JPH06223505A - Recording/reproucing method - Google Patents

Abstract

PURPOSE:To transfer a video signal without any breaks within a specified period of accessing time responding to requests from plural users by solving the problem of multiaccessing to a moving picture database, etc. CONSTITUTION:An input video signal (a) is divided into (n) of big blocks, the big blocks are divided into (m) of small blocks, an obtained signal of (n)-row and (m)-column is rearranged, its format is transformed into a signal of an (m)-row and (n)-column and a recording/reproducing signal (b) is generated. This recording/reproducing signal (b) is reproduced at a transfer speed of (n+1/m)-fold that intrinsic to the video signal. By cyclically transferring a recorded signal from accumulated medium, from its leading information to its last in sequence at a high speed, the video signal is read from its leading information to its last in sequence at a constant cycle as shown an access point (c).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a band-compressed image,
The present invention relates to a method for recording or reproducing voice or the like on a storage medium such as a magnetic disk, an optical disk or a magnetic tape, and more particularly to a recording / reproducing method that enables multiple access.

[0002]

2. Description of the Related Art In recent years, rapid progress in compression technology (high efficiency coding technology) of video signals and audio signals and progress of international standardization (MPEG, etc.), improvement of storage capacity of storage media, and digital represented by ISDN. With the spread of communication, a database service of moving image information by a digital communication network has become feasible. With this moving image database service, request-type services and interactive services, which are difficult to achieve with conventional terrestrial broadcasting, satellite broadcasting, and other broadcast-type services, can be realized, so research and development is actively pursued. ing.

However, in the case of moving image information, one program is from several tens of seconds to several hours, and the storage medium is occupied for a long time during the service. Therefore, it is shared by a plurality of users and responds to each request in real time. In order to do so, multiple access technology is required as a recording / playback method for storage media. Therefore, for example, Sakurai et al., "Multiple Access Technology for Video Information" (Technical Report of the Institute of Television Engineers of Japan, 1999)
(March 27, 2013), multiple access is achieved by increasing the transfer rate of the storage medium and scheduling management.

An example of the recording / reproducing method for realizing the above-described conventional multiple access will be described below with reference to FIGS. 6 and 7. FIG. 6 is a conceptual diagram of multiple access timing according to a conventional recording / reproducing method. In FIG. 6, (a) is a recording / reproducing video signal from a recording medium such as a magnetic disk device, and (b) is a plurality of users (in this case, users). A, user B, user C, user D) access, (c) is an output video signal to each user. FIG. 7 is a tracking operation diagram of a magnetic disk device used as a storage medium. Reference numeral 500 denotes a magnetic disk unit of the magnetic disk device, and 50.
Reference numeral 1 is a recording / reproducing head portion of the magnetic disk device.

When the transfer speed of the storage medium is higher than the transfer speed of the band-compressed video signal (the transfer speed peculiar to decoding in real time), as shown in FIG. By securing the transfer time of the Treal cycle, it is possible to transfer the video signal almost in real time in response to the request.

[0006]

However, in the magnetic disk device or the like used as the storage medium, as shown in FIG. 7, an access time Tacc occurs for each access by a plurality of users. Therefore, the transfer time is lost by an integral multiple of the number of connected users, and the number of connected users cannot be increased for the transfer rate ratio (= [storage medium transfer rate] / [video signal transfer rate]). . For example, in FIG. 6, even though the transfer speed ratio is set to about four times, only the three users can access at the same time because the information of Treal for the user D cannot be transferred to the user D in the remaining time Tlos. The service cannot be received until the transfer to the user A is completed.

This problem is caused by the unique property of moving image information that information must be transferred continuously for several hours. In other words, while using a storage medium such as a magnetic disk whose access speed is relatively slow, it is attempted to realize sharing by allocating time exclusively to completely independent accesses by a plurality of users. The limit will occur, and it will not be possible to handle requests that exceed the limit. Therefore, there arises a problem that information cannot be obtained even if accessed, or that access takes several hours.

In particular, in a moving image database system or the like, resources of storage media must be shared by multiple users without failure. However, in the conventional recording / reproducing method, the above-mentioned problems exist, and thus it has been extremely difficult to put it into practical use.

In view of the above-mentioned problems, the present invention, even when transferring a video signal composed of moving image information for several hours, does not fail in response to requests from a plurality of users and within a predetermined access time. The present invention provides a recording / reproducing method that enables transfer.

[0010]

In order to solve the above problems, the present invention divides a time-series signal into n large blocks in the time axis direction (n is an integer of 2 or more), and n The large blocks of are further divided into m small blocks in the time axis direction for each large block (m is an integer of 2 or more), and the obtained n rows m
A time-series signal of a column is transposed to generate a recording / reproducing signal whose format is converted into a time-series signal of m rows and n columns, and the time-series signal arranged in the recording / reproducing signal is transmitted at a transmission rate specific to the time-series signal. A recording / reproducing method of reproducing at a transmission speed of (n + 1 / m) times as high as the above.

[0011]

According to the present invention, a time series signal such as a video signal is cyclically rearranged in block units in a unique format and recorded on a storage medium by the above method, and the recorded signal is cyclically transferred from the storage medium by high-speed transfer. Read repeatedly. The video information can be restored by intermittently extracting the video signal at a specific phase from the recording / reproducing signal repeatedly read cyclically by this high-speed transfer. Also,
By performing high-speed transfer, the beginning information to the final information of the video signal are sequentially read out at a constant cycle (if the transfer rate ratio is 100 times, about 1/100 of the program length) according to the transfer rate ratio. It is possible to start the video information at this cycle. Therefore, in response to a request from the user, the video signal can be surely transferred within the time corresponding to this cycle, and it can be distributed to a plurality of users who have made a request within the same cycle. It can be handled by transferring.

According to this method, the tracking of the recording / reproducing head such as a magnetic disk used as a storage medium can be a simple and regular operation, so that the loss due to the access time can be minimized. Therefore, the maximum transfer rate of the disk can be obtained, and the time for the above-mentioned head start can be shortened.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A recording / reproducing method according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a conceptual diagram of multiple access timing according to the recording / reproducing method of the present invention. FIG. 1A shows an input video signal having a program length Tp, FIG. 1B shows a recording / playback signal on a storage medium, FIG. 1C is an access point, and FIG. 1D is an output video signal to a plurality of users. In this timing diagram, for simplification of the input video signal (a), the number of divisions n of the large block is set to 4, and the number of divisions m of the small block is set to 3 (generally, n and m). May be an integer of 2 or more).

First, the recording operation on the storage medium will be described. A video signal composed of 12 small blocks is first divided by (n + 1) at intervals shown by hatched portions in FIG.
/ M) times the transfer rate of recording / reproducing at a storage medium (for example, a magnetic disk device) in small block units [1
/ (N + 1 / m)] times time-axis compression and recording at high speed. Here, the tracking of the recording / reproducing head of the magnetic disk device is performed by Tp × [1 / (n + 1 / m)] of the video signal length.
The recording is repeated cyclically for the same recording area of the magnetic disk device, and while the small blocks that have already been recorded are reproduced, the recording is repeated following the small blocks, thereby ending the recording of all video signals.

A format conversion diagram of the recording / reproducing signal obtained as described above is generalized and shown in FIG. In FIG. 2, (a) is a video signal divided into n large blocks and m small blocks, (b) is a recording / reproducing signal, and (c) is a recording / reproducing signal format. Recording / playback signal (b)
Then, the large blocks of the video signal (a) are sequentially arranged from the leading small block, and this sequence is repeated m times to convert the array. By the conversion as described above, the video signal is recorded in the format shown in FIG. 2C in the recording / reproducing direction in order in the magnetic disk.
At this time, the arrangement of the small blocks in FIG. 2C is a transposed matrix when the video signal (a) is represented by a matrix of n rows and m columns.

Next, with reference to FIG. 1, a method of reproducing a signal recorded in the above-described format and supporting a plurality of accesses will be described.

In FIG. 1, the recording / reproducing signal (b) is (n
Since + / m) times high-speed transfer is performed, Tp × [1
/ (N + 1 / m)] cycle, the head information of the video signal (in the figure, ""
1 "is read out. Further, since the video signal is read out in the above-mentioned format, the video signal can be successively and sequentially extracted from the head information, and at this time, the video signal is extracted. The average transmission rate of the output video signal (for example, the hatched portion in (b) in the figure) matches the transmission speed peculiar to the input video signal.
(/ M) times the time axis extension,
The video signal indicated by the diagonal line can be reproduced.

As described above, access start points are obtained at Tp × [1 / (n + 1 / m)] cycles as shown in (c) in the figure, and each access start point is shown in (d) in the figure. Output video signals with different phases can be reproduced. By supplying these to a plurality of users in response to a request, maximum Tp × [1 / (n + 1 / m)]
Multiple access can be realized with the waiting time of. For example, assuming that the video signal at this time is band-compressed by high-efficiency coding at a transmission speed of 1.5 Mbps (corresponding to MPEG1), the program length Tp is 1 hour, and the transfer speed of the magnetic disk is about 150 Mbps. Since the transfer speed ratio is about 100 times, the waiting time can be about 36 seconds.

Next, FIG. 3 shows a block diagram of an embodiment of a recording / reproducing apparatus for realizing the recording / reproducing method of the present invention.

In FIG. 3, reference numeral 300 is a video signal input terminal, 301 to 303 are video signal output terminals, 304 is a time axis compression unit, 305 to 307 is a time axis expansion unit, 308 is a packetization unit, and 309 to 311. Is a discriminator / packet extracting unit, 312 is a recording / reproducing control unit, 313 is a recording / reproducing signal, and 314 is a magnetic disk device used as a storage medium.

In the time axis compression unit 304, the input video signal is time axis compressed in small block units, and the packetization unit 30 is used.
In 8, the program identifier, the block identifier, etc. are added as shown in FIG. 4, and the small blocks are arranged in the information field of the packet.

The recording / reproducing control unit records on the magnetic disk device 314 so that the format shown in FIG. 2 is obtained. At this time, as shown in the tracking operation diagram of the recording / reproducing head portion of the magnetic disk device 314 of FIG. 5, the recording / reproducing head 501 monotonically and sequentially tracks-records in the radial direction of the disk at the above-mentioned transfer speed ratio for recording. Reproduce. As described with reference to FIG. 1, after the input video signal is completely recorded by repeating the radial tracking n times, the recording / reproducing signal 313 has the format shown in FIG.

Identifier judging / packet extracting section 309-31
In No. 1, in response to a request from the user, packets of a specific phase are sequentially extracted from the recording / reproducing signal based on the above-mentioned identifier in the packet, and the time axis extending units 305 to 30
At 7, the time axis is expanded and transferred as an output video signal to a plurality of users.

As described above, according to the present embodiment, the video signal is used as the time-series signal, the format is converted into the magnetic disk device, and the high speed recording / reproducing is performed, whereby the tracking operation of the magnetic disk can be made monotonous. . Therefore, a loss due to the access time Tacc is small and a transfer rate close to the maximum transfer rate of the magnetic disk can be secured, so that it is possible to provide a recording / reproducing apparatus with a short waiting time for a plurality of users.

In this embodiment, the time-series signal is one video signal, but it may be a signal in which a plurality of programs are sequentially arranged or a signal in which a blank is inserted according to the capacity of the storage medium. Further, the transmission rate peculiar to the video signal represents the average rate in variable rate transmission, and is not limited to fixed rate transmission.

Further, the storage medium is a magnetic disk device, which is an optical disk device, a magneto-optical disk device,
It may be a magnetic tape device or a large capacity solid-state memory. In particular, when a solid-state memory is used, the speed can be increased and the waiting time can be extremely shortened, and the address generator can be simplified as in the tracking of the disk device, and at the same time, a bus composed of high-speed recording / reproducing signals can be used. Since the speed is constant, it is possible to have a configuration in which there is no breakdown as compared with a bus using random access.

[0027]

As described above, according to the present invention, multiple access can be performed without restrictions on the number of users, and the tracking mechanism of storage media such as magnetic disks and optical disks can be released from irregular access to prolong the service life. Can be achieved. Therefore,
According to the recording / reproducing method of the present invention, it is possible to realize a moving image database capable of providing a long-term moving image service with high reliability without service failure. Further, by reducing the block for dividing the video signal, the memory capacity for compression / expansion on the time axis can be reduced and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of multiple access timing according to the recording / reproducing method of the present invention.

FIG. 2 is a format conversion diagram of a recording / reproducing signal according to the recording / reproducing method of the present invention.

FIG. 3 is a block diagram showing a recording / reproducing method of the present invention.

FIG. 4 is a packet configuration diagram for multiplexing small blocks.

FIG. 5 is a tracking operation diagram of a magnetic disk device according to the recording / reproducing method of the present invention.

FIG. 6 is a conceptual diagram of multiple access timing according to a conventional recording / reproducing method.

FIG. 7 is a tracking operation diagram of a magnetic disk device according to a conventional recording / reproducing method.

[Explanation of symbols]

 300 Video signal input terminal 301 to 303 Video signal output terminal 304 Time axis compression unit 305 to 307 Time axis expansion unit 308 Packetization unit 309 to 311 Identifier determination / packet extraction unit 312 Recording and reproduction control unit 313 Recording and reproduction signal 314 Magnetic Disk device

Claims (7)

[Claims] 1. A time-series signal is divided into n large blocks in the time axis direction (n is an integer of 2 or more), and each of the n large blocks is further divided into m blocks in the time axis direction. The recording / reproducing method is characterized in that the signal is divided into small blocks (m is an integer of 2 or more), the obtained signal of n rows and m columns is transposed and the format is converted into a signal of m rows and n columns. 2. The recording / reproducing signal in which the time-series signal is transposed and arranged is generated by the format conversion, and the time-series signal arranged in the recording / reproducing signal is transmitted at a transmission rate peculiar to the time-series signal. The recording / reproducing method according to claim 1, wherein the reproduction is repeatedly performed at a transmission speed of (n + 1 / m) times. 3. A recording / reproducing method according to claim 2, wherein the small blocks of the time-series signal are packetized as a unit, and a block identifier is inserted in an overhead portion of the packet and arranged in a recording / reproducing signal. 4. A packet based on the block identifier is extracted from the recording / reproducing signal in units of small blocks of the time-series signal at predetermined intervals based on a large block division number n and a small block division number m, and the time is extracted. The recording / reproducing method according to claim 3, wherein axial extension is performed. 5. The time-series signal is time-axis-compressed in small block units, packetized, and the packets are recorded at predetermined intervals based on a large block division number n and a small block division number m. The recording / reproducing method according to claim 4. 6. The recording / reproducing method according to claim 5, wherein the time-series signal includes a video signal or an audio signal. 7. The recording / reproducing method according to claim 6, wherein the video signal and the audio signal are band-compressed signals.