Audio 3A processing

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Introduction

During real-time audio and video calls or live streaming, audio can be processed using the 3A approach, which mainly includes Acoustic Echo Cancelling (AEC), Automatic Gain Control (AGC), and Active Noise Control (ANS), in order to improve the quality of the calls or live streams and enhance the user experience.

• AEC (Acoustic Echo Cancelling): Filters the captured audio data to reduce echo in the audio.
• AGC (Automatic Gain Control): When enabled, the SDK can automatically adjust the microphone volume to adapt to different distances, ensuring a stable volume.
• ANS (Active Noise Control): Identifies background noise in the audio and eliminates it, making the human voice clearer. You can also enable music scene detection, which can dynamically recognize communication and music scenes in real-time without any additional consumption, further enhancing the audio quality of human voice and music. If users require more aggressive noise reduction strategies, the AI-based noise reduction in real-world scenarios feature can be used.

Download example source code

Please refer to Sample codes to get the source code.

The relevant source code can be found in the “/ZegoExpressExample/AdvancedAudioProcessing/src/main/java/im/zego/advancedaudioprocessing/audio3a” directory.

Default configuration and recommended configuration

The default configuration and recommended configuration for audio 3A processing in the SDK are as follows:

Prerequisites

Before using audio 3A processing, please make sure:

• A project has been created in ZEGOCLOUD Console and applied for a valid AppID and AppSign. For details, please refer to Console - How to view project information .
• ZEGO Express SDK has been integrated into the project to implement basic real-time audio and video functions. For details, please refer to Integrate the SDK and Implement a basic video call.

Steps to use

Set AEC (Acoustic Echo Cancellation)

Developers can follow the steps below to configure echo cancellation:

1. Call the enableAEC interface to enable echo cancellation. After enabling this feature, the SDK will filter the captured audio data to reduce echo.

2. (Optional) Developers can call the enableHeadphoneAEC interface to enable echo cancellation when using headphones.

3. After enabling echo cancellation, developers can call the setAECMode interface to set the echo cancellation mode. The SDK supports the following three echo cancellation modes:

   Enumeration	Description
   ZegoAECMode.AGGRESSIVE	Aggressive echo cancellation, which may have a noticeable impact on audio quality, but effectively eliminates echo.
   ZegoAECMode.MEDIUM	Moderate echo cancellation, which may slightly affect audio quality, but reduces residual echo.
   ZegoAECMode.SOFT	Comfortable echo cancellation, which has minimal impact on audio quality and may leave a small amount of echo, but does not affect normal listening.

For example, to set the echo cancellation mode to "Medium":

// Enable AEC
engine.enableAEC(true);
// Enable AEC when using headphones
engine.enableHeadphoneAEC(true);
// Set AEC mode to ZegoAECMode.MEDIUM
engine.setAECMode(ZegoAECMode.MEDIUM);

Set AGC (Automatic Gain Control)

To configure AGC:

enableAGC needs to be called before startPublishingStream, startPlayingStream, startPreview, createMediaPlayer, createAudioEffectPlayer, and createRealTimeSequentialDataManager interfaces in order to take effect.

Call the enableAGC interface to enable Automatic Gain Control (AGC). After enabling this feature, the SDK will automatically adjust the microphone volume to adapt to different distances, ensuring a stable volume.

// Enable AGC
engine.enableAGC(true);

Set ANS (Acoustic Noise Suppression)

To configure ANS:

enableANS, enableTransientANS, and setANSMode need to be called before startPublishingStream, startPlayingStream, startPreview, createMediaPlayer, createAudioEffectPlayer, and createRealTimeSequentialDataManager interfaces in order to take effect.

Developers can follow the steps below to configure noise suppression:

1. Call the enableANS interface to enable noise suppression. This feature can make the human voice clearer.

2. (Optional) Developers can call the enableTransientANS interface to enable transient noise suppression, which is used to suppress transient noises such as keyboard typing and table tapping.

3. After enabling noise suppression, developers can call the setANSMode interface to set the noise suppression mode. The default value is "Medium". The SDK supports the following three noise suppression modes:

   Enumeration	Description
   ZegoANSMode.AGGRESSIVE	Aggressive noise suppression, which may significantly affect audio quality but has good noise reduction effects.
   ZegoANSMode.MEDIUM	(Default) Moderate noise suppression, which may slightly affect audio quality but has good noise reduction effects.
   ZegoANSMode.SOFT	Mild noise suppression, which has minimal impact on audio quality but may leave some residual noise.

   Note: The Express SDK supports AI-based noise suppression and provides two modes: ZegoANSModeAI and ZegoANSModeAI_BALANCED. These modes effectively eliminate transient noises such as keyboard typing, coughing, wind noise, and car horns, in addition to eliminating steady-state noise. For more details, please refer to AI-based noise reduction in real-world scenarios.

4. (Optional) Enable music detection. Please contact ZEGOCLOUD technical support to configure and enable music detection. Taking setting mild noise suppression as an example:

   // Enable ANS
   engine.enableANS(true);
   // Enable transient noise suppression
   engine.enableTransientANS(true);
   // Set ANS mode to ZegoANSMode.SOFT
   engine.setANSMode(ZegoANSMode.SOFT);

Related documents

• How to deal with the echo issue?