Why is H.264 becoming so pervasive?
Apr 1, 2010 12:00 PM, By Mark Hershey
The H.264 codec is a major influence in the streaming media industry.
The H.264 codec is popular to use for driving video to mobile devices.
H.264 compression, otherwise known as MPEG-4 part 10 Advanced Video Codec, is rapidly becoming a preferred standard for video compression throughout the broadcast industry.
As a fourth-generation codec, H.264 is a popular choice for driving video to mobile devices, with all of the major streaming media vendors delivering at least one product with H.264 compression. Its versatility lends itself to a broad range of applications, but its complexity means setting up and configuring an H.264-based product for optimum performance can be complex, more so than with any of its predecessors. It requires a much higher degree of computing power in both the encode and the decode processes, which limits its use with low-cost, portable devices to the most recent generation.
This article discusses reasons why H.264 is becoming a common compression standard in all phases of broadcasting and how its extremely rapid adoption in the streaming media industry has changed the face of that industry.
What is H.264?
H.264/MPEG-4 part 10 AVC is an advanced compression technology resulting from a collective partnership known as the Joint Video Team (JVT). Made up of representatives from the International Telecommunications Union (ITU) and the Motion Pictures Experts Group (MPEG), JVT first published technically identical ITU-T H.264 and ISO/IEC MPEG-4 Part 10 specifications in 2003. The collaboration virtually guaranteed the codec would be adaptable and have broad acceptance, in both the telecommunications and the broadcast video industries.
The MPEG-4 specification defines 27 different and often independent standards, called Parts, most having some application in the broadcast industry. Some have no design or application relationship to the Part 10 standard. Only Part 10 of the MPEG-4 specification is equivalent functionally to H.264. To help avoid confusion, the industry refers to the standard as H.264 and avoids the more general MPEG-4 name.
H.264 has many parts, called Profiles, each defining a set of capabilities targeting specific classes of applications. Some have been superseded by newer profiles as computing horsepower and other technical achievements happened. The specification is updated frequently as new profiles are defined.
Broadcasters are most interested in the Constrained Baseline Profile, a March 2009 advancement of the original Baseline Profile, used for Internet streaming and streaming to mobile devices. Scalable High and Scalable High-Intra profiles, defined in 2007 as an advancement of the original High Profile, are in video production and some high-bandwidth streaming applications. Recently, H.264 standards were amended to include 3-D (stereoscopic) video, starting with Version 11 (March 2009) and revised again in November 2009. H.264 likely will have a prominent place in the future of 3-D television.
H.264 differs from previous third-generation codecs in several important ways. These differences can be summed up in two areas:
The H.264 codec offers significantly better picture quality at a lower bit rate, which is mostly the result of advances in how frames of digitized video are analyzed, compared with other frames (in some cases both previous and subsequent frames) to detect sameness and differences, and how much prediction can be applied, ultimately to avoid resending data that is unchanged from previous data.
Versatile configuration choices offer absolute control over all the things that must be considered for optimal performance in any particular application. This is important when optimizing compression for bandwidth and resolution-limited devices, as we'll discuss later in this article.
H.264's advantages
The H.264 codec offers many advantages, including the following:
- Lower bit rate for the same video quality
This is important to cable and satellite distribution operators because it can significantly reduce new buildout costs when adding channels. Particularly, HD. H.264 can create a picture comparable to MPEG-2 at half of the MPEG-2 bandwidth, making it attractive to anyone trying to save transmission costs and essential when bandwidth is limited by the available technology.
- Better picture at the same bit rate
This is vital to improving viewer acceptance in bandwidth-limited applications, including streaming to mobile devices. In many cases, MPEG-4 is the first opportunity to video-enable a low-bit rate device. This may become less important when we are all on a global 4G-class cell phone network, but that may be awhile.
- Fewer technologies in play to reach a bigger audience
If you are adding alternative distribution forms, chances are the video compression will be based on some variant of H.264. That offers additional potential for lower headend and other infrastructure costs because the same equipment can more easily tailor video streams for different devices.
- Better compatibility with more devices over a longer period of time
Widespread adoption means every video device can, or soon will, decode and display some form of H.264-encoded content — at least until something better comes along. By then, whatever follows H.264 will need to be sufficiently revolutionary to cause massive displacement, which is not likely to happen any time soon, especially considering the increasing number of new H.264 products.
- Lower deployment cost
Fewer competing standards should lead to less development cost, lower product cost and faster time to market by reducing the need to support several standards. Innovations in both the encoder and player can be developed and deployed faster.
Continue to next page.
| Want to use this article? Click here for options! |  |
