As x.265 encoder produces reconstructed yuv video file after decoding and I know, in open source x.265 encoder you input raw yuv video and it generates HEVC file for you along with reconstructed YUV file.
My question is, can I input HEVC file directly to produce reconstructed yuv file? If yes, how?
No. You can not input HEVC file directly to HEVC encoder as encoders does not have any entropy decoding modules(It includes other decoding modules such as motion compensation, IDCT, Inverse Qunat etc). But entire point of the encoder is to encode raw video to HEVC bit stream. Instead you can provide HEVC stream to a HEVC decoder and get the exact same reconstructed YUV. Bit-matching encoder reconstructed YUV with the decoded YUV from the standard decoder ensures proper working of the encoder