H.264/AVC is newest video coding standard of the ITU-T Video Coding Experts Group and the ISO/IEC Moving Picture Experts Group. The main goals of the H.264/AVC standardization effort have been enhanced compression performance and provision of a "network-friendly" video representation addressing "conversational" (video telephony) and "nonconversational" (storage, broadcast, or streaming) applications. H.264/AVC has achieved a significant improvement in rate-distortion efficiency relative to existing standards. This article provides an overview of the technical features of H.264/AVC, describes profiles and applications for the standard, and outlines the history of the standardization process.

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Overview of the H.264/AVC video coding standard

High Efficiency Video Coding (HEVC) is currently being prepared as the newest video coding standard of the ITU-T Video Coding Experts Group and the ISO/IEC Moving Picture Experts Group. The main goal of the HEVC standardization effort is to enable significantly improved compression performance relative to existing standards-in the range of 50% bit-rate reduction for equal perceptual video quality. This paper provides an overview of the technical features and characteristics of the HEVC standard.

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Overview of the High Efficiency Video Coding (HEVC) Standard

With the introduction of the H.264/AVC video coding standard, significant improvements have recently been demonstrated in video compression capability. The Joint Video Team of the ITU-T VCEG and the ISO/IEC MPEG has now also standardized a Scalable Video Coding (SVC) extension of the H.264/AVC standard. SVC enables the transmission and decoding of partial bit streams to provide video services with lower temporal or spatial resolutions or reduced fidelity while retaining a reconstruction quality that is high relative to the rate of the partial bit streams. Hence, SVC provides functionalities such as graceful degradation in lossy transmission environments as well as bit rate, format, and power adaptation. These functionalities provide enhancements to transmission and storage applications. SVC has achieved significant improvements in coding efficiency with an increased degree of supported scalability relative to the scalable profiles of prior video coding standards. This paper provides an overview of the basic concepts for extending H.264/AVC towards SVC. Moreover, the basic tools for providing temporal, spatial, and quality scalability are described in detail and experimentally analyzed regarding their efficiency and complexity.

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Overview of the Scalable Video Coding Extension of the H.264/AVC Standard

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The Scalable Video Coding Extension of the H.264/AVC Standard

Experimental data are presented that clearly demonstrate the scope of application of peak signal-to-noise ratio (PSNR) as a video quality metric. It is shown that as long as the video content and the codec type are not changed, PSNR is a valid quality measure. However, when the content is changed, correlation between subjective quality and PSNR is highly reduced. Hence PSNR cannot be a reliable method for assessing the video quality across different video contents.

Scope of validity of PSNR in image/video quality assessment

A unified approach to the coder control of video coding standards such as MPEG-2, H.263, MPEG-4, and the draft video coding standard H.264/AVC (advanced video coding) is presented. The performance of the various standards is compared by means of PSNR and subjective testing results. The results indicate that H.264/AVC compliant encoders typically achieve essentially the same reproduction quality as encoders that are compliant with the previous standards while typically requiring 60% or less of the bit rate.

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Rate-constrained coder control and comparison of video coding standards

We study and analyze the computational complexity of a software-based H.264/AVC (advanced video codec) baseline profile decoder. Our analysis is based on determining the number of basic computational operations required by a decoder to perform the key decoding subfunctions. The frequency of use of each of the required decoding subfunctions is empirically derived using bitstreams generated from two different encoders for a variety of content, resolutions and bit rates. Using the measured frequencies, estimates of the decoder time complexity for various hardware platforms can be determined. A detailed example is provided to assist in deriving time complexity estimates. We compare the resulting estimates to numbers measured for an optimized decoder on the Pentium 3 hardware platform. We then use those numbers to evaluate the dependence of the time complexity of each of the major decoder subfunctions on encoder characteristics, content, resolution and bit rate. Finally, we compare an H.264/AVC-compliant baseline decoder to a decoder that is compliant with the H.263 standard, which is currently dominant in interactive video applications. Both "C" only decoder implementations were compared on a Pentium 3 hardware platform. Our results indicate that an H.264/AVC baseline decoder is approximately 2.5 times more time complex than an H.263 baseline decoder.

H.264/AVC baseline profile decoder complexity analysis

A unified approach to the coder control of video coding standards such as MPEG-2, H.263, MPEG-4, and the draft video coding standard JVT/H.26L/AVC is presented. Using this unified framework, the performance of the various standards is compared by means of PSNR and subjective testing results. The results indicate that JVT/H.26L/AVC compliant encoding can typically achieve essentially the same objective PSNR reproduction quality as encoders that are compliant with previous standards while requiring as little as 60% or less of the bit rate of the next best standard, particularly for higher-latency applications and particularly for more difficult source material. Subjective testing shows that the bit savings produced by this draft standard are even larger than the PSNR results indicate.

Performance comparison of video coding standards using Lagrangian coder control

A method of motion vector prediction for use in differential motion vector coding within a block motion-compensation-based video coder. The video coder employs a generalized multiple reference picture buffer which may contain multiple reference pictures in both the forward and backward temporal direction from the current picture. For the purpose of coding selections of reference pictures within the buffer, the pictures are organized into two, potentially overlapping, lists of reference pictures. The prediction of a motion vector that selects a reference picture using a given reference picture list is not dependent upon any motion vectors that select their reference pictures using the other reference picture list. The values of spatially neighbouring motion vectors that use the same list of reference pictures as the notion vector being predicted are used for prediction, regardless of the relative temporal direction of the current and neighbouring motion vectors.

Low-complexity motion vector prediction for video codec with two lists of reference pictures

We give a brief tour of the emerging ITU-T H.26L videocoding standard. Like its predecessors, H.26L is being designed partly for videoconferencing applications; however, many other applications are considered to be within the scope of the design effort and tests indicate that H.26L is fully suitable for a very broad range of applications. Starting from a clean slate, H.26L is a powerful new design that is forward-looking in its performance and scope of applications. We compare H.26L to the highest capabilities of the most complex and newest versions of prior standards such as H.263 and MPEG-4, and provide benchmarks for its performance. Our analysis indicates that the draft H.26L standard offers compelling advantages over all existing video coding standards. It has the potential to redraw the landscape of consumer and enterprise video applications.

Anthony Joch

Papers

Rate-constrained coder control and comparison of video coding standards

H.264/AVC baseline profile decoder complexity analysis

Performance comparison of video coding standards using Lagrangian coder control

Low-complexity motion vector prediction for video codec with two lists of reference pictures

Overview and performance evaluation of the ITU-T draft H.26L video coding standard