// Copyright (C) 2024 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only

/*!
\page qtmultimedia-building-from-source.html
\title Building Qt Multimedia from sources
\brief This document describes how to build Qt Multimedia with full
feature support from source code.

This page describes the process of configuring and building \l{Qt
Multimedia}. This description assumes familiarity with \l{Building Qt
Sources} which specifies build requirements for your platform, as well
as an overview of \l{Qt Configure Options}. For platform-specific
considerations related to the Qt Multimedia module, see \l{Platform
Notes} below.

\section1 Building from source

Building Qt Multimedia with full feature support depends on \l
{https://ffmpeg.org/}{FFmpeg} headers and libraries on most platforms.
It is possible to build Qt Multimedia without the Qt Multimedia FFmpeg
media backend, but this is only recommended when building for platforms
where the FFmpeg backend is not supported.

FFmpeg development libraries required to build Qt Multimedia can be
built from sources or downloaded as binary packages. Qt Multimedia can
use either static linking or dynamic linking to FFmpeg libraries. We
recommend using the same major version of FFmpeg that is listed in
\l{FFmpeg as the default backend}. For information on how to build the FFmpeg
development libraries, see \l{Building FFmpeg from source}.

To build Qt Multimedia with FFmpeg support, specify the \c{-DFFMPEG_DIR}
CMake variable on the configure command line when building Qt. Note the
\c{--} separator which separates ordinary configure arguments from CMake
parameters.

\badcode
qt-source/configure -- -DFFMPEG_DIR=<FFMPEG_DIR>
\endcode

Here, \c{<FFMPEG_DIR>} is the directory containing the FFmpeg include,
lib, and bin directories. To build Qt Multimedia without FFmpeg, omit
the \c{<FFMPEG_DIR>} variable and specify the \c{-no-feature-ffmpeg}
configure option.

If you prefer not to build all Qt's submodules, you can reduce configure
and build times using the \c{-submodules} configure option. This will
configure a build that only builds Qt Multimedia and its dependencies.

\badcode
qt-source/configure -submodules qtmultimedia -- -DFFMPEG_DIR=<FFMPEG_DIR>
\endcode

If you configure Qt Multimedia against FFmpeg built with shared
libraries (dynamic linking), the FFmpeg shared libraries must be in the
module loader's search path to run tests or use examples.

\note Qt Multimedia requires the FFmpeg avformat, avcodec, swresample,
swscale, and avutil libraries during runtime to be able to use the
FFmpeg media backend. If one or more of these dynamic libraries are not
found during application startup, the FFmpeg media backend will fail to
load, and the system will attempt to load the native backend. Qt
Multimedia doesn't support as many features on native backends.

If you don't already have these libraries in the \c{path}, specify the
\c{-DQT_DEPLOY_FFMPEG=ON} configure option. With this option enabled,
the necessary FFmpeg binaries will be copied to Qt's install directory
during the build and install steps:

\badcode
qt-source/configure -submodules qtmultimedia -- -DFFMPEG_DIR=<FFMPEG_DIR> -DQT_DEPLOY_FFMPEG=ON
\endcode

After configuring Qt Multimedia, carefully review the configure summary
(found in the config.summary file). You can verify that FFmpeg is found
under the "Plugin" section. Then follow the regular build and install
steps described in \l{Building Qt Sources}.

\section1 Platform Notes

\section2 Linux

\list
    \li When configuring Qt Multimedia with FFmpeg enabled, the
        pulseaudio development package is required. Without this
        package, FFmpeg will not be recognized.
    \li When using a version of FFmpeg that is built with VAAPI support,
        we recommend building Qt Multimedia with VAAPI support as well
        to make hardware texture conversion possible. To configure Qt
        Multimedia with VAAPI support, VAAPI developer libraries must be
        installed on your system. Review the config.summary file to
        verify that VAAPI support is enabled under the "Hardware
        acceleration and features" section.
    \li When configuring Qt Multimedia with the GStreamer backend, GStreamer
        v1.20 is the minimum requirement. However, we recommend using the
        latest stable GStreamer upstream release if possible.
\endlist
*/
