Sampling grid information for spatial layers in multi-layer video coding
Sampling grid information may be determined for multi-layer video coding systems. The sampling grid information may be used to align the video layers of a coding system. Sampling grid correction may be performed based on the sampling grid information. The sampling grids may also be detected. In some embodiments, a sampling grid precision may also be detected and/or signaled.
1. A method for multi-layer video coding, the method comprising:
receiving a signal including sampling grid information, the sampling grid information including luma plane phase shift data and chroma plane phase shift data, the luma plane phase shift data specifying a luma phase shift between a luma sampling grid of a first picture in a first video layer and a luma sampling grid of a second picture in a second video layer, the chroma plane phase shift data specifying a chroma phase shift between a chroma sampling grid of the first picture and a chroma sampling grid of the second picture;
upsampling the first picture;
performing sampling grid correction based on the sampling grid information during the upsampling of the first picture;
selecting one or more High Efficiency Video Coding (HEVC) poly-phase filters based on the chroma plane phase shift data and the luma plane phase shift data, the sampling grid correction including applying the one or more HEVC poly-phase filters;
aligning the luma sampling grid of the first picture with the luma sampling grid of the second picture based on the sampling grid correction; and
aligning the chroma sampling grid of the first picture with the chroma sampling grid of the second picture based on the sampling grid correction.
2. The method of claim 1 , wherein the chroma plane phase shift data includes at least one of: a horizontal chroma phase shift or a vertical chroma phase shift.
3. The method of claim 1 , wherein the luma plane phase shift data includes at least one of: a horizontal luma phase shift or a vertical luma phase shift.
4. The method of claim 1 , wherein the signal includes a flag, the flag indicating that the sampling grid information is included in the signal.
5. The method of claim 1 , wherein the first video layer is a base layer and the second video layer is an enhancement layer.
6. The method of claim 1 , wherein the chroma plane phase shift data and the luma plane phase shift data indicates a non-zero relative phase shift between the first picture in the first video layer and the second picture in the second video layer.
7. A device comprising:
a receiver configured to receive a signal including sampling grid information, the sampling grid information including luma plane phase shift data and chroma plane phase shift data, the luma plane phase shift data specifying a luma phase shift between a luma sampling grid of a first picture in a first video layer and a luma sampling grid of a second picture in a second video layer, the chroma plane phase shift data specifying a chroma phase shift between a chroma sampling grid of the first picture and a chroma sampling grid of the second picture; and
a processor, configured to:
upsample the first picture;
perform sampling grid correction based on the sampling grid information during the upsampling of the first picture;
select one or more High Efficiency Video Coding (HEVC) poly-phase filters based on the chroma plane phase shift data and the luma plane phase shift data, the processor configured to apply the one or more HEVC poly-phase filters as part of the sampling grid correction;
align the luma sampling grid of the first picture with the luma sampling grid of the second picture based on the sampling grid correction; and
align the chroma sampling grid of the first picture with the chroma sampling grid of the second picture based on the sampling grid correction.
8. The device of claim 7 , wherein the chroma plane phase shift data includes at least one of: a horizontal chroma phase shift or a vertical chroma phase shift.
9. The device of claim 7 , wherein the luma plane phase shift data includes at least one of: a horizontal luma phase shift or a vertical luma phase shift.
10. The device of claim 7 , wherein the signal includes a flag, the flag indicating that the sampling grid information is included in the signal.
11. The device of claim 7 , wherein the chroma plane phase shift data and the luma plane phase shift data indicates a non-zero relative phase shift between the first picture in the first video layer and the second picture in the second video layer.
12. A method for multi-layer video coding, the method comprising:
receiving a signal including sampling grid information, the sampling grid information including luma plane phase shift data and chroma plane phase shift data, the luma plane phase shift data specifying a luma phase shift between a base layer (BL) picture and an enhancement layer (EL) picture, the chroma plane phase shift data specifying a chroma phase shift between the BL picture and the EL picture;
selecting one or more High Efficiency Video Coding (HEVC) poly-phase filters based on the chroma plane phase shift data and the luma plane phase shift data; and
upsampling the BL picture by applying the one or more HEVC polyphase filters to the BL picture, the application of the one or more HEVC polyphase filters comprising:
aligning a luma sampling grid of the upsampled BL picture with a luma sampling grid of the EL picture; and
aligning a chroma sampling grid of the upsampled BL picture with a chroma sampling grid of the EL picture.
13. The method of claim 12 , wherein the chroma plane phase shift data and the luma plane phase shift data indicate non-zero relative phase shifts in chroma and luma respectively between the BL picture and the EL picture.