ANSI SCTE 138:2019 pdf free download – Stream Conditioning For Switching Of Addressable Content In Digital Television Receivers
8.4.2. AVC Video Filler
The following requirements apply when performing an L0 Switch when AVC video content is present: In AVC video streams, Filler shall begin with an IDR picture, and shall consist of alternating IDR and FPP pictures in transmission order throughout the duration of the Filler. Filler may end on an IDR or FPP picture. All IDR pictures shall be preceded by an SPS and appropriate VUI. The coded video sequence comprised of Filler and the adjacent content shall be compliant with [SCTE 128-1]. Field parity shall be maintained during these transitions. In each service carrying Filler there shall be a PCR transmitted on the designated PCR_PID within 5 milliseconds prior to the transmission of the PES header that begins each IDR picture.
8.4.3. HEVC Video Filler
The following requirements apply when performing an L0 switch in the presence of HEVC video: In HEVC video streams, Filler shall begin with an IDR picture, and shall consist of alternating IDR pictures and TRAIL_N pictures in transmission order throughout the duration of the Filler. Filler may end on an IDR or TRAIL_N picture. Each IDR picture shall be contained within a SHRAP access unit as defined in [SCTE 215-1]. The coded video sequence comprised of Filler and the adjacent content shall be compliant with [SCTE 215-1]. Field parity shall be maintained during these transitions. In each service carrying Filler there shall be a PCR transmitted on the designated PCR_PID within 5 milliseconds prior to the transmission of the PES header that begins each IDR picture. The transport of Filler shall meet the requirements of [SCTE 215-2].
8.5. Filler Alignment
For a given Switch, all Filler shall be aligned. This requirement shall apply to all streams involved in a Switch regardless of whether they are contained within the same transport stream or in different transport streams. For alignment purposes, within a service an alignment point is defined as the later of the start of Filler in either the video or audio elementary stream. Across all services involved in a given Switch, all alignment points shall occur within 35 milliseconds. Following the alignment point, all video Filler shall have the same transmission duration. Following the alignment point, all audio Filler shall have the same transmission duration. Note: The alignment point establishes the earliest point at which a Client-DPI Device can initiate a Switch. The start of Filler is aligned to guarantee that a Client-DPI Device which completes a Switch very quickly does not join the destination service before the transmission of Filler on that service has started. The transmission duration of Filler is chosen to guarantee that a Client-DPI Device which completes a Switch slowly does not join the destination service after the transmission of Filler on that service has ended. The minimum Filler transmission duration should be chosen to accommodate the tuning time of the Client-DPI Device. For example if the Client-DPI Device can complete a tune in 500 milliseconds or less the minimum Filler duration would be 533 milliseconds. In certain implementations, Filler transmission duration may be greater than 533 milliseconds based upon other system requirements, for example to accommodate time base discontinuities or to allow for changes in an encryption key.