em8471 ETC-unknow, em8471 Datasheet - Page 9

• Manufacturer Part Number: em8471
• Description: Mpeg Decoder Set-top Streaming Applications
• Manufacturer: ETC-unknow

Hardware vs. Software MPEG Decoding
Use hardware-based MPEG decoding when:
Use software-based MPEG decoding when:
• Delivery of audio and video to a television is the primary function of the system. Standard consumer-oriented connectors
• Home theater quality audio and video (such as 6-channel audio analog outputs, component YPbPr or RGB analog video
• A relatively slow CPU, such as an embedded processor, is used to lower system costs. Slower CPUs also reduce power
• Multiple video streams must be decoded simultaneously to support picture-in-picture (PIP).
• Ancillary data processing, such as copy protection, closed captioning (multiple languages), teletext (multiple languages),
• Alpha blending is required when overlaying text and graphics (such as closed captioning, teletext, EPG, OSD, etc.) over
• High quality video scaling is required for large television screen sizes. Artifacts not noticeable on a small VGA monitor
• MPEG decoding is a secondary, rather than a primary function of the system. (Example: PC.)
• MPEG decoding is used in a single-tasking environment. Since MPEG decoding requires substantial CPU resources,
• A fast CPU is already available on the platform.
• Only standard stereo audio and video (composite or VGA) outputs are needed.
for audio and video must be used, instead of PC-oriented break-out cables and mini jacks. (Example: set-top box.)
outputs and a SPDIF digital audio output) are required. Although specifications for audio and video solutions for the PC
market look good on paper, the products themselves rarely meet consumer expectations.
consumption and eliminate noisy fans. Decoding full-screen MPEG-4 requires a 1 GHz CPU, which is currently far too
costly for low-cost set-top boxes to employ.
v-chip (multiple regions) and widescreen signaling must be performed for each active video stream displayed. Wide-
screen processing must be able to handle anamorphic and letterboxed content for either 4:3 or 16:9 televisions. These
are typically overlooked in software-based solutions.
video to avoid artifacts (such as flicker) when displayed on a television. Such artifacts are caused by the limited-band-
width video connection between the set-top box and television. It is typically implemented using anti-aliased fonts and
graphics.
are magnified on a large television.
using other applications usually affects playback quality.
355 Fairview Way • Milpitas, CA, USA 95035 • Tel: [phone] • Fax: [phone]
www.sigmadesigns.com • [e-mail]
Sigma Designs, Inc.
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