Method of accessing a spatio-temporal part of a video sequence of images

• US 20110305278A1
• Filed: 04/26/2011
• Published: 12/15/2011
• Est. Priority Date: 04/28/2010
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Fablet, Youenn, Denoual, Franck
• Granted Patent: US 9,258,622 B2
• Time in Patent Office: Days
• US Class Current: 375/240.12
• CPC Class Codes: H04N 19/167 Position within a video image, e.g. region of interest [ROI]
• CPC Class Codes: H04N 21/23412 for generating or manipulating the scene composition of objects, e.g. MPEG-4 objects
• CPC Class Codes: H04N 21/2343 involving reformatting operations of video signals for distribution or compliance with end-user requests or end-user device requirements video transcoding H04N19/40; media packet handling at the source H04L65/762
• CPC Class Codes: H04N 21/234318 by decomposing into objects, e.g. MPEG-4 objects
• CPC Class Codes: H04N 21/234345 the reformatting operation being performed only on part of the stream, e.g. a region of the image or a time segment
• CPC Class Codes: H04N 21/234363 by altering the spatial resolution, e.g. for clients with a lower screen resolution
• CPC Class Codes: H04N 21/2387 Stream processing in response to a playback request from an end-user, e.g. for trick-play
• CPC Class Codes: H04N 21/2668 Creating a channel for a dedicated end-user group, e.g. insertion of targeted commercials based on end-user profiles information retrieval from the Internet by querying with filtering and personalisation G06F16/9535; arrangements for replacing or switching information during the broadcast H04H20/10; push services over packet-switching network H04L12/1859; adaptation of message content in packet-switching networks H04L51/063
• CPC Class Codes: H04N 21/45455 applied to a region of the image
• CPC Class Codes: H04N 21/4728 for selecting a Region Of Interest [ROI], e.g. for requesting a higher resolution version of a selected region
• CPC Class Codes: H04N 21/6373 for rate control , e.g. request to the server to modify its transmission rate flow control in packet networks H04L47/10
• CPC Class Codes: H04N 21/6375 for requesting retransmission , e.g. of data packets lost or corrupted during transmission from serverARQ protocols H04L1/18; implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP] H04L69/16
• CPC Class Codes: H04N 21/6581 Reference data, e.g. a movie identifier for ordering a movie or a product identifier in a home shopping application
• CPC Class Codes: H04N 7/17336 Handling of requests in head-ends

Abstract

The invention concerns a method and a device for accessing a spatio-temporal part of a video sequence of images compressed using a coding format implementing a prediction.

The method comprises the steps of:

• • defining a target spatial region corresponding to said spatio-temporal part to access;
  • obtaining compressed data corresponding to a selection spatial region in at least one image of the video sequence, said selection spatial region including said target spatial region;
  • obtaining at least one item of updating information for updating the selection spatial region that is provided for selecting compressed data in a following image of the video sequence, said updating information depending on the decoding of the compressed data corresponding to said target spatial region.

Claims

1. A method of accessing a spatio-temporal part of a video sequence of images compressed using a coding format implementing a prediction, comprising a step of defining a target spatial region corresponding to said spatio-temporal part to access, and further comprising the steps of:

obtaining compressed data corresponding to a selection spatial region in at least one image of the video sequence, said selection spatial region including said target spatial region;

obtaining at least one item of updating information for updating the selection spatial region that is provided for selecting compressed data in a following image of the video sequence, said updating information depending on the decoding of at least the compressed data so obtained which correspond to said target spatial region.

2. A method according to claim 1, comprising the steps of:

decoding said obtained compressed data which correspond to the target spatial region; and

classifying spatial units of images of the video sequence, according their utility on said decoding, so as to obtain an item of updating information on the basis of said classifying.

3. A method according to claim 2, wherein a spatial unit is useful on decoding compressed data corresponding to the target spatial region, when said spatial unit is included in the target spatial region or when said spatial unit comprises reference data used in the predictive coding of said compressed data.

4. A method according to claim 2, wherein said classifying creates a group of selected spatial units which are useful for the decoding of said compressed data corresponding to the target spatial region;

a group of selected spatial units which are not useful for the decoding of said compressed data corresponding to the target spatial region; and

a group of non-selected spatial units which are useful for the decoding of said compressed data corresponding to the target spatial region.

5. A method according to claim 2, wherein said selection spatial region is defined by a set of sides, and the classifying of a spatial unit leads to the updating of at least one parameter for moving a side of the selection spatial region.

6. A method according to claim 5, wherein said updating information comprises the parameters for movement relative to each side of the selection spatial region.

7. A method according to claim 1, implemented in a client terminal of a communication network, the method comprising a step of transmitting the updating information from said client terminal to a remote server storing said compressed video sequence, such that said server can update said selection spatial region for the selection of compressed data in a following image of the video sequence.

8. A method according to claim 7, comprising the steps of:

storing the obtained compressed data;

identifying spatial units that are non-selected and useful for the decoding of said compressed data corresponding to the target spatial region, so as to form said transmitted updating information;

providing corrections to said decoding of the compressed data corresponding to the target spatial region to compensate for the absence of the identified spatial units in order to display a decoded version of said compressed data.

requesting and receiving, from said remote server, said identified spatial units; and

updating the stored compressed data using said received identified spatial units.

9. A method according to claim 1, implemented in a server device of a communication network, the method comprising the steps of:

receiving, from a remote client terminal, a request for access to said spatio-temporal part so as to define a target spatial region identified in said request;

sending said obtained compressed data to said remote client terminal;

receiving said updating information from said client terminal; and

updating said selection spatial region on the basis of said updating information received.

10. A method according to claim 9, comprising a step of storing, by the server device, a processing history of a plurality of access requests, said updating of the selection spatial region for a later access request depending on said history.

11. A method according to claim 1, wherein said obtainment of the compressed data comprises selecting compressed data corresponding to a group of several images, and the updating information depends on the decoding of the compressed data obtained in those several images.

12. A method according to claim 11, wherein the selection of the compressed data corresponding to an image of said group of images comprises the steps of:

adjusting the dimensions of the selection spatial region depending on the type of image concerned; and

selecting the compressed data corresponding to said image, which are included in said adjusted selection spatial region.

13. A method according to claim 1, in which said updating information depends on at least one spatial unit that is not selected and is useful for the decoding of said compressed data corresponding to the target spatial region.

14. A method according to claim 1, in which said updating information depends on at least one spatial unit that is selected and not useful for the decoding of said compressed data corresponding to the target spatial region.

15. A method according to claim 1, comprising a step of updating said selection spatial region, said updating consisting in identifying a spatial region encompassing a set of non-selected spatial units which are useful for the coding of said compressed data corresponding to the target spatial region.

16. A method according to claim 1, comprising a step of updating said selection spatial region, said updating comprising a step of reducing said selection spatial region on the basis of an item of congestion information relative to a communication network on which said obtained compressed data are transmitted.

17. A method according to claim 1, wherein said updating information depends on an average estimation of movement of the target spatial region between two images.

19. A means of information storage that is readable by a computer system, comprising instructions for a computer program adapted to implement the method according to claim 1, when the program is loaded and executed by the computer system.

20. A computer program product readable by a microprocessor, comprising portions of software code adapted to implement the method according to claim 1, when it is loaded and executed by the microprocessor.

18. A device for accessing a spatio-temporal part of a video sequence of images compressed using a coding format implementing a prediction, comprising a means for defining a target spatial region corresponding to said spatio-temporal part to access, and further comprising:

a means for obtaining compressed data corresponding to a selection spatial region in at least one image of the video sequence, said selection spatial region including said target spatial region;

a means for obtaining at least one item of updating information for updating the selection spatial region provided for selecting compressed data in a following image of the video sequence, said updating information depending on the decoding of at least the compressed data so obtained which correspond to said target spatial region.