AirShout - Real-Time Voice Intercom

About AirShout

AirShout is an iOS application that enables real-time voice transmission from your iPhone or iPad to other devices. Simply tap the talk button to start broadcasting your voice to selected output devices; tap again to stop.

Whether you want to shout announcements through HomePods in different rooms, have a quick intercom chat with family members on the same network, or stream audio to any AirPlay-enabled device, AirShout provides a seamless experience.

Key Features

🎯

Tap to Toggle

Tap the button to start or stop voice transmission

📊

Real-Time Waveform

Visual feedback showing your voice level in real-time

🔊

Haptic Feedback

Tactile confirmation when you start and stop speaking

🎧

Background Audio

Continues transmission even when app is in background

Three Transmission Methods

AirShout supports three different transmission methods to suit various use cases and device configurations.

1. AirPlay Built-in

The default transmission method uses Apple's AirPlay technology to stream audio directly to AirPlay-enabled devices such as Apple TV, HomePod, or any AirPlay-compatible speaker.

How it works:

Microphone → AVAudioEngine → AVAudioPlayerNode → AirPlay Device ↓ Audio Level Calculation → Real-time Waveform Display

Audio Specifications:

Parameter	Value
Sample Rate	44100 Hz
Channels	Stereo
Bit Depth	16-bit
Format	Linear PCM

Requirements:

AirPlay device on the same WiFi network
iOS device with microphone access

2. P2P (Multipeer Connectivity) LAN P2P

For direct voice communication between iOS devices on the same local network without requiring any server infrastructure. Uses Apple's Multipeer Connectivity framework for automatic peer discovery and encrypted communication.

How it works:

Microphone → AVAudioEngine.inputNode → Chunk (50ms) ↓ MCSession.send() [unreliable] → Other Devices ↓ AVAudioPlayerNode → Speaker

Audio Specifications:

Parameter	Value
Sample Rate	44100 Hz
Channels	Mono
Bit Depth	16-bit
Chunk Size	50ms (2205 samples)
Format	Raw PCM Data

Key Benefits:

No server required - Pure peer-to-peer communication
Auto discovery - Devices found automatically on LAN
Built-in encryption - MCSession provides automatic encryption
Low latency - Target end-to-end latency under 100ms

3. TCP Network Manual TCP

For reliable, direct TCP connections between devices. Manual IP/port input - no automatic discovery. Once connected, audio streams over TCP with guaranteed delivery.

How it works:

[Manual Setup] User enters: IP Address + Port [Connection Phase] TCP Listener ←→ TCP Connection [Streaming Phase] Microphone → TCP Connection → AVAudioPlayerNode → Speaker

Protocol Format:

[Magic: 2 bytes][Version: 1 byte][Type: 1 byte][Timestamp: 4 bytes][Length: 2 bytes][Payload: n bytes]

Features:

Manual connection - Enter target device IP and port directly
Reliable delivery - TCP ensures all audio packets arrive in order
Packet processing - Handles packet fragmentation and reassembly

Comparison

Feature	AirPlay	P2P (MC)	TCP Network
Target Device	Apple TV, HomePod, AirPlay speakers	iOS devices (AirShout users)	Any device with TCP support
Connection	Via WiFi router	Direct LAN P2P	Direct TCP
Discovery	Automatic via AirPlay	Automatic via MultipeerConnectivity	Manual (enter IP & port)
Latency	Low	Very Low (~100ms target)	Low
Reliability	High	Best effort (UDP-like)	Guaranteed (TCP)
Encryption	Built-in	Built-in (MCSession)	Optional

Technical Architecture

Core Components

Component	Responsibility
AirPlayAudioManager	AirPlay-specific audio routing and playback via AVAudioEngine
P2PAudioManager	Multipeer Connectivity session and P2P audio streaming
NetworkManager	TCP server/client, audio streaming over TCP
PacketProcessor	TCP packet assembly/disassembly, protocol parsing
AudioLevelProcessor	Audio level calculation for waveform display
AudioSessionConfig	AVAudioSession configuration and permission handling

Thread Safety

AirShout uses dedicated serial queues for different subsystems to ensure thread safety:

engineQueue - Audio engine operations
connectionsQueue - TCP connection management
mcQueue - Multipeer Connectivity operations
MainActor - UI updates only

Requirements

iOS Device - iPhone or iPad (simulator not supported)
iOS Version - iOS 15.0 or later
Microphone - Required for voice transmission
Network - All devices on same WiFi for AirPlay/TCP; LAN for P2P

Privacy

AirShout is designed with privacy in mind. Audio is processed locally and transmitted only to selected devices. For more information, see our Privacy Policy.