MXPA95003629A - Method of data reproduction and da reproduction device - Google Patents

Abstract

The present invention relates to a method of reproducing data and a data reproducing apparatus that allows it to work with special reproductions such as a fast reverse playback when specified. In the data reproduction apparatus comprising a demodulation means for demodulating the data read from a digital video disc by means of a pick-up unit, a storage means for temporarily storing the demodulated data and a decoder for decoding the data read from the medium of storage in original video signals, the apparatus further comprises a control circuit for controlling the storage medium so that an area of the unread data and a data area already read in the storage medium requires approximately one-half of the capacity of the total memory, respectively, so that the data necessary for the inverse or similar reproduction is left in the storage medium, allowing the specific reproduction to work quickly

Description

"METHOD OF DATA REPRODUCTION AND DATA REPRODUCTION DEVICE" INVENTORS: NOBUYUKI AOKI, DAISUKE HIRANAKA, HAJIME NITTA and KIYOSHI OTA, Japanese all domiciled Sony Corporation, 7-35, Kitashinaga to 6-chome, Shinaga a-ku, Tokyo, Japan give all their rights to SONY CORPORATION, duly organized society and constituted in accordance with the Laws of JAPAN, domiciled at 7-35 Kitashinagawa 6-chome, Shinagawa-Ku, Tokyo, Japan, for the invention described below.

BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates to a disc data reproduction method and an apparatus for reproducing appropriate disc data to reproduce data such as images and sounds recorded on an optical disc, a magneto-optical disc or the like, and more particularly with a data reproduction method and a data reproducing apparatus that allows carrying out Special reproductions such as fast reverse playback.

DESCRIPTION OF THE RELATED TECHNIQUE The MPEG method (Groups of Experts of Codifisation of Moving Images) has been proposed as a method for compressing and coding the digital image signals recorded in a digital video disc (which will be referred to below as DVD). Then, it will be explained to sontinuasión are reference to FIGURE 9, an example of an MPEG encoder. The MPEG encoder is a type of encoder that is adapted to compress the signals by predictive coding, where the digitized image input signals are blocked in each block (MB) which is a minimum unit of prediction vectors and compensation motion of movement since the prediction of motion compensation is detected by each block in a motion detection circuit 101. While this block is predictively encoded by the following predictive coding section, it is classified into four blocks of (1) an intra-block in which the DCT (Cosine Transformation) Discrete) is implemented directly in the image input signals, (2) a front block in which the prediction is made only from the front diressión, (3) a block back in the sual the predissión is hase only from the direction Subsequent, and (4) a bi-direstive block in the sual the predissión be hase from both diressiones. It is desir, session 103 DCT implements the DCT which is a type of Fourier transformation and a quantization circuit 104 quantifies the DCT coefficients of that result. After quantization, a variable length coding means 109 implements the variable length coding by assigning codes whose lengths vary corresponding to a probability of what is to occur. A reverse quantization circuit 105 inversely quantizes the quantized signals and a reverse DCT section 106 implements an inverse DCT. Then, an output of a frame memory predictor 108 is added thereto to reproduce the original image signals. The reproduced image signals are supplied to a substratum means 102 or subtracted from prediction signals. The output of the predictive coding signals of the variable length coding means 109 is multichannelized with the mode information. prediction and information of the movement vestor in the multi-analysis medium 110. This muitized data is generated at irregular regimes, so that it is sent to and temporarily souled in a buffer 111 so that its sodification regime becomes constant. Note that it is also possible to control an encoding amount by swapping a quantization scale fastor q of the quantifisation means 104, in response to a sanity of sodification stored in the buffer 111, in order to release the average of the coding regimes. FIGURE 10a shows an inter-superseding prediction structure so squeezed and encoded by the MPEG method. In the figure, a GOP (Group of Images) is composed of nine tables for example; a picture of picture I, two pictures of picture P and six pictures of picture B. Note that the GOP is a coding unit in which a sequence of motion pictures is divided. Image I is a predistive codified image within the frame, image P is an inter-frame predictive coded image that is predicted with reference to the previous coded picture (image I or image P) according to the time, image B is an inter-frame predictive coded image predicted with reference to the previous frame and encoded (image I or image P) according to time and image B is a predicted interframe predictive coded image with reference to two frames of the preceding and succeeding frames according to time. That is, as shown in the figure by the arrows, the image, Ig is encoded in a predictive manner only within that frame, the image P, Pg is encoded interred frame with reference to the image I, Ig and the image P, P] _ is encoded in an inter-frame predictive manner with reference to the image P, Pg. In addition, the images B, Bg and B] _ are encoded in an inter-frame predictive manner with reference to two images of the image I , Ig, and the image P, Pg and images B2 and B3 are encoded in an inter-frame predictive manner with reference to two images of the image P, Pg and the image P, P] _. Images are then created through predictive coding in the same way. Accordingly, by desodifying the decoded images in a predictive manner in this way, even though the I image can be decoded by itself, because the I image is predictively encoded within the frame, the P image needs the I image or the previous P image to decode it because the image P is encoded in a predictive manner with reference to the image I or the image P above and the image B requires the image I or the previous and successive image P to decode it because the image B is encoded in a predictive manner with reference to the image I or the previous or succeeding image P. Then, the images are rearranged as shown in FIGURE 10b in order to be able to deodify the images needed in the decoding first. As shown in the figure, this rearrangement is done so that the image I, Ig preseda to the images B, B _] _ and B_2 because the image I, Ig is necessary to decode the images B, B _] _ and B_2, so that the image P, Pg precedes images B, Bg and B] _, because the image P, Pg is necessary to desodify the images B, Bg and Bi, so that the image P, P ] _ precedes the images B, B2 and B3, because the image P, P] _ is necessary to desodify the images B, B2 and B3, and so that the image I, I] preseda the images B, B4 and B5 because the image I, I] _ is necessary to decode images B, B4 and B5. While the images I, the images P and the images B are recorded in DVD in sequence as shown in FIGURE 10b, their amount of coding is not constant between each image and varies corresponding to a complexity and flatness of the image put that those images are encoded in a predictive way as has been previously described. Then, in order to be able to easily handle the data, the data is recorded by means of the sector that is defined by a certain amount of coding and recorded to those images once on DVD. FIGURE 11 shows a way to record the data by means of a sector, where the image I, Ig, for example, registers Sector m, Sestor (m + 1) and a partial area of the Sector (m + 2) and image B B_2 is recorded in the remaining area of the Sector (m + 2) and the Sector (M + 3). Then, each image is recorded in sequencing in the respectable sestores and a GOP is recorded in the Sestores m through (m + 13) in this example. However, the GOP is not always recorded in this number of sestores and usually the number of sectors where the GOP is recorded varies because the amount of coding varies due to the complexity and flatness of each image. Incidentally, the data in the DVD-read sector unit is temporarily stored in a storage medium which is imagined as being represented by a ring shape which is called a ring buffer. The operations of a read pointer and a write pointer in the ring buffer will be explained by referring to FIGURE 12. In FIGURE 12a, the read pointer RP is placed in a directional position at the ring buffer of the write pointer WP is placed in a direction position bl slightly before a. The data in the unit of the sector is supplied to the decoder as the reading pointer moves in a clockwise direction in the figure, reading the data of the ring buffer. The write WP pointer is shortened so as to settle slightly before the time according to the time in order to increase an unread area (URD) as much as possible and not be sorta of data to be reproduced. Therefore, an already read area (ARD) becomes a small area between al and bl and it is also possible to control so that this area becomes zero. FIGURE 12b shows a state where the reading pointer RP has advanced to read the ring buffer data, advancing its address position from a to a2. Because of that, the URD area has become smaller, increasing the ARD area on the other hand. Then, the data is written into the ring buffer while advancing the write pointer WP in clockwise direction so that the unread area URD increases as shown in FIGURE 12c. The data here is the _ new data read from the disk. In this way, the address position of the WP pointer of essritura progresses from bl to b2, reducting the ARD area and increasing the URD area by that amount. Therefore, a large URD area is always maintained in the ring buffer by examining this control. However, there has been a problem that when a special reproduction such as a backward reproduction is to be made during the time when the data in the DVD registered sector unit is reading from the ring buffer to reproduce the video signals , normal playback can not be changed to backward reproductions evenly, because there is almost no data to be played in the reverse direction (ie, the data in the ARD area) in the ring buffer at the time when the mode is changed to backward playback and it is necessary to wait for a supply of the read data having access to DVD. That is, even when it is necessary to read the previous GOP data of. According to the time after the current GOP having access to DVD by capturing in order to decode the video signals that are going to be displayed in the display section during the backward playback, it takes time to read the data because the reading is It performs mechanically and also requires time to decode the images that make up the reading GOPs to obtain the video signals.

The reason why it takes time to decode the images will be explained below. Suppose here that a GOP that precedes the current GOP is composed of the image I, Ig to B5 as shown in FIGURE 10a. Then, in order to carry out the backward reproduction, it is necessary to display an image of the decoded image B, B5, after which an image of the I, I ± decoded image of the current GOP and then exhibit, after that, the images of decoded image B4, image P, Pi, image B, B3, image B, B2, image P, Pg, image B, B] _, image B, Bg and image I , Ig. Because image B, B5 and image B, B4 are predicted with reference to image I, I1 and image P, P] _, the data of image I, Ii and image P,] _ are necessary to decode them. However, because the image P, P ^ is predicted with reference to the image P, Pg and the image P, Ig is predicted with reference to the image I, Ig, it is necessary to decode the image P, Pg with referensia to the image I, Ig and dessodifisar the image P, P1 are referensia to the image P, Ig after all. It is therefore necessary to refer to the image I] _ and the image P, B] _ to decode the image B, B5 and the image B, B4, so that time is required to decode the images.

Therefore, an object of the present invention is to provide a method of reproducing data and a data reproducing apparatus that allows to carry out a special reproduction such as fast backward reproduction.

SUMMARY OF THE INVENTION In order to achieve the aforementioned scope, in a method of reproducing data of the present invention to reproduce original video signals by demodulation and writing data read from a disk by means of capturing in the storage medium and decoding the data After reading from the storage medium, the storage medium is controlled so that an unread data area and a data area already read in the storage medium requires approximately half of a total memory capacity respectively. In addition, in the method of data reproduction, the data is written to the masking medium in a unit of the sector composed of a fixed data quantity. A write pointer moves to an address position that has jumped in the playback direction by a number of sectors from the sum of a number of sectors written at the last time and a number of sectors to be written this time when a backward playback mode is specified and the number of sectors to be written this time is written in the middle of. storage in the reverse direction to the reproduction direction from the address position. Further, in a data reproducing apparatus of the present invention to achieve the aforementioned scope, comprising a demodulation means for demodulating the read data of a digital video disc by means of a capturing means, the storage means for temporarily storing the demodulated data and a decoder for decoding the read data from the storage medium into original video signals, the apparatus is provided with a control circuit for checking the storage medium so that an area of unread data and an area of data already read on the storage medium requires approximately half of a total memory capacity, respectively. The control circuit in the data reproduction apparatus secures the data in the masking medium in a seismic unit composed of a fixed data quantity data. Move a write pointer to a skip address in the playback direction by a number of sectors from the sum of a number of sectors written at the last time and a number of sectors to be written this time, when the reverse playback mode is specified and describes the number of sectors to be written this time on the storage medium in the direction reversed to the address of reprodussión from the address position. In order to achieve the aforementioned scope, in a method of reprodussing data of the present invention to reproduce the image signals by means of the demodulation data read from a disk by means of capturing and decoding it through a buffer , the buffer memory has a capacity capable of storing at least two GOPs composed of a plurality of frames and the data of at least one GOP including a previous GOP in relation to the time to a GOP that is being decoded and read from the GOP. disk and it is stored in the buffer when it specifies that a stationary mode is ready for a special playback mode. In the data reproduction method, the special playback mode is a backward playback mode. In a data reproducing apparatus of the present invention to achieve the aforementioned view, comprising a demodulation means for demodulating the read data of a disk by means of a means of capture, a buffer for temporarily storing the demodulated data and a decoder for decoding the read data from the buffer in image signals, the buffer has a layer capable of storing at least two GOPs composed of a plurality of frames and data of at least one GOP, which includes a previous GOP in relation to the time to a GOP that is being decoded by the decoder. it reads from the disk and is stored in the buffer when a stationary mode is specified as being ready for the special playback mode. In the data reproduction apparatus, the special reproduction mode is a backward reproduction mode. In accordance with the present invention, the writing / reading of the storage medium is controlled so that the unread data area and the data area already read in the storage medium requires approximately one-third of the total volume capacity, respectively , so that the data necessary for the reverse or similar reproduction is left in the storage medium, and the special reproduction is carried out quickly. Due to the same reason, it becomes possible to change the mode from special playback to normal playback quickly. Therefore, in accordance with the present invention, a number of times - The disk is redused and the special reproduction can be carried out by just controlling the buffer in the normal playback mode, masking the data always in the buffer, in accordance with the present invention, because the In the case of special playback, such that backward playback is more likely to be selected after the stalled mode is usually selected, the preceding or previous GOP is read when the stalled mode is specified, then, because the previous GOP already_ has been read for when the special playback mode is specified, the images played in the special playback mode can be quickly displayed on the screen, and if the capacity of the buffer is large enough, it becomes possible to quickly accommodate frame feed or variable speed reproductions this slow reproduction of half or fourth part of normal speed and double speed not only in the reverse direction but also in the normal direction, storing a plurality of GOP before and after a GOP containing images to which output is output within the buffer. Therefore, the present invention allows to reduce a number of times of disk access and move to special playback quickly just controlling the buffer in the normal playback mode, storing previous data more or less always within the buffer. The foregoing and other related objects and features of the present invention will become apparent from a reading of the following description of the disclosure found in the accompanying drawings, and the novelty thereof set forth in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a conceptual view showing a structure of a preferred embodiment of a data reproduction apparatus of the present invention; FIGURE 2 is a table showing the decoded frames soured in the sub-memories during normal playback in the data reprodsion apparatus of the present invention; FIGURE 3 is a chart showing the decoded boxes souled in the sub-memories during the reverse reproduction of the data reproducing apparatus of the present invention; FIGURES 4a, 4b and 4c are diagrams for explaining the movements of a writing pointer and a mouse pointer during normal reproduction of the data reproducing apparatus of the present invention; FIGURES 5a and 5b are diagrams for explaining the movements of the writing pointer during reverse reproduction in the data reproducer apparatus of the present invention; FIGURES 6a, 6b and 6c are diagrams for explaining the movements of the write pointer and the reading pointer during reverse reproduction in the data reproducing apparatus of the present invention; FIGURES 7a and 7b are diagrams for explaining the movement of the read pointer during reverse reproduction in detail in the data reproduction apparatus of the present invention; FIGURES 8a and 8b are diagrams for explaining a movement of the write pointer during reverse reproduction in detail in the data reproduction apparatus of the present invention; FIGURE 9 is a diagram showing a structural example of an encoder for coding the digital video signals by the MPEG method; FIGURES 10a and 10b are diagrams showing an inter-frame prediction structure and a structure of the frames registered in a GOP; FIGURE 11 is a diagram showing a relationship between the sectors recorded on a disk and the images that make up a GOP; FIGURES 12a, 12b and 12c are diagrams for explaining the movements of the read pointer and the write pointer in a ring buffer; FIGURE 13 is a functional diagram of the system showing a structure of another preferred embodiment of the data reproduction apparatus of the present invention; FIGURE 14 is a schematic diagram showing the operations of a buffer and a decoder during normal playback of the data reproduction apparatus of the present invention; FIGURE 15 is a schematic diagram showing the operations of the buffer and the decoder during the stalled mode in the data reproduction apparatus of the present invention; and FIGURE 16 is a schematic diagram showing other exemplary operations of the buffer and the decoder during the stalled mode in the data reproducing apparatus of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED MODALITY FIGURE 1 is a conceptual view of a data reproducing apparatus (DVD reproducing apparatus) according to a preferred embodiment of the present invention. In the figure, a disc (DVD) 1 is a recording medium for recording the digital video data, the digital audio data or the like compressed and encoded by the MPEG method in a sector unit, a capturing unit 2 is a unit of reproduction medium of the fixed-length sector as shown in FIGURE 11 described above, and to give access to disk 1 and read the digital data recorded therein, a sector detection circuit 3 detects a sink of sector and a sector address from the digital data read from disk 1, a ring buffer 4 is a memory medium in which the data read from disk 1 is written to the sector unit under the control of a circuit 8 of control and to supply the read data to a decoder 5 as necessary, and the decoder 5 decodes the data supplied in the sector unit in video signals to be displayed in a display unit.

A frame memory 6 stores three frames decoded by the decoder 5, a display device 7 displays the video signals supplied from the sub-frame memory 6, the control system 8 controls the tracking, routing and focusing or the like as the means of control by sending several control signals to a tracking servo circuit 9, such as the evaluation means or the like and controls the reading / writing of the ring buffer 4, and the tracking servo-monitor 9 controls the tracking of the capture unit 2 for give asseso to the disso 1 under the control of the sircuito 8 of control. An operation of the data reproducing apparatus constructed as described above will be explained below. The disso 1 is controlled in order to rotate with a predetermined number of revolutions by means of a spindle motor not illustrated. The compressed and coded digital data recorded in the tracks of the disc 1 is read when a laser beam is radiated to the tracks from the pick-up unit 2. This digital data is recorded in the unit of the fixed-length sector as shown in FIGURE 11 that has been described above, and the sector sink and sector head are appended to the head of each sector.

The digital data read by the capturing unit 2 is admitted in the sector detection service 3 where the limitations of the sectors are detected when the sector sinks are detected and the sector directions are detected from the sector heads. They are supplied to the control circuit 8. Note that the focus control and tracking control of the pickup unit 2 are carried out by the tracking servo 9 and others under the control of a non-illustrated system control based on focus error signals and error signals of tracking that are obtained from the reading of information of the unit 2 of recruitment. Then, the control circuit 8 controls the writing of the data in the sector unit in the ring buffer 4 based on the direction of the detected sestor. A write address at this time is indicated by a script pointer (WP) 8-1 within the sirsuito 8 of sontrol. Note that the buffer 4 has a storage capacity capable of storing at least two GOPs of digital data. The GOPs composed of images in the sequence shown in FIGURE 10b that is described above, for example, are read from the ring buffer 4 in the sector unit and are supplied to the decoder 5. Then, the - - I images, P images and B images that make up the GOP are decoded to be written in frame 6 sequence. The images are sent from the decoder 5 in the sequence of images shown in FIGURE 10B and are written in each Ml memory., M2 and M3 of frame, composing the frame memory 6. FIGURE 2 shows an example of the decoded frames written in frame memories Ml, M2 and M3 during normal playback. FIGURE 2 will be explained below with reference to FIGURES 10 and 10b. In State 1, the IQ frame obtained by decoding the image I, Ig is written in the frame memory Ml, and the decoded images B, B_2 and B_ with reference to the frame P of the decoded image P preceding the image I, Ig and the Ig box decoded within the frame memory Ml are written to the frame memories M2 and M3, respectively. In State 1, those frames are rearranged to the original picture sequence of frames B-2, Bl e 10 as shown in FIGURE 10a and sent from frame memories Ml, M2 and M3 to display device 7 which is going to be exhibited Next in State 2, the sector of the image P, Pg is read from the ring buffer 4 and the image Pg is decoded with reference to the frame Ig Ml of frame and is written into frame memory M2. Moving towards the State 3, the sector of the image B, BQ is read from the intermediate memory 4 and the image B, Bg is decoded with reference to the frame Ig within the frame memory Ml and the frame Pg within the memory M2 and is written to the frame M3 memory. Then, the frame Bg is read from the frame memory M3 and sent to the display device 7, to display its image. In State 4, the sector of the image B, Bi is read from the ring buffer 4 and the image B, B ^ is decoded with reference to the frame Ig within the frame memory Ml, and the frame Pg within the frame memory M2 and written to the frame memory M3. Then they are sent in a sequence of pictures B] _ and Ig from the memories M3 and Ml of suadro to the display device 7 to display their images. In the following State 5, the sector of the image P, P] _ is read from the ring buffer 4 and the image P, Pi is de-dirty is referensia to the Pg sub-frame within the frame memory Ml and is written to the Ml memory of suadro. In state 6, the sector of the image B, B2 is read from the ring buffer 4 and the image B, B2 is decoded with reference to the frame P] _ within the frame memory Ml, and the frame Pg within from the sub-frame memory M2 and the decoded image B, B2 is written to the frame memory M3. The decoded frame B2 is read from the frame memory M3 and sent to the display device 7 to display its image. The other images are decoded in the same manner and sent to the display device 7 with a sequence of Tables B3, Pl, B4, B5 to display their images in sequence. The images are displayed as described above during normal reproduction. Then, the movements of the write pointer WP of the mouse pointer RP in the ring buffer 4 during normal playback will be explained to continuation with reference to FIGS. 4a, 4b and 4c. FIGURE 4a shows a case when the readout pointer RP 8-2 is placed in a directional position Rl and the handwriting pointer WP 8-1 is soldered in a resolution position Wl. The dextrorotatory direction of the ring buffer 4 in the figure is considered to be the direction of the normal reproduction, and the writing / reading is carried out in this direction. Note that due to the position Rl of direction at the address position Wl which are positioned so that they are almost oriented towards each other in the ring buffer 4, the sizes of an URD area of unread data and an ARD area of read data become almost equal. FIGURE 4b shows a state in which the reading pointer RP advances towards an address position R2 to read the data from the ring buffer 4, decreasing the area of unread data and increasing the area of the data already read. By detecting this state, the control circuit 8 controls the pickup unit 2 for accessing the slot 1 to read a new data and advances the writing pointer WP 8-1 to a steering position W2 shown in FIGURE 4c, to be able to write a sector of the reading data in the intermediate ring memory 4. In this way, the sizes of the unread data area and the area of the data already read become almost equal again. Note that the control circuit 8 performs this control at all times so that the sizes of the unread data area and the already read data area always become almost equal. In this case, when a new data of the disk 1 is not read, the pickup unit 2 is controlled in order to skip a track to read the data in the same track. By the way, when you manipulate a control button to change the mode from the normal playback mode to the reverse playback mode for example, it is necessary to decode the images from the past and reproduced during normal playback in an inverted time sequence and sending the decoded images from the frame memory 6 to the display device 7 to display them. However, in the case of the present invention, because the data already read is stored in the data area already read in the ring buffer 4, as shown in FIGURE 4, the images reproduced inversely can be displayed quickly in the display device 7 just controlling the read / write of the ring buffer 4 to accommodate with reverse reproduction without controlling the pickup unit 2 to return to read a new data. A replay of the images decoded by the decoder 5 during the reverse reproduction mode and the frames stored in the frame memories Ml, M2 and M3 will be explained to continuation with reference to FIGURE 3. In the state 0 in FIGURE 3, the image I, I] _ is deodified and stored in the memory Ml of suadro after finishing the decoding until frame B3. Because the decoded frames have been sent for display are the sequence from the right side to the left side in the arrangement shown in FIGURE 10a during reverse reproduction, the frames Pl and B3 are sent with a - sequence Pl and B3 from the frame memories M2 and M3 to the display device 7 to display their images. Then, since it is necessary to send the frame B2, the image I, I is read from the ring buffer 4 first to be decoded and stored in the frame memory Ml (State 1). After that, the image P, Pg is read from the ring buffer 4 to be decoded with reference to the frame Ig and stored in the memory M3 of supad (state 2). Then, the image B, B2 reads from the ring intermermedia memory 4 to be decoded with reference to the boxes Pl and PO and to be stored in the frame memory Ml. It is then sent to the display device 7 to display an image of the B2 frame (State 3). Then, the I, Ig image is read from the ring buffer 4 again to be decoded and stored in the frame memory M2 (State 4). Then, the image B, B] _ is read from the ring buffer 4 for decoding with reference to the Pl and PO boxes and stored in the frame memory Ml. It is then sent to the display device 7 to display an image of the Bl box (Status 5). The image B, Bg is read from the ring buffer 4 to be decoded in a similar manner with referensia to the boxes Pl and PO and to be stored in the frame memory Ml. It is sent to - - display device 7 to display its image (State 6). The movements of the write pointer WP and the read pointer RP during this reverse reproduction will be explained below with reference to FIGURE 6. In FIGURE 6a, a GOP stored in an area from a steering position R3 to a position R4 of address in the ring buffer memory 4 is being decoded and the reading pointer RP is positioned within area. An unread data area extends from the address position R3 including the area being decoded to a direction position W3, and the remaining area is a data area already read. Note that the write pointer WP is positioned where it is almost oriented towards the address position r3. Because this is the reverse reproduction mode, the left-handed direction is the playback direction in the ring buffer 4. FIGURE 6b shows a state where decoding has advanced to the next GOP. That is, the GOP stored in the area from the address position R4 to an address position R5 is being read from the ring buffer 4 to be decoded. Because unread data area becomes small in this state, control circuit 8 controls unit 2 of pickup to return to the new data read from the past, from the disk 1. At the same time, it causes the writing pointer WP to jump from the address position W3 to the address position W4 and writes the data read from disk 1 to the memory 4 intermediate ring while moving in the clockwise direction WP pointer. In this case, the writing pointer WP 8-1 is controlled in order to jump through an area to which a number of sestores is the sum of a number of sectors written the last time and a number of sectors to be written this time, they can be described at once. Incidentally, in compression by means of the MPEG method, other images can not be encoded in a GOP without reading the image I first as described above. Accordingly, images can not be decoded even when the GOP is read from subsequent images in sequence during reverse playback. Then it is written beforehand in a TOC or similar registered in the head of disk 1, that of whose sectors each GOP is composed. The control circuit 8 memorizes that and assures that the mouse pointer RP jumps to a GOP head during reverse playback and returns while decoding in order from - - the image I, to dessodify an image that is going to be sent next. FIGURE 7 shows the detailed movements of the reading pointer RP during this reverse reproduction, and FIGURE 8 shows the detailed movements of the writing pointer WP. As shown in those figures, each decoded frame can be stored in frame memories Ml, M2 and M3 as shown in FIGURE 3, through the movements of the read pointer RP and the write pointer WP. FIGURE 7a is the same figure as FIGURE 6a and a part surrounded by a broken line in the figure is enlarged and shown in FIGURE 7b. As shown in the figure, the reading pointer RP jumps from the address position R3 to the address position R4 in the playback direction when decoding a GOP to read the image I at the head of the GOP. Next, the read pointer RP is caused to skip once in the reverse direction to the play direction to read the picture P, to jump once in the same direction to read the next picture P and to read the adjacent picture B. on one side of the address position R3. Then, the read images are dessodified in sequence by the decoder 5, and the decoded supers are stored in the memories Ml, M2 and M3 of the frame as shown in FIGURE 3. While the images are decoded in this way to the past in a GOP unit in the reverse reproduction mode, the images are read and decoded in the reverse direction to the playback direction within the GOP because each image referenced during encoding has to be decoded first as described above. FIGURE 8a shows the same state as that shown in FIGURE 6c, wherein a part shown by a broken line is amplified and shown in FIGURE 8b. In the figure, the collateral write pointer WP in the address slot W3 jumps to the address position W4 in the write data. It is in the writing position where the data of a number of sectors of the sum of a number of sectors written in the last time and a number of sectors that are to be written this time can be written in the area from the address position W3 and the address position W4, as described above. Then, returning from address position W4, sectors SO, SI, S2, S3, S4 and S5 ... are written. While the data within GOP is arranged and written in the same direction as that during normal playback, when the mode is specified - - reverse reproduction, the control circuit 8 controls the writing pointer WP so that it is from the next sector that has been programmed to overwrite during normal playback. That is, when it has been programmed to overwrite from Sector 25 during normal playback as shown in FIGURE 5a as for example, and when three sestores from Sector 22 are to be written to Sector 24, the write pointer WP is skipped to the position of Sestor 106 to overwrite Sector 22 therein and Sectors 23 and 24 are overwritten in Sectors 107 and 108, as shown in FIGURE 5b. Note that it is natural for the unread data area (or the already read data area) during normal playback to be inverted into the already read data area (or the unread data area) during reverse playback. It is possible to quickly respond not only to the feed of the sub-frame in the reverse playback mode but also to variable speed reproductions such as slow playback and double speed playback by controlling the writing / reading of the ring buffer 4 by means of the control circuit 8, so that the storage area of the ring buffer 4 is almost halved in the area of unread data and for the data area already read as described above. In addition, it becomes possible to respond to variable speed playback not only during reverse playback but also during normal playback. Note that when the variable speed reproduction mode is specified, it is possible to respond to the variable speed reproduction such as a double speed reproduction by reproducing only the I images or only the I images and the P images. FIGURE 13 is a diagram of system showing a data reproduction apparatus according to another embodiment of the present invention. In the figure, the digital video data, the digital audio data or the like, is compressed and recorded on a disc (DV) 1 by means of the MPEG or similar method. A capture unit 202 reads the digital data recorded from the disk 201, a demodulation circuit 203 demodulates the read digital data, an error correction circuit (ECC) 204 corrects the errors using error correction codes, a memory is inserted intermediate 205 in the buffer at a rate on the decoder side that differs from a rate on the read side and a decoder 206 dismodifies and sends the data encoded in image signals that are to be displayed on the display unit (VIDEO OUT). In addition, a system control 207 sends various control signals to a servo circuit 209 to control focus, tracking and routing, etc. the control keys 208 are buttons, such as a play button, a stop button, a double speed playback button, a reverse play button operated by a user, the 209 servo circuit controls focus, tracking and routing of the capture unit 202 under the control of the control 207 from the system. The operations of the data reproduction aqparato constructed as described above, will now be explained. The disc 201 is controlled to rotate at a predetermined number of revolutions by a spindle motor not illustrated and the recorded digital data is read therefrom when a laser beam is radiated from the pickup unit 202 to the disc 201. This digital data is recorded in the unit of the sector shown in FIGURE 11, as described above, and a sector sink, a sector address and a sector header are appended to the head of each sector. While the feedback unit 2 reads each sector described above, the servo circuit 209 carries out the control of focusing and tracking control based on the focus error signal and the tracking error signal that are obtained from the demodulation circus 203 under the control of the system control 207. The sector demodulated by the demodulation circus 203 undergoes the ECC 204 to correct its error. Its position where a detected sector address is written to and controlled from the data and written to the buffer 205. This buffer 205 is adapted to have a memory capacity capable of storing at least 2 GOPs of the digital data. The GOP data in the frame sequence shown in FIGURE 10b, is read in sequence from the buffer 205 and the images I, the images P and the images B that make up the GOP are decoded by the decoder 206 for playing and sending an image signal of each frame (VIDEO OUT). In this way, when the normal play button of the control key 208 is manipulated, the output of the video signals from the encoder 206 (VIDEO OUT) are supplied to the display unit _, reproducing the video images in the reproduction unit. FIGURE 14 shows diagrammatically the operations of buffer 205 and decoder 206. In this case, suppose that the buffer 205 has a memory capacity of two GOPs. In the figure, the sectors read from the disk 201 are written to the buffer 205. That is, three GOPs are stored in the buffer 205 in GOP order. 1, GOP. 2 and GOP. 3. Then, GOP. 0 read from the buffer 205 is supplied to and decoded by the decoder 206, sending the decoded image signals (VIDEO OUT). When the decoder 206 ends decoding GOP. 0, GOP. 1 to follow GOP. 0 is read from the buffer 205 and is supplied upon decoding 206. Then, the system control 207 controls the capture unit 202 to give access to the disk 201 and to read GOP. 4, the new data to be stored in the buffer 205. The video signals in this way are reproduced and displayed in the display unit one after the other. Note that the rate at which disk data 201 is read is graded to be faster than the rate at which video signals are sent from decoder 206. When a certain amount of data has been stored in buffer 205, the control 207 of the colossal system reproduces from the pickup unit 202 in a pause mode and when the data stored in the buffer 205 is less, it is it places the same to the playback mode for storing the data in the buffer 205. Incidentally, while a ratio between an amount of compressed coding before being decoded by the decoder 206 and an encoding amount after the decoding is made to vary correspondingly to a complexity and flat shape of the video signals as described above, because the rate of the decoded and sent video signals is of generally constant display speed, a regime of the sanctity of the supply of the input of the compressed sodifixed signals to the decoder 206 is made to be random so that it corresponds to the complexity and flat shape of the video signals so that the decoded and sent video signals are continuous. The buffer 205 is provided to the buffer are these variable regimes and is controlled so that a new GOP is written into the buffer 205 when an empty area is collapsed as described above because the rate for the Write data to the buffer 205 normally graduates to make it higher than that to send the data from the decoder 206.

FIGURE 15 shows diagrammatically the operations of buffer 205 and decoder 206, where control key 208 is operated and a staged mode is specified. When the stagnation mode is specified, the mode will generally have a greater possibility of moving to the backward and similar mode to see the images before and after that moment, feeding the frames. As shown in the figure, when the stagnation mode is specified, the system control 207 controls the trapping unit 202 to give access to disk 201 and to read GOP. 0 and GOP. -1 that precedes GOP. 0 in terms of time, and write them in the buffer 205. Then, when the sontrol key 208 is operated and then the table feed button is operated backward after the stalled mode, the decoder 206 can read the GOP. -1 of the buffer 205, which is to be decoded immediately after finishing the GOP decoding. 0 that is being decoded. Therefore, because the dessodifisador 206 can be supplied with the GOP. -1 immediately after finishing the GOP decoding. 0 that is being decoded and can supply image signals (VIDEO OUT) of GOP. -1 quickly decoded to the display unit, the user does not feel a sense of Incompatibility when specifying the backward playback mode. Note that the reason why he also writes the GOP. 0 that is being decoded in buffer 205, is due to the images that make up the GOP. 0 already decoded need to be decoded and the I image that is placed in the GOP head. 0 is necessary for decoding as described above. When it is specified to feed the tables in the normal direction after the stop mode the GOP. 1 is read from the buffer 205 after the GOP is decoded. 0 and is supplied to the decoder 206. Furthermore, it becomes possible to accommodate not only the frame feeding but also with the variable speed reproductions such as a double speed reproduction increasing the sapacity of the buffer 205 as shown in the FIGURE 16 and writing GOP again. 0, GOP. -1 and GOP. -2- in the buffer 205 giving access to the disk 201 by controlling the pickup unit 202 when the stalling mode is thickened and when decoding the GOP. 0 as shown in FIGURE 16. Still further it becomes possible to accommodate with variable speed playback not only in the reverse playback mode but also in the directional playback mode normal. Note that when the variable speed production mode is specified, it is also possible to accommodate with the variable speed reproduction such as the double speed reproduction by reproducing only the I images or only the I images and the P images for example. Although preferred embodiments have been described, variations will be made to those skilled in the art within the scope of the present inventive concepts that are delineated by the following claims.

Claims (10)

N O V E D A D I N V E N C L I N Having described the invention, it is considered as a novelty and, therefore, it is claimed that it is contained in the following CLAIMS: "

1. A method of reproducing data to reproduce original video signals by demodulating and writing the read data from a disk by means of a capture unit to the storage medium and decoding the data read from the storage medium, the storage means is controlled so that a unread data area and a data area already read in the storage medium, requires approximately one-half of a total memory capacity, respectively.

2. The method of reproducing data according to claim 1, wherein the data is written to the storage medium in a unit of the sector composed of a fixed amount of data.

The data reprodusion method according to claim 2, wherein a write pointer is moved to a skip address in the reproduction direction by a number of sectors of the sum of a number of sectors written in the last time and a number of sectors to be written this time, when a reverse playback mode is specified and the number of sectors to be written this time is written to the storage medium in the reverse direction to the playback direction from the direction position.

A data reproducing apparatus comprising a demodulation means for demodulating the read data from a digital video disc by means of a pickup unit, the storage means for temporarily storing the demodulated data and a decoder for decoding the read data of the means of storing in original video signals, further comprising: a control circuit for controlling the storage medium so that the area of the unread data and an area of the data already read in the storage medium require approximately half of the Layer of total memory, respectably.

5. The data reproduction apparatus according to claim 4, wherein the control circuit writes the data to the storage medium in a unit of the sector composed of the fixed data amount data. 13 -. 13 -

6. The sonicity data reproducing apparatus with claim 4, wherein the control circuit moves a write pointer to a chirped address position in the reproduction direction by a number of sectors from the sum of a number of sectors written in the last time and a number of sectors to be written this time when a reverse reproduction mode is specified and write the number of sectors to be written this time to the storage medium in the reverse direction to the playback direction from the address position.

7. A method of reproducing data to reproduce image signals by demodulating the data read from a disk by means of a capture unit and decoding it through a buffer, the buffer has a capacity capable of 'storing at least two GOP composed of a plurality of frames, at least one GOP includes a previous GOP in relation to the time to a GOP that is being decoded and read from the disk and that is being stored in the buffer when a stalled mode is specified to work in a special playback mode.

8. The data reproduction method according to claim 7, wherein the mode of Special reprodusion is a backward playback mode.

9. A data reproducing apparatus comprising a demodulation means for demodulating data read from a disk by means of a pickup unit, a buffer for temporarily storing the demodulated data and a decoder for decoding the read data from the buffer, in image signals, the buffer memory has a capacity capable of storing at least two GOPs composed of a plurality of frames, at least one GOP includes a previous GOP in relation to the time to a GOP that is being decoded by the decoder that is being read from the disk and that it stores in the intermediate memory when a stalled mode is specified to operate in a special reprodus mode.

10. The data reproduction data according to claim 9, wherein the special reproduction mode is a reproduction mode backwards. SUMMARY OF THE INVENTION A method of reproducing data and a data reproduction apparatus that allows it to operate with special reproductions such as a fast reverse playback when specified. In the data reproducing apparatus comprising a demodulation means for demodulating the read data from a digital video disc by means of a pickup unit, a storage means for temporarily storing the demodulated data and a decoder for decoding the read data from the medium of storage in original video signals, the apparatus further comprises a control circuit to control the storage medium so that an area of the unread data and a data area already read in the storage medium requires approximately one-half the capacity of the total memory, respectively, so that the data necessary for the reverse or similar reproduction is left in the storage medium, allowing the special reproduction to work quickly. In testimony of which, I have signed the above description and novelty of the invention as attorney of SONY CORPORATION, in Mexico City, Federal District today, the 23rd of August, 1995. p.p.de SONY CORPORATION. EDUARDO CORREA E.