Reference layer and scaled reference layer offsets for scalable video coding
A process for determining the selection of filters and input samples is provided for scalable video coding. The process provides for re-sampling using video data obtained from an encoder or decoder process of a base layer (BL) in a multi-layer system to improve quality in Scalable High Efficiency Video Coding (SHVC). It is proposed that a single scaled reference layer offset be derived from two scaled reference layer offset parameters, and vice-versa. It is also proposed that a single scaled reference layer offset or a single reference layer offset be derived from a combination of a scaled reference layer offset parameter and a reference layer offset parameter.
1. An apparatus capable of at least one of coding or decoding a bitstream configured for scalable video for predicting values at pixel locations in a video coding layer, the bitstream comprising:
a first coding layer comprising a first video encoder and/or a first video decoder for coding video with a base resolution;
a second coding layer comprising a second video encoder and/or a second video decoder for coding video with an enhanced resolution having a higher resolution than said base resolution;
wherein pixel values in the second coding layer are predicted based on pixel values in the first coding layer;
wherein the prediction of a value at a pixel location in the second coding layer is based on a corresponding value at a pixel location in the first coding layer, without reference to any motion information, wherein said pixel location in said first coding layer and said pixel location in said second coding layer are both part of the same temporal frame in said scalable video;
wherein the corresponding pixel location in the first coding layer is computed based on the pixel location in the second coding layer;
wherein the computation uses a scaled reference layer offset parameter α that specifies an offset between a sample in the second layer that is collocated relative to the top-left sample of the first layer and the top-left sample of the second layer and an offset β that specifies an offset between a region in the first layer and a corresponding region in the second layer relative to the top-left sample of the first layer and the top-left sample of the second layer;
wherein the at least one scaled reference layer offset parameter represents a coarse offset component defined in terms of an integer number of pixels offset and a fine offset component defined in terms of a number of sub-pixels offset, which is not an integer number of pixels, used in the video coding system as a single value; and
wherein the apparatus uses the at least one scaled reference layer offset parameter to at least one of code or decode the bitstream.
2. The system of claim 1 , wherein the scaled reference layer offset parameter specifies the horizontal component of the offset.
3. The system of claim 1 , wherein the scaled reference layer offset parameter specifies the vertical component of the offset.