JP2012244587A - Storage server - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a response delay at data acquisition time in a system which acquires video/audio data stored in a storage and transmits the acquired data for reproduction, thereby enabling video/audio to be reproduced smoothly in whichever mode it is reproduced, double-speed or reverse.SOLUTION: A storage server 102 transmits video/audio data acquired from a storage 107 in which the video/audio data is stored to a decoder 101 included in a video/audio data reproduction device. The storage server 102 includes three memory buffers A104 to C106 as the buffers in which to buffer the video/audio data. Of these memory buffers A104 to C106, the one used for data acquisition is used as a current memory buffer, while the others are used as a future memory buffer and a past memory buffer, respectively.

Description

  The present invention relates to a storage server, and in particular, when acquiring video / audio data stored in a storage and transmitting it to a playback device, video / video for reducing a time lag during continuous playback of video data in the playback device. The present invention relates to a storage server for audio data.

  As a conventional technique related to the present invention, for example, a technique described in Patent Document 1 is known. This technology is a system for producing and sending a program by performing editing processing that edits and processes the material video into a broadcast video. When transmitting material video data via a communication network, the readout delay of the material video Therefore, the bandwidth of the communication network is ensured so that the transfer delay is less than a certain time and screen freeze does not occur.

JP 2000-83192 A

  In general, a system that reads video / audio data stored in a storage, and transmits the read video / audio data to a playback device for playback can only acquire and play back the video / audio data collectively. In a configuration in which the capacity cannot be secured on the playback device side, there is a problem of how to eliminate the time lag that occurs when video / audio data is played back / reversely (the playback direction changes). Further, the above-described system is required to display a smooth screen even when normal continuous playback or reverse playback is performed or when the playback speed is changed.

  In addition, the system described above generates a response delay for reading data from the physical disk when accessing the physical disk of the storage every time playback is performed in order to acquire video / audio data at any time. In addition, when performing high-speed playback or reverse playback, it is necessary to perform random access to the storage, resulting in a larger response delay.

  As a conventional technique capable of preventing the delay as described above, every time the storage server that controls access to the storage requests video / audio data to be played back from the playback device, the video from the physical disk・ Rather than acquiring audio data, video / audio data of a certain size is buffered in advance on the memory of the storage server, and when the request is received, the contents of the buffer are sent to the playback device. There is something.

  In this way, a part of the data on the physical disk is buffered and held in the memory, so that the response speed can be improved. However, the above-described conventional technique in which video / audio data is buffered in advance on the memory of the storage server clears the memory when it reaches the end of the buffer when there is only one buffer and removes it from the disk. There is a problem that it is necessary to read, and a delay occurs at that time. For this reason, a technique of preparing two buffers and using them alternately is generally adopted. However, such a conventional technique also has a problem that a delay occurs when the reproduction direction is reversed. Cause it to occur.

  The object of the present invention is to solve the above-mentioned problems of the prior art, reduce the response delay as described above in the system that acquires the video / audio data stored in the storage, transmits it to the playback device, and plays it back. It is an object of the present invention to provide a buffer control method and a storage server for video / audio data in a storage server capable of smoothly reproducing video / audio in any reproduction such as double speed reproduction and reverse reproduction.

  The purpose is, for example, buffer control for video / audio in a storage server that acquires video / audio data stored in a storage, transmits it to a playback device, and plays back the video / audio data. It has a three-sided memory buffer that holds audio data, a certain amount of video / audio data being used by the playback device, a certain amount of video / audio data in the future direction, and a certain amount of video / audio data in the past direction This is accomplished by controlling the three-sided memory buffer to hold data in each of the three-sided memory buffers.

  Even if the playback-side apparatus does not acquire the video / audio files all together, the video / audio can be smoothly played back in any playback, including double-speed playback and reverse playback.

1 is a block diagram illustrating a configuration example of a playback system that includes a storage server according to an embodiment of the present invention, acquires video / audio data stored in a storage, and transmits the acquired video / audio data to a playback device. It is a figure explaining the 1st example of the control method of the memory buffer with respect to video / audio data implement | achieved by this invention. It is a flowchart explaining the 2nd example of the control method of the memory buffer with respect to video / audio data implement | achieved by this invention. It is the figure which showed the example of the acquisition request of the video / audio data from a decoder as a table in order of request.

  Hereinafter, embodiments of a buffer for video / audio data according to the present invention will be described in detail with reference to the drawings. In the embodiment of the present invention described herein, a storage server that controls access to a storage that holds video / audio data is configured to include three memory buffers that hold video / audio data. Response delay in response to a video / audio data acquisition request from the user, and smooth playback and reverse playback can be performed.

  FIG. 1 is a block diagram illustrating a configuration example of a playback system that includes a storage server according to an embodiment of the present invention, acquires video / audio data stored in a storage, and transmits the acquired video / audio data to a playback device.

  The example of the reproduction system shown in FIG. 1 is a storage 107 storing video / audio data, and is connected to the storage 107 and transmits video / audio data acquired from the storage 107 to the decoder 101. The storage server 102 according to the embodiment and a video / audio data reproducing device (not shown) including the decoder 101 are configured.

  In the above description, the video / audio data reproducing apparatus (not shown) may have any configuration having the decoder 101. The video / audio data required for reproduction is requested from the storage server 102, and the decoder 101 stores the data. Any device that can display and output the decoded video / audio received from the server may be used.

  The storage 107 includes a plurality of disks such as HDDs, accumulates video / audio data in the disks, and sends the requested video / audio data to the storage server 102 in response to a request from the storage server 102. The function to transmit to.

  In addition, as is well known, the storage server 102 is not shown, but includes a storage device such as an HDD that stores a CPU, memory, OS, application programs, and the like, and a display device used by an administrator if necessary. The information processing apparatus includes an input device such as a keyboard. In response to a request from the decoder 101, the storage 107 is accessed to acquire the requested video / audio data from the storage 107, and the acquired video / audio data is stored in the decoder 101. It has the function to transmit to. In addition, for the present invention, the storage server 102 is a control unit that controls transmission / reception of data and the like between the decoders and the three-surface memory buffers A104 to C106 for storing video / audio data acquired from the storage 107 103.

  A storage device (not shown) of the storage server 102 stores a program for constructing a functional unit that controls the memory buffer according to the present invention. The program is loaded into the memory and executed by the CPU under the OS. As a result, a memory buffer control function in the embodiment of the present invention, which will be described later, is constructed.

  FIG. 2 is a diagram for explaining a first example of a memory buffer control method for video / audio data realized by the present invention. The memory buffer control method described here is the video / audio requested by the storage server 102 from the decoder 101 in an initial state in which all of the three memory buffers A104 to C106 provided in the storage server 102 are empty. The control for acquiring data from the disk of the storage 107 and transferring it to the decoder will be described.

(1) As shown as state 1, the decoder 101 first requests the storage server 102 for video / audio data from the beginning to be reproduced. Upon receipt of this request, the storage server 102 reads out and acquires a predetermined amount of video / audio data 1 (displayed only as video in FIG. 2) 1 from the storage 107, stores it in the memory buffer A104, and video / audio. Data 1 is transferred to the decoder 101 to reproduce the head video / audio, and at the same time, a predetermined amount of video / audio data 2 and 3 following the video / audio data 1 from the head is acquired from the storage 107 and the memory buffer Stored in B105 and C106.

(2) Next, it is assumed that the decoder 101 requests the storage server 102 for the next data 2 after the first video / audio data 1 to be reproduced, as shown as state 2. Receiving this request, the storage server 102 transfers the video / audio data 2 stored in the memory buffer B 105 to the decoder 101 to reproduce the video / audio of the next video / audio data 2. At this time, the storage server 102 stores the video / audio in the three memory buffers A104 to C106 so that the request from the decoder 101 can cope with either forward playback or reverse playback. Keep data 1-3.

(3) Next, it is assumed that the decoder 101 requests the storage server 102 for video / audio data 3 to be reproduced next, as indicated by state 3. Upon receiving this request, the storage server 102 transfers the video / audio data 3 stored in the memory buffer C106 to the decoder 101, and reproduces the video / audio of the video / audio data 3 to be reproduced next. At this time, the storage server 102 continuously holds the video / audio data 2 in order to prepare for playback in the reverse direction, discards the video / audio data 1 that is two generations older, frees up the memory buffer A104, and A predetermined amount of video / audio data 4 following the video / audio data 3 is acquired from the storage 107 and stored in the memory buffer A104 for reproduction in the direction.

(4) Next, it is assumed that the decoder 101 requests the storage server 102 for video / audio data 2 as video / audio data to be played back in order to perform playback in the reverse direction, as indicated by state 4. Upon receiving this request, the storage server 102 transfers the video / audio data 2 held in the memory buffer B105 to the decoder 101, and reproduces the video / audio of the video / audio data 2 in the reverse direction. At this time, the storage server 102 continues to hold the video / audio data 3 for forward playback, and predicts that playback in the reverse direction will continue. Discard it, free up the memory buffer A104, and obtain the video / audio data 1 in the reverse direction of the video / audio data 2 from the storage 107 for the next reverse reproduction and store it in the memory buffer A104.

  In the embodiment of the present invention, the memory buffer is controlled as described above, so that the playback side device does not acquire video / audio files all at once, including double speed playback and reverse playback. Even in the case of such reproduction, video / audio can be reproduced smoothly.

  FIG. 3 is a flowchart for explaining a second example of the memory buffer control method for video / audio data realized by the present invention. FIG. 4 shows an example of an acquisition request for video / audio data from the decoder 101 in the order of request. Next, a second example of a memory buffer control method for video / audio data will be described with reference to FIGS. 3 and 4 as well as FIG. The memory buffer control method described here is shown in FIG. 4 when the storage server 102 is connected to the decoder 102 from the decoder in a state where video / audio data is stored in all of the three memory buffers A104 to C106 provided in the storage server 102. The control of acquiring the requested video / audio data from the disk of the storage 107 and transferring it to the decoder when receiving such a request will be described.

  In this example, the maximum number of frames read from the memory buffer is set to 5, and each buffer holds data for 10 frames. However, these values are determined depending on the system configuration. It can be set arbitrarily depending on the situation. As shown in FIG. 4, the video / audio data acquisition request from the decoder 101 includes an ID for uniquely identifying the request, a mode indicating a read state, a playback mode indicating a playback direction and a playback speed, and a start frame number. In the example described here, an acquisition request for video / audio data from the decoder 101 is ID001. To the forward storage server. Further, it is assumed that 10 frames of video / audio data of 30 frames having frame numbers −10 to 20 are stored in the memory buffers A104 to C106 in the storage server 102.

(1) Upon receiving the video / audio data acquisition request from the decoder 101, the storage server 102 sets a loop so as to repeat the processing up to the completion of the data acquisition request (steps 201 and 202).

(2) Thereafter, the control unit 103 of the storage server 102 analyzes the request from the decoder 101 to identify the frame start position, determines the playback direction and playback speed from the playback mode included in the request, and is designated to send back. The specified frame is specified (steps 203 and 204).

(3) Next, the control unit 103 of the storage server 102 determines whether or not a frame that straddles the three memory buffers is requested. For example, if the acquisition request from the decoder 101 is an acquisition request with ID = 001, the necessary frames are five frames 3 to 7, and these frames are held in the memory buffer B105. Since it can be determined that no buffer crossing has occurred, and all frames can be acquired from the memory buffer B105, the acquisition request frame is extracted from the memory buffer B105 and sent back to the decoder 101 to process the next request. (Steps 205 and 206).

(4) Necessary when a frame across three memory buffers is requested in the determination in step 205, for example, when an acquisition request from the decoder 101 is an acquisition request for ID = 002 which is the next request It is determined that there are five frames 8 to 12 and the frame extends from the memory buffer B105 to the memory buffer C106. In this case, the control unit 103 extracts the extraction target frames 8 to 12 and returns them to the decoder 101. At this time, when the frame to be extracted moves from the memory buffer B 105 to the memory buffer C 106, the control unit 103 discards the video / audio data held in the memory buffer A 104, releases the memory buffer A 104, and stores the storage 107 10 frames after frame 21 are pre-read from the disk, a buffer called a future plane is generated in the memory buffer A 104 here, a memory buffer C 106 is a buffer called a current plane, and a memory buffer B 105 is a past plane. The buffer to be called is prepared for the next acquisition request (step 207).

(5) After the process of step 206 or 207, if the data acquisition request repeated process in the loop set in the process of step 202 has been completed, the process is terminated (step 208).

  Next, assuming that the acquisition requests of ID = 003 and ID = 004 have arrived in order from the decoder 101, the processing after step 205 will be described.

  It is assumed that an acquisition request with ID = 003 is received from the decoder 101. This acquisition request of ID = 003 requests the frame of the current plane held by the memory buffer C106 and the past plane held by the memory buffer B105 in reverse playback. It is determined that straddling has occurred. Then, the control unit 103 extracts and returns the frames 12 to 8 which are the frames to be extracted, and at the same time the buffer storing the frame to be extracted is switched, and at the same time, prefetching is performed in the request processing of ID = 002. The memory buffer A104 holding the video / audio data in the future direction is released, the video / audio data in the past direction is prefetched from the disk of the storage 107 and stored in the memory buffer A104, and the memory buffer A104 is stored in the past screen. Prepare for the next acquisition request as a buffer called.

  Subsequently, it is assumed that an acquisition request with ID = 004 is received from the decoder 101. In this case, the playback process in the reverse direction is performed as it is, but since the reverse playback is at double speed, the frames thinned out one frame at a time in the process of step 204, that is, frames 8, 6, 4, 2, and -1 are included. Identified. Since the frame to be acquired exists in the memory buffers B105 and A104, it is determined in step 205 that the memory buffer is straddled. Then, the control unit 103 extracts the extraction target frame and returns it to the decoder 101. At that time, as described above, the control unit 103 switches the buffer storing the frame to be extracted, and at the same time, releases the memory buffer C106 and pre-reads video / audio data in the past direction from the storage disk. A buffer for the past plane is generated in the memory buffer C106 to prepare for the next acquisition request. At this time, the memory buffer B105 is a future plane buffer, and the memory buffer A104 is a current plane buffer.

  In the embodiment of the present invention, stable video / audio data can be distributed to a playback device and played back by performing the control described above.

  In the playback mode of 3x speed or higher, frames are not acquired from the memory buffer, the necessary frames are extracted from the storage, returned to the playback device, the memory buffer is released as necessary, and the next request You should be prepared for.

101 Decoder 102 Storage Server 103 Control Unit 104 Memory Buffer A
105 Memory buffer B
106 Memory buffer C
107 storage

Claims (3)

In a storage server that acquires video / audio data stored in storage, sends it to a playback device, and plays it back,
Three memory buffers for holding video / audio data acquired from the storage, a certain amount of video / audio data being used by the playback device, a certain amount of video / audio data in the future direction, and a past direction A storage server comprising control means for controlling the three-surface memory buffer so as to hold a certain amount of video / audio data in each of the three-surface memory buffer.   When the playback device performs playback in the forward direction and the video / audio data to be played becomes the video / audio data in the memory buffer holding the video / audio data in the future direction, the video in the past direction 2. A memory buffer holding audio data is released, and a certain amount of video / audio data in the future direction is further acquired from the storage and held in the released memory buffer. Storage server.   When the playback device performs playback in the reverse direction and the video / audio data to be played becomes the video / audio data in the memory buffer holding the video / audio data in the past direction, the video in the future direction 2. A memory buffer holding audio data is released, and a certain amount of video / audio data in the past direction is acquired from the storage and held in the released memory buffer. Storage server.

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