Syntax and semantics for buffering information to simplify video splicing

A computer system comprising one or more processing units and memory, wherein the computer system implements a video decoder configured to perform operations comprising:

• receiving a concatenation flag and a coded picture buffer removal delay (“CPBRD”) delta value signaled as part of a supplemental enhancement information message associated with a given access unit, the concatenation flag having a given value;
• receiving encoded data in a bitstream for a given decoding unit of the given access unit, the given access unit corresponding to a current picture among pictures of a video sequence, wherein the given decoding unit is a subset of the current picture;
• determining a nominal coded picture buffer (“CPB”) removal time of a preceding access unit based on a nominal CPB removal time of a last decoding unit of the preceding access unit, the preceding access unit corresponding to a preceding picture among the pictures of the video sequence, wherein the last decoding unit is a subset of the preceding picture;
• determining a value of a constraint that ensures that delay is at least as long as delay would be if decoding started at the given access unit;
• and
• determining a nominal CPB removal time based at least in part on a sum of (a) the nominal CPB removal time of the preceding access unit and (b) a product of a clock tick value and a factor, wherein the factor depends on the higher of the CPBRD delta value and the value of the constraint.

A storage device having stored thereon encoded data in a bitstream for a given decoding unit of a given access unit, the given access unit corresponding to a current picture among pictures of a video sequence, wherein the given decoding unit is a subset of the current picture, the bitstream further including a concatenation flag and a coded picture buffer removal delay (“CPBRD”) delta value signaled as part of a supplemental enhancement information message associated with the given access unit, the concatenation flag having a given value, the bitstream being organized to facilitate decoding with operations comprising:

• determining a nominal coded picture buffer (“CPB”) removal time of a preceding access unit based on a nominal CPB removal time of a last decoding unit of the preceding access unit, the preceding access unit corresponding to a preceding picture among the pictures of the video sequence, wherein the last decoding unit is a subset of the preceding picture;
• determining a value of a constraint that ensures that delay is at least as long as delay would be if decoding started at the given access unit;
• and
• determining a nominal CPB removal time based at least in part on a sum of (a) the nominal CPB removal time of the preceding access unit and (b) a product of a clock tick value and a factor, wherein the factor depends on the higher of the CPBRD delta value and the value of the constraint.

One or more non-transitory computer-readable media having stored thereon computer-executable instructions for causing one or more processing units, when programmed thereby, to perform encoding operations comprising:

• setting a concatenation flag and a coded picture buffer removal delay (“CPBRD”) delta value, the concatenation flag having a given value;
• encoding a given decoding unit of a given access unit, the given access unit corresponding to a current picture among pictures of a video sequence, wherein the given decoding unit is a subset of the current picture, thereby producing encoded data for the given decoding unit of the given access unit;
• and
• outputting the encoded data in a bitstream, the bitstream further including the concatenation flag and the CPBRD delta value signaled as part of a supplemental enhancement information message associated with the given access unit, thereby enabling a video decoder to perform decoding operations comprising:
• determining a nominal coded picture buffer (“CPB”) removal time of a preceding access unit based on a nominal CPB removal time of a last decoding unit of the preceding access unit, the preceding access unit corresponding to a preceding picture among the pictures of the video sequence, wherein the last decoding unit is a subset of the preceding picture;
• determining a value of a constraint that ensures that delay is at least as long as delay would be if decoding started at the given access unit;
• and
• determining a nominal CPB removal time based at least in part on a sum of (a) the nominal CPB removal time of the preceding access unit and (b) a product of a clock tick value and a factor, wherein the factor depends on the higher of the CPBRD delta value and the value of the constraint.