We claim:
1. A method for sharing media contents between several users, said method comprising:
sending (C212), by a first client application executing on a first user device of an initiating
user, to a server application, at least one request for registering a media content as a topic of a media content exchange between several users,
allowing (C215), by a second client application executing on a second user device, a contributing user to make a first contribution to said topic relatively to a first portion of the topic media content,
sending (C216), by the second client application, to said server application at least one request for registering first association data (ASCI) representing said first contribution, wherein said first association data (ASCI) represent an association between the first portion of the topic media content and at least one first contribution media content selected to form said first contribution,
receiving (C217), by a third client application executing on a user device of a recipient user, from said server application, contribution reproduction data comprising the first association data, and
reproducing (C218), by the third client application, said first contribution by rendering a first combined media content resulting from a combination of at least one portion of said first contribution media content with said first portion of the topic media content.
2. The method according to claim 1, further comprising:
receiving, by the second client application from the server application, first access data for accessing from a user device to the topic media content via a remote media server,
receiving, by the third client application from the server application, first access data for accessing from a user device to the topic media content via said remote media server,
accessing, by the second client application, to the topic media content via said remote media server using said first access data, and
accessing, by the third client application, to the topic media content via said remote media server using said first access data,
3. The method according to claim 1 or 2, further comprising:
receiving by the third client application from the server application second access data for accessing from a user device to the contribution media content via a remote media server, and
accessing by the third client application to the contribution media content via said remote media server using said second access data.
4. The method according to claim 1, wherein
said first association data comprises an identification of said first portion of the topic media content, said identification comprising at least one first rendering coordinate identifying a

rendering point for the topic media content relatively to at least one axis of a rendering coordinate system associated with the topic media content.
5. The method according to claim 4, wherein
said topic media content is a three-dimensional content,
said rendering coordinate system is a four-dimensional rendering coordinate system comprises a three-dimensional coordinate system for defining camera positions and a temporal axis for defining temporal positions in the three-dimensional content,
said at least one first rendering coordinate comprises a camera position and a temporal position, and
said first said portion of said topic media content being a group of at least one image viewed from said camera position and starting at said temporal position.
6. The method according to claim 1, wherein
said first association data (ASCI) represent an association between said first portion of the topic media content, the first contribution media content and said second user, and
said first association data (ASCI) comprise a user identifier of said second user, the method further comprising displaying (C218), by the first client application, the user identifier of said second user.
7. The method according to claim 1, further comprising:
obtaining, by the second client application, at least one combination parameter (CPU, CP12),
sending, by the second client application, to said server application said at least one combination parameter, and
receiving, by the third client application, from said server application, said at least one combination parameter,
wherein said combination is performed by the third client application according to said at least one combination parameter.
8. The method according to claim 1, further comprising:
obtaining, by the second client application, at least one filtering parameter (FP1),
sending, by the second client application, to said server application said at least one filtering parameter, and
receiving, by the third client application, from said server application, said at least one filtering parameter,
wherein said rendering is performed by the third client application by applying to said first portion of said topic media content a filter according to said at least one filtering parameter.
9. The method according to claim 1, further comprising:
allowing (C215), by a fourth client application executing on a user device of a second

contributing user, said second contributing user to make a second contribution to said topic relatively to a second portion of the topic media content,
sending (C216), by the fourth client application, to said server application at least one request for registering second association data representing the second contribution, wherein said second association data represent an association between the second portion of the topic media content and at least one second contribution media content selected to form said second contribution,
receiving (C217), by a fifth client application executing on a user device of a second recipient user, from said server application, second contribution reproduction data comprising the second association data, and
reproducing (C218), by the fifth client application, said second contribution by rendering a second combined media content resulting from a combination of at least one portion of said second contribution media content with said second portion of the topic media content.
10. The method according to claim 9, further comprising:
obtaining, by the fifth client application, a rendering order parameter defining a rendering order for the first contribution and the second contribution, and
reproducing, by the fifth client application, said first contribution by rendering a first combined media content resulting from a combination of at least one portion of said first contribution media content with said first portion of the topic media content,
wherein the rendering of the first combined media content and of the second combined media content is performed according to said rendering order parameter.
11. The method according to claim 10, further comprising:
obtaining, by the fourth client application, logical dependency data (LD1) defining at least one logical dependency between the first contribution media content and the second contribution media content,
sending, by the fourth client application, to said server application said logical dependency data (LD1), and
receiving, by the fifth client application, from said server application, said logical dependency data (LD1),
wherein said rendering order parameter is a dependency-based order based on said logical dependency data (LD1).
12. The method according to claim 1, further comprising:
uploading, by the first client application, the topic media content from the first user device to a first remote media server, and
downloading, by the second client application, from said first remote media server, at least one portion of the topic media content,
downloading, by the third client application, from said first remote media server, at least

one portion of the topic media content.
13. A user device comprising: a processor,
a memory operatively coupled to the processor, said memory comprising instructions of a client application configured to communicate with a server application, said instructions comprising instructions for:
sending (C212) to said server application at least one request for registering a media content as a topic of a media content exchange between several users,
allowing (C215) a contributing user to make a first contribution to said topic relatively to a first portion of the topic media content,
sending (C216) to said server application at least one request for registering first association data (ASCI) representing said first contribution, wherein said first association data (ASCI) represent an association between the first portion of the topic media content and at least one first contribution media content selected to form said first contribution,
receiving (C217), from said server application, contribution reproduction data comprising registered association data representative of a second contribution to said topic, and
reproducing (C218) said second contribution by rendering a first combined media content resulting from a combination of at least one portion of a second contribution media content with a second portion of the topic media content.
14. A system comprising
a processor, a memory operatively coupled to the processor, said memory comprising instructions of a
server application configured to communicate with at least one client application, said instructions
comprising instructions for
registering (C212), on request of a first client application executing on a user device of an initiating user, a media content as a topic of a media content exchange between several users,
registering (C216), on request of a second client application executing on a user device of a contributing user, first association data (ASCI) representing a first contribution to said topic relatively to a first portion of the topic media content, wherein said first association data (ASCI) represent an association between the first portion of the topic media content and at least one first contribution media content selected to form said first contribution, and
sending (C217), to a third client application executing on a user device of a recipient user, contribution reproduction data comprising the first association data, said contribution reproduction data enabling a reproduction by the third client application of said first

contribution, said reproduction comprising rendering a first combined media content resulting from a combination of at least one portion of said first contribution media content with said first portion of the topic media content.
15. A computer-readable storage medium storing computer-executable instructions
comprising instructions of a client application configured to communicate with a server application, said instructions comprising instructions for:
sending (C212) to said server application at least one request for registering a media content as a topic of a media content exchange between several users,
allowing (C215) a user to make a first contribution to said topic relatively to a first portion of the topic media content,
sending (C216) to said server application at least one request for registering first association data (ASCI) representing said first contribution, wherein said first association data (ASCI) represent an association between the first portion of the topic media content and at least one first contribution media content selected to form said first contribution,
receiving (C217), from said server application, contribution reproduction data comprising registered association data representative of a second contribution to said topic, and
reproducing (C218) said second contribution by rendering a first combined media content resulting from a combination of at least one portion of a second contribution media content with a second portion of the topic media content.