Video coding using a coded picture buffer

An apparatus for encoding a video into a data stream wherein the data stream is ought to be decoded by being fed to a decoder comprising a coded picture buffer (CPB), the apparatus configured to

• encode, into a data stream, pictures of a video encoded in a coding order as a sequence of access units (AU),
• determine first CPB parameters relating to a first operation point and second CPB parameters relating to a second operation point, each of the first and the second CPB parameters being indicative of a CPB size, a predetermined temporal offset, a predetermined temporal removal delay and a predetermined bitrate, wherein the first CPB parameters differ from the second CPB parameters at least with respect to the predetermined bitrate, and perform the determining such that interpolating between the predetermined temporal offset of the first CPB parameters and the predetermined temporal offset of second CPB parameters at each of a plurality of selected bitrates yields an interpolated temporal offset and an interpolated temporal removal delay so that feeding the data stream to the decoder via the CPB by
• feeding the sequence of AUs sequentially into the CPB using the respective selected bitrate with halting the feeding with respect to access units for which a virtual time of availability according to a temporal frame removal raster preponed by, for a first access unit in the coding order, an interpolated temporal removal delay and, for subsequent access units in coding order, a sum of the interpolated temporal removal delay and an interpolated temporal offset has not yet been reached, until the virtual time of availability is reached;
• removing the AUs from the CPB AU-wise using the temporal raster,
• does not lead to any underflow and any overflow, and
• encode the CPB parameters into the data stream,
• wherein the apparatus is configured to, in encoding the AUs,
• encode a current picture using inter-picture prediction from a referenced reference picture stored in a decoded picture buffer (DPB) into a current AU, and
• insert a decoded version of the current picture in the DPB into the DPB,
• assign to each reference picture stored in the DPB a classification as one of a short-term reference picture, a long-term reference picture and an unused-for-reference picture,
• write DPB mode information into the current AU,
• if the DPB mode information indicates a first mode, remove one or more reference pictures classified as a short-term picture, according to a FIFO strategy, from the DPB,
• if the DPB mode information indicates a second mode,
• write memory management control information comprising at least one command into the current AU, the command being instructive to change the classification assigned to at least one of the reference pictures stored in the DPB, wherein the classification of the reference pictures in the DPB, is used for managing reference picture removal from the DPB.

A method for video decoding by use of a coded picture buffer and a decoded picture buffer (DPB), the method comprising

• receiving a data stream having pictures of a video encoded thereinto along a coding order as a sequence of access units,
• feeding the sequence of access units sequentially into the CPB using a selected bitrate with halting the feeding with respect to access units for which a virtual time of availability according to a temporal frame removal raster preponed by, for a first access unit in the coding order, a selected temporal removal delay and, for subsequent access units in coding order, a sum of the selected temporal removal delay and a selected temporal offset has not yet been reached, until the virtual time of availability is reached;
• removing the AUs from the CPB AU-wise using the temporal raster,
• extracting from the data stream first CPB parameters relating to a first operation point and second CPB parameters relating to a second operation point, each of the first and the second CPB parameters being indicative of a CPB size, a predetermined temporal offset, a predetermined temporal removal delay and a predetermined bitrate, wherein the first CPB parameters differ from the second CPB parameters at least with respect to the predetermined bitrate,
• determining the selected temporal offset by interpolating, at the selected bitrate, between the predetermined temporal offset indicated by the first CPB parameters and the predetermined temporal offset indicated by the second CPB parameters and the selected temporal removal delay by interpolating, at the selected bitrate, between the predetermined temporal removal delay indicated by the first CPB parameters and the predetermined temporal removal delay indicated by the second CPB parameters,
• decoding a current AU removed from the CPB using inter-picture prediction from a referenced reference picture stored in the DPB to acquire a decoded picture, and
• inserting the decoded picture into the DPB,
• assigning to each reference picture stored in the DPB a classification as one of a short-term reference picture, a long-term reference picture and an unused-for-reference picture,
• reading DPB mode information from the current AU,
• if the DPB mode information indicates a first mode, remove one or more reference pictures classified as a short-term picture, according to a FIFO strategy, from the DPB,
• if the DPB mode information indicates a second mode,
• reading memory management control information comprising at least one command in the current AU and execute the at least one command so as to change the classification assigned to at least one of the reference pictures stored in the DPB, and use the classification of the reference pictures in the DPB, for managing reference picture removal from the DPB.