corresponding to the B picture from the read image data. In order to realize this, the transfer rate is set higher at the time of high-speed playback than at the time of normal playback. .

First, a high-speed reproduction signal is input from a terminal 13 from a CPU (not shown) or the like. For example, the high-speed reproduction signal includes a signal indicating a speed at which an image is reproduced at a triple speed, a double speed, or the like. The high-speed reproduction control circuit 8 controls the motor drive circuit 9 based on the received high-speed reproduction signal to increase the rotation speed of the optical disk 1. The rotation speed of the optical disc 1 at the time of high-speed reproduction is set to n times the minimum rotation speed required for realizing the transfer rate at the time of normal reproduction, assuming that images are reproduced at n times speed. For example, if the transfer rate during normal playback is set to 3.0 Mbps and the rotation speed during normal playback of the optical disc 1 is set to the minimum rotation speed capable of realizing this transfer rate, an image at triple speed is set. At the time of reproduction, the rotation speed of the optical disk 1 is tripled. When the rotation speed is tripled, the transfer rate becomes 9.0 Mbps, and as shown in FIG. 5D, the time required to read one GOP worth of data from the optical disk 1 becomes one third. In this way, the transfer rate is increased to three times that in normal reproduction, and all image data is read.

Upon receiving the high-speed reproduction signal, the high-speed reproduction control circuit 8 outputs a high-speed reproduction control signal to the image decoder circuit 6. The controller 69 of the image decoder circuit 6 receives a signal from the high-speed reproduction control circuit 8. Hereinafter, the operation of the image decoder circuit 6 will be described. The image data signal output from the signal processing circuit 4 is subjected to inverse quantization and inverse discrete cosine transform from the terminal 61 as described above, and output as an image signal from the adder 64 as described above. 67 is input. The switch 67 is controlled by the controller 69 so that an image signal is
Since it is controlled to close when corresponding to a picture and open when corresponding to a B picture, only image signals corresponding to I and P pictures are input to the output buffer 68. The image signal input to the output buffer 68 is output once per frame. Therefore, a signal for displaying one image one time at a time is output to the terminal 11 as a reproduced image signal.

FIG. 5E shows a pattern of a reproduced image signal output from the image decoder circuit 6 to the terminal 11. As described above, the image decoder circuit 6 of the present optical disk device
Excludes the image data signal corresponding to the B picture,
Only the reproduced image signal corresponding to the picture and the P picture is output to the terminal 11 for 1/30 sec per frame as in the case of reproducing the image at a normal speed. Therefore, unlike a conventional optical disc apparatus that outputs only a reproduced image signal corresponding to an I picture, image reproduction at triple speed can be realized by outputting an image of one frame only once per GOP. Further, since not only the I picture but also the P picture are used, the temporal resolution can be improved as compared with the conventional optical disc device, and a smoother image can be reproduced.

The operation of the audio decoder circuit 7 when reproducing an image at triple speed is almost the same as the operation when reproducing an image at a normal speed. First, audio data corresponding to the first 1 GOP is input to the input buffer 73. The input audio data signal A 1
Output to M74. As described above, the speed at which the audio data signal A1 is output is such that the audio data signal input first after the switch 72 is closed corresponds to the audio data signal stored in the input buffer 73 during normal reproduction. It is set so as to correspond to one GOP following one GOP. When the remaining amount of the audio data signal A1 stored in the input buffer 73 falls below a predetermined amount, a detection circuit (not shown) detects this and outputs a detection signal to the controller 75. Upon receiving the detection signal, the controller 75 generates a control signal to close the switch 72. continue,
The audio data signal input from the terminal 71 first after the switch 72 is closed is input to the input buffer 73. Here, as shown in FIG. 5D, when an image is reproduced at triple speed, data for one GOP is read out in one third of the time during normal reproduction.
Output the audio data signal A1 to the DEM 74, the audio data signals A2 and A3 are read from the optical disk 1 and input from the terminal 71 to the switch 72. Therefore, the audio data signal A4 is input to the input buffer 73 following the audio data signal A1. Similarly, after the audio data signal A4, the audio data signal A7 is input to the input buffer 73.

The audio data signal input to the input buffer 73 is output from the DEM 74 to the terminal 12. At this time, each of the audio data signals is supplied with an image of one GOP at the terminal 1 at the time of normal reproduction, similarly to the time of normal reproduction.
1 is output for the same time as the time required for outputting to 1. FIG. 5 (e) shows the terminal 12 together with the pattern of the reproduced image signal output to the terminal 11 when reproducing an image at 3 × speed.
2 shows a pattern of the reproduced audio signal output to the first section. As can be seen from this figure, the present optical disc device reproduces the reproduced audio signal at the same speed as that for reproducing an image at a normal speed, though discrete, and in synchronization with the reproduced image signal when viewed in 3 GOP units. It can output to the terminal 12.

In this manner, the present optical disk apparatus can reproduce an image with sound at a smooth triple speed. In this optical disk device, the sound is A1, A4,
Although the content is reproduced discretely as indicated by A7, if the content is reproduced at this level, the content can be sufficiently grasped.

Next, the operation of the optical disk device in the case of performing reproduction at double speed will be described. In this case as well, the motor drive circuit 9 controls the rotation speed of the optical disc by the high-speed reproduction control circuit 8 to reduce the rotation speed required for reproducing the image at the normal speed, as in the case of reproducing the image at the triple speed. It is controlled so as to be set to twice the speed.

The operation of the image decoder circuit 6 is almost the same as that of reproducing an image at 3 × speed, but the output buffer 68 outputs the reproduced image signal to the terminal 11 in three ways.
This is different from image playback at double speed. The image data signal from the signal processing circuit 4 input from the terminal 61 is subjected to inverse quantization and inverse discrete cosine transform as described above, and
Is input to The image signal input to the switch 67 is
It contains all image signals corresponding to I picture, P picture and B picture. The image signal input to the switch 67 is sent to the output buffer 68 after only the image signal corresponding to the B picture is omitted by opening and closing the switch 67.

The image signals corresponding to the I picture and the P picture stored in the output buffer 68 are output to the terminal 11 once per frame when the image is reproduced at 3 × speed. Is reproduced a plurality of times for some frames and once for other frames. In the present optical disc device, as shown in FIG. 5F, the first, seventh, thirteenth, nineteenth, twenty-fifth, and third
Image signals of one frame or the like are output twice each, and image signals of other frames are output once each. As described above, when the image is reproduced at 2 × speed, the image signal corresponding to the I picture and the image signal corresponding to the middle P picture of the P pictures of each GOP are transmitted twice by the I
The image signals corresponding to the P pictures immediately before and after the picture are output to the terminal 11 once and supplied to the image display unit from the terminal 11 as a reproduced image signal.

As described above, in the present optical disc apparatus, the image signal of a part of the frame is output a plurality of times, as in the case of reproducing the image at double speed in the conventional apparatus. In this case, not only the I picture but also the P picture are used, so that the temporal resolution can be remarkably improved as compared with the related art.

The operation of the audio decoder circuit 7 when reproducing an image at double speed is the same as the case of reproducing an image at normal speed and the case of reproducing an image at triple speed.
FIG. 5F shows a pattern of the reproduced audio signal output to the terminal 12 in this case. After the audio data signal A1, the audio data signal A3 is input to the input buffer 73, and subsequently, the audio data signals A5 and A7 are input in that order. The input audio data signal is subjected to predetermined processing by the DEM 74 and output from the terminal 12 as a reproduced audio signal. Therefore, when an image is reproduced at 2 × speed, the reproduced audio signal is output from the terminal 12 almost in synchronization with the reproduced image signal output from the terminal 11 in 2 GOP units. In this way, the present optical disc device can reproduce discrete but almost synchronized audio with an image.

As described above, the present optical disk apparatus can reproduce an image at twice the speed, with a sound that is substantially synchronized with the image, and more smoothly than before. Note that the audio is discretely reproduced as A1, A3, A5, and A7, but if reproduced to this extent, the contents can be sufficiently grasped.

In the present optical disk apparatus, even when an image is reproduced at double speed and triple speed, sound is reproduced at a normal speed. However, to obtain more complete audio information, it is also possible to decode all audio data signals and temporally compress the decoded audio signals. For example, the audio signal
As a method of temporally compressing the sound to half, there is a method of doubling the output clock of audio. However, in this method, the voice pitch (frequency) increases by an octave. Recently, a method of temporally compressing an audio signal without changing the audio pitch has also been proposed. If this method is used, all sounds can be reproduced as shown in FIG.

FIG. 6 schematically shows a configuration of the audio decoder circuit 107 in the case where the audio signal is temporally compressed without changing the audio pitch. The audio data signal from the signal processing circuit 4 is input from a terminal 171. When playing an image at normal speed, the switch 172 is closed,
The switch 177 is open, and all audio data signals input from the terminal 171 are input to the input buffer 173 and subsequently input to the DEM 174. The audio signal output from DEM 174 is input to switch 175. At the time of normal reproduction, the switch 175 is in a state shown by a solid line in the figure, and the audio signal input to the switch 175 is
The signal is input to the terminal 12 as it is. Here, it is assumed that the switches 172, 175 and 177 are controlled by a controller (not shown).

When an image is reproduced at double speed, only one of the switches 172 and 177 is controlled to open and close alternately. For example, when the first audio data signal A1 is input from the terminal 171,
The switch 172 is closed, the switch 177 is open, and the audio data signal A1 is input to the input buffer 173 via the switch 172. When the next audio data signal A2 is input, the switch 172 is opened and the switch 177 is closed, and the audio data signal A2 is input to the input buffer 178. In this manner, the odd-numbered audio data signals are input to the input buffer 173, and the even-numbered audio data signals are input to the input buffer 178. The audio data signal input to the input buffer 173 is subjected to predetermined processing by the DEM 174,
Output to switch 175. The switch 175 is in a state shown by a broken line in the figure when reproducing an image at 2 × speed. Therefore, the audio signal from the DEM 174 is input to the multiplexer 181 after being halved by the audio compression circuit 176. Also, the even-numbered audio data signal passes through the input buffer 178 and the DEM 179, is halved by the audio compression circuit 180, and is then multiplexed by the multiplexer 1.
81 is input. The multiplexer 181 combines the odd-numbered audio signal and the even-numbered audio signal, and outputs the synthesized audio signal from the terminal 12 as a reproduced audio signal.

In this way, the audio signal can be temporally compressed to half and reproduced without changing the audio pitch. In addition to the above-described method, if a known audio compression technique is used, all audio data can be reproduced.

Further, in the above-described embodiment, when an image is reproduced at a normal speed, the optical disc 1 is rotated at the minimum rotational speed necessary to realize the transfer rate in this case. The optical disc 1 may be rotated at the above rotation speed. In such a case, when a predetermined amount of data sent from the reproduction head 2 to the reproduction signal processing unit 3 is stored in the buffer, a so-called intermittent reproduction in which the apparatus stands still and waits is performed. Further, if the rotation speed of the optical disc 1 when reproducing an image at a normal speed is the minimum rotation speed required to realize a transfer rate required when reproducing an image at a double speed, It is not necessary to increase the rotation speed of the optical disc 1 when performing double speed image reproduction. Furthermore, if the optical disc 1 is rotating at the minimum rotation speed required for reproducing images at 3 × speed during normal playback,
There is no need to increase the rotation speed when playing back images at 2x speed and 3x speed. In this case, the above-described intermittent reproduction is performed at the time of image reproduction at double speed.

The increase in the rotation speed, that is, the increase in the transfer rate is not limited to twice or three times as described in the above embodiment. Even if the transfer rate is increased about 10 times, the same effect as the effect described in the above embodiment can be obtained. In this case, it is necessary to increase the frequency of the clock used for processing the reproduction signal as the transfer rate increases. Also, during normal playback, if the optical disc 1 is rotating at a rotation speed that can realize a transfer rate higher than that at the time of image playback at 2 × speed or 3 × speed, high speed playback is performed. There is no need to increase the rotation speed.

In the above embodiment, an example in which the image of the same frame is displayed once or twice during high-speed reproduction has been described. However, the number of times the image of the same frame is displayed is not limited to once or twice. Switching may be performed between one time and three times according to the speed at which the image is reproduced.

In the above embodiment, the case of reproducing the intra-frame or inter-frame coded image data has been described. However, the present invention is also applicable to the case of reproducing the intra-field or inter-field coded image data. It can, of course, be applied.

In the above embodiment, the opening and closing of the switches of the image decoder circuit and the audio decoder circuit are controlled by the controller. However, the control of the opening and closing of the switch may be performed by any method. If the control is performed so that the I picture and the P picture are closed and the B picture is opened, the above-described effects are obtained. Similar effects can be obtained.

In the above embodiment, the audio data is reproduced in units of 1 GOP, but the unit for reproducing the audio data is 1 unit.
The present invention is not limited to the GOP, and may be, for example, in units of one second or several seconds. In this case, the sound and the image do not need to be played back completely synchronously.
It is sufficient that the audio and the image are synchronized when viewed in OP units or several seconds.

[0052]

According to the present invention, at the time of high-speed reproduction, the transfer rate is made higher than the normal transfer rate, so that the image data signal corresponding to the B picture can be omitted after reading out all the data. As a result, it is possible to reproduce only the I picture and the P picture, and it is possible to greatly improve the temporal resolution as compared with the conventional apparatus that reproduces only the I picture. Therefore, a smoother image can be reproduced at a higher speed than before.

Further, according to the present invention, although discrete, the sound can be reproduced almost in synchronization with the image, so that high-speed image reproduction with sound can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of a method of encoding image data recorded on an optical disk.

FIG. 2 is a configuration diagram of an optical disk device of the present invention.

FIG. 3 is a configuration diagram of an image decoder circuit of the present invention.

FIG. 4 is a configuration diagram of an audio decoder circuit of the present invention.

FIG. 5 is a schematic view of a pattern of a reproduction signal according to the embodiment of the present invention.

FIG. 6 is another configuration diagram of the audio decoder circuit of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 optical disk 2 playback head 3 playback signal processing unit 4 signal processing circuit 5 decoder circuit 6 image decoder circuit 7 audio decoder circuit 8 high-speed playback control circuit 9 motor drive circuit 10 motor

Claims (9)

(57) [Claims] 1. A signal processing means for reading image data and audio data from an optical disc, generating an image data signal and an audio data signal in accordance with the read image data and audio data, and Image decoding means for receiving the image data signal and generating a reproduction image signal based on the received image data signal; and control means for generating a high-speed reproduction control signal for switching from normal reproduction to high-speed reproduction. , Usually at high speed playback
As in the case of playback, the optical disc is
Reads all image data from the
And then, the image decoder means, and the image data decoding means for decoding the image data signals, sometimes received a high-speed reproduction control signal from the control means, the image data signal
And decodes only signals corresponding to the intra-coded image data and the forward prediction-coded image data, and outputs the decoded data as the reproduced image signal.
Means for decoding all image data signals and outputting the decoded data as the reproduced image signal. 2. The optical disk device according to claim 1, wherein the image decoder outputs a reproduced image signal corresponding to one frame at least once. 3. The optical disk device according to claim 1, wherein the image decoder outputs a reproduced image signal corresponding to one field at least once. 4. The optical disc apparatus further comprises an audio decoder for generating a reproduced audio signal based on an audio data signal from the signal processor, and the audio decoder receives a high-speed reproduction control signal from the controller. In this case, only the portion of the audio data signal generated in the first period is demodulated, and the portion generated in the second period following the first period is demodulated without demodulation. Only the portion generated during the first period is output as the reproduced audio signal. At other times, the entire audio data signal is decoded and output as the reproduced audio signal. 2. The optical disk device according to claim 1, wherein the period is alternately repeated. 5. The optical disk device according to claim 4, wherein the first period corresponds to nGOP (n ≧ 1), and the second period corresponds to mGOP (m ≧ 1). 6. The optical disk device further includes a motor for rotating the optical disk, and a motor driving unit for driving the motor, wherein the motor driving unit receives a high-speed reproduction control signal from the control unit. 2. The optical disk device according to claim 1, wherein the rotation speed of the motor is increased according to the high-speed reproduction control signal. 7. The optical disk device according to claim 6, wherein the motor driving means increases the rotation speed of the motor from a minimum rotation speed required for normal speed reproduction in response to the high speed reproduction control signal. 8. An optical disk device receives an audio data signal from a signal processing means, and generates a reproduced audio signal substantially in synchronism with the corresponding reproduced image signal based on the received audio data signal. The audio decoder further includes a decoder, wherein the audio decoder demodulates the audio data signal and, when receiving the high-speed reproduction control signal from the control unit, temporally compresses the demodulated audio data signal to generate the audio data signal. 2. The optical disk apparatus according to claim 1, further comprising: means for outputting as a reproduced audio signal, and otherwise outputting the reproduced audio signal without compressing the demodulated audio data signal. 9. The audio decoder means outputs a reproduced audio signal,
9. The optical disk apparatus according to claim 8, wherein the optical disk apparatus is generated in synchronization with a signal corresponding to intra-coded image data in the reproduced image signal.