Decoded picture buffer management

A device for coding video data, the device comprising:

• memory configured to stored reference pictures;
• and
• a video coder configured to:
• code information indicative of reference pictures stored in the memory that belong to a reference picture set, wherein the reference picture set identifies the reference pictures that can potentially be used for inter-predicting a current picture and can potentially be used for inter-predicting one or more pictures following the current picture in decoding order;
• construct a plurality of reference picture subsets that each identifies zero or more of the reference pictures of the reference picture set, wherein to construct the plurality of reference picture subsets, the video coder is configured to:
• construct a first reference picture subset that identifies short-term reference pictures that are prior to the current picture in decoding order and prior to the current picture in output order and that can potentially be used for inter-predicting the current picture and one or more of the one or more pictures following the current picture in decoding order, and excludes short-term reference pictures that are prior to the current picture in output order and cannot be used for inter-predicting the current picture;
• construct a second reference picture subset that identifies short-term reference pictures that are prior to the current picture in decoding order and subsequent to the current picture in output order and that can potentially be used for inter-predicting the current picture and one or more of the one or more pictures following the current picture in decoding order, and excludes short-term reference pictures that are subsequent to the current picture in output order and cannot be used for inter-predicting the current picture;
• and
• construct a third reference picture subset that identifies long-term reference pictures that are prior to the current picture in decoding order and that can potentially be used for inter-predicting the current picture and one or more of the one or more pictures following the current picture in decoding order, and excludes long-term reference pictures that are prior to the current picture in decoding order and that cannot be used for inter-predicting the current picture;
• after construction of the first, second, and third reference picture subsets, determine which reference pictures are usable for inter-prediction of the current picture based on which pictures are identified in the first, second, and third reference picture subsets;
• subsequent to determining which reference pictures are usable for inter-prediction of the current picture, construct an initial reference picture list and a second reference picture list based on reference pictures in the first, second, and third reference picture subsets that are determined to be usable for inter-prediction of the current picture;
• and
• based on reference picture list modification of the initial reference picture list or the second reference picture list being needed after the construction of the initial reference picture list and the second reference picture list:
• identify a reference picture, wherein the reference picture is in at least one of the first, second, or third reference picture subsets;
• add the identified reference picture in a current entry of the initial reference picture list or in a current entry of the second reference picture list to construct a modified reference picture list or a second modified reference picture list respectively;
• and
• code the current picture based on the modified reference picture list or on the second modified reference picture list.

A non-transitory computer-readable storage medium having stored thereon instructions that, when executed, cause a processor of a device for coding video data to:

• code information indicative of reference pictures that belong to a reference picture set, wherein the reference picture set identifies the reference pictures that can potentially be used for inter-predicting a current picture and can potentially be used for inter-predicting one or more pictures following the current picture in decoding order;
• construct a plurality of reference picture subsets that each identifies zero or more of the reference pictures of the reference picture set, wherein the instructions that cause the processor to construct the plurality of reference picture subsets comprise instructions that cause the processor to:
• construct a first reference picture subset that identifies short-term reference pictures that are prior to the current picture in decoding order and prior to the current picture in output order and that can potentially be used for inter-predicting the current picture and one or more of the one or more pictures following the current picture in decoding order, and excludes short-term reference pictures that are prior to the current picture in output order and cannot be used for inter-predicting the current picture;
• construct a second reference picture subset that identifies short-term reference pictures that are prior to the current picture in decoding order and subsequent to the current picture in output order and that can potentially be used for inter-predicting the current picture and one or more of the one or more pictures following the current picture in decoding order, and excludes short-term reference pictures that are subsequent to the current picture in output order and cannot be used for inter-predicting the current picture;
• and
• construct a third reference picture subset that identifies long-term reference pictures that are prior to the current picture in decoding order and that can potentially be used for inter-predicting the current picture and one or more of the one or more pictures following the current picture in decoding order, and excludes long-term reference pictures that are prior to the current picture in decoding order and that cannot be used for inter-predicting the current picture;
• after construction of the first, second, and third reference picture subsets, determine which reference pictures are usable for inter-prediction of the current picture based on which pictures are identified in the first, second, and third reference picture subsets;
• subsequent to determining which reference pictures are usable for inter-prediction of the current picture, construct an initial reference picture list and a second reference picture list based on reference pictures the first, second, and third reference picture subsets that are determined to be usable for inter-prediction of the current picture;
• and
• based on the reference picture list modification of the initial reference picture list or the second reference picture list being needed after the construction of the initial reference picture list and the second reference picture list:
• identify a reference picture, wherein the reference picture is in at least one of the first, second, or third reference picture subsets;
• add the identified reference picture in a current entry of the initial reference picture list or in a current entry of the second reference picture list to construct a modified reference picture list or the second modified reference picture list respectively;
• and
• code the current picture based on the modified reference picture list or on the second modified reference picture list.

A device for coding video data, the device comprising:

• means for coding information indicative of reference pictures that belong to a reference picture set, wherein the reference picture set identifies the reference pictures that can potentially be used for inter-predicting a current picture and can potentially be used for inter-predicting one or more pictures following the current picture in decoding order;
• means for constructing a plurality of reference picture subsets that each identifies zero or more of the reference pictures of the reference picture set, wherein the means for constructing the plurality of reference picture subsets comprises:
• means for constructing a first reference picture subset that identifies short-term reference pictures that are prior to the current picture in decoding order and prior to the current picture in output order and that can potentially be used for inter-predicting the current picture and one or more of the one or more pictures following the current picture in decoding order, and excludes short-term reference pictures that are prior to the current picture in output order and cannot be used for inter-predicting the current picture;
• means for constructing a second reference picture subset that identifies short-term reference pictures that are prior to the current picture in decoding order and subsequent to the current picture in output order and that can potentially be used for inter-predicting the current picture and one or more of the one or more pictures following the current picture in decoding order, and excludes short-term reference pictures that are subsequent to the current picture in output order and cannot be used for inter-predicting the current picture;
• and
• means for constructing a third reference picture subset that identifies long-term reference pictures that are prior to the current picture in decoding order and that can potentially be used for inter-predicting the current picture and one or more of the one or more pictures following the current picture in decoding order, and excludes long-term reference pictures that are prior to the current picture in decoding order and that cannot be used for inter-predicting the current picture;
• means for determining which reference pictures are usable for inter-prediction of the current picture based on which pictures are identified in the first, second, and third reference picture subsets after construction of the first, second, and third reference picture subsets;
• means for constructing, subsequent to determining which reference pictures are usable for inter-prediction of the current picture, an initial reference picture list and a second reference picture list based on reference pictures in the first, second, and third reference picture subsets that are determined to be usable for inter-prediction of the current picture;
• means for identifying a reference picture, wherein the reference picture is in at least one of the first, second, or third reference picture subsets based on reference picture list modification of the initial reference picture list or of the second reference picture list being needed after the construction of the initial reference picture list and the second reference picture list;
• means for adding the identified reference picture in a current entry of the initial reference picture list or in a current entry of the second reference picture list to construct a modified reference picture list or a second modified reference picture list respectively based on reference picture list modification of the initial reference picture list or the second reference picture list being needed after the construction of the initial reference picture list and the second reference picture list;
• and
• means for coding the current picture based on the modified reference picture list or on the second modified reference picture list based on reference picture list modification of the initial reference picture list or the second reference picture list being needed after the construction of the initial reference picture list and the second reference picture list.