Transmitting method and receiving method
A transmitting method for transmitting encoded data obtained by hierarchically encoding a video image includes: generating an encoded stream that includes time information and the encoded data, the time information indicating a time at which decoding or displaying processing of the encoded data is performed, and transmitting the generated encoded stream, wherein the encoded data includes a plurality of sets each including a plurality of access units and the time information includes first time information which indicates a time at which the processing performed on a first access unit of the first set is performed and which is based on a reference clock, and second time information used to specify a time at which the processing performed on a second access unit of the second set is performed and which is based on the reference clock.
1. A transmitting method for transmitting encoded data obtained by hierarchically encoding a video image into a basic layer and an extended layer, the transmitting method comprising:
generating an encoded stream that includes time information and the encoded data, the time information indicating a time at which decoding or displaying processing of the encoded data is performed; and
transmitting the generated encoded stream,
wherein the encoded data includes a plurality of sets each including a plurality of access units,
each of the plurality of access units which configure at least one first set is independently decoded or is decoded by referring to decoded data of another access unit of the basic layer, the at least one first set being for a set of the basic layer among the plurality of sets,
each of the plurality of access units which configure at least one second set is decoded by referring to decoded data of an access unit of the basic layer, the at least one second set being a set for the extended layer among the plurality of sets
the time information includes first time information which indicates a time at which the processing performed on a first access unit of the first set is performed and which is based on a reference clock, and second time information used to specify a time at which the processing performed on a second access unit of the second set is performed and which is based on the reference clock,
the plurality of access units which configure the at least one second set is displayed at a frame rate higher than a frame rate for displaying only the plurality of access units which configure the at least one first set among the plurality of access units which configure the at least one first set and the plurality of access units which configure the at least one second set, by being displayed alternately with the plurality of access units which configure the at least one first set, and each of the plurality of access units which configure the at least one first set is decoded according to a first relative time based on the first time information by referring to the decoded data of the another access unit of the basic layer, the first relative time being a difference in decoding or displaying times of the access units.
2. The transmitting method according to claim 1 , wherein
the first access unit is an access unit of the first set on which the processing is performed first, and
the second access unit is an access unit of the second set on which the processing is performed first.
3. The transmitting method according to claim 2 , wherein
the processing is decoding,
each of the plurality of access units other than the first access unit of the first set is associated with the first relative time which is based on a time indicated by the first time information,
a time at which each of the plurality of access units of the first set is displayed is specified based on a second relative time which is based on a time at which each of the plurality of access units is decoded,
each of the plurality of access units other than the second access unit of the second set is associated with a third relative time which is based on a time indicated by the second time information, and
a time at which each of the plurality of access units of the second set is displayed is specified based on a fourth relative time which is based on a time at which each of the plurality of access units is decoded.
4. The transmitting method according to claim 2 , wherein
the processing is displaying,
each of the plurality of access units other than the first access unit of the first set is associated with a fifth relative time which is based on a time indicated by the first time information,
a time at which each of the plurality of access units of the first set is decoded is specified based on a sixth relative time which is based on a time at which each of the plurality of access units is displayed,
each of the plurality of access units other than the second access unit of the second set is associated with a seventh relative time which is based on a time indicated by the second time information, and
a time at which each of the plurality of access units of the second set is decoded is specified based on an eighth relative time which is based on a time at which each of the plurality of access units is displayed.
5. The transmitting method according to claim 1 , wherein the second time information is a time offset that is a difference value from a first absolute time indicated by the first time information.
6. The transmitting method according to claim 1 , wherein
the first set is a random access unit to which a random access is made, and
the first access unit and the second access unit are random access points.
7. The transmitting method according to claim 6 , wherein each of the at least one first set is associated with a corresponding one of the at least one second set.
8. The transmitting method according to claim 7 , wherein the second sets is decoded by referring only to decoded data of the first sets associated with the second sets on the one-on-one basis.
9. The transmitting method according to claim 8 , wherein each of the second sets further includes second header information in which identification information used to identify each of the first sets associated with the second sets on the one-on-one basis, and the second time information are stored.
10. The transmitting method according to claim 8 , wherein each of the first sets further includes first header information in which identification information used to identify each of the second sets associated with the first sets on the one-on-one basis, and the second time information are stored.
11. The transmitting method according to claim 8 , wherein
the encoded stream includes association information in which first identification information used to identify each of the first sets and second identification information used to identify each of the second sets associated with each of the first sets on the one-on-one basis are associated with each other, and
the second time information is stored in the association information.
12. The transmitting method according to claim 1 , wherein the time information is stored in control information of the encoded stream.
13. The transmitting method according to claim 1 , wherein the second time information indicates a second absolute time different from a first absolute time indicated by the first time information.
14. The transmitting method according to claim 1 , wherein
the generating step includes generating a first encoded stream including the first set and a second encoded stream including the second set, and
the transmitting step includes transmitting the first encoded stream by using a first channel, and transmitting the second encoded stream by using a second channel different from the first channel.
15. The transmitting method according to claim 14 , wherein the generating includes generating one of the first encoded stream and the second encoded stream according to MPEG-2 TS (Moving Picture Experts Group-2 Transport Stream), and
generating the other one of the first encoded stream and the second encoded stream according to MMT (MPEG Media Transport).
16. The transmitting method according to claim 14 , wherein
one of the first channel and the second channel is a channel for broadcasting, and
the other one of the first channel and the second channel is a channel used for communication.
17. The transmitting method according to claim 1 , wherein
the first time information includes a first display time at which a first basic access unit is displayed, and a second display time at which a second basic access unit to be displayed subsequently to the first basic access unit is displayed, the first basic access unit and the second basic access unit being included in the plurality of access units which configure the at least one first set, and
the second time information includes a third display time at which an extended access unit is displayed among extended access units which configure the at least one second set, the third display time being a time between the first display time and the second display time.
18. The transmitting method according to claim 1 , wherein each of the plurality of access units which configure the at least one second set is decoded according to a second relative time based on the second time information by referring to the decoded data of the access unit of the basic layer.
19. The transmitting method according to claim 1 , wherein the second time information used to specify the time at which the processing performed on the second access unit of the second set is performed is an absolute value or a difference value from the time indicated by the first time information.
20. A receiving method for receiving encoded data obtained by hierarchically encoding a video image into a basic layer and an extended layer, the receiving method comprising:
receiving an encoded stream including time information which indicates a time at which processing of decoding or displaying the encoded data is performed, and the encoded data; and
performing the processing on the encoded data of the received encoded stream at a time indicated by the time information,
wherein the encoded data includes a plurality of sets each including a plurality of access units,
each of the plurality of access units which configure a first set that is the set of the basic layer among the plurality of sets is independently decoded or is decoded by referring to decoded data of another access unit of the basic layer,
each of the plurality of access units which configure a second set that is the set of the extended layer among the plurality of sets is decoded by referring to decoded data of the access unit of the basic layer, and
the time information includes first time information which indicates a time at which the processing performed on a first access unit of the first set is performed, and second time information used to specify a time at which the processing performed on a second access unit of the second set is performed,
the plurality of access units which configure the at least one second set is displayed at a frame rate higher than a frame rate for displaying only the plurality of access units which configure the at least one first set among the plurality of access units which configure the at least one first set and the plurality of access units which configure the at least one second set, by being displayed alternately with the plurality of access units which configure the at least one first set, and each of the plurality of access units which configure the at least one first set is decoded according to a first relative time based on the first time information by referring to the decoded data of the another access unit of the basic layer, the first relative time being a difference in decoding or displaying times of the access units.
21. The receiving method according to claim 20 , wherein each of the plurality of access units which configure the at least one second set is decoded according to a second relative time based on the second time information by referring to the decoded data of the access unit of the basic layer.
22. The receiving method according to claim 20 , wherein the second time information used to specify the time at which the processing performed on the second access unit of the second set is performed is an absolute value or a difference value from the time indicated by the first time information.