# US 2014/0192882 A1 · Video buffering operations for random access in video coding > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0192882 A1 - Document ID: US20140192882A1 - Status: Published application - Kind: A1 - Application number: 14/089,495 - Filed: 2013-11-25 - Published: 2014-07-10 - Earliest claimed: 2013-01-07 - Assignees: QUALCOMM Incorporated - Applicants: QUALCOMM Incorporated - Inventors: Ye-Kui Wang; Adarsh Krishnan Ramasubramonian; Ying Chen - Web page: https://patentgrep.com/patent/US20140192882A1 ## CPC - H04N 19/107: between spatial and temporal predictive coding, e.g. picture refresh - H04N 19/433: characterised by techniques for memory access - H04N 19/70: characterised by syntax aspects related to video coding, e.g. related to compression standards - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract In an example, the present disclosure provides for receiving in a video bitstream an access unit having a first random access point (RAP) picture and receiving in the video bitstream, after the access unit in the bitstream, a subsequent access unit having a second RAP picture. In a case that one or more random access skipped leading (RASL) pictures for the subsequent access unit are not present in the received video bitstream, shifting a picture buffer removal time earlier based on a picture buffer removal delay offset. Another example provides for receiving an access unit after an earlier initialization of the hypothetical reference decoder (HRD), the access unit having a RAP picture, wherein associated access units containing RASL pictures are not received and initializing a picture buffer removal time and a picture buffer removal delay offset in response to receiving the access unit and not receiving the associated access units containing RASL pictures. ## Claims ### Claim 1 A method of processing video data, the method comprising: receiving in a video bitstream an access unit having a first random access point (RAP) picture; receiving in the video bitstream, after the access unit in the bitstream, a subsequent access unit having a second RAP picture; and in a case that one or more random access skipped leading (RASL) pictures for the subsequent access unit are not present in the received video bitstream, shifting a picture buffer removal time for a picture buffer earlier based on a picture buffer removal delay offset. ### Claim 2 (depends on 1) The method of claim 1, wherein the picture buffer comprises a coded picture buffer (CPB) and the picture buffer removal delay offset comprises a CPB removal delay offset. ### Claim 3 (depends on 2) The method of claim 2, wherein the CPB removal delay offset is signaled for the RAP picture of the subsequent access unit. ### Claim 4 (depends on 1) The method of claim 1, wherein the picture buffer comprises a decoded picture buffer (DPB) and the picture buffer removal delay offset comprises a DPB removal delay offset. ### Claim 5 (depends on 1) The method of claim 1, further comprising receiving the picture buffer removal delay offset for the access unit. ### Claim 6 (depends on 1) The method of claim 1, further comprising receiving the picture buffer removal delay offset in a buffering period SEI message. ### Claim 7 (depends on 1) The method of claim 1, wherein the RAP picture includes one of a clean random access (CRA) picture and a broken link access (BLA) picture. ### Claim 8 A method of processing video data, the method comprising: receiving an access unit after an earlier initialization of a hypothetical reference decoder (HRD), the access unit having a random access point (RAP) picture, wherein associated access units containing random access skipped leading (RASL) pictures are not received; and re-initializing the HRD, including re-initializing a picture buffer removal time and a picture buffer removal delay offset, in response to receiving the access unit and not receiving the associated access units containing RASL pictures. ### Claim 9 (depends on 8) The method of claim 8, wherein the picture buffer removal time comprises a coded picture buffer (CPB) removal time and the picture buffer removal delay offset comprises a CPB removal delay offset. ### Claim 10 (depends on 9) The method of claim 9, wherein the CPB removal delay offset is signaled for the RAP picture of a subsequent access unit. ### Claim 11 (depends on 8) The method of claim 8, wherein the picture buffer removal time comprises a decoded picture buffer (DPB) removal time and the picture buffer removal delay offset comprises a DPB removal delay offset. ### Claim 12 (depends on 8) The method of claim 8, wherein the RAP picture is a clean random access (CRA) picture. ### Claim 13 (depends on 8) The method of claim 8, wherein the RAP picture is a broken link access (BLA) picture that may have associated RASL pictures or random access skipped decodable (RADL) pictures. ### Claim 14 (depends on 8) The method of claim 8, wherein the RAP picture is one of a broken link access (BLA) picture that does not have associated RASL pictures, but may have RADL pictures, and a BLA picture that does not have associated leading pictures. ### Claim 15 (depends on 8) The method of claim 8, further comprising processing the received access unit as the first access unit in a bitstream. ### Claim 16 (depends on 8) The method of claim 8, further comprising receiving the picture buffer removal delay offset in a buffering period SEI message. ### Claim 17 A device for processing video data comprising: a processor configured to: receive in a video bitstream an access unit having a first random access point (RAP) picture; receive in the video bitstream, after the access unit in the bitstream, a subsequent access unit having a second RAP picture; and in a case that one or more random access skipped leading (RASL) pictures for the subsequent access unit are not present in the received video bitstream, shift a picture buffer removal time for a picture buffer earlier based on a picture buffer removal delay offset. ### Claim 18 (depends on 17) The device of claim 17, wherein the picture buffer comprises a coded picture buffer (CPB) and the picture buffer removal delay offset comprises a CPB removal delay offset. ### Claim 19 (depends on 18) The device of claim 18, wherein the CPB removal delay offset is signaled for the RAP picture of the subsequent access unit. ### Claim 20 (depends on 17) The device of claim 17, wherein the picture buffer comprises a decoded picture buffer (DPB) and the picture buffer removal delay offset comprises a DPB removal delay offset. ### Claim 21 (depends on 17) The device of claim 17, wherein the processor is further configured to receive the picture buffer removal delay offset for the access unit. ### Claim 22 (depends on 17) The device of claim 17, further comprising receiving the picture buffer removal delay offset in a buffering period SEI message. ### Claim 23 (depends on 17) The device of claim 17, wherein the RAP picture includes one of a clean random access (CRA) picture and a broken link access (BLA) picture. ### Claim 24 A device for processing video data comprising: a processor configured to: receiving an access unit after an earlier initialization of a hypothetical reference decoder (HRD), the access unit having a random access point (RAP) picture, wherein associated access units containing random access skipped leading (RASL) pictures are not received; and re-initializing the HRD, including re-initializing a picture buffer removal time and a picture buffer removal delay offset, in response to receiving the access unit and not receiving the associated access units containing RASL pictures. ### Claim 25 (depends on 24) The device of claim 24, wherein the picture buffer removal time comprises a coded picture buffer (CPB) removal time and the picture buffer removal delay offset comprises a CPB removal delay offset. ### Claim 26 (depends on 25) The device of claim 25, wherein the CPB removal delay offset is signaled for the RAP picture of a subsequent access unit. ### Claim 27 (depends on 24) The device of claim 24, wherein the picture buffer removal time comprises a decoded picture buffer (DPB) removal time and the picture buffer removal delay offset comprises a DPB removal delay offset. ### Claim 28 (depends on 24) The device of claim 24, wherein the RAP picture is a clean random access (CRA) picture. ### Claim 29 (depends on 24) The device of claim 24, wherein the RAP picture is a broken link access (BLA) picture that may have associated RASL pictures or random access skipped decodable (RADL) pictures. ### Claim 30 (depends on 24) The device of claim 24, wherein the RAP picture is one of a broken link access (BLA) picture that does not have associated RASL pictures, but may have RADL pictures, and a BLA picture that does not have associated leading pictures. ### Claim 31 (depends on 24) The device of claim 24, wherein the processor is further configured to designate the received access unit as the first access unit in a bitstream. ### Claim 32 (depends on 24) The device of claim 24, further comprising receiving the picture buffer removal delay offset in a buffering period SEI message. ### Claim 33 A device for processing video data comprising: means for receiving in a video bitstream an access unit having a first random access point (RAP) picture; means for receiving in the video bitstream, after the access unit in the bitstream, a subsequent access unit having a second RAP picture; and means for shifting a picture buffer removal time for a picture buffer earlier based on a picture buffer removal delay offset in a case that one or more random access skipped leading (RASL) pictures for the subsequent access unit are not present in the received video bitstream. ### Claim 34 (depends on 33) The device of claim 33, wherein the picture buffer comprises a coded picture buffer (CPB) and the picture buffer removal delay offset comprises a CPB removal delay offset. ### Claim 35 (depends on 33) The device of claim 33, wherein the picture buffer comprises a decoded picture buffer (DPB) and the picture buffer removal delay offset comprises a DPB removal delay offset. ### Claim 36 (depends on 33) The device of claim 33, further comprising means for receiving the picture buffer removal delay offset for the access unit. ### Claim 37 (depends on 33) The device of claim 33, further comprising receiving the picture buffer removal delay offset in a buffering period SEI message. ### Claim 38 (depends on 33) The device of claim 33, wherein the RAP picture includes one of a clean random access (CRA) picture and a broken link access (BLA) picture. ### Claim 39 A device for processing video data comprising: means for receiving an access unit after an earlier initialization of the hypothetical reference decoder (HRD), the access unit having a random access point (RAP) picture, wherein associated access units containing random access skipped leading (RASL) pictures are not received; and means for re-initializing the HRD, including re-initializing a picture buffer removal time and a picture buffer removal delay offset, in response to receiving the access unit and not receiving the associated access units containing RASL pictures. ### Claim 40 (depends on 39) The device of claim 39, wherein the picture buffer removal time comprises a coded picture buffer (CPB) removal time and the picture buffer removal delay offset comprises a CPB removal delay offset. ### Claim 41 (depends on 39) The device of claim 39, wherein the picture buffer removal time comprises a decoded picture buffer (DPB) removal time and the picture buffer removal delay offset comprises a DPB removal delay offset. ### Claim 42 (depends on 39) The device of claim 39, wherein the RAP picture is a clean random access (CRA) picture. ### Claim 43 (depends on 39) The device of claim 39, wherein the RAP picture is a broken link access (BLA) picture that may have associated RASL pictures or random access skipped decodable (RADL) pictures. ### Claim 44 (depends on 39) The device of claim 39, wherein the RAP picture is one of a broken link access (BLA) picture that does not have associated RASL pictures, but may have RADL pictures, and a BLA picture that does not have associated leading pictures. ### Claim 45 (depends on 39) The device of claim 39, further comprising means for processing the received access unit as the first access unit in a bitstream. ### Claim 46 (depends on 39) The device of claim 39, further comprising receiving the picture buffer removal delay offset in a buffering period SEI message. ### Claim 47 A non-transitory computer readable storage medium storing instructions that upon execution by one or more processors cause the one or more processors to: receive in a bitstream an access unit having a first random access point (RAP) picture; receive in the video bitstream, after the access unit in the bitstream, a subsequent access unit having a second RAP picture; and shift a picture buffer removal time for a picture buffer earlier based on a picture buffer removal delay offset in a case that one or more random access skipped leading (RASL) pictures for the subsequent access unit are not present in the received video bitstream. ### Claim 48 A non-transitory computer readable storage medium storing instructions that upon execution by one or more processors cause the one or more processors to: receive an access unit having a random access point (RAP) picture, wherein associated access units containing random access skipped leading (RASL) pictures are not received; and re-initialize the HRD, including re-initializing a picture buffer removal time and a picture buffer removal delay offset, in response to receiving the access unit and not receiving the associated access units containing RASL pictures. ### Claim 49 A method of processing video data comprising: signaling a CPB removal delay offset for each CRA or BLA access unit; shifting the CBP removal time of each of the access units following the CRA or BLA access unit in decoding order is earlier by the CPB removal delay offset for each CRA or BLA access unit for which the associated RASL pictures are not present; and regardless of whether the HRD initializes at the CRA or BLA access unit.