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H.264 / AVC
The Emerging Video Compression Goliath
Significant advances in video compression over the last 15 years have enabled this technology to embed itself in a great diversity of products and services. From DVD players to video phones, compressed video is now an indispensable part of our daily life. While innovations in video compression methods are ongoing, much of what affects the market is employed using a relatively few standards. The new H.264 / AVC standard is at the forefront of this technology. The following article covers the history of compressed video leading up to H.264 / AVC as well as design suggestions for those venturing in this area today.
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Background
In the early 1990s, the Motion Picture Experts Group ratified their first standardized CODEC, MPEG1. MPEG1 was subsequently seen in everything from VideoCDs to computer games and in the earliest downloadable online videos.
This standard still enjoys the broadest level of compatibility but left plenty of room for improvement. Following MPEG1 was MPEG2 (also known as H.262) ratified in 1994 by a joint committee of the MPEG group and the other major video standards group, the ITU-T Video Coding Experts Group. MPEG2 is employed as the basis of many diverse technologies including HDTV, Satellite TV, DVD and others. This standard addresses the quality issues associated with MPEG1, but file size was now becoming a concern. In an effort to maintain picture quality but reduce file size, MPEG4 was ratified at Version 2 in 2000. This standard provides an approximate 25% reduction in file size with the same perceptual quality level as MPEG2. MPEG4 was also more compatible with video streaming technology, allowing for better on-demand services over the web and over other networks where connectivity concerns were present. These features moved MPEG4 into areas such as mobile phones, video conferencing devices, and streaming web downloads.
  Move to late 2003, where the compressed video market is ripe for another shift. Since the late 90s the MPEG group had been researching several candidates for the next generation video compression algorithm. After weaning the prospective applicants down to a few (very similar) encoder technologies, a joint MPEG and VCEG committee chose a technology called H.264 / AVC. The committee then ratified this compression method as an extension to MPEG4, naming it MPEG4 Part 10. Although it is called by many different names such as, MPEG4 Part 10, H.264, Advanced Video Codec, and more, it is commonly known as H.264 / AVC. This new standard has all the advantages of MPEG4 but further reduces file sizes by a conservative estimate of 50% over MPEG2 for the same quality. In many areas, H.264 / AVC will trump the use of MPEG4 and has even been given preliminary approval as one of the three mandatory CODECs to be incorporated into all forthcoming HD-DVD players (the high resolution / high capacity follow-up to current DVD players). With all these advantages, H.264 / AVC is poised to empower a new wave of compressed video applications and products.
The Three H.264 / AVC Profiles
The H.264 / AVC standard is broken up into 3 "profiles": Baseline, Extended, and Main. These profiles are slightly different implementations of the compression technology within the same standard. In this way, the user can select one of the three profiles that is most synergistic with the intended application.
Baseline profile: Designed with those applications in mind that run on the platforms with low processing power and in an environment with large packet losses. Among the three Profiles, it has the least coding efficiency.
Extended profile: A Super set of Baseline, more complex, and provides better coding efficiency than Baseline.
Main Profile: Designed to provide the highest possible coding efficiency.
Encoder and Decoder Options
Since H.264 / AVC is such a new standard, it is still growing technology market with select companies offering cutting edge products. Following are a few of the current options; more are coming to market soon.
W&W Communications
Using advanced DSP techniques to efficiently encode H.264 / AVC video, W&W communications is a leader in the H.264 / AVC arena. They provide a diverse product line with everything from single DSP baseline encoding to multiple DSP main profile encoding as well as complimentary decoders. W&W solutions are based on TI C64x DSP architecture.
UBVideo
Another major player with complete H.264 / AVC solutions, UBVideo specializes in real-time video applications with a focus on quality. Building on their H.263 and MPEG4 offerings, UBVideo has a very impressive solution including encoders and decoders at the forefront of H.264 technology. UBVideo solutions are based on TI C64x DSP architecture.
Equator Technology and Digilink
Equator and their partner Digilink offer an H.264 encoder and decoder implemented on Equator's own DSP technology. The Digilink solution also incorporates embedded Linux support and network video streaming.
Cradle Technologies
Cradle offers an H.264 solution utilizing their own multiprocessing DSP solution. Cradle's DSP combines multiple cores and onchip memories for an advanced solution.
Videosoft
Videosoft has a realtime H.264 encoder and decoder running in a PC environment using an Intel processor and Windows XP.
A High Quality Architecture Option for Embedded Video Encoding Products
The design of an embedded video product using H.264 (such as a surveillance camera, video capture device, or digital camera) is more limited than when using more established encoder technology such as MPEG2 or MPEG4. The older standards have complete ASIC options as well as multiple programmable DSP and FPGA options. The current H.264 solutions require advanced DSP algorithms utilizing new technologies.
A well-formed architecture for an H.264 solution can be brought together using DSP technology, such as the TI's C64x series of DSPs. In particular there is a well-integrated device specifically for video applications, called the DM642. This device provides input and output ports designed for interfacing (using standard video protocols) to imaging devices, video encoders, and video decoders. This processor is also very cost-effective and power-efficient for this form of application
Beyond the DSP for processing power, the other equally important component is the compression algorithm codec itself. For this form of application the codec will typically be delivered as a library. For TI DSPs, these libraries can be easily used as part of the TI XDAIS standard. For an embedded video encoding product using H.264, you'll typically use a baseline version of the encoder, as this will allow for a good balance of cost and functionality. A suitable encoder for this can be licensed from W&W Communications. Using W&W's encoder library on the DM642 from TI you can encode video at D1 resolution (standard full-size TV video) at up to 30 frames per second in real-time.
How Do I Find A Solution Specifically for my Needs?
Nuvation has extensive experience in the H.264 / AVC arena as well as other video processing technologies. With H.264 / AVC poised as the next generation video compression algorithm of choice, we can help you navigate the market and design a system quickly and efficiently. Please contact us if we can be of service.
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