Format-tuned codec, encoder contend for relevance
By Brian Dipert -- EDN, January 6, 2005
Protocom has chosen to hard-wire the video and ADPCM (adaptive-differential pulse-code-modulation) audio-encoding capabilities of its $19 (100,000) GoldenReel PR828 device, along with the incremental full-duplex video and ADPCM decoding functions in its $22 PR818S codec (Picture). In making this determination, Protocom has rejected the more common approach of implementing these capabilities in software running on a DSP core. The company's decision is encouraging for the MPEG-4 Advanced Simple Profile format that the chips support (to D1 resolutions and 30-frame/sec rates); it indicates that MPEG-4 AS finally is sufficiently mature to be "frozen" in dedicated circuitry. And hard-wired approaches tend, all other factors being equal, to deliver higher throughput per megahertz and lower power draw per megahertz than firmware-centric alternatives. With all functions enabled, the estimated power draw of the PR828 is 400 mW; that of the PR818S is 550 mW.
But where are the noteworthy applications? Certainly, a closed-loop architecture, such as a video-security system or a service-provider-proprietary video-on-cell-phone service, is a candidate. But anyone attempting to migrate MPEG-4 AS content to the PC or the living room will quickly run into roadblocks. Windows Media Player doesn't support MPEG-4, Quicktime Version 6 supports only low-quality Simple Profile. (The Version 6 beta implemented some AS functions, which Apple disabled when it released the final version of the program.) And the DiVX Player and Nero Media Player aren't pervasive on PCs and Macs, except perhaps in college dorms (see "Video characterization creates hands-on headaches," EDN, July 25, 2002, pg 53). DiVX implements a subset of, along with proprietary extensions to, the MPEG-4 AS specification, so DiVX-compliant DVD players aren't guaranteed to play MPEG-4 AS content.
Because of the high quality and consequent success of proprietary codes, such as RealVideo, On2's VP6, and Microsoft's Windows Media Version 9, MPEG-aligned companies, including Protocom, are working as quickly as possible to finalize and roll out the follow-on MPEG-4 part 10 (also known as H.264 or MPEG-4 AVC) codec.
So, it's unclear how long MPEG-4 AS will live. Nonetheless, the PR818S and PR828 also include a hard-wired JPEG codec and a 160-MHz ARM922T core. The core tackles multimedia-content multiplexing and demultiplexing; the encoding and decoding of other audio formats, such as MP3, AAC, and WMA; image processing; Linux-operating-system execution; and other functions. (The company also plans support for Windows CE, VxWorks, and other operating systems.) The chips also transcode between MPEG-2 (ML@MP) and MPEG-4. Both devices are now available; the company also offers the Emerge engineering-development platform.
Protocom Technology, 1-408-343-0976, www.protocomtech.com.
