Use of Libav of FFmpeg in Cinegy Software

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Cinegy uses the AC-3 component of the libav library, which is a part of FFmpeg, as a dynamically loaded plugin for optional AC-3 encoding. It is a highly specialized Windows dynamic-loading library that contains only the AC-3 encoding component, with all other FFmpeg / Libav functionality disabled.

This article describes the steps required to install and use this AC-3 plugin.

Overview

The FFmpeg-limited-vcpkg GitHub repository contains a Windows build script and patch files to automate building the core FFmpeg libav library, producing a very limited binary that can then be used within Cinegy software to provide AC-3 encoding.

No program code was modified; only appropriate compilation flags were set to ensure:

  • inclusion of only LGPL-compliant code;

  • exclusion of all other unnecessary, non-required code, which significantly reduces the size of the resulting DLL.

Prerequisites

The Git command-line client and Visual Studio 2019 or higher should be installed on the machine.

It is also recommended (but not required) to install 7-Zip and add it to the PATH for convenience.

Instructions

Clone the ffmpeg-limited-vcpkg repository and run the ffmpeg-limited-vcpkg.bat file.

The vcpkg repository will be downloaded by the build script, which will then download any other required source packages to build.

GNU Lesser General Public License

The GNU Lesser General Public License (LGPL) text can be found here.