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This paper reports on verification testing of the coding performance of the screen content coding (SCC) extensions of the High Efficiency Video Coding (HEVC) standard (Rec. ITU-T H.265 | ISO/IEC 23008-2 MPEG-H Part 2). The coding performance of HEVC screen content model (SCM) reference software is compared with that of the HEVC test model (HM) without the SCC extensions, as well as with the Advanced Video Coding (AVC) joint model (JM) reference software, for both lossy and mathematically lossless compression using All-Intra (AI), Random Access (RA), and Lowdelay B (LB) encoding structures and using similar encoding techniques. Video test sequences in 1920×1080 RGB 4:4:4, YCbCr 4:4:4, and YCbCr 4:2:0 colour sampling formats with 8 bits per sample are tested in two categories: “text and graphics with motion” (TGM) and “mixed” content. For lossless coding, the encodings are evaluated in terms of relative bit-rate savings. For lossy compression, subjective testing was conducted at 4 quality levels for each coding case, and the test results are presented through mean opinion score (MOS) curves. The relative coding performance is also evaluated in terms of Bjontegaard-delta (BD) bit-rate savings for equal PSNR quality. The perceptual tests and objective metric measurements show a very substantial benefit in coding efficiency for the SCC extensions, and provided consistent results with a high degree of confidence. For TGM video, the estimated bit-rate savings ranged from 60–90% relative to the JM and 40–80% relative to the HM, depending on the AI/RA/LB configuration category and colour sampling format.

Perspective motion is commonly represented in video content that is captured and compressed for various applications including cloud gaming, vehicle and aerial monitoring, etc. Existing approaches based on an eight-parameter homography motion model cannot deal with this efficiently, either due to low prediction accuracy or excessive bit rate overhead. In this paper, we consider the camera motion model and scene structure in such video content and propose a joint global and local homography motion coding approach for video with perspective motion. The camera motion is estimated by a computer vision approach, and camera intrinsic and extrinsic parameters are globally coded at the frame level. The scene is modeled as piece-wise planes, and three plane parameters are coded at the block level. Fast gradient-based approaches are employed to search for the plane parameters for each block region. In this way, improved prediction accuracy and low bit costs are achieved. Experimental results based on the HEVC test model show that up to 9.1% bit rate savings can be achieved (with equal PSNR quality) on test video content with perspective motion. Test sequences for the example applications showed a bit rate savings ranging from 3.7 to 9.1%.

This paper presents a comparison-based test of the objective compression performance of the High Efficiency Video Coding (HEVC) standard, its format range extensions (RExt), and its draft screen content coding extensions (SCC). The current dominant standard, H.264/MPEG-4 AVC, is used as an anchor reference in the comparison. The conditions used for the comparison tests were designed to reflect relevant application scenarios and to enable a fair comparison to the maximum extent feasible – i.e., using comparable quantization settings, reference frame buffering, intra refresh periods, rate-distortion optimization decision processing, etc. It is noted that such PSNR-based objective comparisons generally provide more conservative estimates of HEVC benefit than are found in subjective studies. The experimental results show that, when compared with H.264/MPEG-4 AVC, HEVC version 1 provides a bit rate savings for equal PSNR of about 23% for all-intra coding, 34% for random access coding, and 38% for low-delay coding. This is consistent with prior studies and the general characterization that HEVC can provide about a bit rate savings of about 50% for equal subjective quality for most applications. The HEVC format range extensions provide a similar bit rate savings of about 13–25% for all-intra coding, 28–33% for random access coding, and 32–38% for low-delay coding at different bit rate ranges. For lossy coding of screen content, the HEVC screen content coding extensions achieve a bit rate savings of about 66%, 63%, and 61% for all-intra coding, random access coding, and low-delay coding, respectively. For lossless coding, the corresponding bit rate savings are about 40%, 33%, and 32%, respectively.

Screen content video coding extension of HEVC (SCC) is being developed by Joint Collaborative Team on Video Coding (JCT-VC) of ISO/IEC MPEG and ITU-T VCEG. Screen content usually features a mix of camera captured content and a significant proportion of rendered graphics, text, or animation. These two types of content exhibit distinct characteristics requiring different compression scheme to achieve better coding efficiency. This paper presents an efficient block matching schemes for coding screen content to better capture the spatial and temporal characteristics. The proposed schemes are mainly categorized as a) hash based global region block matching for intra block copy b) selective search based local region block matching for inter frame prediction c) hash based global region block matching for inter frame prediction. In the first part, a hash-based full frame block matching algorithm is designed for intra block copy to handle the repeating patterns and large motions when the reference picture constituted already decoded samples of the current picture. In the second part, a selective local area block matching algorithm is designed for inter motion estimation to handle sharp edges, high spatial frequencies and non-monotonic error surface. In the third part, a hash based full frame block matching algorithm is designed for inter motion estimation to handle repeating patterns and large motions across the temporal reference picture. The proposed schemes are compared against HM-13.0+RExt-6.0, which is the state-of-art screen content coding. The first part provides a luma BD-rate gains of -26.6%, -15.6%, -11.4% for AI, RA and LD TGM configurations. The second part provides a luma BD-rate gains of -10.1%, -12.3% for RA and LD TGM configurations. The third part provides a luma BD-rate gains of -12.2%, -11.5% for RA and LD TGM configurations.

This paper presents the results of an informal subjective quality comparison between the current state of the emerging High Efficiency Video Coding (HEVC) draft standard and the well-established H.264 / MPEG-4 AVC High Profile (HP) for low-delay applications. The tests consisted of two basic encoding comparisons. First, we compare the Main profile low-delay configuration of the HEVC reference software (HM) against a similarly configured H.264 / MPEG-4 AVC HP reference encoder (JM). Additionally, to complement these results, the widely-recognized production-quality H.264 / MPEG-4 AVC encoder known as x264 is compared with a production-quality HEVC implementation from eBrisk Video. The encoding configurations are designed to reflect relevant application scenarios and to enable a fair comparison to the maximum extent feasible. When viewing HM and JM encoded video side-by-side in which the JM was configured to use approximately twice the bit rate of the HM encoded video, viewers indicated that they preferred the HM encoded video in approximately 74% of trials. Similarly, when comparing the eBrisk HEVC and x264 H.264 / MPEG-4 AVC production encoders in which x264 was configured to use approximately twice the bit rate of the eBrisk encoded video, viewers indicated they preferred the eBrisk HEVC encoded video in approximately 62% of trials. The selection of which encoding was displayed on which side for the side-by-side viewing was established in a randomized manner, and the subjective viewing experiments were administered in a double-blind fashion. The results reported in this paper generally confirm that the HEVC design (as represented by HM version 7.1 and separately by a production-quality HEVC implementation) exhibits a substantial improvement in compression capability beyond that of H.264 / MPEG-4 AVC (as represented by a similarly-configured JM version 18.3 and x264 version core 122 r2184, respectively) for low-delay video applications, with HEVC exhibiting roughly twice or more of the overall compression capability of H.264 / MPEG-4 AVC.

Line-based coding has shown its potential in improving the coding efficiency of intra-frame/image coding due to its flexibility in prediction. In our previous work we proposed an efficient line-based image coding method (LIC) by adaptive line-by-line prediction (ALP) and adaptive residue coding. In this paper we further improve this line-based coding scheme by exploiting long-distance correlations in prediction. Line-by-line template matching (LTM) is introduced to perform the long-distance prediction. Experiments in the KTA software show that the LTM scheme can effectively improve the performance of LIC at low bitrates and also brings some improvement at high bitrates. Up to 1db gain is achieved compared to previous LIC and 1.5db compared to KTA on images with regular patterns or strong edges. Up to 20% rate reduction over KTA is also achieved on some standard video sequences with different resolutions.

This paper presents a new rate allocation algorithm for MCTF-based video coding with the aim to control quality fluctuation. Distortion analysis is conducted for MCTF using a simplified signal model. Based on the analysis, the aim to control quality fluctuation is posed as a quadratic programming problem and its solution forms the basis for our proposed algorithm. After discussions on some extensions of the proposed rate allocation method, we verify it on MPEG SVC reference software and the experimental results demonstrate that the proposed rate allocation scheme can reduce quality fluctuation significantly.

This paper presents a new Base Layer coding scheme which introduces the rate-distortion optimization mode decision into hierarchical-fashion B-picture coding with open-loop structure. It can not only achieve high coding performance for Base Layer bit-rate point and meanwhile, but the scheme also keep the strong correlation between Base Layer and Enhancement Layer implemented by 3D subband scalable video codec, because they share the similar lifting based Motion-Compensated Temporal Filtering (MCTF) decomposition structure. In addition, how to exploit the correlation between Base Layer and Enhancement Layer is also investigated. Experimental results show this method improves the coding performance and visual quality at both low and high bit-rate points.

This paper makes a comparative study on the various spatial scalable coding frameworks. The frameworks with multiple image-domain motion aligned temporal filtering at various spatial resolutions, named as multi-T+2D, are mainly investigated. First we investigate a multi-T+2D scheme based on redundant frame representation. The cross spatial layer redundancy and prediction methods are discussed. The redundancy brings significant performance loss for schemes providing wide range SNR spatial scalability. To remove the redundancy produced in the multi-resolution temporal filtering while retaining the advantage of spatial-domain motion compensation, a novel non-redundant multi-T+2D scheme is proposed. Performance comparison is given among the discussed frameworks and it shows that the proposed non-redundant multi-T+2D framework has a good performance for fully scalable video coding. We also verify that the redundant multi-T+2D framework with cross spatial layer reconstruction feedback is practical in providing narrow range SNR scalability for each spatial layer.

The shift-variant property of discrete wavelet transform leads to the intrinsic coupling across various spatial subbands during motion aligned temporal filtering. It brings a big challenge how to achieve a better trade-off between subband independency and motion alignment efficiency in the context of providing spatial scalability in 3D wavelet video coding. This paper first investigates the issue of subband coupling in-depth. From the investigations on analysis and synthesis filters, we verify the existence and causes of subband coupling phenomenon and illustrate the subband leakage due to motion shift. Furthermore, we propose a method to measure the strength of this kind of coupling. Based on these investigations, we focus on schemes which preserving most subband coupling relationship and recommend that spatial highpass subbands should not be dropped completely. The issue of rate allocation for spatial highpass subbands is considered in this paper. An error propagation model is proposed to describe the effect of subband coupling in video reconstruction. The synthesis gain of each subband is estimated according to this model and it is finally adopted to guide the rate allocation algorithm. Experimental results have fully demonstrated the promising of the proposed techniques in improving both objective and subjective qualities of low resolution video, especially at middle and high bit rates, for 3D video coding schemes with spatial scalability.

In most of the existing in-band wavelet video coding schemes, over-complete form of reference bands is used to solve the wavelet shift-variance problem on motion compensated temporal filtering (MCTF) in wavelet domain. It can more or less improve the coding efficiency of the in-band MCTF scheme. However, there is a dilemma always existing when the input video is decomposed into a low-pass band and several high-pass bands. If the temporal filtering in the lowpass band does not use any information from the high-pass bands, the coding efficiency will decrease significantly for the higher resolution reconstructed video. If the temporal filtering in the low-pass band does use data from the high-pass bands, it will bring serious drifting error when the high-pass bands are not available at the decoder. In this paper, for the latter case, we analyze when drifting errors occur and how they will propagate along the lifting structure for decoding at the lower resolution. Based on the analysis, we introduce two new inter coding modes at macroblock level for spatial low-pass band MCTF to make a better trade-off between the lower resolution drifting error and the high resolution coding efficiency. Furthermore, we present the criterion to adaptively select the proper coding mode for each macroblock of spatial low-pass band. The experiment results show that our proposed scheme can dramatically reduce the drifting error about 0.4~2.6dB for different bit rates at low resolution, while for the high resolution, the performance loss is marginal.

3-D wavelet-based scalable video coding provides a viable alternative to standard MC-DCT coding. However, many current 3-D wavelet coders experience severe boundary effects across group of picture (GOP) boundaries. This paper proposes a memory efficient transform technique via lifting that effectively computes wavelet transforms of a video sequence continuously on the fly, thus eliminating the boundary effects due to limited length of individual GOPs. Coding results show that the proposed scheme completely eliminates the boundary effects and gives superb video playback quality.