Patent ID: 11902593
Assignee: FRAUNHOFER GESELLSCHAFT ZUR FÖRDERUNG DER ANGEWANDTEN FORSCHUNG E.V.
Field: Audio-visual technology (Electrical engineering)
Classification: CPC H | IPC H

Claim 17:
18. A method 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) and a decoded picture buffer (DPB), the method comprising
encoding pictures of a video into a data stream in a coding order as a sequence of access units (AU),
determining 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; and
removing the AUs from the CPB AU-wise using the temporal raster,
does not lead to any underflow and any overflow, and

encoding the CPB parameters into the data stream,
wherein the AUs are encoded by
encoding a current picture using inter-picture prediction from a referenced reference picture which is to be, by the decoder, stored in the DPB, into a current AU, and
writing DPB mode information into the current AU, so that the decoder is able to decode the data stream by
inserting a decoded version of the current picture in the DPB 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,
if the DPB mode information indicates a first mode, removing 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,
using memory management control information comprising at least one command in 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,

wherein the method further comprises
encoding an entropy coding mode indicator into the data stream, so that the entropy coding mode indicator indicates a context adaptive variable length coding mode or a context adaptive binary arithmetic coding mode and
encoding prediction residual data into a current AU using the context adaptive variable length coding mode if the entropy coding mode indicator indicates the context adaptive variable length coding mode, and using the context adaptive binary arithmetic coding mode if the entropy coding mode indicator indicates the context adaptive binary arithmetic coding mode,
wherein the encoding the prediction residual data into the current AU using the context adaptive variable length coding mode comprises using
a first syntax element indicating a total number of non-zero transform coefficient levels in a transform block,
a second syntax element indicating a total number of zero-valued transform coefficient levels in the transform block,
third syntax elements indicting a number of consecutive transform coefficient levels in a scan order with zero value from a current scan position onwards before a non-zero transform coefficient level is encountered,
one or more fourth syntax elements for each non-zero valued transform coefficient except trailing one transform coefficients, which one or more fourth syntax elements indicate a transform coefficient level value of the respective non-zero valued transform coefficient, and
one or more fifth syntax elements indicating a sign of the trailing one transform coefficient levels.