Method for assigning multimedia data to distributed storage devices

• US 20080065975A1
• Filed: 08/27/2007
• Published: 03/13/2008
• Est. Priority Date: 09/05/2006
• Status: Active Grant

• Current Assignee: Thomson Licensing (Vantiva SA)
• Original Assignee: Thomson Licensing (Vantiva SA)
• Inventors: Massoulie, Laurent, Neumann, Christoph, Champel, Mary-Luc
• Granted Patent: US 8,442,989 B2
• Time in Patent Office: Days
• US Class Current: 715/201
• CPC Class Codes: G11B 27/002 Programmed access in sequence to a plurality of record carriers or indexed parts, e.g. tracks, thereof, e.g. for editing; transfer of record carriers from magazine G11B15/68, G11B17/10; G11B17/22
• CPC Class Codes: H04L 67/5681 Pre-fetching or pre-delivering data based on network characteristics

Abstract

The invention concerns a method for assigning parts of multimedia files to distributed storage devices, the number of said devices being an integer n, characterized in that it comprises the following steps: a step consisting in dividing each multimedia file in windows, which represent data for contiguous playback of a given duration; a step consisting, for each multimedia file, in determining a number k so that any original window of file can be recovered from any k distinct symbols; a step consisting, for each window of each said multimedia files, in assigning n corresponding symbols to said devices, one to each device, the n distinct symbols being created using erasure coding; and a step consisting in partially or totally filling the storage memory left on each device after said first steps with prefix windows of said multimedia files.

Claims

1. Method for assigning parts of multimedia files to distributed storage devices, the number of said devices being an integer n, wherein it comprises the steps of:

(a) dividing each multimedia file in windows, which represent data for contiguous playback of a given duration;

(b) for each multimedia file, determining a number k so that any original window of file can be recovered from any k distinct symbols;

(c) for each window of each said multimedia files, assigning n corresponding symbols to said devices, one to each device, the n distinct symbols being created using erasure coding; and

(d) partially or totally filling the storage memory left on each device after said first steps with prefix windows of said multimedia files.

2. Method for assigning parts of multimedia files to distributed storage devices according to claim 1 wherein said method further comprises the step of broadcasting each file.

3. Method for assigning parts of multimedia files to distributed storage devices according to claim 1 wherein the sizes of the parts the files to be stored on a device, are chosen to minimize the probability that for any given file, playback events of this file are either delayed or interrupted.

4. Method for assigning parts of multimedia files to distributed storage devices according to claim 1 wherein data corresponding to step (d) from files not being played back are overwritten by downloaded data from a file being played back.

5. Method for assigning parts of multimedia files to distributed storage devices according to claim 2 wherein, during the broadcast of a file, any device stores a desired prefix having a size, which is equal to the size of the file to be stored on this device, and in that, beyond this prefix, it creates window-by-window the encoded data it will keep for this particular file.

6. Method for assigning parts of multimedia files to distributed storage devices according to claim 2 wherein original files augmented with a first stage of erasure codes are broadcasted, and in that the devices generate random codes.

7. Method for assigning parts of multimedia files to distributed storage devices according to claim 1 wherein step (d) is performed using indications of the popularity of said multimedia files.