README

Delphi GStreamer (G2D)

G2D is a Delphi / Object Pascal bridge for GStreamer.

Its goal is to let Delphi developers build multimedia applications and custom media pipelines without dropping down to C, C++, Python, or Java. This repository contains:

• Delphi wrappers around GStreamer types, APIs, and objects
• a higher-level framework layer for building pipelines from Delphi
• tutorial ports and examples
• examples of building custom audio and video filters in Delphi

The project is currently tested mostly with practical Delphi VCL Windows desktop development using 64-bit builds. It can also compile and run with Delphi FMX, and the repository includes an Android FMX video example that installs and runs on an Android device. Explaining Delphi FMX deployment for Android, iOS, and other mobile targets is beyond the scope of this project and is assumed to be handled by experienced Delphi developers.

Current Status

This project is still evolving but the main branch is stable.

What is stable:

• Basics:
  • using GStreamer from Delphi code
  • building pipelines from Delphi
  • following the GStreamer tutorials in Delphi form
  • experimenting with custom audio and video filters
• Building your own elements:
  • building and running your filters (audio & video) by subclassing video or audio filters Delphi provided classes
  • building and running your filters (audio & video) by using OnProcess procedures in the classic Delphi way
  • building and running your Plugins (*.dll files) by subclassing (audio & video) provided plugins

Current limitations:

• mainly tested on Windows 10/11 & Delphi 10 or above
• mainly tested with 64-bit builds on Delphi VCL
• FMX examples are available under Tutorials\FMX:
  • a Win64 FMX video overlay example
  • an Android FMX example that initializes GStreamer and renders videotestsrc

Who This Is For

This repository is useful if you want to:

• Build, and route audio/video streams in Delphi
• Building your own elements, inline filters & plugins in Delphi
• learn GStreamer through Delphi examples
• build your own GStreamer-backed tools or applications
• create custom filters in Delphi

If you are looking for the companion written guide, see:

• G2D.docx

Quick Start

1. Clone the repository

git clone https://github.com/sharonido/Delphi_GStreamer.git

Keep the repository folder structure intact.

2. Install GStreamer

Install the official 64-bit Windows GStreamer runtime/development package.

Example download page:

• GStreamer Windows downloads

This project has been tested with the MSVC 64-bit Windows build of GStreamer.

3. Open the Delphi projects

You can start with:

• the tutorial projects under Tutorials
• the custom filter examples under Building new Elements

4. Build for Win64

The current project setup is primarily intended for 64-bit Delphi builds.

Repository Layout

Core wrapper layers

• G_Types GStreamer-related Pascal types and records
• G_API Low-level bindings to GStreamer DLL functions
• G_DBase Base Delphi wrapper classes over GStreamer objects
• G_DUnits Higher-level framework classes and helper abstractions
• G_DPlugin Reusable base classes and helpers for real GStreamer plugin elements

Learning and examples

• Tutorials Delphi versions of the official GStreamer tutorials
• FMX Tutorials FireMonkey examples for Win64 and Android
• Building new Elements Examples of custom filters/elements written in Delphi

Other folders

• DLLs Local DLL-related material used by the project
• OpenCVWrapper OpenCV-related wrapper/helper code used by some examples

Tutorials

The Tutorials folder follows the structure of the official GStreamer tutorials:

• GStreamer tutorials

In general:

• example1, example2, ... map to the corresponding tutorial topics
• console and VCL examples are both included
• files with W in the name are typically VCL / windowed examples

FMX examples live under Tutorials/FMX:

• Ex2Win Win64 FireMonkey version of tutorial 2.
• Ex2Android Android FireMonkey version of tutorial 2. It uses the Android GStreamer bootstrap, renders videotestsrc into an Android surface, and allows switching the video pattern.

If you are new to G2D, this is the best place to start.

Custom Filters

The Building new Elements folder shows how to build custom filters in Delphi.

There are two custom-filter styles in the repository:

• simple Delphi-side filters built with appsink / appsrc
• real GStreamer plugin DLLs that can be loaded by GStreamer like ordinary elements

Recent work in this repository includes safer audio-filter building blocks, including a managed audio filter chain that wraps:

audioconvert -> audioresample -> appsink -> Delphi filter -> appsrc -> audioconvert -> audioresample

This makes it easier to build practical Delphi-side audio filters without manually wiring the full normalization chain each time.

Real plugin DLLs

The plugin framework lives in G_DPlugin. It is intended to make a real GStreamer plugin element feel like ordinary Delphi inheritance work.

For a first video filter, the usual path is:

1. Create a subclass of TG2DVideoFilter.
2. Override ProcessVideoFrame for the actual frame operation.
3. Add any element properties by overriding SetProperty / GetProperty.
4. Create a small plugin .dpr that registers the element type and metadata.
5. Build the project as a Win64 DLL.

For a first audio filter, the path is the same idea:

1. Create a subclass of TG2DAudioFilter.
2. Override ProcessAudioFrame for the actual audio operation.
3. Add normal GObject properties for runtime parameters, for example band0=10.
4. Keep the VCL/demo code small: build the pipeline and set element properties.
5. Build the project as a Win64 DLL.

For non-video filters, start from TG2DBaseFilter. It already provides the common element behavior:

• sink/src pads
• chain, event, and query forwarding
• debug, debugfile, and filter properties
• bypass support when filter=false

The current full-plugin examples are:

• VideoInvert Builds g2dinvert, a simple RGB video invert filter.
• VideoRotate Builds g2drotate, a BGRx video rotate filter using the OpenCV helper DLL.
• AudioEqualizer Builds g2dequalizer, an 8-band F32LE audio equalizer plugin with band0..band7 integer dB properties and a VCL demo that starts with Tutorials/MediaFiles/test.mp3.

Each folder contains:

• the plugin element source unit
• the plugin DLL project
• a VCL demo project
• a prebuilt plugin DLL in the folder root so the demo can run without rebuilding the plugin first

Design Overview

G2D is organized in layers so you can work at the level you need:

1. G_Types Raw type definitions
2. G_API Raw imported GStreamer functions
3. G_DBase Delphi wrappers around GStreamer objects
4. G_DUnits Higher-level framework and custom-element helpers
5. G_DPlugin Base classes and helpers for real plugin DLL elements

That means you can either:

• stay close to the C/GStreamer model when needed
• or use higher-level Delphi abstractions for faster application work

Recommended Companion Technologies

If your work goes beyond stream routing and playback, the following libraries often fit well alongside GStreamer:

• FFmpeg Great for container/codec-oriented media work
• OpenCV Great for image/video analysis and computer vision
• GStreamer Great for media pipelines, routing, playback, capture, and filtering

They overlap, but each has a different sweet spot.

Notes

• The project has mainly been exercised with Delphi 10+.
• The code may work with other Pascal compilers, but that is not the main tested path today.
• The focus of the examples is practical usage, not full wrapper completeness.

Contributing

Issues, improvements, fixes, and wrapper extensions are welcome.

If you improve an example, add a missing wrapper, or make pipeline building easier for Delphi users, that is valuable work for this project.

Author

• ido@pitaron.info