The Joint Collaborative Team on Video Coding (jct-vc) of itu-t wp3/16 and iso/iec jtc 1/ sc 29/ wg 11 held its tenth meeting during 11-20 July 2012 at the City Conference Centre (ccc), a k. a

5.10.2NSQT

JCTVC-J0138 NSQT Simplification [X. Zheng, Y. Yuan, H. Yu, Y. He (??)]

This document provides a simplification of NSQT. Both software implementation and text modification are provided in this contribution. The proposed solution simplifies the non-square transform quadtree split process, and merges the luma non-square transform quadtree and chroma non-square transform quadtree. As a result, NSQT has become a lot easier to describe and implement. Experimental results show that the proposed solution does not have negative impact on coding performance. Both software encoding and decoding time are slightly reduced compared to HM7.0 anchor.

It is suggested to inhibit splitting of non-square transform blocks into square transform blocks at the last splitting stage.
Compared to the old method, class F shows small loss (0.1+%), otherwise approx. equal.
Gain of the new NSQT version versus RA main is about 0.4%, versus LDB main about 1% (not much different for HE 10).
Comments:

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  Text still has some problems (and would need careful checking)
  
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  From view point hardware implementation, it is a little bit better but does not solve the biggest problem (irregularity by branching from the square-shaped quadtree, computation of memory addresses etc.).
  

Still too complex to be considered in the main profile.

In general, this new version of NSQT is seen as a step in the right direction. Some discussion about whether the current NSQT should be removed entirely or be replaced by the new scheme. After this it was suggested to leave everything as it is in the DIS (considering that more urgency is on other issues)

Further study.