Template matching for JVET intra prediction
A method of decoding JVET video, comprising defining a coding unit (CU) template within a decoded area of a video frame, the CU template being positioned above and/or to the left of a current decoding position for which data was intra predicted, defining a search window within the decoded area, the search window being adjacent to the CU template, generating a plurality of candidate prediction templates based on pixel values in the search window, each of the plurality of candidate prediction templates being generated using different intra prediction modes, calculating a matching cost between the CU template and each of the plurality of candidate prediction templates, selecting an intra prediction mode that generated the candidate prediction template that had the lowest matching cost relative to the CU template, and generating a prediction CU for the current decoding position based on the intra prediction mode.
1. A method of decoding JVET video, comprising:
defining a plurality of coding unit (CU) templates within a decoded area of a video frame, each of the CU templates being positioned above and/or to the left of a current decoding position for which data was intra predicted and being spaced apart from the current decoding position by a different number of reference lines;
defining a search window within said decoded area for each of said plurality of CU templates, each search window being within an associated reference line;
generating a plurality of candidate prediction templates for each of said plurality of CU templates based on pixel values in the search window associated with the CU template, each of said plurality of candidate prediction templates being generated using different intra prediction modes;
calculating a matching cost between each of said plurality of CU templates and each of said plurality of candidate prediction templates;
selecting an intra prediction mode that generated the candidate prediction template that had the lowest matching cost relative to one of said plurality of CU templates; and
generating a prediction CU for said current decoding position based on said intra prediction mode.
2. The method of claim 1 , wherein each of said plurality of CU templates is shaped with a row of pixels immediately above an associated reference line and a column of pixels immediately to the left of the associated reference line.
3. The method of claim 1 , wherein calculating said matching costs comprises calculating the sum of absolute differences between the CU templates and their associated plurality of candidate prediction templates.
4. The method of claim 1 , wherein each search window extend beyond the ends of the associated CU template.
5. The method of claim 1 , wherein the steps of defining said CU templates and said search windows, calculating said matching costs, selecting said intra prediction mode, and generating said prediction CU based on said intra prediction mode are performed when information identifying an intra prediction mode for the current decoding position is absent from a bitstream.
6. The method of claim 1 , further comprising adding said prediction CU to a reconstructed residual CU to generate a reconstructed CU for output video.