HI-FI Bluetooth Audio Solution (based on CSR8675)

 Bluetooth mainstream audio encoding format type and description


    APTX is a lossless fidelity audio format for Bluetooth transmission developed by Audio Processing Technology (combined by CSR) and named apt-X. CSR has continuously launched APTX-L, APTX-LL.

     After Qualcomm merged with CSR, the latest aptX-HD was released to achieve near-lossless sound quality. At this stage, Bluetooth wireless supports up to 24Bit/48Khz in CSR8675. Currently, high-end Qualcomm chips will support it.

APTX is capable of playing 16-bit/44.1 kHz audio at up to 352 kbps, and aptxHD can support up to 24-bit/48 kHz audio with bit rates up to 576 kbps.

APTX technology enables the world's top smartphones, speakers, sound bars, headsets and tablets to deliver pure wireless sound.



ASupport APTX-L: CSR8645 chip (free lincense fee), CSRA64215 (free lincense fee), QCC3002/3005

/3008 (free lincense fee), CSR57E687 (requires lincense fee), CSR8670 (requires lincense fee), CSR8675 (requires lincense fee)

BSupport APTX-LL: CSRA64215 (free lincense fee), QCC3002/3005/3008 (free lincense fee), CSR57E687 (requires lincense fee), CSR8670 (requires lincense fee), CSR8675 (requires lincense fee)

CSupport aptX-HD CSR8675 (requires lincense fee)


2. HWA-LHDC (Huawei)

      HWA-LHDC is the Bluetooth audio HD standard. Huawei launched the domestic Bluetooth audio coding this year, which is comparable to LDAC. At present, there are fewer HWA-LHDC mobile phones, mainly Huawei mobile phone P20 series and MATE 10, and Bluetooth audio transmission of LHDC can be realized by installing APP on Android and iOS.

     There are technical support fees and lincense fees for each product.

At present, the Bluetooth audio decoding hardware is only supported by the CSR8670/CSR8675 chip module.


3. LDAC/Hi-Res (High Resolution Audio) (Sony Sony, Japan)

    LDAC/Hi-Res is called High Resolution Audio, also known as high resolution audio. Hi-Res Audio is a high quality audio product designed and defined by Sony and developed by JAS (Japan Audio Association) and CEA (Consumer Electronics Association). standard.

      LDAC is powered by Sony's Bluetooth audio encoding, enabling Hi-Res-level audio transmission. After Android 8.0, the new system, LDAC becomes the default Bluetooth audio encoding supported by the system. All apps can output audio through LDAC.

   At present, the technical support is from Japan's Sony SONY, because it is also loaded into its own products, the market is less likely to have a competitive advantage.

LDAC is from Sony and licensed the technology to Google. You can hear the sound quality (24-bit/96 kHz) close to Hi-Res Audio.

LDAC also has a lincense fee.


4. AAC (Apple APPLE)

AAC (Advanced Audio Coding), Chinese name: Advanced Audio Coding, appeared in 1997, based on MPEG-2 audio coding technology. Developed by Fraunhofer IIS, Dolby Laboratories, AT&T, Sony, etc., to replace the MP3 format.

AAC sound quality is better than SBC, APPLE Apple uses Bluetooth encoding, and is widely supported by other mobile phones. The mobile phone plays AAC audio files, and the AAC Bluetooth code transmission can reduce the number of steps of encoding conversion, and the sound quality is more fidelity.

Free application, if you need to play LOGO, there will be membership fees.


5. SBC (all Bluetooth audio chips are supported)

This is the earliest Bluetooth audio transmission encoding, the sound quality is also the worst, but the compatibility is the best, any Bluetooth of a mobile phone supports SBC.


Qualcomm CSR8670 chip introduction

CSR8675 is Qualcomm's Bluetooth 5.0 version, supports the latest ADK development kit, the most powerful; includes an upgraded digital signal processor (DSP) core with processing performance up to 120MIPS, thus capable of supporting advanced audio processing algorithms, with super high Quality enhanced audio performance. Coupled with the chip's 24-bit digital audio support, the high-performance core enables high-definition audio output on devices based on the CSR8675 platform, making it possible for consumers to experience a wireless cable headset that is close to wired products.


The main features of CSR8675 include:

  · DSP processing performance is improved by up to 120MIPS;

  Integrated high performance stereo DAC and ADC;

  · 24-bit digital audio support;

  · 2 × I2S interface;

  · 1 × SPDIF interface;

  · 2 × standby GPIO (more than CSR8670);

  ·Bluetooth v5.0 support;

  16Mb of built-in eFlash and up to 64Mb of external serial flash memory;

  · 6 × capacitive touch sensor input;

  · Up to 6 digital microphone inputs;

  · Support ANC feedforward architecture.


Support program:

A.    CSR8675 (supports APTX-HD) is sent to the DAC/DSP through the I2S output to restore the APTX-HD high-fidelity lossless audio format.

B.     CSR8675 (add HWA-LHDC) is sent to the DAC/DSP through the I2S output to restore the LHDC high definition audio format.

C.    CSR8675 (add SONY-HDAC, need to have SONY technical support), send DAC/DSP through I2S output, restore HDAC high resolution audio format, apply to HI-FI player, high-end Bluetooth amp, HI-FI Bluetooth headset, HI-FI Bluetooth stereo, etc.