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. A video coding method implemented in a scalable video coding system for predicting values at pixel locations in a video coding layer, said method comprising:
a first coding layer comprising video encoding and/or video decoding for coding video with a base resolution;
a second coding layer comprising video encoding and/or video decoding 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 pixel value at a pixel location in the second coding layer is based on a corresponding pixel 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 uses a scaled reference layer offset parameter α that specifies an offset between a sample in the second layer that is collocated with the top-left sample of the first layer and a top-left sample of the second layer;
wherein scaled reference layer offset parameter α represents a coarse offset component and a fine phase offset component, and is used by the video coding system as a single value.
2. The method of claim 1 , wherein the scaled reference layer offset parameter specifies the horizontal component of the offset.
3. The method of claim 1 , wherein the scaled reference layer offset parameter specifies the vertical component of the offset.
4. A video coding method implemented in a scalable video coding system for predicting pixel values at pixel locations in a video coding layer, said method comprising:
a first coding layer comprising video encoding and/or video decoding for coding video with a base resolution;
a second coding layer comprising video encoding and/or video decoding 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 pixel value at a pixel location in the second coding layer is based on a corresponding pixel 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 of the scaled reference layer offset uses a combination of two scaled reference layer offset parameters that specify an offset between the sample in the second layer that is collocated with the top-left sample of the first layer and the top-left sample of the second layer; and
wherein one of the scaled reference layer offset parameters is a coarse offset component and the other scaled reference layer offset parameter is a fine phase offset component.
5. A video coding method implemented in a scalable video coding system for predicting pixel values at pixel locations in a video coding layer, said method comprising:
a first coding layer comprising video encoding and/or video decoding for coding video with a base resolution;
a second coding layer comprising video encoding and/or video decoding 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 pixel value at a pixel location in the second coding layer is based on a corresponding pixel 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 uses a single reference layer offset parameter δ that is derived from a scaled reference layer phase offset α and a reference layer offset β, and where the single reference layer offset parameter δ is used by the video coding system as a single value.
6. The method of claim 5 , wherein the single reference layer offset parameter specifies the horizontal component of the offset.
7. The method of claim 5 , wherein the single reference layer offset parameter specifies the vertical component of the offset.
8. The method of claim 5 , comprising:
a scaled reference layer offset parameter α that specifies an offset between the sample in the second layer that is collocated with the top-left sample of the first layer and the top-left sample of the second layer;
a reference layer offset parameter β that specifies an offset between a sample in the second layer and a top-left sample of the second layer; and
a scale factor s that represents the ratio of the first layer width to the second layer width,
wherein δ is computed as α*s−β.
9. A video coding method implemented in a scalable video coding system for predicting pixel values at pixel locations in a video coding layer, said method comprising:
a first coding layer comprising video encoding and/or video decoding for coding video with a base resolution;
a second coding layer comprising video encoding and/or video decoding 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 pixel value at a pixel location in the second coding layer is based on a corresponding pixel 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 uses a single scaled reference layer offset parameter α that is derived from a scaled reference layer phase offset α and a reference layer offset β, and where the single reference layer offset parameter σ is used by the video coding system as a single value.
10. The method of claim 9 , wherein the single scaled reference layer offset parameter specifies the horizontal component of the offset.
11. The method of claim 9 , wherein the single scaled reference layer offset parameter specifies the vertical component of the offset.
12. The method of claim 9 , comprising:
a scaled reference layer offset parameter α that specifies an offset between the sample in the second layer that is collocated with the top-left sample of the first layer and the top-left sample of the second layer;
a reference layer offset parameter β that specifies an offset between a sample in the second layer and a top-left sample of the second layer;
a scale factor s that represents the ratio of the first layer width to the second layer width,
wherein σ is computed as α*s−β.