Patent ID: 9516329
Filing Date: 2016-12-06
CPC Classification: H04N

Claim Text:
1. A method of dual-pass rate control video encoding, comprising: receiving uncompressed input video including a sequence of pictures with a video encoder, the input video including a plurality of contiguous sequences of pictures included in a Group of Pictures (GOP) that, when coded, begin with an I-picture in display order and end with a last picture before a next I-picture, the GOP also including picture types encoded as P pictures, B pictures and B-reference pictures; performing a first encoding pass of the uncompressed video with the video encoder to detect scene changes, to assign macroblocks to a pre-determined number of activity classes, and to determine a complexity of each picture within the sequence of pictures, each of the macroblocks being rectangular arrays of luma samples and two corresponding blocks of chroma samples in the pictures, each of the activity classes being different defined classes of macroblocks based on luma values of the pictures of the input video, the complexity being a number of bits generated per picture and activity class; performing a second encoding pass for rate control of the uncompressed video with the video encoder at a delay relative to the first encoding pass, information from the first encoding pass related to the scene changes, the activity classes, and the complexity being used for rate control determined in the second encoding pass for producing and outputting a bit stream of compressed video, quantizer values for rate control being determined by the second encoding pass for each macroblock on a per picture type and activity class basis; and during the second encoding pass, encoding each macroblock determined to require a maximum quantizer value by the video encoder as a skip picture if encoding the macroblock with a maximum quantizer value would cause an overflow of a coded picture buffer (CPB) of the video encoder.