SinchRemoteAudioFrameDelegate

public protocol SinchRemoteAudioFrameDelegate : AnyObject

The delegate for remote audio playout events.

The callbacks allow observing and modifying the decoded PCM audio received from the remote party before it is written to the audio output device.

Assign via SinchAudioController.remoteAudioFrameDelegate.

Important

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

  • Called for every 10 ms audio buffer received from the remote party, before it is written to the audio output device.

    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 is played out (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 onRemoteAudioFrame(_ frame: AVAudioPCMBuffer) -> Bool

    Parameters

    frame

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

    Return Value

    true to play out the frame contents (as-is or modified); false to discard the frame and play silence instead.

  • audioPlayoutDidStart(with:) Default implementation

    Called when remote audio playout has started, before the first onRemoteAudioFrame(_:) call.

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

    Default Implementation

    Declaration

    Swift

    func audioPlayoutDidStart(with format: AVAudioFormat)

    Parameters

    format

    Playout format in use.
  • audioPlayoutDidStop(with:) Default implementation

    Called when remote audio playout has stopped, after the final onRemoteAudioFrame(_:) call; no further frames will be delivered for this session. Audio already handed to the output device may continue to play out briefly after this method call.

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

    Default Implementation

    Declaration

    Swift

    func audioPlayoutDidStop(with format: AVAudioFormat)

    Parameters

    format

    Playout format that was in use.