Debargha Mukherjee
Dr. Debargha Mukherjee received his M.S./Ph.D. degrees in ECE from University of California Santa Barbara in 1999. Since 2010 he has been with Google, where he is currently a Principal Engineer/Director leading next generation video codec research and development efforts. Prior to that he was with Hewlett Packard Laboratories, conducting research on video/image coding and processing. Debargha has made extensive research contributions in the area of image and video compression throughout his career, and was elected to IEEE Fellow for leadership in standard development for the video-streaming industry. He has (co-)authored more than 120 papers on various signal processing topics, and holds more than 200 US patents, with many more pending. He currently serves as a Senior Area Editor of the IEEE Trans. on Image Processing, and as a member of the IEEE Visual Signal Processing and CommunicationsTechnical Committee (VSPC-TC).
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AN OVERVIEW OF CORE CODING TOOLS IN THE AV1 VIDEO CODEC
Adrian Grange
Andrey Norkin
Ching-Han Chiang
Hui Su
Jean-Marc Valin
Luc Trudeau
Nathan Egge
Paul Wilkins
Peter de Rivaz
Sarah Parker
Steinar Midtskogen
Thomas Davies
Zoe Liu
The Picture Coding Symposium (PCS) (2018)
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AV1 is an emerging open-source and royalty-free video compression format, which is jointly developed and finalized in early 2018 by the Alliance for Open Media (AOMedia) industry consortium. The main goal of AV1 development is to achieve substantial compression gain over state-of-the-art codecs while maintaining practical decoding complexity and hardware feasibility. This paper provides a brief technical overview of key coding techniques in AV1 along with preliminary compression performance comparison against VP9 and HEVC.
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Novel modes and adaptive block scanning order for intra prediction in AV1
Ofer Hadar
Ariel Shleifer
Itai Mazar
Michael Yuzvinsky
Nitzan Tavor
Nati Itzhak
Raz Birman
SPIE Optical Engineering + Applications, 10396 (2017), 10396 - 10396 - 10
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The demand for streaming video content is on the rise and growing exponentially. Networks bandwidth is very costly and therefore there is a constant effort to improve video compression rates and enable the sending of reduced data volumes while retaining quality of experience (QoE). One basic feature that utilizes the spatial correlation of pixels for video compression is Intra-Prediction, which determines the codec’s compression efficiency. Intra prediction enables significant reduction of the Intra-Frame (I frame) size and, therefore, contributes to efficient exploitation of bandwidth. In this presentation, we propose new Intra-Prediction algorithms that improve the AV1 prediction model and provide better compression ratios. Two (2) types of methods are considered: )1( New scanning order method that maximizes spatial correlation in order to reduce prediction error; and )2( New Intra-Prediction modes implementation in AVI. Modern video coding standards, including AVI codec, utilize fixed scan orders in processing blocks during intra coding. The fixed scan orders typically result in residual blocks with high prediction error mainly in blocks with edges. This means that the fixed scan orders cannot fully exploit the content-adaptive spatial correlations between adjacent blocks, thus the bitrate after compression tends to be large. To reduce the bitrate induced by inaccurate intra prediction, the proposed approach adaptively chooses the scanning order of blocks according to criteria of firstly predicting blocks with maximum number of surrounding, already Inter-Predicted blocks. Using the modified scanning order method and the new modes has reduced the MSE by up to five (5) times when compared to conventional TM mode / Raster scan and up to two (2) times when compared to conventional CALIC mode / Raster scan, depending on the image characteristics (which determines the percentage of blocks predicted with Inter-Prediction, which in turn impacts the efficiency of the new scanning method). For the same cases, the PSNR was shown to improve by up to 7.4dB and up to 4 dB, respectively. The new modes have yielded 5% improvement in BD-Rate over traditionally used modes, when run on K-Frame, which is expected to yield ~1% of overall improvement.
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Novel inter and intra prediction tools under consideration for the emerging AV1 video codec
Sarah Parker
Hui Su
Angie Chiang
Zoe Liu
Chen Wang
Emil Keyder
SPIE Optical Engineering + Applications, 10396 (2017), 10396 - 10396 - 13
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Google started the WebM Project in 2010 to develop open source, royalty-free video codecs designed specifically for media on the Web. The second generation codec released by the WebM project, VP9, is currently served by YouTube, and enjoys billions of views per day. Realizing the need for even greater compression efficiency to cope with the growing demand for video on the web, the WebM team embarked on an ambitious project to develop a next edition codec AV1, in a consortium of major tech companies called the Alliance for Open Media, that achieves at least a generational improvement in coding efficiency over VP9. In this paper, we focus primarily on new tools in AV1 that improve the prediction of pixel blocks before transforms, quantization and entropy coding are invoked. Specifically, we describe tools and coding modes that improve intra, inter and combined inter-intra prediction. Results are presented on standard test sets.
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The latest open-source video codec VP9 - An overview and preliminary results
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Jingning Han
Jim Bankoski
Ronald S Bultje
Adrian Grange
John Koleszar
Paul Wilkins
Yaowu Xu
SMPTE Motion Imaging Journal, 124 (2015)
The latest open-source video codec VP9 - An overview and preliminary results
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Adrian Grange
John Koleszar
Paul Wilkins
Ronald S Bultje
Picture Coding Symposium (2013)
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The hybrid transform coding scheme that alternates amongst the asymmetric discrete sine transform (ADST) and the discrete cosine transform (DCT) depending on the boundary prediction conditions, is an efficient tool for video and image compression. It optimally exploits the statistical characteristics of prediction residual, thereby achieving significant coding performance gains over the conventional DCT-based approach. A practical concern lies in the intrinsic conflict between transform kernels of ADST and DCT, which prevents a butterfly structured implementation for parallel computing. Hence the hybrid transform coding scheme has to rely on matrix multiplication, which presents a speed-up barrier due to under-utilization of the hardware, especially for larger block sizes. In this work, we devise a novel ADST-like transform whose kernel is consistent with that of DCT, thereby enabling butterfly structured computation flow, while largely retaining the performance advantages of hybrid transform coding scheme in terms of compression efficiency. A prototype implementation of the proposed butterfly structured hybrid transform coding scheme is available in the VP9 codec repository.
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Video Description Length Guided Constant Quality Video Coding with Bitrate Constraint
Lei Yang
Dapeng Wu
Multimedia and Expo Workshops (ICMEW), 2012 IEEE International Conference on, IEEE, 2001 L Street, NW. Suite 700 Washington, DC 20036-4910 USA, pp. 366-371
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In this paper, we propose a new video encoding strategy - Video description length guided Constant Quality video coding with Bitrate Constraint (V-CQBC), for large scale video transcoding systems of video charing websites with varying unknown video contents. It provides smooth quality and saves bitrate and computation for transcoding millions of videos in both real time and batch mode. The new encoding strategy is based on the average bitrate-quality regression model and adapt to the encoded videos. Furthermore, three types of video description length (VDL), describing the video overall, spatial and temporal content complexity, are proposed to guide video coding. Experimental results show that the proposed coding strategy with saved computation could achieve better or similar RD performance than other coding strategies.
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