We explore the use of separate partitioning structures for luma and chroma channels in the design of next generation video codecs. The proposed methods are evaluated relative to the Quad-Tree, Ternary-Tree and Binary-Tree (QTTTBT) partitioning framework currently implemented in the BenchMark Set (BMS-1.0) software being used in the development of the Versatile Video Coding (VVC) project. VVC is the next generation video compression standard under development by the Joint Video Experts Team (JVET), which is joint collaboration between MPEG and the ITU-T. In the paper, the performance of using shared or separate partitioning tree structures for luma and chroma channels is measured for sequences including those used for the Joint Call for Proposals on video compression with capability beyond HEVC issued by MPEG/ITU-T and trends are analyzed. The use of separate partitioning tree structures is restricted to intra coded regions. Objective performance is reported using the Bjøntegaard Delta (BD) bitrate, and visual observations are also provided. To demonstrate the efficacy of using different partition structures, bitrate savings are computed using simulations and show an average improvement of 0.46%(Y)/7.83%(Cb)/7.96%(Cr) relative to state-ofthe-art. It is asserted that the coding efficiency improvement is especially pronounced in sequences with occlusions/emergence of objects or dynamic changing content (e.g. fire, water, smoke). In the tests conducted, the Campfire sequence which has a large portion of the picture exhibiting a burning fire, shows the most BD bitrate saving of 1.79%(Y)/5.45%(Cb)/1.82%(Cr).
Displays capable of showing a greater range of luminance values can render content containing high dynamic range information in a way such that the viewers have a more immersive experience. This paper introduces the design aspects of a high dynamic range (HDR) system, and examines the performance of the HDR processing chain in terms of compression efficiency. Specifically it examines the relation between recently introduced Society of Motion Picture and Television Engineers (SMPTE) ST 2084 transfer function and the High Efficiency Video Coding (HEVC) standard. SMPTE ST 2084 is designed to cover the full range of an HDR signal from 0 to 10,000 nits, however in many situations the valid signal range of actual video might be smaller than SMPTE ST 2084 supported range. The above restricted signal range results in restricted range of code values for input video data and adversely impacts compression efficiency. In this paper, we propose a code value remapping method that extends the restricted range code values into the full range code values so that the existing standards such as HEVC may better compress the video content. The paper also identifies related non-normative encoder-only changes that are required for remapping method for a fair comparison with anchor. Results are presented comparing the efficiency of the current approach versus the proposed remapping method for HM-16.2.
The high efficiency video coding (HEVC) standard being developed by ITU-T VCEG and ISO/IEC MPEG
achieves a compression goal of reducing the bitrate by half for the same visual quality when compared with
earlier video compression standards such as H.264/AVC. It achieves this goal with the use of several new tools
such as quad-tree based partitioning of data, larger block sizes, improved intra prediction, the use of sophisticated
prediction of motion information, inclusion of an in-loop sample adaptive offset process etc. This paper describes
an approach where the HEVC framework is extended to achieve spatial scalability using a multi-loop approach.
The enhancement layer inter-predictive coding efficiency is improved by including within the decoded picture
buffer multiple up-sampled versions of the decoded base layer picture. This approach has the advantage of
achieving significant coding gains with a simple extension of the base layer tools such as inter-prediction, motion
information signaling etc. Coding efficiency of the enhancement layer is further improved using adaptive loop
filter and internal bit-depth increment. The performance of the proposed scalable video coding approach is
compared to simulcast transmission of video data using high efficiency model version 6.1 (HM-6.1). The bitrate
savings are measured using Bjontegaard Delta (BD) rate for a spatial scalability factor of 2 and 1.5 respectively
when compared with simulcast anchors. It is observed that the proposed approach provides an average luma BD
rate gains of 33.7% and 50.5% respectively.
In this paper, we consider the problem of video decoding for very high resolution image content. Our focus is on future
applications, and our emphasis is on the specific problem of entropy decoding. Here, we introduce the concept of an
"entropy slice" that partitions a bit-stream into units that can be individually entropy decoded without effecting the
reconstruction process. This allows us to parallelize the entropy decoding process of an H.264/AVC decoder with little
impact on coding performance. We compare the entropy slice technique to the standard H.264/AVC slice method to
parallelization and observe that the proposed method improves coding efficiency. Specifically, compared to the standard
slice method, results show an average bit-rate savings of 5.5%. As an additional contribution of this "entropy slice"
concept, we also propose the use of a transcoder to convert an H.264/AVC compliant bit-stream to the parallelized
entropy slice format. The transcoding operation has the desirable property of allowing highly parallel decoding of
current, standards compliant material without affecting the reconstructed image data.