Video coding and decoding
There is disclosed a method, an apparatus, a server, a client and a non-transitory computer readable medium comprising a computer program stored therein for multi view video coding and decoding. View random access (VRA) pictures or access units are coded into a multiview bitstream. VRA pictures enable starting the decoding of a subset of the views present in the bitstream. The views selected to be accessible in VRA pictures are alternated in successive VRA pictures so that all views are gradually reconstructed when two or more VRA pictures have been decoded.
1. A method comprising:
determining a first view which is correctly decodable when starting at a random access position of at least one bitstream relative to a second view for which decoding is omitted when starting at the random access position;
encoding a first picture from a first sequence representing the first view and a second picture from a second sequence representing the second view into a first access unit at the random access position of the at least one bitstream;
encoding an indication of the random access position and an indication of the first view that is decodable when decoding is started at the random access position into the at least one bitstream;
encoding into the at least one bitstream an indication of a change of an inter-view prediction dependency order between a first inter-view prediction order and a second inter-view prediction order in order to alter a view from among a plurality of views that serves as a base view in accordance with the access unit being coded, wherein the first inter-view prediction order indicates a prediction of the first view from the second view in the first access unit and the second inter-view prediction order indicates a prediction of the second view from the first view; and
encoding a third picture from the first sequence and a fourth picture from the second sequence into a second access unit of the at least one bitstream, the second access unit following the random access position, the third picture being intra coded and the fourth picture being predicted from the second picture.
2. The method according to claim 1 further comprising:
encoding a fifth picture from a third sequence into the first access unit wherein the third sequence represents a third view; and
encoding a sixth picture from the third sequence into the second access unit using prediction from the third picture.
3. An apparatus comprising at least one processor, and 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:
determine a first view which is correctly decodable when starting at a random access position of at least one bitstream relative to a second view for which decoding is omitted when starting at the random access position;
encode a first picture from a first sequence representing the first view and a second picture from a second sequence representing the second view into a first access unit at the random access position of the at least one bitstream;
encode an indication of the random access position and an indication of the first view that is decodable when decoding is started at the random access position into the at least one bitstream;
encode into the at least one bitstream an indication of a change of an inter-view prediction dependency order between a first inter-view prediction order and a second inter-view prediction order in order to alter a view from among a plurality of views that serves as a base view in accordance with the access unit being coded, wherein the first inter-view prediction order indicates a prediction of the first view from the second view in the first access unit and the second inter-view prediction order indicates a prediction of the second view from the first view; and
encode a third picture from the first sequence and a fourth picture from the second sequence into a second access unit of the at least one bitstream, the second access unit following the random access position, the third picture being intra coded and the fourth picture being predicted from the second picture.
4. The apparatus according to claim 3 , said at least one memory includes computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the apparatus to use prediction to:
encode a fifth picture from a third sequence into the first access unit wherein the third sequence represents a third view; and
encode a sixth picture from the third sequence into the second access unit using prediction from the third picture.
5. The apparatus according to claim 3 , wherein the apparatus is an encoder, a wireless communication device, or a server.
6. A computer program embodied on a non-transitory computer readable medium, the computer program comprising instructions causing, when executed on at least one processor, at least one apparatus to:
determine a first view which is correctly decodable when starting at a random access position of at least one bitstream relative to a second view for which decoding is omitted when starting at the random access position;
encode a first picture from a first sequence representing the first view and a second picture from a second sequence representing the second view into a first access unit at the random access position of the at least one bitstream;
encode an indication of the random access position and an indication of the first view that is decodable when decoding is started at the random access position into the at least one bitstream;
encode into the at least one bitstream an indication of a change of an inter-view prediction dependency order between a first inter-view prediction order and a second inter-view prediction order in order to alter a view from among a plurality of views that serves as a base view in accordance with the access unit being coded, wherein the first inter-view prediction order indicates a prediction of the first view from the second view in the first access unit and the second inter-view prediction order indicates a prediction of the second view from the first view; and
encode a third picture from the first sequence and a fourth picture from the second sequence into a second access unit of the at least one bitstream, the second access unit following the random access position, the third picture being intra coded and the fourth picture being predicted from the second picture.
7. A method comprising:
concluding a first random access position from at least one bitstream based upon an indication encoded into the at least one bitstream and determining a first view that is correctly decodable when decoding is started at the first random access position based upon the indication encoded into the at least one bitstream, the first random access position being followed by a first access unit comprising a first coded picture from the first view and a second coded picture from a second view, the first coded picture being intra coded and the second coded picture being predicted from a picture preceding the first random access position;
starting the decoding from the first random access position;
decoding the first coded picture; and
decoding one or more subsequent coded pictures from the first view,
wherein the first coded picture and the one or more subsequent coded pictures from the first view are decoded while the second coded picture from the second view is omitted from decoding when starting the decoding from the first random access position,
wherein a first inter-view prediction order indicates a prediction of the first view from the second view in the first access unit and a second inter-view prediction order indicates a prediction of the second view from the first view, and wherein the method further comprises decoding an indication of a change of the inter-view prediction dependency order between the first inter-view prediction order and the second inter-view prediction order from the at least one bitstream in order to alter a view from among a plurality of views that serves as a base view in accordance with the access unit being decoded.
8. The method according to claim 7 comprising:
concluding a second random access position from the at least one bitstream, the second random access position being followed by a second access unit comprising a third coded picture from the first view and a fourth coded picture from the second view, the fourth coded picture being intra coded;
decoding the third coded picture; and
decoding the fourth coded picture.
9. An apparatus comprising at least one processor, memory including computer program code, the memory and the computer program code configured to, with the at least one processor, cause the apparatus to:
conclude a first random access position from at least one bitstream based upon an indication encoded into the at least one bitstream and determine a first view that is correctly decodable when decoding is started at the first random access position based upon the indication encoded into the at least one bitstream, the first random access position being followed by a first access unit comprising a first coded picture from the first view and a second coded picture from a second view, the first coded picture being intra coded and the second coded picture being predicted from a picture preceding the first random access position;
start the decoding from the first random access position;
decode the first coded picture; and
decode one or more subsequent coded pictures from the first view,
wherein the first coded picture and the one or more subsequent coded pictures from the first view are decoded while the second coded picture from the second view is omitted from decoding when starting the decoding from the first random access position,
wherein a first inter-view prediction order indicates a prediction of the first view from the second view in the first access unit and a second inter-view prediction order indicates a prediction of the second view from the first view, and wherein the memory and the computer program code are further configured to, with the at least one processor, cause the apparatus to decode an indication of a change of the inter-view prediction dependency order between the first inter-view prediction order and the second inter-view prediction order from the at least one bitstream in order to alter a view from among a plurality of views that serves as a base view in accordance with the access unit being decoded.
10. The apparatus according to claim 9 , said at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the apparatus to
conclude a second random access position from the at least one bitstream, the second random access position being followed by a second access unit comprising a third coded picture from the first view and a fourth coded picture from the second view, the fourth coded picture being intra coded;
decode the third coded picture; and
decode the fourth coded picture.
11. The apparatus according to claim 9 , wherein the apparatus is a decoder, a wireless communication device, or a client device.
12. A computer program embodied on a non-transitory computer readable medium, the computer program comprising instructions causing, when executed on at least one processor, at least one apparatus to:
conclude a first random access position from at least one bitstream based upon an indication encoded into the at least one bitstream and determine a first view that is correctly decodable when decoding is started at the first random access position based upon the indication encoded into the at least one bitstream, the first random access position being followed by a first access unit comprising a first coded picture from the first view and a second coded picture from a second view, the first coded picture being intra coded and the second coded picture being predicted from a picture preceding the first random access position;
start the decoding from the first random access position;
decode the first coded picture; and
decode one or more subsequent coded pictures from the first view,
wherein the first coded picture and the one or more subsequent coded pictures from the first view are decoded while the second coded picture from the second view is omitted from decoding when starting the decoding from the first random access position,
wherein a first inter-view prediction order indicates a prediction of the first view from the second view in the first access unit and a second inter-view prediction order indicates a prediction of the second view from the first view, and wherein the computer program further comprising instructions causing, when executed on the at least one processor, the at least one apparatus to decode an indication of a change of the inter-view prediction dependency order between the first inter-view prediction order and the second inter-view prediction order from the at least one bitstream in order to alter a view from among a plurality of views that serves as a base view in accordance with the access unit being decoded.
13. The computer program according to claim 12 comprising instructions causing, when executed on at least one processor, the at least one apparatus to
conclude a second random access position from the at least one bitstream, the second random access position being followed by a second access unit comprising a third coded picture from the first view and a fourth coded picture from the second view, the fourth coded picture being intra coded;
decode the third coded picture; and
decode the fourth coded picture.
14. An apparatus comprising:
means for determining a first view which is correctly decodable when starting at a random access position of at least one bitstream relative to a second view for which decoding is omitted when starting at the random access position;
means for encoding a first picture from a first sequence representing the first view and a second picture from a second sequence representing the second view into a first access unit of the at least one bitstream;
means for encoding an indication of the random access position and an indication of the first view that is decodable when decoding is started at the random access position into the at least one bitstream;
means for encoding into the at least one bitstream an indication of a change of an interview prediction dependency order between a first inter-view prediction order and a second interview prediction order in order to alter a view from among a plurality of views that serves as a base view in accordance with the access unit being coded, wherein the first inter-view prediction order indicates a prediction of the first view from the second view in the first access unit and the second inter-view prediction order indicates a prediction of the second view from the first view; and
means for encoding a third picture from the first sequence and a fourth picture from the second sequence into a second access unit of the at least one bitstream, the second access unit following the random access position, the third picture being intra coded and the fourth picture being predicted from the second picture.
15. An apparatus comprising:
means for concluding a first random access position from at least one bitstream based upon an indication encoded into the at least one bitstream and means for determining a first view that is correctly decodable when decoding is started at the first random access position based upon the indication encoded into the at least one bitstream, the first random access position being followed by a first access unit comprising a first coded picture from the first view and a second coded picture from a second view, the first coded picture being intra coded and the second coded picture being predicted from a picture prior to the first random access position, and the first coded picture and the second coded picture representing a first moment of time;
means for starting the decoding from the first random access position;
means for decoding the first coded picture; and
means for decoding one or more subsequent coded pictures from the first view,
wherein the first coded picture and the one or more subsequent coded pictures from the first view are decoded while the second coded picture from the second view is omitted from decoding when starting the decoding from the first random access position,
wherein a first inter-view prediction order indicates a prediction of the first view from the second view in the first access unit and a second inter-view prediction order indicates a prediction of the second view from the first view, and wherein the apparatus further comprises means for decoding an indication of a change of the inter-view prediction dependency order between the first inter-view prediction order and the second inter-view prediction order from the at least one bitstream in order to alter a view from among a plurality of views that serves as a base view in accordance with the access unit being decoded.