https://github.com/theweird-kid/echo-link
udp based peer to peer voice chat application
https://github.com/theweird-kid/echo-link
asio cpp17 multithreading opus-codec portaudio udp
Last synced: 3 months ago
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udp based peer to peer voice chat application
- Host: GitHub
- URL: https://github.com/theweird-kid/echo-link
- Owner: theweird-kid
- Created: 2025-06-13T12:01:39.000Z (4 months ago)
- Default Branch: main
- Last Pushed: 2025-06-23T14:32:55.000Z (4 months ago)
- Last Synced: 2025-06-23T15:24:38.911Z (4 months ago)
- Topics: asio, cpp17, multithreading, opus-codec, portaudio, udp
- Language: C++
- Homepage:
- Size: 3.9 MB
- Stars: 0
- Watchers: 0
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
echo-link/README.md
# Echo-Link
## Overview
**Echo-Link** is a real-time audio streaming application designed to capture audio from a system's input device (e.g., microphone), encode it, transmit it over a network, decode it on the receiving end, and play it back through the system's output device (e.g., speakers). The project leverages modern C++ features, PortAudio for cross-platform audio I/O, Opus for high-quality audio compression, and ASIO for efficient networking.
---
## High-Level Architecture
The diagram above illustrates the main components and data flow in Echo-Link:
1. **Audio Capture**
- `PortAudioCapture` interfaces with the OS audio subsystem (ALSA, Core Audio, WASAPI, etc.) via PortAudio.
- Captures raw PCM audio frames from the hardware audio input buffer (microphone).
- Frames are pushed into a thread-safe queue.
2. **Audio Encoding**
- `AudioCodec` encodes PCM frames into compressed Opus packets for efficient network transmission.
3. **Network Transmission**
- `NetworkManager` handles UDP-based asynchronous sending and receiving of audio packets using ASIO.
- Outgoing packets are sent to the remote peer; incoming packets are received and queued for decoding.
4. **Audio Decoding**
- `AudioCodec` decodes received Opus packets back into PCM frames.
5. **Audio Playback**
- `PortAudioPlayback` pulls decoded PCM frames from a queue and writes them to the hardware audio output buffer (speakers/headphones) via PortAudio.
6. **ThreadSafeQueue**
- Generic, thread-safe queues are used throughout to safely pass audio frames and network packets between threads and modules.
---
## Main Classes and Responsibilities
| Class/Interface | Description |
|------------------------|----------------------------------------------------------------------------------------------|
| `Application` | Central orchestrator. Manages modules, queues, and threads for encoding, decoding, and I/O. |
| `IAudioSource` | Abstract interface for audio sources (capture). |
| `PortAudioCapture` | Captures audio from the system input device using PortAudio. |
| `FakeAudioSource` | Simulates an audio source by reading from a file (for testing). |
| `IAudioPlayback` | Abstract interface for audio playback devices. |
| `PortAudioPlayback` | Plays audio to the system output device using PortAudio. |
| `AudioCodec` | Encodes/decodes audio frames using the Opus codec. |
| `NetworkManager` | Handles UDP networking using ASIO. |
| `ThreadSafeQueue` | Thread-safe queue for passing data between modules/threads. |
---
## Audio Data Flow
1. **Capture:**
Audio is captured from the system's hardware audio input buffer via `PortAudioCapture`.
2. **Encode:**
Captured PCM frames are encoded to Opus packets by `AudioCodec`.
3. **Transmit:**
Encoded packets are sent over the network by `NetworkManager`.
4. **Receive:**
Incoming packets are received by `NetworkManager` and queued for decoding.
5. **Decode:**
Received Opus packets are decoded back to PCM frames by `AudioCodec`.
6. **Playback:**
Decoded PCM frames are played back through the system's hardware audio output buffer via `PortAudioPlayback`.
---
## Building and Running
### Prerequisites
- C++17 or newer compiler
- [PortAudio](http://www.portaudio.com/) (development headers and libraries)
- [Opus](https://opus-codec.org/) (development headers and libraries)
- [ASIO](https://think-async.com/Asio/) (standalone or Boost)
- CMake (recommended for building)
### Build Instructions
```bash
mkdir build
cd build
cmake ..
make
```
### Running
After building, run the application binary. You may need to specify configuration parameters (e.g., input/output device, network peer address) depending on your setup.
---
## Extending Echo-Link
- **Custom Audio Sources:** Implement the `IAudioSource` interface for new capture methods.
- **Custom Playback Devices:** Implement the `IAudioPlayback` interface for new playback methods.
- **Alternative Codecs:** Extend or replace `AudioCodec` for different audio codecs.
---