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Title:  Complexity management of H.264/AVC video compression. 
Authors:  Kannangara, Chaminda Sampath 
Supervisors:  Richardson, I. E. G. Zhao, Yafan Miller, Tony 
Issue Date:  Oct2006 
Publisher:  The Robert Gordon University 
Citation:  KANNANGARA, C.S., RICHARDSON, I.E.G., BYSTROM, M., ZHAO, Y., SOLERA, J., MACLENNAN, A. and COONEY, R., 2006. Low complexity skip prediction for H.264 through Lagrangian cost estimation. IEEE Transactions on Circuits and Systems for Video Technology, 16(2), pp. 202208 RICHARDSON, I.E.G. and KANNANGARA, C.S., 2004. Fast subjective video quality measurement with user feedback. IEE Electronic Letters, 40(13), pp.799800. KANNANGARA, C.S., RICHARDSON, I.E.G. and MILLER, A.J., 2008. Computational complexity managemen of realtime H.264/AVC encoder. IEEE Transactions on Circuits and Systems for Video Technology, 18(9), pp. 11911200. KANNANGARA, C.S., RICHARDSON, I.E.G. and MILLER, A.J., 2006. Computational management of an H.264 encoder. In: PCS 2006, Beijing, China, 2426 April 2006. KANNANGARA, C.S. and RICHARDSON, I.E.G., 2005. Computational control of an H.264 encoder through Lagrangian cost function estimation. In: VLBV 2005, Sardinia, Italy, 1516 September 2005 KANNANGARA, C.S., RICHARDSON, I.E.G., BYSTROM, M., SOLERA, J., ZHAO, Y., MACLENNAN, A. and COONEY, R., 2005. Complexity reduction of H.264 using Lagrange optimization methods. In: IEE VIE 2005, Glasgow, 46 April 2005. KANNANGARA, C.S., RICHARDSON, I.E.G. and ZHAO, Y., 2004. H.264 complexity management using macroblock skipmode prediction. In: PGNet, Liverpool, 2829 June 2004 RICHARDSON, I.E.G. and KANNANGARA, C.S., 2005. Encoder control system. UK Patent application 0524663.2, December 2005. RICHARDSON, I.E.G. and KANNANGARA, C.S., 2005. Subjective video quality measurement with user feedback. European patent application EP20050252018, 2005. 
Abstract:  The H. 264/AVC video coding standard offers significantly improved compression
efficiency and flexibility compared to previous standards. However, the high
computational complexity of H. 264/AVC is a problem for codecs running on lowpower
hand held devices and general purpose computers. This thesis presents new techniques to
reduce, control and manage the computational complexity of an H. 264/AVC codec.
A new complexity reduction algorithm for H. 264/AVC is developed. This algorithm
predicts "skipped" macroblocks prior to motion estimation by estimating a Lagrange ratedistortion
cost function. Complexity savings are achieved by not processing the
macroblocks that are predicted as "skipped". The Lagrange multiplier is adaptively
modelled as a function of the quantisation parameter and video sequence statistics.
Simulation results show that this algorithm achieves significant complexity savings with
a negligible loss in ratedistortion performance.
The complexity reduction algorithm is further developed to achieve complexityscalable
control of the encoding process. The Lagrangian cost estimation is extended to
incorporate computational complexity. A target level of complexity is maintained by
using a feedback algorithm to update the Lagrange multiplier associated with complexity.
Results indicate that scalable complexity control of the encoding process can be achieved
whilst maintaining near optimal complexityratedistortion performance.
A complexity management framework is proposed for maximising the perceptual quality
of coded video in a realtime processingpower constrained environment. A realtime
framelevel control algorithm and a perframe complexity control algorithm are combined
in order to manage the encoding process such that a high frame rate is maintained without
significantly losing frame quality. Subjective evaluations show that the managed
complexity approach results in higher perceptual quality compared to a reference encoder
that drops frames in computationally constrained situations.
These novel algorithms are likely to be useful in implementing realtime H. 264/AVC
standard encoders in computationally constrained environments such as lowpower
mobile devices and general purpose computers. 
Appears in Collections:  Theses (Engineering)

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