Method and device for transmitting video content and method and device for receiving video content

1. A method of transmitting video content through a plurality of assets, the method comprising:

transmitting an asset descriptor comprising information indicating whether a content transmitted through an asset is a spatial subset of the video content in omnidirectional media format (OMAF);

identifying a first asset including a sub-picture, wherein the sub-picture is configured to constitute a composition picture related to the video content;

obtaining sub-picture asset information comprising information about at least one of second asset including another sub-picture configured to constitute the composition picture related to the video content; and

transmitting the sub-picture asset information for the at least one of the second asset related to the first asset and the content transmitted through the first asset.

2. The method of claim 1 , wherein the asset is a logical group of media processing units (MPUs) for carrying encoded media data.

3. The method of claim 1 , wherein the video content is data compressed according to OMAF technology defined by ISO/IEC.

4. The method of claim 1 ,

wherein, in case that the content transmitted through the asset is a spatial subset of the video content, a receiving device receiving the content renders the content only by referring to the information about at least one of second asset, and

wherein, in case that the content transmitted through the asset is an entire composition picture, the receiving device independently renders the content.

5. The method of claim 1 , further comprising:

transmitting a virtual reality (VR) asset descriptor comprising a sub_picture flag indicating whether the content transmitted through the asset is the spatial subset of the video content,

wherein, in case that the content transmitted through the first asset is the sub-picture, the sub_picture flag is set to 1, and

wherein, in case that the content transmitted through the first asset is an entire composition picture, the sub_picture flag is set to 0.

6. The method of claim 1 , wherein the sub-picture asset information comprises at least one of coverage information covered by a picture, an identifier of the second asset, or a number of second assets described by the sub-picture asset information.

7. The method of claim 6 , wherein the coverage information includes coverage information covered by a sub-picture transmitted through the second asset and coverage information covered by the composition picture.

8. The method of claim 1 , further comprising:

receiving feedback information;

updating the sub-picture asset information based on the feedback information; and

transmitting the updated sub-picture asset information,

wherein the feedback information comprises at least one of viewport information, bandwidth information, buffer information, or delay information.

9. A method of receiving video content through a plurality of assets, the method comprising:

receiving an asset descriptor that comprises information indicating whether a content received through an asset is a spatial subset of the video content in omnidirectional media format (OMAF);

determining whether the content received through a first asset is a sub-picture, wherein the sub-picture is configured to constitute a composition picture related to the video content;

in case that the content received through the first asset is the sub-picture, identifying sub-picture asset information comprising information about at least one of second asset including another sub-picture configured to constitute the composition picture related to the video content; and

receiving and rendering the composition picture based on the sub-picture asset information, the content received through the first asset, and content received through at least one of the second asset.

10. The method of claim 9 , wherein the asset is a logical group of media processing units (MPUs) for carrying encoded media data.

11. The method of claim 9 , wherein the video content is data compressed according to OMAF technology defined by ISO/IEC.

12. The method of claim 9 ,

wherein the receiving of the asset descriptor comprises:

receiving a VR asset descriptor comprising a sub_picture flag indicating whether the content transmitted through the asset is the spatial subset of the video content, and

wherein the determining of whether the content received through the first asset is the sub-picture based on information of the asset descriptor comprises:

in case that the sub_picture flag is 1, determining that the content received through the first asset is the sub-picture, and

in case that the sub_picture flag is 0, determining that the content received through the first asset is an entire composition picture.

13. The method of claim 9 , wherein the receiving and rendering of the composition picture comprises:

in case that the content received through the first asset is an entire composition picture, rendering the content received through the first asset alone.

14. The method of claim 9 , wherein the sub-picture asset information comprises at least one of coverage information covered by a picture, an identifier of the second asset, or a number of second assets described by the sub-picture asset information.

15. The method of claim 14 , wherein the coverage information comprises coverage information covered by a sub-picture received through the second asset and coverage information covered by the composition picture.

16. The method of claim 9 , further comprising:

transmitting feedback information; and

in response to the feedback information, receiving updated sub-picture asset information,

wherein the feedback information comprises at least one of viewport information, bandwidth information, buffer information, or delay information.

17. A device comprising:

a communication interface configured to receive video content through a plurality of assets; and

at least one processor connected to the communication interface,

wherein the at least one processor is configured to:

based on an asset descriptor received through the communication interface, determine whether content received through a first asset is a sub-picture,

in case that the content received through the first asset is the sub-picture, identify sub-picture asset information comprising information about at least one of second asset including another sub-picture configured to constitute a composition picture related to the video content, and

receive and render the composition picture based on the sub-picture asset information, the content received through the first asset, and content received through at least one of the second asset,

wherein the asset descriptor comprises information indicating whether a content received through an asset is a spatial subset of the video content in omnidirectional media format, OMAF, and

wherein the sub-picture is configured to constitute a composition picture related to the video content.