Sign in Join

Live chat for Free Pascal, Lazarus, Delphi and every Pascal programmer.

Catalog · How the catalog works
Anything · Lazarus or Delphi
Random projectRandom project

IAP

A Library bundled for the ITDevCon 2014 presentation "Immersive Audio Programming", which contains the necessary code to build a platform independent audio environment with Delphi.

View on GitHub

Member rating

No ratings yet.

Sign in to rate this project.

README

IAP - Immersive Audio Programming Library

A cross-platform audio programming library written in pure Object Pascal, originally created for the ITDevCon 2014 presentation "Immersive Audio Programming". This library provides the necessary components to build platform-independent audio applications with Delphi and Free Pascal.

📦 Quick Download

Pre-built demo applications are available for download:

Each release includes all 4 demo applications ready to run!

Features

  • Pure Object Pascal implementation for maximum portability
  • Cross-platform audio I/O via PortAudio bindings
  • DSP (Digital Signal Processing) components including:
    • Filters (highpass, lowpass, bandpass, etc.)
    • FFT (Fast Fourier Transform) for frequency domain processing
    • Convolution for reverb and other effects
    • Simple oscillators for signal generation
  • Audio file support for WAV and MPEG formats
  • Real-time audio processing capabilities
  • Demo applications showcasing library features

Platform Support

Platform Delphi Free Pascal (FPC) Status
Windows ✅ XE+ ✅ 3.2.2+ Fully Supported
Linux ❌ ✅ 3.2.2+ Fully Supported
macOS ✅ XE+ ✅ 3.2.2+ Should work (untested)

Note: The library uses generics and other modern language features, requiring Delphi XE or above and FPC 3.2.2 or above.

Requirements

Common Requirements (All Platforms)

  • PortAudio library (v19 or later)
    • Provides cross-platform audio I/O functionality

Delphi Requirements

  • Delphi XE or later (tested with XE-11)
  • Windows: Comes with PortAudio DLL
  • macOS: Install PortAudio via Homebrew

Free Pascal Requirements

  • Free Pascal Compiler (FPC) 3.2.2 or later
  • Lazarus IDE 2.0+ (recommended for GUI applications)
  • Lazarus LCL (Lazarus Component Library) for GUI demos

Development Tools (Optional but Recommended)

  • just - Command runner for task orchestration (Install)
    • Simplifies building, testing, formatting, and linting
    • Run just --list to see all available commands
  • dos2unix - Line ending converter
  • entr - File watcher for auto-rebuild (optional)

Quick Start with Just

If you have just installed, you can use these convenient commands:

bash
just --list          # List all available commands
just install-deps    # Install all dependencies (Ubuntu/Debian)
just build           # Build all demos
just lint            # Run all linting checks
just format          # Format all Pascal files
just ci              # Run all CI checks locally
just dev             # Format, lint, and build (full dev cycle)

See the justfile for all available commands.

Building with Delphi

Windows (Delphi)

  1. Install Dependencies:
    • Ensure portaudio.dll is available in your system PATH or next to the executable
    • The library is usually included in the Binaries folder
  2. Open Project:
    pascal
    Open Demos/Demos.groupproj in Delphi IDE
  3. Build Individual Demos:
    • Navigate to Demos/[Demo Name]/
    • Open the .dproj file
    • Press F9 to compile and run
  4. Build All Demos:
    • Use the group project: Demos/Demos.groupproj
    • Right-click → Build All

macOS (Delphi)

  1. Install PortAudio:
    bash
    brew install portaudio
  2. Open and Build:
    • Open project files in Delphi for macOS
    • The library should automatically link to libportaudio.2.dylib
    • Build as you would on Windows

Note: macOS support with Delphi is untested but should work based on the PortAudio bindings.

Building with Free Pascal (FPC)

Linux (FPC/Lazarus)

  1. Install FPC and Lazarus:

    Ubuntu/Debian:

    bash
    sudo apt-get update
sudo apt-get install fpc lazarus

    Fedora:

    bash
    sudo dnf install fpc lazarus

    Arch Linux:

    bash
    sudo pacman -S fpc lazarus

  2. Install PortAudio:

    Ubuntu/Debian:

    bash
    sudo apt-get install libportaudio2 portaudio19-dev

    Fedora:

    bash
    sudo dnf install portaudio portaudio-devel

    Arch Linux:

    bash
    sudo pacman -S portaudio

  3. Compile from Command Line:

    bash
    cd Demos/[Demo Name]
fpc -Fu../../Source \
    -Fu/usr/lib/lazarus/3.0/lcl/units/x86_64-linux \
    -Fu/usr/lib/lazarus/3.0/lcl/units/x86_64-linux/gtk2 \
    -Fu/usr/lib/lazarus/3.0/components/lazutils/lib/x86_64-linux \
    -Fi/usr/lib/lazarus/3.0/lcl/include \
    -dLCL -dLCLgtk2 \
    [ProgramName].dpr

  4. Or Use Lazarus IDE:

    • Create a new project and add the demo source files
    • Configure project options to include the Source directory
    • Build and run

macOS (FPC/Lazarus)

  1. Install FPC and Lazarus:
    bash
    brew install fpc
# Download Lazarus from: https://www.lazarus-ide.org/
  2. Install PortAudio:
    bash
    brew install portaudio
  3. Compile:
    bash
    cd Demos/[Demo Name]
fpc -Fu../../Source \
    -Fu/usr/local/lib/lazarus/lcl/units/x86_64-darwin \
    -Fu/usr/local/lib/lazarus/lcl/units/x86_64-darwin/cocoa \
    -dLCL -dLCLcocoa \
    [ProgramName].dpr

Note: Paths may vary depending on your Lazarus installation location.

Windows (FPC/Lazarus)

  1. Install FPC and Lazarus:
  2. Install PortAudio:
    • Download portaudio.dll for Windows
    • Place it in the demo executable directory or Windows\System32
  3. Compile from Command Line:
    cmd
    cd Demos\[Demo Name]
fpc -Fu..\..\Source ^
    -Fu"C:\lazarus\lcl\units\x86_64-win64" ^
    -Fu"C:\lazarus\lcl\units\x86_64-win64\win32" ^
    -dLCL -dLCLwin32 ^
    [ProgramName].dpr
  4. Or Use Lazarus IDE:
    • Open Lazarus
    • Create a new project or open demo files
    • Configure library paths in Project Options
    • Build and run

Demo Applications

The library includes several demo applications located in the Demos/ folder:

1. Sine Generator

Demonstrates basic audio output by generating sine wave tones at variable frequencies and amplitudes.

Features:

  • Real-time frequency control
  • Volume/amplitude adjustment
  • PortAudio driver selection

2. Noise Generator

Creates white noise output with adjustable volume.

Features:

  • White noise generation
  • Volume control
  • Simple audio callback demonstration

3. Effect Generator

Advanced demo showing convolution-based audio effects and filtering.

Features:

  • Convolution reverb
  • Various filter types (highpass, lowpass)
  • Audio file playback (MP3/WAV)
  • Real-time effect processing

4. VU Meter

Demonstrates audio input monitoring with level metering.

Features:

  • Real-time audio input
  • Peak level detection
  • VU meter visualization

Project Structure

pascal
IAP/
 Source/              # Library source files
    IAP.PortAudio.*  # PortAudio bindings
    IAP.DSP.*        # DSP components (filters, FFT, etc.)
    IAP.AudioFile.*  # Audio file format support
    IAP.Math.*       # Math utilities
    IAP.Types.pas    # Common types and definitions
 Demos/               # Example applications
    Sine Generator/
    Noise Generator/
    Effect Generator/
    VU Meter/
 Binaries/            # Pre-compiled libraries (Windows)

Library Components

Audio I/O

  • IAP.PortAudio.Host - High-level PortAudio wrapper
  • IAP.PortAudio.Binding - Dynamic PortAudio binding (Windows)
  • IAP.PortAudio.BindingStatic - Static PortAudio binding (macOS/Linux)

DSP

  • IAP.DSP.Filter - Various digital filter implementations
  • IAP.DSP.FilterSimple - Simple first-order filters
  • IAP.DSP.FilterBasics - Filter design utilities
  • IAP.DSP.Convolution - Convolution engine for reverb
  • IAP.DSP.FftReal2Complex - FFT implementation
  • IAP.DSP.SimpleOscillator - Basic waveform generators

Audio Files

  • IAP.AudioFile.WAV - WAV file reading/writing
  • IAP.AudioFile.MPEG - MPEG/MP3 file support
  • IAP.Chunk.Classes - RIFF/chunk-based file handling

Math & Utilities

  • IAP.Math - Math functions and utilities
  • IAP.Math.Complex - Complex number operations
  • IAP.Types - Common type definitions

Conditional Compilation

The library uses conditional compilation to support both Delphi and FPC:

pascal
{$IFDEF FPC}
  {$MODE DELPHI}  // Use Delphi syntax mode in FPC
{$ENDIF}

uses
  {$IFDEF FPC}
  LCLIntf, LCLType,  // FPC: Use LCL units
  SysUtils, Classes,
  {$ELSE}
  WinApi.Windows,     // Delphi: Use VCL units
  System.SysUtils, System.Classes,
  {$ENDIF}
  IAP.PortAudio.Host;

Troubleshooting

PortAudio Library Not Found

Linux:

bash
# Check if PortAudio is installed
ldconfig -p | grep portaudio

# If not found, install it
sudo apt-get install libportaudio2

macOS:

bash
# Check installation
brew list portaudio

# Install if needed
brew install portaudio

Windows:

  • Ensure portaudio.dll is in your PATH or application directory
  • Check if you have the correct architecture (32-bit vs 64-bit)

Compilation Errors with FPC

Error: "Can't find unit Interfaces"

  • Install Lazarus LCL: sudo apt-get install lcl-units-3.0
  • Ensure you include the LCL unit paths in fpc command

Error: "Can't find unit System.SysUtils"

  • The library should handle this automatically with conditional compilation
  • If issues persist, ensure you're using FPC 3.2.2 or later

Runtime Issues

No audio devices listed:

  • Check if PortAudio can detect your audio hardware
  • On Linux, verify ALSA or PulseAudio is working
  • Try running the application with elevated permissions (temporarily for testing)

Audio crackling or glitches:

  • Increase the PortAudio buffer size
  • Check system audio settings
  • Ensure your CPU isn't overloaded

Continuous Integration

This project uses GitHub Actions for continuous integration and code quality checks:

Build Workflow

Automatically builds all demo applications on:

  • Linux (Ubuntu with FPC/Lazarus)
  • Windows (FPC/Lazarus via Chocolatey)
  • macOS (FPC with Homebrew)

Each successful build produces artifacts (compiled binaries) available for download.

Code Quality Workflow

Performs comprehensive code quality checks including:

Syntax Checks:

  • FPC syntax validation for all Pascal source files
  • Compilation with maximum warning levels

Code Analysis:

  • Detection of TODO/FIXME comments
  • Potential memory leak detection (missing Free/FreeAndNil calls)
  • Windows-specific code without proper conditional compilation
  • Code duplication patterns

Formatting Checks:

  • File encoding validation (UTF-8)
  • Line ending consistency checks
  • Indentation consistency (tabs vs spaces)
  • Trailing whitespace detection
  • Long line detection (>120 characters)
  • Lines of code statistics

Compiler Warnings:

  • Full compilation with all warnings and hints enabled
  • Warning and hint reports uploaded as artifacts

All checks run automatically on:

  • Every push to main/master/develop branches
  • All pull requests
  • Feature branches (claude/**)

Running Checks Locally

Before pushing your changes, you can run the same quality checks locally.

Using Just (Recommended):

bash
# Run all checks (same as CI)
just ci

# Quick pre-commit checks
just pre-commit

# Individual checks
just lint              # All linting checks
just lint-syntax       # Syntax only
just lint-formatting   # Formatting only
just build            # Build all demos
just format           # Auto-format code

Using Scripts Directly:

bash
# Check code quality
./scripts/check-code-quality.sh

# Check syntax
./scripts/check-syntax.sh

# Check formatting
./scripts/check-formatting.sh

# Build all demos
./scripts/build-all-demos.sh

All scripts exit with an error code if issues are found, making them suitable for pre-commit hooks.

Setup Pre-commit Hook:

bash
just setup-hooks

This installs a git hook that automatically runs just pre-commit before each commit.

Contributing

Contributions are welcome! Please read CONTRIBUTING.md for detailed guidelines.

Quick overview:

  • Fork the repository and create a feature branch
  • Follow the Pascal coding standards
  • Run local checks before committing
  • Ensure all CI checks pass
  • Submit a pull request with a clear description

We welcome contributions for:

  • Bug fixes
  • Platform compatibility improvements
  • New DSP algorithms
  • Additional demo applications
  • Documentation improvements

License

Please check with the original author for licensing information.

Credits

Created for the ITDevCon 2014 presentation "Immersive Audio Programming"

PortAudio: http://www.portaudio.com/ Cross-platform audio I/O library used by this project.

Support & Contact

For questions, issues, or contributions, please use the GitHub issue tracker.