SinchLocalAudioFrameDelegate

public protocol SinchLocalAudioFrameDelegate : AnyObject

The delegate for local audio recording events.

The callbacks allow observing and modifying the raw PCM audio captured from the microphone before it is handed to the WebRTC engine for processing, encoding and transmission.

Assign via SinchAudioController.localAudioFrameDelegate.

Important

All callbacks are delivered synchronously on the SDK’s internal real-time audio threads, in the order audioRecordingDidStart(with:), onLocalAudioFrame(_:), audioRecordingDidStop(with:). Implementations must not block — any significant delay will cause audio glitches.

  • Called for every 10 ms audio buffer captured from the microphone, before it is handed to the WebRTC engine.

    The frame contains interleaved 16-bit PCM samples; the sample rate and the number of channels are described by frame.format. The samples may be modified in-place (via frame.int16ChannelData) to transform the audio before it reaches WebRTC (e.g. gain adjustment, filtering).

    Important

    The frame buffer is only valid for the duration of this method call and must not be retained or accessed afterwards.

    Declaration

    Swift

    func onLocalAudioFrame(_ frame: AVAudioPCMBuffer) -> Bool

    Parameters

    frame

    Buffer containing the raw PCM samples. Safe to read and modify in-place.

    Return Value

    true to pass the frame contents (as-is or modified) to WebRTC; false to discard the frame and send silence instead.

  • audioRecordingDidStart(with:) Default implementation

    Called when audio recording has started, before the first onLocalAudioFrame(_:) call.

    Optional — implement to initialize per-session state that depends on the recording format. A single delegate may observe several recording sessions; this is invoked at the start of each one.

    Default Implementation

    Declaration

    Swift

    func audioRecordingDidStart(with format: AVAudioFormat)

    Parameters

    format

    Recording format in use.
  • audioRecordingDidStop(with:) Default implementation

    Called when audio recording has stopped, after the final onLocalAudioFrame(_:) call.

    Optional — implement to release any resources allocated in audioRecordingDidStart(with:).

    Default Implementation

    Declaration

    Swift

    func audioRecordingDidStop(with format: AVAudioFormat)

    Parameters

    format

    Recording format that was in use.