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DSPs enable Dolby Digital in HD-DVD, Blu-ray

Posted: 15 Nov 2006 ?? ?Print Version ?Bookmark and Share

Keywords:Texas Instruments? Aureus? Dolby Digital? DA710? DA708?

Texas Instruments Inc. (TI) has enhanced its Aureus generation of audio DSPs by offering a higher-speed memory interface for the DA710 and DA708 devices as well as higher CPU performance. As home theatre systems transition to blue laser technology, TI said its Aureus processors are the first to support Dolby Digital Compatible Output technology, which enables next-generation optical disc (HD-DVD and Blu-ray) players to deliver a 640Kbps Dolby Digital-encoded, surround-sound signal and compatible playback through any existing Dolby Digital equipped A/V receiver with a digital audio input (S/PDIF or optical).

The Aureus processors target a wide range of home theatre and automotive products that require multichannel decoding and high-speed encoding, including: HDTVs, home media servers, automotive jukeboxes, MP3 player docking stations and emerging HD-DVD and Blu-ray Disc equipment.

High-definition market
The Aureus DSPs, including the upgraded DA710 and DA708, is suited for emerging applications such as audio mixing and re-encoding in HD-DVD or Blu-ray Disc players. TI supports this market with production-ready multichannel audio encoders, such as Dolby Digital Compatible Output technology, offering a simple, cost-effective way for CE manufacturers to guarantee playback of a Dolby Digital surround-sound signal through tens of millions of Dolby Digital-equipped legacy A/V receivers on the market.

Using a DA7xx DSP, the mixing and re-encoding functions can be implemented in a single device. The mixing function is necessary for next-generation optical disc players supporting dual audio streams. Mixing a secondary audio stream with a primary audio stream, such as a movie soundtrack, enables new applications, including downloading a stream of secondary director's commentary or commercial content over a broadband Internet connection. A DA7xx DSP is capable of mixing primary and secondary audio streams, even if they have different sample rates, as well as a third audio stream for controls or "button sounds." Because it can handle several audio streams, the DA7xx DSP can accommodate audio enhancements, such as virtualization or surround-sound technology for headphones.

Many audio algorithms and advanced processing features are memory-intensive and therefore require access to external memory. For example, effects such as reverb or virtualization use long delay buffers, which exceed the capacity of internal memory resources. The enhanced devices increase SDRAM access bandwidth up to 133MHz with processor speeds of 300MHz and 275MHz for the DA710 and 266MHz for the DA708. Faster external memory access decreases processing latency of delay buffers, improving overall codec performance and audio quality.

Greater memory bandwidth
Increased memory interface bandwidth also improves performance for algorithm and application updates. When the software for an existing product is upgraded, such as to support a new algorithm or new functionality, the new code and data cannot be stored in the DSP's on-chip ROM. In most cases, it is stored in external memory. Increasing memory bandwidth drastically reduces the impact this external code and data have on algorithm performance.

The DA710 devices with 133MHz memory interface are available today in an industry-standard GDH package. The 300MHz DA710 costs $21.63 each, while the 275MHz DA710 costs $16.05 each, both in quantities of 10,000 or more. The 266MHz DA708 with a 133MHz memory interface is available in an RFP package and costs $13.52 each in quantities of 10,000 or more.

The DA710 and DA708 are also available for automotive applications that are Q100-qualified and rated for operation in extended temperatures. The DA710 for automotive applications provides 275MHz while DA708 offers 250MHz. Both devices have the enhanced 133MHz SDRAM interface.

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