ANSI SCTE 215-2-2018 pdf free download – HEVC Video Constraints for Cable Television Part 2- Transport.
6.4HEVC Program Constraints
MPEG-2 Programs shall be constrained to carry at most one HEVC video elementary stream component with astream_type value of Ox24; as defined in ISO/IEC 13818-1:2013 with FDAM 3[7].
6.4.1 SCTE HEVC Random Access Point (SHRAP)Access Unit Composition
An SCTE HEVC Random Access Point access unit (SHRAP) demarcates a location within an HEVC bitstreamwhere an HEVC Receiver is able to begin decoding video.The spacing of successive random access points is animportant contributor to channel change time, but is not the only factor contributing to channel change time. Otherfactors that contribute to channel change time include physical device tuning constraints,RF tuning, or conditionalaccess operations. Picture coding constraints for low delay mode are found in SCTE HEVC Coding Constraints [2]6.4.2SHRAP Transport Constraints
An SHRAP shall meet the following transport constraints.6.4.2.1 TS Packet Header and Adaptation Field Constraints
A TS packet containing the first byte of a PES packet header of an SHRAP shall have an adaptation field.Thepayload_unit_start_indicator bit shall be set to *1′ in the TS packet header and the adaptation_field_control bitsshall be set to ‘l1′(as per ISO/IEC 13818-1 [7]). In addition, the random_access_indicator bit in the adaptation fieldof the TS packet that contains the first byte of the PES packet header containing the SHRAP shall be set to ‘1’ andshall follow the constraints as specified in ISO/IEC 13818-1 [7] in Subclause 2.4.3.5.
Per ISO/IEC 13818-1 [7], the elementary_stream_priority_indicator bit shall be set to ‘1’ in the adaptation field ofthe TS packet that contains the first slice start code of the SHRAP Picture.
The first byte of the PES Packet Header containing an SHRAP and the first byte of the first slice start code of theSHRAP picture shall occur either in the same TS packet or in successive TS packets of the same PID. If both occurin the same TS packet, then both the random_access_indicator and elementary_stream_priority_indicator bits shallbe set to ‘1’ in the adaptation field of this TS packet. If the first byte of the PES header and the first slice start codeof the SHRAP picture occur in successive TS packets of the same PID, then both TS packets shall contain
adaptation fields. The first TS packet adaptation field shall contain random_access_indicator = 1. The second TSpacket shall contain elementary_stream_priority_indicator = 1.
NOTE 5: Setting of both a random_access_indicator and elementary_stream priority_indicator bits for the
access uit signifies an SHRAP access unit.
NOTE 6: Multiple PPSs may be present in an SHRAP access unit.The number of PPSs that may be present in
an SHRAP acces unit is constrained by the TSpacket restrictions above (requiring both RAI andESPI bits set in either the same TS packet or of successive TS packets).According to MPEG-2Systems 13818-1 [7], this requires all the bytes between the access unit delimiter NAL Unit and thestart of the first slice of the SHRAP Picture to be part of the payload of either the same TS packet ortwo successive TS packets.
6.4.2.2SHRAP Picture Decoding Time Stamp and SHRAP Picture Presentation Time Stamp ConstraintsThe HEVC Bitstream shall contain necessary elements such that all pictures with PTS greater than or equal toDTSsHRAP +0.5 seconds (where DTSsHRAp represents the decoding time stamp of an SHRAP Picture) are fullyreconstructable and displayable when decoding starts at the SHRAP picture.
NOTE 7:This implies that any picture that has a PTS >=[DTSwRAp + 0.5 seconds] cannot be predicted directly or indirectly from reference pictures that were transmitted prior to the SHRAP (i.e.with a lower value of DTS than DTSsHRAF). This also implies that any picture that was
transmitted prior to the SHRAP as well as any partially reconstructed pictures in the time interval[DTSsHRAP, DTSsHRAP + 0.5 seconds] , cannot have a PTS that is greater than or equal to [DTSHRAP+0.5 seconds].
NOTE 8:This also implies that the PTS of the first clean displayed picture output is less than or equal to[DTSsHRAr+ 0.5 seconds].ANSI SCTE 215-2 pdf download.