Witness the development of H.265

Current Status of H.265 (as at July 2008)

2008-07-01 KTA View Comments Views(19,407)

H.265 is a long-term video coding standard, launched by VCEG. As indicated in ITU-T SG16′s homepage, VCEG plans to complete the requirement definition and begin the detailed algorithm design for H.265 in the study period 2005-2008, and if the progress in contribution technology is sufficient, H.265 is expected to be finalized in 2009-2010.

Currently, H.265 hasn’t been formalized and VCEG keeps seeking proposals and information regarding the possibility of a major gain in performance to justify the step from H.264 to H.265. Though the necessary scope of H.265 is yet to be determined, it is agreed that among the goals will be [AA01]:

  • simplicity and “back to basics” approach
  • high coding efficiency, e.g., two times compared with H.264
  • computational efficiency, considering both encoder and decoder
  • loss/error robustness
  • network friendliness
  • other considerations as necessary 

Backward/forward compatibility is not assumed to be required for H.265, as H.265 is a brand new standard instead of an extension of H.264.

During the recent 3-4 years, the contributions to VCEG mainly focus on improving coding efficiency. To better evaluate these contributions and retain progress, KTA (key technical area) is developed as the software platform, which uses JM11 as the baseline and continuously integrates promising coding tools. The tools adopted in KTA are listed as below.

  • 2-D non-separable adaptive interpolation filter (AIF) [AD08]
  • separable AIF [COM16-C219-E]
  • directional AIF [AG21]
  • motion compensation with 1/8-pel motion vectors [AD09]
  • adaptive prediction error coding (APEC) in spatial and frequency domain [AD07]
  • adaptive quantization matrix selection (AQMS) [AD06]
  • competition-based scheme for motion vector selection and coding [AC06]
  • mode-dependent transform customization for intra coding [AG11]

All these techniques improve the coding performance by multi-pass encoding. The latest version of KTA is 1.9 and the latest test conditions are specified in [AH10]. An AHG on coding efficiency, coordinated by T. Wedi and T.K. Tan, was formed to conduct the work between two meetings, such as implementation, testing, and discussion. However, all the current work in VCEG is not intended to imply any need for near-term planning to start drafting H.265, but rather for determining whether and when work on H.265 should be formalized.

In summary, there is no evidence of readiness of technical advances sufficient to justify embarking on a concentrated effort toward H.265, and all the contributions are actually in the direction of an “H.264+”. VCEG is waiting for more promising techniques and algorithm maturity. At this point, H.264 still represents the state-of-the-art technology.

Permanent Link: Current Status of H.265 (as at July 2008)

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