US 12,348,719 B2
Control and use of chroma quantization parameter values
Gary J. Sullivan, Bellevue, WA (US); and Sandeep Kanumuri, Redmond, WA (US)
Assigned to Microsoft Technology Licensing, LLC, Redmond, WA (US)
Filed by Microsoft Technology Licensing, LLC, Redmond, WA (US)
Filed on Sep. 26, 2022, as Appl. No. 17/953,120.
Application 15/202,933 is a division of application No. 13/732,356, filed on Dec. 31, 2012, granted, now 9,414,054, issued on Aug. 9, 2016.
Application 17/953,120 is a continuation of application No. 17/145,535, filed on Jan. 11, 2021, granted, now 11,457,212.
Application 17/145,535 is a continuation of application No. 16/600,287, filed on Oct. 11, 2019, granted, now 10,924,740, issued on Feb. 16, 2021.
Application 16/600,287 is a continuation of application No. 16/277,704, filed on Feb. 15, 2019, granted, now 10,491,898, issued on Nov. 26, 2019.
Application 16/277,704 is a continuation of application No. 15/202,933, filed on Jul. 6, 2016, granted, now 10,250,882, issued on Apr. 2, 2019.
Claims priority of provisional application 61/667,381, filed on Jul. 2, 2012.
Prior Publication US 2023/0036446 A1, Feb. 2, 2023
This patent is subject to a terminal disclaimer.
Int. Cl. H04N 19/124 (2014.01); H04N 19/126 (2014.01); H04N 19/174 (2014.01); H04N 19/186 (2014.01); H04N 19/44 (2014.01); H04N 19/70 (2014.01); H04N 19/146 (2014.01)
CPC H04N 19/124 (2014.11) [H04N 19/126 (2014.11); H04N 19/174 (2014.11); H04N 19/186 (2014.11); H04N 19/44 (2014.11); H04N 19/70 (2014.11); H04N 19/146 (2014.11)] 20 Claims
OG exemplary drawing
 
1. A computer system comprising:
a buffer, implemented with memory of the computer system, configured to receive encoded data in at least part of a bitstream for a video sequence, the encoded data including syntax elements that indicate a picture-level chroma quantization parameter (QP) offset and a slice-level chroma QP offset; and
a video decoder, implemented with one or more processing units of the computer system, configured to perform operations to decode the encoded data to reconstruct a coding unit of a picture of the video sequence for which values of QP vary according to a relationship between a luma component and one or more chroma components, wherein the operations include:
determining a luma QP;
determining a final chroma QP based at least in part on the luma QP, the picture-level chroma QP offset, and the slice-level chroma QP offset, wherein an upper limit of range of quantization step size (QSS) indicated by the final chroma QP substantially matches an upper limit of range of QSS indicated by the luma QP, including:
determining a QP index using the luma QP;
mapping the QP index to an intermediate chroma QP, including setting the intermediate chroma QP based on the QP index according to a piecewise mapping between different values of QP index and corresponding values of intermediate chroma QP; and
adjusting the intermediate chroma QP to determine the final chroma QP; and
performing inverse quantization operations for the coding unit of picture based at least in part on the luma QP and the final chroma QP.