High Efficiency Video Coding (HEVC) is known to be the state of the art in video compression. However, aiming at real-time applications, its very high number of possible coding options makes it necessary to approximate the selection of coding modes by fast algorithms. For this purpose Coding Unit (CU) split decisions are made by Support Vector Machine (SVM) classifiers in this paper. We use one SVM model per depth and the traditional Rate-Distortion Optimization (RDO) is used as fallback method in the case of uncertain SVM decisions. Regarding the sequence classes ClassB to ClassE, the proposed algorithm achieves encoding time reductions of more than 60%, accompanied by only 1.8% additional bitrate (low delay main configuration). Considering all sequence classes from ClassA to ClassF, the additional bitrate increases to 4% for the lowdelay main and about 3% for the random access main configuration, with a similar encoding time reduction of more than 60%.