Transmission apparatus, transmission method, reception apparatus, and reception method
The present disclosure relates to a transmission apparatus, a transmission method, a reception apparatus, and a reception method which make it possible to control redundancy of a header in packet communication. A region representing a packet length in a header of a packet is set according to a size of a payload of an input packet. A header of a baseband packet includes a minimum fixed length header including type identification information for identification of a type of the input packet or the stream and information of a packet length of the input packet or the stream stored in a payload of the baseband flame packet.
1. A transmission apparatus comprising:
circuitry configured to
generate a first packet from an input packet or a stream; and
transmit the first packet, wherein
a header of the first packet includes a fixed length header, the fixed length header including
type identification information indicating a type of the input packet or the stream,
first packet length information, and
mode identification information indicating whether the header of the first packet further includes an additional header in addition to the fixed length header, wherein
when the mode identification information indicates that the header of the first packet does not include the additional header, a packet length of the first packet is represented in the header using the first packet length information, and
when the mode identification information indicates that the header of the first packet further includes the additional header, the additional header includes second packet length information, and the packet length of the first packet is represented in the header using the first packet length information and the second packet length information.
2. The transmission apparatus according to claim 1 , wherein, when the mode identification information indicates that the header of the first packet further includes the additional header,
the packet length of the first packet is represented by total packet length information,
the first packet length information corresponds to a first set of bits of the total packet length information, and
the second packet length information corresponds to a second set of bits of the total packet length information occupying a bit position higher than the first set of bits.
3. The transmission apparatus according to claim 2 , wherein
the additional header further includes a division flag,
when the division flag indicates that the input packet or the stream is divided into a plurality of packets, the additional header further includes a division fragment header, and
the division fragment header includes a fragment ID for identification of the input packet or the stream, and a fragment counter for identification of the first packet among the plurality of packets.
4. The transmission apparatus according to claim 2 , wherein
the additional header further includes an additional header flag indicating whether there is a second additional header to be added to the additional header,
when the additional header flag indicates that there is the second additional header, the header of the first packet includes the second additional header in addition to the fixed length header and the additional header, and
the second additional header includes
additional header identification information identifying a type of the second additional header,
extension packet length information corresponds to a third set of bits of the total packet length information occupying a bit position higher than the second set of bits, and
additional information header flag indicating whether there is an additional information header.
5. The transmission apparatus according to claim 4 , wherein when the additional information header flag indicates that there is the additional information header, the header of the first packet includes the additional information header, which includes predetermined information, in addition to the fixed length header, the additional header, and the second additional header.
6. The transmission apparatus according to claim 4 , wherein when the additional header identification information indicates label information, the header of the first packet includes the additional information header, which includes predetermined label information, in addition to the fixed length header, the additional header, and the second additional header.
7. The transmission apparatus according to claim 1 , wherein the circuitry is configured to identify the type of the input packet or the stream, and generate the first packet corresponding to the identified type.
8. The transmission apparatus according to claim 1 , wherein the first packet length information is set to have a value corresponding to the packet length offset by a predetermined minimum value.
9. The transmission apparatus according to claim 1 , wherein, when the type identification information indicates that the type of the input packet or the stream is a transport stream packet, the header further includes
null packet deletion information indicating whether at least one null packet in the transport stream packet is deleted, and
information of the number of transport stream packets indicating a number of transport stream packets in the first packet.
10. The transmission apparatus according to claim 9 , wherein, when the packet deletion information indicates that at least one null packet in the transport stream packet is deleted, the header of the first packet further includes information indicating a number of deleted null packets.
11. The transmission apparatus according to claim 1 , wherein the type identification information includes unspecified protocol information indicating a protocol other than that of information for specification of a protocol of the input packet or the stream, and
when the type identification information is the unspecified protocol information, the header of the first packet includes, in addition to the fixed length header, predetermined protocol information for specification of a predetermined protocol.
12. A transmission method comprising:
generating a first packet from an input packet or a stream; and
transmitting the first packet, wherein
a header of the first packet includes a fixed length header, the fixed length header including
type identification information indicating a type of the input packet or the stream,
first packet length information, and
mode identification information indicating whether the header of the first packet further includes an additional header in addition to the fixed length header, wherein
when the mode identification information indicates that the header of the first packet does not include the additional header, a packet length of the first packet is represented in the header using the first packet length information, and
when the mode identification information indicates that the header of the first packet further includes the additional header, the additional header includes second packet length information, and the packet length of the first packet is represented in the header using the first packet length information and the second packet length information.
13. A reception apparatus comprising:
circuitry configured to
receive a transmitted signal including a first packet; and
generate an input packet or a stream based on at least a header of the first packet, wherein
the header of the first packet includes a fixed length header, the fixed length header including
type identification information indicating a type of the input packet or the stream,
first packet length information, and
mode identification information indicating whether the header of the first packet further includes an additional header in addition to the fixed length header, wherein
when the mode identification information indicates that the header of the first packet does not include the additional header, a packet length of the first packet is represented in the header using the first packet length information, and
when the mode identification information indicates that the header of the first packet further includes the additional header, the additional header includes second packet length information, and the packet length of the first packet is represented in the header using the first packet length information and the second packet length information.
14. A reception method comprising:
receiving a transmitted signal including a first packet; and
generating an input packet or a stream based on at least a header of the first packet, wherein
the header of the first packet includes a fixed length header, the fixed length header including
type identification information indicating a type of the input packet or the stream,
first packet length information, and
mode identification information indicating whether the header of the first packet further includes an additional header in addition to the fixed length header, wherein
when the mode identification information indicates that the header of the first packet does not include the additional header, a packet length of the first packet is represented in the header using the first packet length information, and
when the mode identification information indicates that the header of the first packet further includes the additional header, the additional header includes second packet length information, and the packet length of the first packet is represented in the header using the first packet length information and the second packet length information.
15. The transmission method according to claim 12 , wherein, when the mode identification information indicates that the header of the first packet further includes the additional header,
the packet length of the first packet is represented by total packet length information,
the first packet length information corresponds to a first set of bits of the total packet length information, and
the second packet length information corresponds to a second set of bits of the total packet length information occupying a bit position higher than the first set of bits.
16. The transmission method according to claim 15 , wherein
the additional header further includes a division flag,
when the division flag indicates that the input packet or the stream is divided into a plurality of packets, the additional header further includes a division fragment header, and
the division fragment header includes a fragment ID for identification of the input packet or the stream, and a fragment counter for identification of the first packet among the plurality of packets.
17. The reception apparatus according to claim 13 , wherein, when the mode identification information indicates that the header of the first packet further includes the additional header,
the packet length of the first packet is represented by total packet length information,
the first packet length information corresponds to a first set of bits of total packet length information, and
the second packet length information corresponds to a second set of bits of the total packet length information occupying a bit position higher than the first set of bits.
18. The reception apparatus according to claim 17 , wherein
the additional header further includes a division flag,
when the division flag indicates that the input packet or the stream is divided into a plurality of packets, the additional header further includes a division fragment header, and
the division fragment header includes a fragment ID for identification of the input packet or the stream, and a fragment counter for identification of the first packet among the plurality of packets.
19. The reception apparatus according to claim 17 , wherein
the additional header further includes an additional header flag indicating whether there is a second additional header to be added to the additional header,
when the additional header flag indicates that there is the second additional header, the header of the first packet includes the second additional header in addition to the fixed length header and the additional header, and
the second additional header includes
additional header identification information identifying a type of the second additional header,
extension packet length information corresponds to a third set of bits of the total packet length information occupying a bit position higher than the second set of bits, and
additional information header flag indicating whether there is an additional information header.
20. The reception apparatus according to claim 19 , wherein when the additional information header flag indicates that there is the additional information header, the header of the first packet includes the additional information header, which includes predetermined information, in addition to the fixed length header, the additional header, and the second additional header.
21. The reception apparatus according to claim 19 , wherein when the additional header identification information indicates label information, the header of the first packet includes the additional information header, which includes predetermined label information, in addition to the fixed length header, the additional header, and the second additional header.
22. The reception apparatus according to claim 13 , wherein the circuitry is configured to identify the type of the input packet or the stream based on the type identification information, and generate the input packet or the stream based on the identified type.
23. The reception apparatus according to claim 13 , wherein the first packet length information is set to have a value corresponding to the packet length offset by a predetermined minimum value.
24. The reception apparatus according to claim 13 , wherein, when the type identification information indicates that the type of the input packet or the stream is a transport stream packet, the header further includes
null packet deletion information indicating whether at least one null packet in the transport stream packet is deleted, and
information of the number of transport stream packets indicating a number of transport stream packets in the first packet.
25. The reception apparatus according to claim 24 , wherein, when the packet deletion information indicates that at least one null packet in the transport stream packet is deleted, the header of the first packet further includes information indicating a number of deleted null packets.
26. The reception apparatus according to claim 13 , wherein the type identification information includes unspecified protocol information indicating a protocol other than that of information for specification of a protocol of the input packet or the stream, and
when the type identification information is the unspecified protocol information, the header of the first packet includes, in addition to the fixed length header, predetermined protocol information for specification of a predetermined protocol.
27. The reception method according to claim 14 , wherein, when the mode identification information indicates that the header of the first packet further includes the additional header,
the packet length of the first packet is represented by total packet length information,
the first packet length information corresponds to a first set of bits of the total packet length information, and
the second packet length information corresponds to a second set of bits of the total packet length information occupying a bit position higher than the first set of bits.
28. The reception method according to claim 27 , wherein
the additional header further includes a division flag,
when the division flag indicates that the input packet or the stream is divided into a plurality of packets, the additional header further includes a division fragment header, and
the division fragment header includes a fragment ID for identification of the input packet or the stream, and a fragment counter for identification of the first packet among the plurality of packets.
29. The reception method according to claim 27 , wherein
the additional header further includes an additional header flag indicating whether there is a second additional header to be added to the additional header,
when the additional header flag indicates that there is the second additional header, the header of the first packet includes the second additional header in addition to the fixed length header and the additional header, and
the second additional header includes
additional header identification information identifying a type of the second additional header,
extension packet length information corresponds to a third set of bits of the total packet length information occupying a bit position higher than the second set of bits, and
additional information header flag indicating whether there is an additional information header.