Nippon Telegraph and Telephone Corporation

Nippon Telegraph & Telephone Co.

Kazutoshi Nishimura

Hideharu Suzuki

Hideki Sakamoto

Tatsuo Mori

Yutaka Ishibashi

Tomoaki Kawaguchi

Mitsuru Maruyama

Minoru Takahata

Hiroyuki Kimiyama

Chikara Sasaki

Osamu Nakano

Kazuo Okada

Katsuhiko Fukazawa

Akira Uemori

Hiroshi Sugiyama

Kouichi Itoh

A video data storage and playback scheme in which the playback of video data that has been interrupted due to the occurrence of the overtaking at the storage device can be automatically resumed at the playback device is disclosed. The storage device is controlled to transmit the read out video data to the playback device by attaching control data indicating that it is video data read out after an overtaking occurred, when the read out video data is video data stored after an occurrence of the overtaking in which a reading position of video data in a process of being read out from the storage device in response to the request from the playback device overtook a writing position of video data in a process of being written into the storage device. Then, the playback device is controlled to resume playback of video data that has been interrupted due to the occurrence of the overtaking, upon detecting the control data.

Video data storage and playback scheme with automatic playback continuation after overtaking

A distributed multimedia server device for delivering requested multimedia data to terminals is formed by more than one storage server modules for distributedly storing fixed length multimedia blocks dividing each multimedia data, and reading out multimedia blocks in response to multimedia block read requests, more than one communication server modules, each capable of receiving a multimedia data read request for one multimedia data from a terminal through a connection set up with respect to the terminal, issuing the multimedia block read requests to the storage server modules so that the storage server modules read out multimedia blocks corresponding to that one multimedia data, and periodically delivering the multimedia blocks read out and transferred by the storage server modules to the terminal through the connection using a delivery period corresponding to a playback time of one multimedia block, and an inter-server module network for supporting communications between any of the storage server modules and any of the communication server modules.

Distributed multimedia server device and distributed multimedia server data access method

A video data playback system for reproducing requested video data by switching coded video data to be reproduced between normal playback coded video data and fast playback coded video data according to a requested playback mode, where the normal playback coded video data are encoded by a first video coding scheme using both intra-frame coding and inter-frame coding, while the fast playback coded video data are encoded by a second video coding scheme using only intra-frame coding and having a playback bit rate and a frame rate identical to those of the normal playback coded video data. The normal playback coded video data can be obtained by encoding the original video data first, then the fast playback coded video data can be obtained by encoding selectively decoded normal playback coded video data. Alternatively, the normal and fast playback coded video data can be obtained by synchronizing start and end of encoding by the first video coding scheme and encoding by the second video coding scheme.

Video data playback system using effective scheme for producing coded

A multiple readout of digital video data, capable of realizing the fast forward and fast reverse modes even under the logically multiplexed circumstances, and reducing a time required for the playback mode switching. A cycle for a readout operation is formed by a plurality of slots, each slot representing a unit time for reading a unit amount of the digital video data for each channel assigned to each user terminal; at least one of the plurality of slots forming each cycle is allocated to each channel and at least one of the plurality of slots not yet used for any channel in each cycle is additionally allocated to a user terminal which is requesting a playback mode switching; and the readout operation to read the digital video data for each channel from the storage device is carried out at every slot allocated to each channel in each cycle, by cyclically repeating the cycle for the readout operation. The requested playback mode switching can be a switching to a fast forward/reverse mode.

Method and apparatus for multiple readout of digital video data with

A method of multiplexed data reading and visual search, in which each video program is divided into a plurality of video data groups which are stored in a prescribed order among the memory devices, and m memory control units are connected with mxn input/output channels selectively and sequentially in units of time-slots such that each memory control unit is connected with each of input/output channel at least once within a prescribed period. Then, the reading operations of the video data groups stored in the memory devices are carried out by making accesses from m memory control units in parallel at each time-slot. Also, the visual search operations are carried out by abandoning a time-slot allocated to one input/output channel in a next small period when a request for changing a current playback mode to a new playback mode is received from a terminal in a current small period, allocating a new time-slot at which a next video data group to be accessed in the next small period according to the new playback mode is accessible to that input/output channel in the next small period, and reading and buffering the next video data group by using the new time-slot in the next small period.

Method of multiplexed data reading and visual search suitable for

A video library system capable of shortening the worst response time with respect to each video data reading request, without lowering the possible level of multiplexing. The multiplexed video data reading is achieved by distributedly storing video data divided into segments among a plurality of data storage devices, where each segment is capable of being read out in one time-slot; selectively connecting each data storage devices with one of data transfer targets by a plurality of switches provided in correspondence to the data storage devices; generating a plurality of control time-slot sequences formed by periodic time-slots in correspondence to the data storage devices with mutually displaced phases in each period of the control time-slot sequences; and controlling the data storage devices and switches such that, in response to a request for reading video data from a data transfer target, an earliest available idle time-slot is selected from the control time-slot sequences, and the segments of the requested video data are sequentially read out from the data storage devices at time-slots corresponding to the selected earliest idle time-slot in the control time-slot sequences and transmitted to the requesting data transfer target as the data storage devices are sequentially switched to the requesting data transfer target by the switches.

Method and apparatus for multiplexed video data reading in video library

A method of multiplexed data reading/writing capable of admitting more than n requests simultaneously in a configuration in which m sets of n-fold multiplexed sub-systems are provided in parallel. Each data is divided into a plurality of segment data which are stored in a prescribed order among the memory devices, and m memory control units are connected with m.times.n input/output channels selectively and sequentially in units of time-slots such that each memory control unit is connected with each of input/output channel at least once within a prescribed period. Then, the reading/writing operations of the segment data stored in the memory devices are carried out by making accesses from m memory control units in parallel at each time-slot such that each segment data read/written by each memory control unit from/into one of the memory devices connected thereto at each time-slot is transmitted to/from one of m.times.n input/output channels connected thereto at each time-slot.

Method of multiplexed data reading/writing suitable for video-on-demand

A visual search control of digital video files capable of realizing a high quality image even in the fast forward and fast reverse modes, while facilitating a quick mode switching among the normal playback mode and the fast forward and fast reverse modes. Each digital video file contains: normal playback data for a normal playback mode; fast forward and fast reverse data for fast forward and fast reverse modes; and a frame management information containing an entry for each frame in the normal playback data and the fast forward and fast reverse data, where each entry registers a frame number of each frame, and a switching target frame number indicating a frame number of a next frame to be read out next when a mode switching occurs; such that when a mode switching request is received along with a currently displayed frame number from a user terminal, an entry in the frame management information which registers the frame number identical to the received currently displayed frame number is looked up to obtain the switching target frame number registered therein and the requested mode switching is made by making an access to the next frame indicated by the obtained switching target frame number, reading out digital video data starting from the next frame, and transferring the read out digital video data to the user terminal.

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Tokyo, Japan

Kazutoshi Nishimura