US 11,843,776 B2
Video encoder with quantization control
Krishnakanth Rapaka, San Jose, CA (US); Munehiro Nakazato, San Jose, CA (US); Jiandong Shen, Cupertino, CA (US); Ganesh G. Yadav, Fremont, CA (US); Sorin Constantin Cismas, Saratoga, CA (US); Jim C. Chou, San Jose, CA (US); and Hao Pan, Sunnyvale, CA (US)
Assigned to APPLE INC.
Filed by Apple Inc., Cupertino, CA (US)
Filed on Jun. 17, 2022, as Appl. No. 17/843,160.
Application 17/843,160 is a continuation of application No. 16/844,168, filed on Apr. 9, 2020, granted, now 11,399,180.
Claims priority of provisional application 62/831,259, filed on Apr. 9, 2019.
Prior Publication US 2022/0329805 A1, Oct. 13, 2022
Int. Cl. H04N 19/124 (2014.01); H04N 19/60 (2014.01); H04N 19/126 (2014.01)
CPC H04N 19/124 (2014.11) [H04N 19/126 (2014.11); H04N 19/60 (2014.11)] 20 Claims
OG exemplary drawing
 
1. A method comprising:
at an electronic device including one or more processors and non-transitory memory:
receiving an image comprising a plurality of pixels having respective plurality of pixel locations and a respective plurality of pixel values;
applying a frequency transform to a spatial portion of the image to generate a plurality of frequency coefficients respectively associated with a plurality of spatial frequencies;
obtaining a quantization matrix including, for each of the plurality of spatial frequencies, a respective quantization parameter;
determining a category of the spatial portion of the image based on a relation between a plurality of thresholds associated with a plurality of quantization scaling parameters and a bit rate of the spatial portion of the image at the plurality of quantization scaling parameters;
determining a quantization scaling parameter for the spatial portion of the image based the category;
quantizing the plurality of frequency coefficients according to the quantization matrix and the quantization scaling parameter for the spatial portion of the image to generate a plurality of quantized frequency coefficients; and
transmitting the plurality of quantized frequency coefficients.