av_audio.mm File Reference

Implementation of macOS audio capture with dual input paths. More...

import "av_audio.h"
#include "coreaudio_helpers.h"
#include "src/logging.h"
#include "src/utility.h"
import <AudioToolbox/AudioConverter.h>
import <CoreAudio/CATapDescription.h>

Include dependency graph for av_audio.mm:

Functions
OSStatus	platf::audioConverterComplexInputProc (AudioConverterRef inAudioConverter, UInt32 *ioNumberDataPackets, AudioBufferList *ioData, AudioStreamPacketDescription **outDataPacketDescription, void *inUserData)
	Real-time AudioConverter input callback for format conversion. Provides audio data to AudioConverter during format conversion process using pure C++ for optimal performance. This function must avoid all Objective-C runtime calls to meet real-time audio constraints.
OSStatus	platf::systemAudioIOProc (AudioObjectID inDevice, const AudioTimeStamp *inNow, const AudioBufferList *inInputData, const AudioTimeStamp *inInputTime, AudioBufferList *outOutputData, const AudioTimeStamp *inOutputTime, void *inClientData)
	Real-time audio processing function for Core Audio IOProc callbacks. Handles system-wide audio capture with format conversion and buffering using pure C++ for optimal performance. This function must avoid all Objective-C runtime calls to meet real-time audio constraints.

Detailed Description

Implementation of macOS audio capture with dual input paths.

This file implements the AVAudio class which provides two distinct audio capture methods:

1. Microphone capture - Uses AVFoundation framework to capture from specific microphone devices
2. System-wide audio tap - Uses Core Audio taps to capture all system audio output (macOS 14.0+)

The implementation handles format conversion, real-time audio processing, and provides a unified interface for both capture methods through a shared circular buffer.

Function Documentation

audioConverterComplexInputProc()

OSStatus platf::audioConverterComplexInputProc	(	AudioConverterRef	inAudioConverter,
		UInt32 *	ioNumberDataPackets,
		AudioBufferList *	ioData,
		AudioStreamPacketDescription **	outDataPacketDescription,
		void *	inUserData )

Real-time AudioConverter input callback for format conversion. Provides audio data to AudioConverter during format conversion process using pure C++ for optimal performance. This function must avoid all Objective-C runtime calls to meet real-time audio constraints.

Parameters

inAudioConverter	The audio converter requesting input data
ioNumberDataPackets	Number of data packets to provide
ioData	Buffer list to fill with audio data
outDataPacketDescription	Packet description for output data
inUserData	User data containing AudioConverterInputData structure

Returns

OSStatus indicating success (noErr) or error code

systemAudioIOProc()

OSStatus platf::systemAudioIOProc	(	AudioObjectID	inDevice,
		const AudioTimeStamp *	inNow,
		const AudioBufferList *	inInputData,
		const AudioTimeStamp *	inInputTime,
		AudioBufferList *	outOutputData,
		const AudioTimeStamp *	inOutputTime,
		void *	inClientData )

Real-time audio processing function for Core Audio IOProc callbacks. Handles system-wide audio capture with format conversion and buffering using pure C++ for optimal performance. This function must avoid all Objective-C runtime calls to meet real-time audio constraints.

Parameters

inDevice	The audio device identifier
inNow	Current audio time stamp
inInputData	Input audio buffer list from the device
inInputTime	Time stamp for input data
outOutputData	Output audio buffer list (not used in our implementation)
inOutputTime	Time stamp for output data
inClientData	Client data containing AVAudioIOProcData structure

Returns

OSStatus indicating success (noErr) or error code