Low-Power, Low-Overhead, High-Fidelity Digital Sound for SOCs: Low-Power, Low-Overhead, High-Fidelity Digital Sound for SOCs Steve Leibson Technology Evangelist Tensilica, Inc. sleibson@tensilica.com


Why Listen to This Presentation?: Why Listen to This Presentation? Learn about digital audio subsystem alternatives for SOC design Advantages and disadvantages for each alternative Tradeoffs Learn about key decision factors for choosing one alternative over another Learn about energy consequences of digital audio implementation choices


Agenda: Agenda Introduction to digital audio concepts Implementation choices for on-chip audio Implementation examples Concluding thoughts


A Brief History of Audio: A Brief History of Audio


The Era of Digital Audio: The Era of Digital Audio Vinyl is Dead


Digital Audio Applications: Digital Audio Applications


Digital Audio Applications: Digital Audio Applications Cell Phones


Digital Audio Applications: Digital Audio Applications Cell Phones Personal Media Players PMPs MP3 players


Digital Audio Applications: Digital Audio Applications Cell Phones Personal Media Players PMPs MP3 players High-definition Audio for Video Players and Televisions Blu-ray HD DVD HDTV


Digital Audio Applications: Digital Audio Applications Cell Phones Personal Media Players PMPs MP3 players High-definition Audio for Video Players and Televisions Blu-ray HD DVD HDTV Automotive Audio HD Radio Satellite Radio


Digital Audio Applications: Digital Audio Applications Cell Phones Personal Media Players PMPs MP3 players High-definition Audio for Video Players and Televisions Blu-ray HD DVD HDTV Automotive Audio HD Radio Satellite Radio GPS Navigation Units


Introduction to Digital Audio: Introduction to Digital Audio


Introduction to Digital Audio: Introduction to Digital Audio The digital audio codec (coder/decoder) is the foundation of digital audio


Introduction to Digital Audio: Introduction to Digital Audio The digital audio codec (coder/decoder) is the foundation of digital audio MP3 was the first widely used audio codec


Introduction to Digital Audio: Introduction to Digital Audio The digital audio codec (coder/decoder) is the foundation of digital audio MP3 was the first widely used audio codec More advanced multi-channel audio codecs use increasingly sophisticated algorithms to improve fidelity They require more processing power too Codec vendors introduce new codecs regularly


Introduction to Digital Audio: Introduction to Digital Audio The digital audio codec (coder/decoder) is the foundation of digital audio MP3 was the first widely used audio codec More advanced multi-channel audio codecs use increasingly sophisticated algorithms to improve fidelity They require more processing power too Codec vendors introduce new codecs regularly Large number of digital audio codecs now in use


Many Digital Audio Codecs, Here are a Few: Many Digital Audio Codecs, Here are a Few Notes: Encode/Decode Different Data Rates Different Numbers of Channels


Digital Audio Implementation Choices: Digital Audio Implementation Choices General-purpose processor Hardware codecs DSP Audio-specific processor


General-Purpose Processor Core: General-Purpose Processor Core


General-Purpose Processor Core – Advantages and Disadvantages: General-Purpose Processor Core – Advantages and Disadvantages Advantages Probably one on the chip anyway Can implement multiple codecs for multi-purpose products using additional instruction memory Accommodates new codecs (if the bandwidth is available)


General-Purpose Processor Core – Advantages and Disadvantages: General-Purpose Processor Core – Advantages and Disadvantages Advantages Probably one on the chip anyway Can implement multiple codecs for multi-purpose products using additional instruction memory Accommodates new codecs (if the bandwidth is available) Disadvantages No audio glitches allowed and audio quality is sensitive to latency, so sharing one processor is problematic Not optimized for audio, so clock rate and energy consumption will be higher


Hardware Codec: Hardware Codec


Hardware Codec – Advantages and Disadvantages: Hardware Codec – Advantages and Disadvantages Advantages Small on-die area Low power


Hardware Codec – Advantages and Disadvantages: Hardware Codec – Advantages and Disadvantages Advantages Small on-die area Low power Disadvantages Die size grows with each new codec Hard to change if… There’s a change in the codec spec There’s a bug Impossible to change to accommodate a new codec Must add additional hardware codecs


Multiple Hardware Codecs: Multiple Hardware Codecs


DSP Core for Audio: DSP Core for Audio


DSP Core –Advantages and Disadvantages: DSP Core – Advantages and Disadvantages Advantages Integral multiplier helps lower the clock rate, vs. general-purpose processor Can implement multiple codecs for multi-purpose products using additional instruction memory Accommodates new codecs (if the bandwidth is available)


DSP Core –Advantages and Disadvantages: DSP Core – Advantages and Disadvantages Advantages Integral multiplier helps lower the clock rate, vs. general-purpose processor Can implement multiple codecs for multi-purpose products using additional instruction memory Accommodates new codecs (if the bandwidth is available) Disadvantages DSPs not good for general-purpose control Need control processor and DSP Task splitting and inter-processor communications are problematic 16-bit DSPs not enough for good audio 32-bit DSPs overkill (really need 24 bits)


Audio-Specific Processor Core: Audio-Specific Processor Core


Audio-Specific Core –Advantages and Disadvantages: Audio-Specific Core – Advantages and Disadvantages Advantages Instructions matched to the task of implementing digital audio codecs Lowers the clock rate and energy consumption Can implement multiple codecs for multi-purpose products using additional instruction memory Accommodates new codecs (if the bandwidth is available) Retains all the abilities of a general-purpose processor core


Audio-Specific Core –Advantages and Disadvantages: Audio-Specific Core – Advantages and Disadvantages Advantages Instructions matched to the task of implementing digital audio codecs Lowers the clock rate and energy consumption Can implement multiple codecs for multi-purpose products using additional instruction memory Accommodates new codecs (if the bandwidth is available) Retains all the abilities of a general-purpose processor core Disadvantages Not as familiar as the other alternatives


Anatomy of an Audio-Specific Processor: Tensilica’s HiFi 2 Audio Engine: Anatomy of an Audio-Specific Processor: Tensilica’s HiFi 2 Audio Engine


Anatomy of an Audio-Specific Processor: Tensilica’s HiFi 2 Audio Engine: Anatomy of an Audio-Specific Processor: Tensilica’s HiFi 2 Audio Engine Exploits configurability and extensibility of Tensilica’s Xtensa LX2 processor core


Anatomy of an Audio-Specific Processor: Tensilica’s HiFi 2 Audio Engine: Anatomy of an Audio-Specific Processor: Tensilica’s HiFi 2 Audio Engine Exploits configurability and extensibility of Tensilica’s Xtensa LX2 processor core Second generation set of audio extensions Two hardware multipliers Executes one or two operations per instruction 16-, 24-, and 64-bit instructions Lower clock rate when executing audio codec code


Anatomy of an Audio-Specific Processor: Tensilica’s HiFi 2 Audio Engine: Anatomy of an Audio-Specific Processor: Tensilica’s HiFi 2 Audio Engine Exploits configurability and extensibility of Tensilica’s Xtensa LX2 processor core Second generation set of audio extensions Two hardware multipliers Executes one or two operations per instruction 16-, 24-, and 64-bit instructions Lower clock rate when executing audio codec code Wide audio-specific registers Handles stereo 24-bit/channel data samples as a native data type


Anatomy of an Audio-Specific Processor: Tensilica’s HiFi 2 Audio Engine: Anatomy of an Audio-Specific Processor: Tensilica’s HiFi 2 Audio Engine Exploits configurability and extensibility of Tensilica’s Xtensa LX2 processor core Second generation set of audio extensions Two hardware multipliers Executes one or two operations per instruction 16-, 24-, and 64-bit instructions Lower clock rate when executing audio codec code Wide audio-specific registers Handles stereo 24-bit/channel data samples as a native data type 300 audio-specific instructions


Anatomy of an Audio-Specific Processor: Tensilica’s HiFi 2 Audio Engine: Anatomy of an Audio-Specific Processor: Tensilica’s HiFi 2 Audio Engine Exploits configurability and extensibility of Tensilica’s Xtensa LX2 processor core Second generation set of audio extensions Two hardware multipliers Executes one or two operations per instruction 16-, 24-, and 64-bit instructions Lower clock rate when executing audio codec code Wide audio-specific registers Handles stereo 24-bit/channel data samples as a native data type 300 audio-specific instructions Comprehensive and growing set of digital audio codecs


Tensilica’s Diamond 330HiFi Audio Engine: Tensilica’s Diamond 330HiFi Audio Engine Ready-made audio processor core Leverages HiFi 2 audio engine and HiFi codecs Adds 32-bit input and output queue interfaces to get ADC and DAC traffic off of the bus Higher efficiency, lower power way to talk to peripherals


Diamond 330 HiFi Audio Engine Block Diagram: Diamond 330 HiFi Audio Engine Block Diagram


Diamond 330 HiFi Audio Engine Block Diagram: Diamond 330 HiFi Audio Engine Block Diagram Audio-specific registers


Diamond 330 HiFi Audio Engine Block Diagram: Diamond 330 HiFi Audio Engine Block Diagram Audio-specific registers Audio-specific instruction-execution units


Tensilica HiFi 2 Audio Engine Instruction Groups: Tensilica HiFi 2 Audio Engine Instruction Groups ~ 300 Audio-Specific Instructions


The HiFi 2 Audio Engine (recap): The HiFi 2 Audio Engine (recap) Tensilica’s configured Diamond 330HiFi processor core incorporates the HiFi 2 Audio Engine


The HiFi 2 Audio Engine (recap): The HiFi 2 Audio Engine (recap) Tensilica’s configured Diamond 330HiFi processor core incorporates the HiFi 2 Audio Engine The HiFi 2 Audio Engine is available as an option for Tensilica’s configurable Xtensa LX2 processor core


The HiFi 2 Audio Engine (recap): The HiFi 2 Audio Engine (recap) Tensilica’s configured Diamond 330HiFi processor core incorporates the HiFi 2 Audio Engine The HiFi 2 Audio Engine is available as an option for Tensilica’s configurable Xtensa LX2 processor core All Tensilica digital-audio codecs run on both the Diamond 330HiFi processor core and the Xtensa LX2 processor core with the HiFi 2 Audio Engine option


Tensilica HiFi 2 and Diamond 330HiFiCellular Handset and Audio Entertainment Codec Set: Tensilica HiFi 2 and Diamond 330HiFi Cellular Handset and Audio Entertainment Codec Set * As of 7/18/07


Wide Adoption of Tensilica HiFi Digital AudioThe new standard in mobile audio, video, & DTV: Wide Adoption of Tensilica HiFi Digital Audio The new standard in mobile audio, video, & DTV Siemens SL75 Samsung SPH-V7800 Samsung SGH-910 Motorola KRZR Motorola RIZR Cingular 2125 ( HTC ) LG-LB1500 LT1000 Korean T-DMB Standard LG-SB120 LD1200 DVB-H LG-KD1200 LG-LB1200 LG-KB1300 Cingular 8125 (HTC) Most top mobile handset makers ship Tensilica-based multimedia LG Prada Panasonic 705


Design for Portable Audio Applications: Design for Portable Audio Applications Audio playback alone versus audio with enhancements and effects Equalization, Bass Enhancement, 3D Audio, MIDI synthesis, etc.


Design for Portable Audio Applications: Design for Portable Audio Applications Audio playback alone versus audio with enhancements and effects Equalization, Bass Enhancement, 3D Audio, MIDI synthesis, etc. Enhancements and effects may require an extra 100-200 MHz May require synthesizing the audio processor for higher frequency operation Makes the audio processor bigger and makes it dissipate more energy


Design for Portable Audio Applications: Design for Portable Audio Applications Audio playback alone versus audio with enhancements and effects Equalization, Bass Enhancement, 3D Audio, MIDI synthesis, etc. Enhancements and effects may require an extra 100-200 MHz May require synthesizing the audio processor for higher frequency operation Makes the audio processor bigger and makes it dissipate more energy For low-power applications, consider a second processor for audio effects Allows very low-power operation for simple playback Long battery life during playback


Diamond 330Hifi on the Bus: Diamond 330Hifi on the Bus


Diamond 330Hifi on the Bus: Diamond 330Hifi on the Bus Potential Bottleneck, especially for 5.1- to 10.1-channel systems Audio quality is sensitive to latency


Diamond 330Hifi using Output Queue: Keep Audio Traffic Off the Bus: Diamond 330Hifi using Output Queue: Keep Audio Traffic Off the Bus


Many Systems Only Need One Processor (Get Rid of the Host): Many Systems Only Need One Processor (Get Rid of the Host)


Slide55: One processor handles audio, housekeeping, and simple user interface at low MHz Many Systems Only Need One Processor (Get Rid of the Host)


Move Audio Processor Memory to Local Interconnect: Move Audio Processor Memory to Local Interconnect


Final Conclusions: Key Points: Final Conclusions: Key Points Paths to low-power, on-chip digital audio Low clock rate Low Bus Traffic Optimize use of local memory and cache Keep audio sample traffic off of the bus!!! Things to look for: 24-bit audio processing ability Comprehensive and growing codec set Find out more at www.tensilica.com