1. A method for luma-based chroma intra-prediction in a video encoder or a video decoder, the method comprising: receiving immediate top neighboring reconstructed luma samples of a first reconstructed luma block of a largest coding unit (LCU), at least some of the immediate top neighboring reconstructed luma samples being neighboring reconstructed luma samples from one or more inter-predicted prediction units (PUs); replacing the neighboring reconstructed luma samples from the inter-predicted PUs with other samples without replacing second top neighboring reconstructed luma samples to generate padded immediate top neighboring reconstructed luma samples; down sampling the padded immediate top neighboring reconstructed luma samples; computing parameters Î± and Î² of a linear model using the down sampled padded immediate top neighboring reconstructed luma samples and left neighboring reconstructed luma samples of the first reconstructed luma block and reconstructed neighboring chroma samples of a chroma block corresponding to the first reconstructed luma block, and without using the second top neighboring reconstructed luma samples, wherein the linear model is Pred C [x,y]=Î±Â·Rec L â€²[x,y]+Î², wherein x and y are sample coordinates, Pred C is predicted chroma samples, and Rec L â€² is samples of the down sampled first reconstructed luma block, and wherein the immediate top neighboring reconstructed luma samples are the only top neighboring reconstructed luma samples used; and computing samples of a first predicted chroma block from corresponding samples of the first reconstructed luma block using the linear model and the parameters.