Strong consumer demand together with advances in technology for portable multimedia devices are challenging device manufacturers to integrate more features and services into smaller, cheaper and more versatile products. Nowadays, the list of technologies integrated into a typical cell phone extends far beyond cellular capabilities. Embedded cameras, MP3 players and LCD screens supporting imaging and video playback are de facto standards in every mid- to high-end phone on the market. Along with Personal Media Players (PMP), MobileTV and Personal Navigation Devices (PND), the markets for these multimedia-rich portable devices are expected to grow at a phenomenal rate. Research firm IDC predicts worldwide sales of mobile phones to top 1.2 billion units in 2010 with Informa Telecoms & Media forecasting the MobileTV market to grow from a total of 0.13 million units in 2005 to 83.5 million by 2010.
Three of the key parameters for developing a successful product capable of taking a share in this lucrative portable multimedia market are price, performance and reusability. The implications of the price and performance parameters are well quantified as it has direct implications on the cost of goods (COGs) of the chip. The same goes for reusability, but moreover, the importance of reusability goes beyond the COGs. Reusability has significant importance on the company's ability to easily adapt and leverage its R&D investments to generate incremental revenue out of multiple markets and applications.
To better understand how to create a value-rich, differentiated and reusable platform, let's first look at the range of technologies that a typical portable multimedia device is capable of performing:
Multimedia: video, audio and imaging decode and encode of multiple standards such as H.264, VC-1, MPEG4, AAC, MP3, JPEG and many more
Wireless: Legacy standards such as GSM or CDMA; evolving standards such as WCDMA, TD-SCDMA, 1xEV-DO, etc. and; going forward, standards such as WiMAX.
Graphics: Including 2D and 3D used for gaming and advanced GUI.
Voice Recognition: Standard in almost every new cell phone on the market today.
Connectivity and Location based technology: Such as Bluetooth, GPS, WiFi, UWB, WiMAX including antennas, RF and baseband processing.
Of these technologies, multimedia represents a very dynamic and fragmented area with multiple standards that are being invented or upgraded frequently. That said, multimedia processing in general and video in specific presents the biggest set of technical challenges when developing a portable multimedia SoC. This article addresses these challenges and outlines a number of suitable architectural approaches a designer can adopt when developing their SoC.
When designing the multimedia processing engine on an SoC, there are many factors that must be taken into account. For a start, there are a number of different applications that the engine must be able to support, such as video recording, video playback, content streaming and MobileTV. Each of these different applications makes use of various video standards, and within any application there is no single common standard in use. For example:
Video Playback/Record (movies, clips, Podcasts, etc.) uses H.264, MPEG4,VC-1 or MPEG2
Video conferencing uses H.263 (MPEG4 short header) or H.264
MobileTV uses either H.264 or VC-1
The proliferation of video standards brings about the issue of interoperability, a common obstacle in the uptake of new technologies. For example, in the U.S., MobileTV is not yet fully engaged by the cell phone and network operators, who are reluctant to commit to the technology until either the standards war is resolved or interoperability is guaranteed. Furthermore, within the numerous video standards commonly associated with today's portable multimedia devices, there exists a variety of content types and file formats. An example of these file formats and types of content include:
3gp, m4v, mpg, avi etc.
Types of content
File-based: used when playing or recording a clip or movie stored on the device's local memory
Streaming: used for playing clips transmitted via operators' network
Broadcast: used for MobileTV applications
Interactive: allowing user interaction with multimedia content
To support all the above standards and types of content in a portable device, there are three approaches available to semiconductor manufacturers, which we discuss below.
Choosing the right approach for portable multimedia
The three main approaches for developing multimedia based SoCs are: hardwired accelerators, video co-processors and general purpose processors. By evaluating each of these in detail, the SoC designer can ascertain which approach best meets their particular requirements.
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