JPH0955915A - Video data recording and reproducing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a double speed reproduced picture whose movement is natural when digital video data is recorded and reproduced in a disk-like recording medium. SOLUTION: Compressed video data for one second (thirty frames) are set to be one stripe. The compressed video data of one stripe is divided into six data blocks and they are recorded into a disk. The data block (6n-5)a, (6n-3)a... are reproduced from the disk, and they are written into the six data blocks in a buffer memory. At first, data of a stripe (a) are sequentially read out, and then data of a stripe (b) are read out. Reproduced data are arranged in the order of first, third and fifth frames, and double speed reproduced data is obtained. Then, triple and sextuple speed reproduced data can similarly be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video data recording / reproducing method for recording video data on a disk-shaped recording medium such as a hard disk or an optical disk, and more particularly,
The present invention relates to a video data recording / reproducing method capable of double-speed reading.

[0002]

2. Description of the Related Art When a video server is composed of hard disks, a system is known which uses a plurality of hard disk drives and can supply video data to a plurality of channels simultaneously. In this case, in consideration of the data rate of video data, the transfer rate of a hard disk, the number of channels, etc., various studies have been made on how to write and read video data to and from a plurality of hard disks.

FIG. 1 shows a schematic configuration of a video server using a hard disk. In the example of FIG. 1, the number of channels that can be input / output simultaneously is six. Input / output data of 6 channels CH1 to CH6 are IO
It is coupled to the hard disk array 2 via the processors 1 ₁ , 1 ₂ , 1 ₃ , 1 ₄ , 1 ₅ , 1 ₆ . IO processor ₁ 1 to 1 _6, each have a buffer memory, IO
Control signals are supplied to the processors 1 ₁ to ₁₆ . The input / output data is video data,
For example, it is video data compressed by MPEG2. However, the compression is not always necessary.

The hard disk array 2 is composed of a plurality of hard disk drives. A control signal is supplied from the system controller 3 to the IO processors 1 ₁ to ₁₆ and the hard disk array 2. The control signal is, IO processor ₁ 1 to 1
_The control signal for the buffer memory _{6 and} the control signal for the hard disk array 2.

The data rate of one channel is 30 Mbps
Then, it is necessary to transfer data of 30 × 6 = 180 Mbps by time-division multiplexing 6-channel data. The hard disk array 2 is composed of 16 hard disk drives, and one hard disk drive has an effective transfer rate of 2
When reading / writing in units of 56 KB and assuming about 4 Mbytes / sec, 4 × 8 × 16 = 512 Mbps, and there is a sufficient margin even when considering seek time at the time of access.

As shown in FIG. 2, data of channels CH1 to CH6 are time-division multiplexed in a fixed time slot. For example, the data stream of each channel is divided into stripes having a length corresponding to 1 second (30 frames). The divided stripes D1 to D6 are time-division multiplexed and then supplied to the hard disk array 2. That is, 1 second of data is written in 1/6 second. The rate of the time division multiplexed data is 180 Mbps.

[0007]

When the video data is continuously input / output, 1x speed reproduction (or 1x speed reproduction) is performed.
Then, in the case of editing, when wanting to see the contents of the program quickly, etc., it is required to have a function of double speed reproduction with a double speed ratio of 2 or more. For example, in 2 × speed reproduction, the read speed of 2 × from the buffer memory of the IO processor during 1 × speed reproduction
It is conceivable to read at twice the speed. However, this method has a problem that the content of the buffer memory becomes empty because the reading speed of the hard disk drive cannot keep up. Therefore, while playing the data intermittently from the hard disk, the image of the same frame is
Reading is performed once and repeatedly. The image read in this way becomes a reproduced image which is scattered over time, and there is a problem in that the image has an unnatural movement.

Therefore, an object of the present invention is to obtain a double-speed reproduced image with natural movement when reproducing video data from a disk medium such as a hard disk, MO (magneto-optical disk), PD (phase change disk). It is an object of the present invention to provide a video data recording / reproducing method capable of performing the above.

[0009]

In order to achieve the above-mentioned object, the present invention records compressed or uncompressed digital video data on a disc-shaped recording medium and outputs the digital video data from the disc-shaped recording medium. In the video data recording / reproducing method adapted to reproduce, a data buffer capable of storing N data blocks each of which is an integral multiple of the speed ratio of the double speed reproduction is used for M frames (M
Is an integer multiple of N), one frame at a time is sequentially written, N data blocks are read out and recorded on the disk-shaped recording medium, and N data blocks reproduced from the disk-shaped recording medium are recorded. Writing sequentially to the buffer and reading the video data from the data buffer. In the reading step, a predetermined data block corresponding to the speed ratio is intermittently read from the disk-shaped recording medium and written to the data buffer, A video data recording / reproducing method is characterized in that video data is read from a data buffer in an order according to a speed ratio.

In the disk drive, the amount of data that can be reproduced in one second, for example, is limited due to restrictions on the access speed and the need for seek time. When recording / reproducing by dividing one second of a continuous stream of video data into M frames, the data obtained by equally dividing M frames into N data blocks is formed into N data blocks. A data buffer is used to form the data block, and the data buffer forms a data block in which the frame order is exchanged with the original data. The disk-shaped recording medium is accessed for each data block to record data. Then, in the case of double speed reproduction, the data blocks are intermittently reproduced from the disk-shaped recording medium, written in the data buffer, and the data is read from the data buffer in the order corresponding to the double speed ratio. This makes it possible to obtain a favorable double-speed reproduced image with natural movement.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. A video data recording / reproducing apparatus to which the present invention is applied is as shown in FIG.
IO processor 1 ₁ to 1 _6, a hard disk array 2 and the system controller 3, in which the 6-channel data is possible to output the multiplexed data.

FIG. 3 shows a process for writing (recording) one-channel video data in the hard disk.
A stream of input video data is written in the buffer memory of the IO processor every M frames, for example, 1 second (30 frames) of data (stripe) from the beginning,
Also, the data is read from the buffer memory in this unit. Figure 3
B shows a state in which one stripe of data (for example, data compressed by MPEG2) is stored in the buffer memory.
The buffer memory is composed of six data buffers that respectively store data blocks of five frames, for example.

To each data buffer constituting the buffer memory, as shown in FIG. 3C, the data of the first frame are sequentially written one frame at a time in the vertical direction, and as shown in FIG. 3D, they are arranged in the horizontal direction. Data blocks of 5 frames are read from the data buffer in order. Such writing and reading control can be performed by address control based on a command from the system controller. Also, a two-bank configuration may be used in order to perform writing and reading simultaneously. 6n, 6n-1, 6n- for the data blocks written in each data buffer
2, 6n-3, 6n-4, 6n-5 and data block numbers are given. n is an integer of 1 or more. The data read from each data buffer is collected in the order shown in FIG. 3E. The data in the order shown in FIG. 3E is supplied to the hard disk array and recorded by 16 hard disk drives.

At the time of 1 × speed reproduction, data of all frames are read from the hard disk array to obtain the data in the order shown in FIG. Therefore, 30 frames of data are read from the buffer memory in the original time-series order.

FIG. 4 shows the operation during double speed reproduction. During 2 × speed reproduction, generally, 6n-a, 6n-a + 2, 6
As represented by n-a + 4, data is read from the disk intermittently and the read data is written in the data buffer of the buffer memory. In FIG. 4, reference numerals a and b are used to distinguish the stripes. FIG. 4A shows
The data read from the disk in the hard disk array is shown. From stripe a to data block (6n
-5) a, (6n-3) a, (6n-1) a are read, and the block (6n-5) b, from the next stripe b
(6n-3) b and (6n-1) b are read.

The read data is written in each of the six data buffers of the buffer memory as indicated by the arrow in FIG. 4C. Therefore, when the reproduced data is written in the buffer memory, the data is arranged as shown in FIG. 4B. From the buffer memory,
As indicated by the arrow in D, the data is read by a method of first reading the data of stripe a and then the data of stripe b. Therefore, as shown in FIG. 4E, the read data from the buffer memory is the data of the ratio of 1 frame to 2 frames, such as the first, the third, the fifth, ... The data is for double speed reproduction. During double-speed reproduction, the image can be reproduced from the time when three blocks of data are read.

FIG. 5 is for explaining the triple speed reproduction operation. 6n-a, 6n-a + during 3x speed playback
As indicated by 3, data is intermittently read from the disk in block units, and the read data is written in each data buffer of the buffer memory. In FIG. 5, in order to distinguish data (stripe) for 30 frames, a, b,
The reference numeral of c is used. FIG. 5A shows data read from a disk in the hard disk array. From stripe a to blocks (6n-5) a, (6n
-2) a is read, blocks (6n-5) b and (6n-2) b are read from the next stripe b, and blocks (6n-5) c and (6n are read from the next stripe c.
-2) c is read.

The read data is written in each data buffer of the buffer memory as indicated by an arrow in FIG. 5C. Therefore, when the reproduced data is written in the buffer memory, the data is arranged as shown in FIG. 5B. Data is read from the buffer memory in the order of stripes a, b, and c, as indicated by the arrow in FIG. 5D. Therefore, as shown in FIG. 5E, the read data from the buffer memory is the data of the ratio of 1 frame to 3 frames as shown in the first, fourth, seventh, ... It becomes the data of 3 times speed reproduction. In the 3 × speed reproduction, the reproduction of the image can be started from the time when the data of 2 blocks is read.

FIG. 6 is for explaining the 6 × speed reproduction operation. During 6 × speed reproduction, data is intermittently read from the disk at a rate of 1 frame per 6 frames, and the read data is written in each data buffer of the buffer memory, as indicated by 6n-a. In FIG. 6, reference numerals a, b, c, d, e, and f are used to distinguish the stripes. FIG. 6A shows data read from a disk in the hard disk array. The block (6n-5) a is read from the stripe a, the block (6n-5) b is read from the next stripe b, and the block (6n-5) c is read from the next stripe c. Furthermore, (6n-5) d, (6n-5)
e and (6n-5) f are sequentially read.

The read data is written in the buffer memory as shown by the arrow in FIG. 6C. Therefore,
When the reproduced data is written in the buffer memory, the data is arranged as shown in FIG. 6B. From the buffer memory, as indicated by the arrow in FIG. 6D,
The data is read. This read operation is similar to the write operation. Therefore, as shown in FIG. 6E, the read data from the buffer memory is the data of the ratio of 1 frame to 6 frames, such as the 1st, 7th, 13th ,. The data becomes 6-times speed reproduction. During 6 × speed reproduction, image reproduction can be started from the time when one block of data is read.

As described above, not only 1 × speed but 2
It is possible to obtain playback video data of double speed, triple speed, and 6 × speed. The maximum time required to read / write data for one data block (5 frames) is 20 [ms] at the time of random access, and reading / writing is performed up to 8 times within the time slot time (166 ms) assigned to each channel. It is possible. In one embodiment of the invention, NTS
As in the C system, one second image is composed of 30 frames and one block is 5 frames, so that the double speed ratio can be double speed, triple speed, and 6x speed, and the double speed ratio can be continuously changed. You cannot do it. In the above description, the double speed reproduction operation in the FWD (forward) direction has been described.
A double speed reproduction operation in the EV (reverse) direction is also possible.

Further, one embodiment of the present invention can also operate at 12 × speed and 30 × speed. FIG. 7 is for explaining a 12 × speed reproduction operation. FIG. 7A shows, for example, a block (6n-4) recorded on the disc. There is a time difference of 1 second between the block (6n-4) a of the stripe a and the block (6n-4) b of the stripe b. 2 when accessing the hard disk
The block at the second ahead is reproduced intermittently and written in the buffer memory. That is, in the case of FIG. 7A, (6n-4) a,
(6n-4) c, (6n-4) e, (6n-4) g,
The blocks of ... Are read and sequentially stored in the buffer memory.

Next, when reading from the buffer memory, starting from the eighth frame of stripe a, as shown in FIG.
8th frame is read, then the 20th frame of stripe a is read repeatedly 4 times, then the 8th frame of stripe b is read again, and the 20th frame of stripe b is repeated 4 times. Read it. By repeating such a read operation, 12 × speed reproduction is possible. Note that when reading from the buffer memory, it is possible to repeatedly read the frame of the same number, for example, the eighth frame of each stripe, five times, but FIG.
In the above method, since both the eighth frame and the twentieth frame are used, the unnaturalness of the motion of the reproduced image can be eliminated to some extent.

Although not shown, in the same manner as described above, in the case of reproducing at 30 times speed under the condition that only 6 blocks can be read out in 1 second, 6 data blocks out of 30 data blocks are recorded on the disk. It is read from, stored in the buffer memory, and repeatedly read.

Although a hard disk drive is used in the above description, a disk drive such as an MO drive or PD drive may be used. The present invention can also be applied to the PAL system. In the PAL system, since one second is 25 frames, the number of data blocks read out in one second is 5, so that the required time is 1
It takes only 08 ms and can fulfill the same function as the NTSC system. Furthermore, 6 pieces of 1 stripe data (PA
It is not limited to the example in which the data is divided into 5 data blocks in the L system, but may be divided into 12 (10 in the PAL system) data blocks. In this case, 2
Double speed, triple speed, quadruple speed, and quintuple speed are possible.

As can be understood from the above description, in the present invention, the number of data blocks per channel that can be accessed per second is 6 (or 6) (or 1x speed, 2, 3 or 6x speed). 5) and is constant. This means that the read / write rate of the buffer memory is constant. Further, the process of writing the data blocks read from the disc at the time of reproduction into the data buffer is the same regardless of the speed ratio. The system controller issues an instruction to the hard disk array to access 6 (or 5) predetermined data blocks, and also reads data from the buffer memory of the IO processor in response to the speed ratio. A control command that specifies the method is issued.

[0027]

As described above, according to the present invention, a plurality of disk recording / reproducing devices in stripe units can be used.
When the access speed of the recording / reproducing apparatus is specified, the double speed reproduction can be performed by simple control.
In particular, the present invention does not repeatedly reproduce the same frame of data, but has an advantage that a double-speed reproduced image with a natural motion can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a video server to which the present invention can be applied.

FIG. 2 is a schematic diagram for explaining multiplexing of video data of a plurality of channels.

FIG. 3 is a schematic diagram for explaining a recording method of video data.

FIG. 4 is a schematic diagram for explaining a double speed reproduction method.

FIG. 5 is a schematic diagram for explaining a method of 3 × speed reproduction.

FIG. 6 is a schematic diagram for explaining a 6 × speed reproduction method.

FIG. 7 is a schematic diagram for explaining a 12 × speed reproduction method.

[Explanation of symbols]

1 ₁ 1 ₂ 1 ₃ 1 ₄ 1 ₅ 1 ₆ IO processor 2 Hard disk array

Claims (4)

[Claims] 1. A video data recording / reproducing method in which compressed or non-compressed digital video data is recorded on a disc-shaped recording medium and the digital video data is reproduced from the disc-shaped recording medium. Video data of M frames (M is an integer multiple of N) is sequentially written for each frame to a data buffer capable of storing N data blocks each having an integral multiple of the speed ratio, and the N data blocks are written. Each of the steps comprises reading and recording the data on the disc-shaped recording medium, and sequentially writing N data blocks reproduced from the disc-shaped recording medium to the data buffer and reading video data from the data buffer. , In the reading step, a predetermined data block according to the speed ratio is A video data recording / reproducing method characterized by intermittently reading from the disc-shaped recording medium, writing to the data buffer, and reading video data from the data buffer in an order according to the speed ratio. 2. The video data recording / reproducing method according to claim 1, wherein (N = 6) (M = 30) is set to enable 2 × speed reproduction, 3 × speed reproduction and / or 6 × speed reproduction. Characteristic video data recording and reproducing method. 3. The video data recording / reproducing method according to claim 1, wherein the number N of data blocks is defined by an access speed of a drive of a disk-shaped recording medium. 4. The video data recording / reproducing method according to claim 1, wherein video data of a plurality of channels is time-division multiplexed and input / output.