	US 12,238,344 B2
	Trim-pass correction for cloud-based coding of HDR video
Harshad Kadu, Santa Clara, CA (US); and Guan-Ming Su, Fremont, CA (US)
Assigned to Dolby Laboratories Licensing Corporation, San Francisco, CA (US)
Appl. No. 18/044,775
Filed by Dolby Laboratories Licensing Corporation, San Francisco, CA (US)
PCT Filed Sep. 17, 2021, PCT No. PCT/US2021/050957 § 371(c)(1), (2) Date Mar. 9, 2023, PCT Pub. No. WO2022/061169, PCT Pub. Date Mar. 24, 2022.
Claims priority of provisional application 63/089,154, filed on Oct. 8, 2020.
Claims priority of provisional application 63/080,255, filed on Sep. 18, 2020.
Claims priority of application No. 20196876 (EP), filed on Sep. 18, 2020; and application No. 20200781 (EP), filed on Oct. 8, 2020.
Prior Publication US 2023/0388555 A1, Nov. 30, 2023
Int. Cl. H04N 19/85 (2014.01); H04N 19/136 (2014.01); H04N 19/172 (2014.01); H04N 19/179 (2014.01)

CPC H04N 19/85 (2014.11) [H04N 19/136 (2014.11); H04N 19/172 (2014.11); H04N 19/179 (2014.11)]

14 Claims

1. A method for trim-pass correction for a video segment to be encoded in a computing node, the method comprising:

receiving in a current computing node a first video sequence comprising video frames in a high dynamic range;

generating (455) for each video frame in the first video sequence a first forward reshaping function and frame-based trim-pass correction parameters, wherein a forward reshaping function maps frame-pixels from the high dynamic range to a second dynamic range lower than the high dynamic range;

for a subscene in the first video sequence that is part of a parent scene to be processed by the current computing node and one neighbor computing node:

determining (457) a trim-pass parameter window comprising frames in the first video sequence and bumper frames, wherein the bumper frames comprise video frames to be processed by the neighbor computing node;

computing (459) scene-based trim-pass correction parameters based on the frame-based trim-pass correction parameters of the frames in the trim-pass parameter window;

generating a scene-based forward reshaping function based on the first forward reshaping functions of the frames in the subscene; and

generating for the subscene an output forward reshaping function based on the scene-based trim-pass correction parameters and the scene-based forward reshaping function, and

if the neighbor computing node is prior to the current computing node, then the trim-pass parameter window comprises all (B) bumper frames before the first frame of the first video sequence (C₀), up to, but not including, frame C_s=C₀+B; and

if the neighbor computing node is subsequent to the current computing node, then the trim-pass parameter window comprises frame C_s=C_L−1−B and all subsequent frames, including all bumper frames after the last frame of the first video sequence, wherein L denotes the number of frames in the video segment.