1. Book and Slides
The book " " is a good reference in addition to the spec. It covers
(1) High-level syntax of HEVC
(2) Block structures and parallelism
(3) Intra-picture prediction
(4) Inter-picture prediction
(5) Transform and quantization
(6) In-loop filtering
(7) Entropy coding
(8) Compression performance
(9) Decoder hardware architecture design
(10) Encoder hardware architecture design
Two good tutorial slides
(1) "Design and Implementa/on of Next Genera/on Video Coding Systems (H.265/HEVC Tutorial)" by Vivienne Sze, et al.
(2) "HEVC/H.265 Video Coding Standard (v. 2), Including Range, Scalable, and Multiview Extensions” by Dan Grois, et al.
ITU-I H.265 High efficiency video coding in ITU website.
The reference software for HEVC is called HM (HEVC Test Model). It is maintained in a Subversion repository. Please use a Subversion client to access the repository links directly or use the source browser for web browser access.
5. Analysis Tool
Two years ago I compared the available HEVC/H.265 bistream analysis tools. Currently it seems Intel® Video Pro Analyzer (Intel® VPA) 2016 is the best.