Video Coding and Online Streaming Technologies: Principles and Practice of AVC, HEVC, AV1, VVC, HLS, MSS, and MPEG-DASH
Television has promoted understanding and cooperation among people all over the world. It is the most engaging source of information and entertainment. Many teenagers spend more than three times of their spare time watching TV than on social media. TV viewing used to be confined within the living room. The global footprint of live and on-demand TV has been expanded by the internet, which has opened up new ways for discovering, sharing, and consuming video content anywhere, anytime, and on any device. These online services allow TV content and movies to be streamed instantly or downloaded on demand. Conversely, it takes nothing more than a smartphone and a YouTube channel to become a global broadcaster and producer of live events.
Online TV has become the mainstream media platform for the distribution of video entertainment. More consumers are watching online movies than using DVDs, Blu-ray discs, and other physical video formats. The migration from pay-TV to over-the-top (OTT) internet TV services has gained great momentum with both consumers and advertisers moving in the same direction. In the past decade, major U.S. cable providers have been losing hundreds of thousands of TV subscribers each quarter to online TV providers but gaining more broadband internet subscribers. The number of subscribers for Netflix is about twice the combined total of video, internet, and phone customers for Comcast. Even the movie theaters are not spared from the online TV revolution. Warner Bros. will release all of its 2021 films on its HBO Max streaming service and in theaters concurrently. Disney+ has also adopted this simultaneous release strategy.
The internet platform comes with many advantages over the pay-TV platform. For example, state-of-the-art video coders and decoders can be deployed quickly, allowing online providers to stay ahead of the pack when rolling out 4K ultra high-definition (UHD) services and premium content. In contrast, much of pay-TV’s video delivery infrastructure is still constrained by legacy set-top boxes. However, online streaming platforms perform differently in terms of the quality and smoothness of the video playback. The performance can vary from impeccable playback of high quality video to choppy playback, long pauses in ad-insertion, and disrupted content in trick mode support. Despite rapid advances in video coding standards, many online TV systems require relatively high rates for streaming. Typical rates are 2160p @ 15 Mbit/s, 1080p @ 5 Mbit/s, 720p @ 3 Mbit/s, 576p @ 1.4 Mbit/s, and 360p @ 1 Mbit/s. In addition, high resolution videos such as 4K UHD videos sometimes look like HD videos after compression.
This all-in-one book addresses the end-to-end video chain, from coding to streaming to playback. The first part of the book describes the key principles of current and emerging video coding standards. It provides invaluable insights on video coding optimization, including how bit rates can be reduced by several orders of magnitude for a wide variety of content without compromising video quality. For instance, a properly coded 1080p video should consume a bit rate of 1.5 to 2 Mbit/s whereas a 720p video can be transported at under 1 Mbit/s. Video coding standards develop on 7 to 9 year cycles and each new generation reduces the bit rate by 40 to 50%. The performance of a given standard can continue to improve for 10 to 20 years using the latest extensions. Because improvements in video compression require additional tools and options, each generation of video codecs has a new syntax defining a bitstream so newer codecs are typically not backward compatible with older generation decoders. State-of-the-art standards such as Versatile Video Coding (VVC) and AOM Video 1 (AV1) will bring even greater efficiencies using highly complex tools. These competing standards are covered extensively in the book and a comparative assessment is provided.
Significant improvements in video coding efficiencies entail a corresponding increase in encoding computation and complexity. For example, very high quality encoding may only be suitable for non-realtime applications. As a consequence, video codec development will become increasingly optimized toward specific applications in future. As you will discover, optimizing the efficiency of video coding requires a painstaking effort and a systematic approach in analyzing the coding performance using a wide variety of video content and coding parameters. Factors such as resolution, color/brightness volume, frame rate, and amount of information loss in video coding all impact the visual quality. Standards such as VVC, AV1, HEVC, and AVC will be assessed and compared in terms of coding efficiencies, encoding/decoding time, memory usage, complexity of motion estimation, transform precision, and parallel processing capability. Back-of-the-envelope calculations are always useful for a quick practical evaluation of core technology mechanisms. To this end, the book uses many numerical examples to illustrate the impact and tradeoffs when combining coding parameters as well as effective tips in coding implementation. The impact of the human visual system is also analyzed in this book. Very large TVs and close viewing distances may be needed to spot the difference between HD and 4K UHD video quality, not taking into account the excellent up-conversion often performed in today’s 4K displays.
The second part of this book addresses the online TV revolution and the main principles of the underlying adaptive streaming technology. It offers a careful analysis of actual streaming measurements, and important considerations in bandwidth management, system optimization, and advanced design. The numerical examples serve to demonstrate the impact of the system parameters. The powerful combination of video streaming and wireless networks further expands the reach of on-the-go TV entertainment. Video consumes over 80% of internet bandwidth while Netflix takes up one-third of all internet traffic. More importantly, over 80% of all mobile data traffic contains video. To this end, the book presents wireless video streaming over Wi-Fi and 4G-LTE, and discusses vital technical strategies to minimize wireless bandwidth consumption.
In the era of watching content when you want, where you want, and on any device you choose, online TV viewing is getting more pervasive than ever before. The online TV ecosystem is constantly evolving and has become very competitive. The ability to concurrently support 4K UHD, high frame rate, and high dynamic range in live sports streaming is the ultimate game-changer in the online TV revolution. With Oscar-winning content now available exclusively to subscribers and free ad-supported OTT providers revitalizing the good old broadcast TV business model, online TV’s popularity will continue to grow and spread in future.
444 pages. Available on Amazon.
