本发明提供一种HEVC编码最佳参考图框的选择方法、设备和编码器，该方法包括：至少针对层深度最小的预测单元进行如下处理：获取与目前预测单元空间相邻的预测单元的最佳参考图框；根据同层深度空间相邻预测单元的最佳参考图框的相关性，确定目前预测单元的最佳参考图框。这样，至少针对最小层深度的预测单元不再进行遍历性的率失真代价计算，而是采用相关性直接确定对应的最佳参考图框，可以减少计算量，提高编码效率。

A method, an apparatus and a coder for selecting an optimal reference frame in HEVC coding are disclosed. The method includes obtaining optimal reference frames of prediction units spatially adjacent to a current prediction unit, and determining an optimal reference frame of the current prediction unit based on a correlation between optimal reference frames of the spatially adjacent prediction units in a same layer depth for prediction unit(s) of a minimum layer depth. In this way, an ergodic rate distortion cost calculation is not needed to be performed at least for the prediction unit(s) of the minimum layer depth, and the corresponding optimal reference frame is directly determined using the correlation, thus reducing the amount of calculations and enhancing the coding efficiency.