File server for multimedia file distribution

• US 6,397,251 B1
• Filed: 01/13/1999
• Issued: 05/28/2002
• Est. Priority Date: 09/02/1997
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: International Business Machines Corporation
• Inventors: Graf, Marcel
• Primary Examiner(s): Rinehart, Mark H.
• Assistant Examiner(s): Vu, Thong H
• Application Number:
  US09/231,395
• Time in Patent Office: 1,231 Days
• Field of Search: 709/202,231,253,226,227,236,204,218,219,225 707/501,10,513,203 370/85,410 713/159 345/327 364/514
• US Class Current: 709/225
• CPC Class Codes: H04L 65/1101 Session protocols
• CPC Class Codes: H04L 65/612 for unicast
• CPC Class Codes: H04L 65/752 adapting media to network capabilities
• CPC Class Codes: H04L 65/762 at the source reformatting of additional data in video distribution servers H04N21/2355
• CPC Class Codes: H04N 21/23805 Controlling the feeding rate to the network, e.g. by controlling the video pump
• CPC Class Codes: H04N 21/2625 for delaying content or additional data distribution, e.g. because of an extended sport event
• CPC Class Codes: H04N 21/44004 involving video buffer management, e.g. video decoder buffer or video display buffer
• CPC Class Codes: H04N 21/47202 for requesting content on demand, e.g. video on demand

Abstract

Disclosed is a technique for distribution of multimedia files from file servers (110) over arbitrary telecommunication networks (150) to consumers (160) where those networks offer connections of a certain bandwidth for transmission. The consumers deliver requests for presentation of multimedia files, and the file servers deliver those files with respect to said requests for presentation. According to the proposed method, the transmission rates of the multimedia files are smoothed by spreading the transmission over time leading to additional delays in the delivery of said information. Minimum transmission rates for maximum values of the delays are calculated, and these values are provided as control data for the transmission. These control data are appended to the respective multimedia files, and the multimedia files are delivered to the receivers with respective additional, delays between the requests for presentation and the presentation of the files, corresponding to the maximum delays. By the proposed method, time critical files being encoded with a variable amount of data over time, like video-on-demand files, can be transmitted with constant quality despite given fluctuations in the amount of coded data, and without any interaction of the user, and thus a continuous play-back of a demanded video is provided.

Claims

1. A file server for distributing multimedia files within a network offering limited bandwidth connections for transmission of said multimedia files, said file server comprising:

a mass storage device for storing a plurality of digitized multimedia files together with control data;

a control unit for receiving and parsing a respective digitized multimedia file from said mass storage device to determine transmission parameters from said control data for said respective multimedia file, wherein said transmission parameters include a receiver buffer size, a receiver delay, and a cell segmentation rate, said control unit;

delivering said transmission parameters to a transmission unit, wherein said transmission unit delivers said multimedia files to said receiver buffer in accordance with said transmission parameters;

delivering said cell segmentation rate to said network; and

delivering said receiver delay value to a video decoder that receives input from said receiver buffer.

2. The file server according to claim 1, where said control data include a receiver buffer size, a peak transmission rate, and an additional delay.

3. The file server according to claim 1, where said transmission unit is characterized by:

a credit token generator reading data blocks of said multimedia files from said mass storage, parsing said data blocks for data units, and generating for each data unit a credit token which consists of;

a timestamp representing the time the respective receiver will take said data unit out of its buffer;

a credit value representing the size of said data unit;

a credit token buffer buffering said credit tokens;

a data buffer buffering said data blocks read from said mass storage;

a segmentation unit reading data from said databuffer and segmenting said data in cells with respect to said credit tokens; and

a system clock providing a reference clock for said segmentation unit.

4. The file server according to claim 3, where said credit token generator is further characterized by:

a decoding time stamp extractor parsing said multimedia files and extracting for each of said data units a decoding time stamp;

a size extractor parsing said multimedia files and extracting for each of said data units the size;

an adder unit adding the values of said decoding time stamp together with said control data; and

a combiner unit combining the resulting timestamp with said size of said data unit to form a credit token.

5. The file server according to claim 3, where said segmentation unit is further characterized by:

a segmenter unit segmenting said multimedia files in said cells;

a credit counter controlling said segmenter by keeping track of free receiver buffer; and

a credit token consumer receiving said system clock, and using said system clock to read said credit tokens from said credit token buffer at the time instants indicated by the respective timestamps.

6. The file server according to claim 1, which is further characterized by means for parsing the multimedia files to gather said control data.