US 11,871,003 B2
Systems and methods of rate control for multiple pass video encoding
Sorin C Cismas, Saratoga, CA (US); and Ganesh G Yadav, Fremont, CA (US)
Assigned to Apple Inc., Cupertino, CA (US)
Filed by Apple Inc., Cupertino, CA (US)
Filed on Jan. 31, 2022, as Appl. No. 17/589,642.
Claims priority of provisional application 63/243,711, filed on Sep. 13, 2021.
Prior Publication US 2023/0084718 A1, Mar. 16, 2023
Int. Cl. H04N 19/14 (2014.01); H04N 19/174 (2014.01); H04N 19/186 (2014.01); H04N 19/149 (2014.01); H04N 19/30 (2014.01)
CPC H04N 19/149 (2014.11) [H04N 19/14 (2014.11); H04N 19/174 (2014.11); H04N 19/186 (2014.11); H04N 19/30 (2014.11)] 14 Claims
OG exemplary drawing
 
1. An electronic device comprising:
a network interface configured to stream image data to another electronic device; and
video encoder circuitry configured to prepare the image data for streaming at least in part by:
performing a first pass of rate control on the image data to perform size estimation for each slice of the image data;
performing a second pass of rate control on the image data to assign quantization parameters and perform additional size estimation for each slice of the image data;
performing a third pass of rate control using one or more image frame statistics collected during the second pass of rate control, wherein the third pass of rate control comprises:
scaling a target coefficient size and a maximum coefficient size based on the one or more image frame statistics;
calculating an updated quantization parameter value based on the scaled target coefficient size and the scaled maximum coefficient size values; and
encoding one or more slices of the image data based on the calculated updated quantization parameter value.