Patent ID: 9667969
Date: 2017-05-30
CPC Classifications: G06T,H04N

Claim:
1. A method for encoding a video stream having a first transparency information channel in view of a predetermined target bit rate for said first transparency information channel, said transparency information channel specifying a respective transparency value for pixel coordinates, said method comprising: tentatively applying a first encoding to a portion of said first transparency information channel, said first encoding comprising a lossless vector graphics encoding scheme; if said first encoding results in an encoded bitrate within said predetermined target bitrate, selecting said first encoding to produce an encoded version of said portion of said first transparency information channel; otherwise, tentatively applying a second encoding to said portion of said first transparency information channel, said second encoding comprising a mathematical representation encoding scheme, said mathematical representation being obtained by segmenting said transparency information in differentiable regions onto which is fitted a polynomial, quadric, or plane function of said pixel coordinates and alpha values; if said second encoding results in an encoded bitrate within said predetermined target bitrate, selecting said second encoding to produce an encoded version of said portion of said first transparency information channel; otherwise, selecting a third encoding to produce an encoded version of said portion of said first transparency information channel, said third encoding comprising an MPEG-based encoding scheme.