Scalable Video Coding using Phase Offset Flag Signaling
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). In order to accommodate other applications such as interlace/progressive scalability, it is proposed that three flags be used in the determination of the phase offset adjustment parameters.
1 . A system for scalable video coding, comprising:
a first coding layer comprising modules for coding video with a base resolution;
a second coding layer comprising modules for coding video with an enhanced resolution having a higher resolution than a 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;
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 derives horizontal phase offset parameters phaseX and deltaX and vertical phase offset parameters phaseY and deltaY based on the three flags VertPhasePositionAdjustFlag, CrossLayerPhaseAlignmentFlag, and VertPhasePositionFlag as follows for luma:
phase X =phase Y =CrossLayerPhaseAlignmentFlag<<1
delta X =CrossLayerPhaseAlignmentFlag<<3
delta Y =((CrossLayerPhaseAlignmentFlag<<3)>>VertPhasePositionAdjustFlag)+(VertPhasePositionFlag<<3).
2 . The system of claim 1 , wherein the CrossLayerPhaseAlignmentFlag is derived from cross_layer_phase_alignment_flag, and cross_layer_phase_alignment_flag is signaled at the SPS level.
3 . A system for scalable video coding, comprising:
a first coding layer comprising modules for coding video with a base resolution;
a second coding layer comprising modules for coding video with an enhanced resolution having a higher resolution than a 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;
wherein the corresponding pixel location in the first coding layer is computed based on the pixel location in the second coding layer; and
wherein the computation derives horizontal phase offset parameters phaseX and deltaX and vertical phase offset parameters phaseY and deltaY based on the three flags VertPhasePositionAdjustFlag, CrossLayerPhaseAlignmentFlag, and VertPhasePositionFlag as follows for chroma:
phase X =cross_layer_phase_alignment_flag
delta X =cross_layer_phase_alignment_flag<<2
phase Y =cross_layer_phase_alignment_flag+1
delta Y =((cross_layer_phase_alignment_flag<<2)>>VertPhasePositionAdjustFlag)+(VertPhasePositionFlag<<3)+2).
4 . The system of claim 3 , wherein the CrossLayerPhaseAlignmentFlag is derived from cross_layer_phase_alignment_flag, and cross_layer_phase_alignment_flag is signaled at the SPS level.
5 . A method for scalable video coding, comprising:
determining VertPhasePositionAdjustFlag from vert_phase_position_enable_flag, VertPhasePositionFlag from vert_phase_position_flag, and CrossLayerPhaseAlignmentFlag from cross_layer_phase_alignment_flag;
determining offset parameters phaseX, deltaX, phaseY, and deltaY from VertPhasePositionAdjustFlag, VertPhasePositionFlag, and CrossLayerPhaseAlignmentFlag;
determining reference layer position locations based on the offset parameters for use in selecting and filtering reference layer values.