LPAPlayer (Low Power Audio Player) in Android stagefright

高通在Android libstagefright 框架中添加了LPAPlayer*：

frameworks/base/media/libstagefright/LPAPlayer.cpp 

frameworks/base/media/libstagefright/LPAPlayerALSA.cpp   

frameworks/base/media/libstagefright/LPAPlayerION.cpp 

frameworks/base/media/libstagefright/LPAPlayerPMEM.cpp

以调用"Low Power Audio Codec" ：

GENERAL DESCRIPTION

The SSM2603 is a low power, high quality stereo audio codec for portable digital audio applications with one set of stereo programmable gain amplifier (PGA) line inputs and one monaural microphone input. It features two 24-bit analog-todigital converter (ADC) channels and two 24-bit digital-toanalog (DAC) converter channels.  

The SSM2603 can operate as a master or a slave. It supports various master clock frequencies, including 12 MHz or 24 MHz for USB devices; standard 256 fS or 384 fS based rates, such as 12.288 MHz and 24.576 MHz; and many common audio sampling rates, such as 96 kHz, 88.2 kHz, 48 kHz, 44.1 kHz, 32 kHz, 24 kHz, 22.05 kHz, 16 kHz, 12 kHz, 11.025 kHz, and 8 kHz.

The SSM2603 can operate at power supplies as low as 1.8 V for the analog circuitry and as low as 1.5 V for the digital circuitry. The maximum voltage supply is 3.6 V for all supplies. 

The SSM2603 software-programmable stereo output options provide the user with many application possibilities. Its volume control functions provide a large range of gain control of the audio signal.

The SSM2603 is specified over the industrial temperature range of −40°C to +85°C. It is available in a 28-lead, 5 mm × 5 mm lead frame chip scale package (LFCSP).

FEATURES

Stereo, 24-bit analog-to-digital and digital-to-analog converters
DAC SNR: 100 dB (A-weighted), THD: −80 dB at 48 kHz, 3.3 V
ADC SNR: 90 dB (A-weighted), THD: −80 dB at 48 kHz, 3.3 V
Highly efficient headphone amplifier
Stereo line input and monaural microphone input 
Low power
7 mW stereo playback (1.8 V/1.5 V supplies)
14 mW record and playback (1.8 V/1.5 V supplies)
Low supply voltages
Analog: 1.8 V to 3.6 V
Digital core: 1.5 V to 3.6 V
Digital I/O: 1.8 V to 3.6 V  
256/384 oversampling rate in normal mode; 250/272 oversampling rate in USB mode 
Audio sampling rates: 8 kHz, 11.025 kHz, 12 kHz, 16 kHz, 
22.05 kHz, 24 kHz, 32 kHz, 44.1 kHz, 48 kHz, 88.2 kHz, 
and 96 kHz
28-lead, 5 mm × 5 mm LFCSP (QFN) package

APPLICATIONS

Mobile phones
MP3 players
Portable gaming
Portable electronics
Educational toy

更多细节可参考： http://www.analog.com/static/imported-files/data_sheets/SSM2603.pdf