Patent ID: 11962813
Assignee: FRAUNHOFER GESELLSCHAFT ZUR FÖRDERUNG DER ANGEWANDTEN FORSCHUNG E.V.
Field: Audio-visual technology (Electrical engineering)
Classification: CPC H | IPC H

Claim 18:
19. 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 first-in-first-out (FIFOI 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,

one or more of:
if the at least one command in the current AU is a first command,
re-classifying a reference picture in the DPB, classified to be a short-term reference picture, as an unused-for-reference picture,

if the at least one command in the current AU is a second command,
re-classifying a reference picture in the DPB, classified to be a long-term reference picture, as an unused-for-reference picture,

if the at least one command in the current AU is a third command,
re-classifying a reference picture in the DPB, classified to be a short-term picture, as a long-term reference picture, and assign a frame index to the re-classified reference picture,

if the at least one command in the current AU is a fourth command,
setting an upper frame index limit according to the fourth command, and re-classify all reference picture in the DPB, classified to be a long-term picture, and having assigned thereto a frame index exceeding the upper frame index limit, as an unused-for-reference picture,

if the at least one command in the current AU is a fifth command,
classifying the current picture as a long-term picture, and assigning a frame index to the current picture.