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

5.20.3Encoder optimization

JCTVC-J0242 Encoding with fixed Lagrangian multipliers [J. Xu (Microsoft)]

This contribution presents a fixed Lagrange multiplier encoding method that is applied instead of using fixed QP encoding (as used in HM). When using the proposed fixed Lagrange multiplier encoding algorithm, −1.7%, −1.8%, −1.4%, and −1.4% Y BD-Rate changes are reported for RA-Main, RA-HE10, LD-Main, and LD-HE10, respectively. The bit rate savings for U and V are reportedly somewhat larger. The encoding/decoding times of the proposed fixed Lagrange multiplier encoding algorithm are approximately unchanged. This contribution does not include any normative changes.

This contribution is a follow-up of JCTVC-I0426 for which several questions were raised

The approach is to assign lower QP / higher rate to temporal layer 0, and less quality to other layers.

Typically at one given QP point, the bit rate is higher.

It is reported that the visual quality is not affected.

A version with rate control is also presented, but this is still work in progress.

A version with LCU-based multi-pass is also investigated with additional gain.

Decision (SW): Adopt as encoder option.
JCTVC-J0134 Cross-check of Encoding with Fixed Lagrangian Multipliers (JCTVC-J0242) [Y. Chiu, W. Zhang (??)], J. Zhang (Intel) [late]