Multi-user, on-demand video storage and retrieval system including video signature computation for preventing excessive instantaneous server data rate

• US 5,519,435 A
• Filed: 09/01/1994
• Issued: 05/21/1996
• Est. Priority Date: 09/01/1994
• Status: Expired due to Term

• Current Assignee: Intel Network Systems, Inc. (Intel Corporation)
• Original Assignee: Micropolis Corp.
• Inventors: Anderson, Michael H.
• Primary Examiner(s): Kim, Ken S.
• Application Number:
  US08/299,829
• Time in Patent Office: 628 Days
• Field of Search: 348/7, 348/8, 348/6, 395/550, 455/4.1, 455/4.2
• US Class Current: 725/92
• CPC Class Codes: H04N 21/47202 for requesting content on demand, e.g. video on demand
• CPC Class Codes: H04N 7/17318 Direct or substantially direct transmission and handling of requests

Abstract

A plurality of movies are distributively stored in digitally encoded form on a mass storage unit such as a Redundant Array of Inexpensive Drives (RAID) disk drive array such that they can be viewed on demand by multiple users. A video server receives movie requests from users, and retrieves and transmits the requested movie data from the RAID array to processors at the respective user locations. The processors decode the retrieved data to produce video picture and audio information and display the corresponding movies on monitors. Temporal instantaneous digital data rate signatures for the movies are computed and stored, and a current composite signature is computed by summing the signatures for all movies currently being shown. When an additional movie is requested, the signature for the additional movie is combined with the current composite signature to produce a new composite signature. If any part of the new composite signature exceeds the maximum data rate capability of the server, the signature for the movie is shifted forward in time by a predetermined increment, and again combined with the current composite signature to produce a recalculated new composite signature. This is repeated as required until a new composite signature is obtained with no part thereof exceeding the maximum data rate capability of the server, and retrieval and showing of the additional movie is initiated at time corresponding to the total time shift.

Claims

1. A data storage and retrieval system, comprising:

a storage for storing a plurality of digital data files;

a plurality of processors for concurrently processing data files transmitted thereto from the storage;

a server for concurrently retrieving selected data files from the storage and transmitting said selected data files to selected processors respectively;

a memory for storing one temporal instantaneous digital data rate signature for each of said data files respectively; and

a computer that is programmed to perform the steps of;

(a) computing a current composite signature by summing said signatures for said selected data files respectively;

(b) when an additional data file is selected for retrieval and transmittal, computing a new composite signature by summing a new signature constituted by said signature for said additional data file with said current composite signature;

(c) comparing said new composite signature with a predetermined maximum data rate criteria;

(d) if said new composite signature satisfies said criteria, controlling the server to retrieve and transmit said additional data file; and

(e) if said new composite signature does not satisfy said criteria, computing a shifted signature by temporally shifting said new signature forward by a predetermined time increment, recomputing said new composite signature by summing said shifted signature with said current composite signature and jumping to step (c).

2. A system as in claim 1, in which the storage stores each of said data files as comprising a plurality of digitally encoded pictures.

3. A system as in claim 2, in which:

said pictures are encoded as comprising numbers of picture bits that vary in accordance with video contents of said pictures; and

the memory stores said signatures as comprising a predetermined function of said numbers of picture bits for said pictures respectively.

4. A system as in claim 3, in which the memory stores said signatures such that said predetermined function comprises numbers of picture bits for predetermined time increments respectively.

5. A system as in claim 4, in which said criteria comprises a predetermined maximum value of said numbers of picture bits for said predetermined time increments respectively.

6. A system as in claim 5, in which:

said criteria is satisfied if none of said numbers of picture bits for said predetermined time increments exceeds said maximum value; and

said criteria is not satisfied if any of said numbers of picture bits for said predetermined time increments exceeds said maximum value.

7. A system as in claim 6, in which said maximum value corresponds to a maximum data throughput rate of the server.

8. A system as in claim 1, in which said criteria comprises a maximum data throughput rate of the server.

9. A system as in claim 1, in which:

the storage stores said data files as movies comprising pluralities of digitally encoded pictures respectively; and

each processor comprises a decoder for decoding said movies and a monitor for displaying said decoded movies.

10. A system as in claim 9, in which the storage comprises a Redundant Array of Inexpensive Drives (RAID) disk drive array that distributively stores said movies.

11. A data storage and retrieval method, comprising the steps of:

(a) storing a plurality of digital data files in a storage;

(b) concurrently retrieving selected data files from the storage and transmitting said selected data files to selected processors respectively;

(c) storing one temporal instantaneous digital data rate signature for each of said data files respectively;

(d) computing a current composite signature by summing said signatures for said selected data files respectively;

(e) when an additional data file is selected for retrieval and transmittal, computing a new composite signature by summing a new signature constituted by said signature for said additional data file with said current composite signature;

(f) comparing said new composite signature with a predetermined maximum data rate criteria;

(g) if said new composite signature satisfies said criteria, controlling the server to retrieve and transmit said additional data file; and

(h) if said new composite signature does not satisfy said criteria, computing a shifted signature by temporally shifting said new signature forward by a predetermined time increment, recomputing said new composite signature by summing said shifted signature with said current composite signature and jumping to step (f).

12. A method as in claim 11, in which step (a) comprises storing each of said data files as comprising a plurality of digitally encoded pictures.

13. A method as in claim 12, in which:

said pictures are encoded as comprising numbers of picture bits that vary in accordance with video contents of said pictures respectively; and

step (c) comprises storing said signatures as comprising a predetermined function of said numbers of picture bits for said pictures respectively.

14. A method as in claim 13, in which step (c) comprises storing said signatures such that said predetermined function comprises numbers of picture bits for predetermined time increments respectively.

15. A method as in claim 14, in which said criteria comprises a predetermined maximum value of said numbers of picture bits for said predetermined time increments respectively.

16. A method as in claim 15, in which:

step (g) comprises determining that said criteria is satisfied if none of said numbers of picture bits for said predetermined time increments exceeds said maximum value; and

step (h) comprises determining that said criteria is not satisfied if any of said numbers of picture bits for said predetermined time increments exceeds said maximum value.

17. A method as in claim 16, in which said maximum value in steps (g) and (h) corresponds to a predetermined maximum data throughput rate.

18. A method as in claim 11, in which said criteria in steps (g) and (h) comprises a predetermined maximum data throughput rate.

19. A method as in claim 11, in which:

step (a) comprises storing said data files as movies comprising pluralities of digitally encoded pictures respectively; and

step (b) further comprises decoding and displaying said movies.

20. A method as in claim 19, in which step (a) comprises distributively storing said movies on said storage as comprising a Redundant Array of Inexpensive Drives (RAID) disk drive array.

21. A multi-user, on-demand video server system, comprising:

a Redundant Array of Inexpensive Drives (RAID) disk drive array for distributively storing a plurality of digitally encoded movies;

a plurality of decoders for concurrently decoding movies transmitted thereto from the array for display on video monitors respectively;

a PC server for concurrently retrieving selected movies from the array and transmitting said selected movies to selected decoders respectively;

a memory for storing one temporal instantaneous digital data rate signature for each of said movies respectively; and

a computer that is programmed to perform the steps of;

(a) computing a current composite signature by summing said signatures for said selected movies respectively;

(b) when an additional movie is selected for retrieval and transmittal, computing a new composite signature by summing a new signature constituted by said signature for said additional movie with said current composite signature;

(c) comparing said new composite signature with a predetermined maximum data rate criteria;

(d) if said new composite signature satisfies said criteria, controlling the PC server to retrieve and transmit said additional data file; and

(e) if said new composite signature does not satisfy said criteria, computing a shifted signature by temporally shifting said new signature forward by a predetermined time increment, recomputing said new composite signature by summing said shifted signature with said current composite signature and jumping to step (c).