Method and an apparatus and a computer program product for video encoding and decoding

An apparatus comprising at least one processor, at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to:

• decode a first spatial region sequence at a first picture rate, the first spatial region sequence covering a first spatial region;
• decode a second spatial region sequence at a second picture rate, the second spatial region sequence covering a second spatial region, wherein the second spatial region is different from the first spatial region and the first picture rate is greater than the second picture rate, and wherein the first spatial region sequence comprises a first sub-sequence at the second picture rate and a second sub-sequence comprising pictures of the first spatial region sequence not in the first sub-sequence, and wherein pictures of the first sub-sequence are temporally aligned with pictures of the second spatial region sequence, wherein to decode the first spatial region sequence the apparatus is further caused to decode the first spatial region sequence from a first scalable layer of a bitstream, and wherein to decode the second spatial region sequence the apparatus is further caused to decode the second spatial region sequence from a second scalable layer of the bitstream;
• obtain first viewport parameters of a viewport;
• in response to the first spatial region covering the viewport, display at least a first subset of the decoded first spatial region sequence;
• and
• in response to the first spatial region not covering the viewport:
• form a combination of the decoded first spatial region sequence and the second spatial region sequence;
• and
• display at least a second subset of said combination.

A computer program product embodied on a non-transitory computer readable medium, comprising computer program code configured to, when executed on at least one processor, cause an apparatus or a system to:

• decode a first spatial region sequence at a first picture rate, the first spatial region sequence covering a first spatial region;
• decode a second spatial region sequence at a second picture rate, the second spatial region sequence covering a second spatial region, wherein the second spatial region is different from the first spatial region and the first picture rate is greater than the second picture rate, and wherein the first spatial region sequence comprises a first sub-sequence at the second picture rate and a second sub-sequence comprising pictures of the first spatial region sequence not in the first sub-sequence, and wherein pictures of the first sub-sequence are temporally aligned with pictures of the second spatial region sequence, wherein to decode the first spatial region sequence the apparatus or the system is further caused to decode the first spatial region sequence from a first scalable layer of a bitstream, and wherein to decode the second spatial region sequence the apparatus or the system is further caused to decode the second spatial region sequence from a second scalable layer of the bitstream;
• obtain first viewport parameters of a viewport;
• in response to the first spatial region covering the viewport, display at least a first subset of the decoded first spatial region sequence;
• and
• in response to the first spatial region not covering the viewport:
• form a combination of the decoded first spatial region sequence and the second spatial region sequence;
• and
• display at least a second subset of said combination.