# Qt AVPlayer

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**A free, open-source media player library for Qt, powered by FFmpeg.**

QtAVPlayer lets you decode, play, filter, and mux video/audio/subtitle streams in your Qt application — with hardware acceleration, accurate seeking, and full control over how frames are rendered.

> Works with Qt 5.6 through Qt 6.x, on **Linux, Windows, macOS, iOS, and Android**.

---

## Table of Contents

- [Why QtAVPlayer?](#why-qtavplayer)
- [Quick Start](#quick-start)
- [Usage Examples](#usage-examples)
  * [Opening a source](#opening-a-source)
  * [Getting video, audio & subtitle frames](#getting-video-audio--subtitle-frames)
  * [Hardware accelerated decoding](#hardware-accelerated-decoding)
  * [Rendering](#rendering)
    + [Video](#video)
    + [Audio](#audio)
    + [Subtitles](#subtitles)
  * [FFmpeg filters](#ffmpeg-filters)
  * [Multiple streams](#multiple-streams)
  * [Muxing streams](#muxing-streams)
  * [Accurate seeking](#accurate-seeking)
  * [Stepping frame by frame](#stepping-frame-by-frame)
  * [Listening to player signals](#listening-to-player-signals)
- [Installation & Build Options](#installation--build-options)
  * [Build Flags](#build-flags)
  * [QMake](#qmake)
  * [CMake](#cmake)
  * [Building as a Shared Library](#building-as-a-shared-library-libqtavplayer)
  * [Android Setup](#android-setup)
- [License](#license)
---

## Why QtAVPlayer?

- Demuxes and decodes **video / audio / subtitle** frames.
- Supports [FFmpeg Bitstream Filters](https://ffmpeg.org/ffmpeg-bitstream-filters.html) and [FFmpeg Filters](https://ffmpeg.org/ffmpeg-filters.html), including `filter_complex`. It runs multiple parallel filters on one input — one input frame can produce several output frames.
- Hardware-accelerated decoding or encoding. Also for filters.
- Hardware-accelerated rendering via `QAVWidget_OpenGL`, with support for Windows as well.
- You decide how frames are processed:
  - *Experimental* support for converting frames to `QVideoFrame` for copy-free rendering (note: not all Qt renderers support this, and best performance still depends on both decode and render being hardware-accelerated).
  - Audio playback via `QAVAudioOutput`, a thin wrapper around Qt's `QAudioSink`.
- Muxes and encodes streams from multiple sources into a single output file — or re-muxes the current streams into an output file without re-encoding them.
- Decodes all available streams simultaneously — for example, frames from multiple audio streams at once.
- Accurate seeking — jumps straight to the closest matching frame.
- Designed to be bundled directly into your app (via CMake or QMake), or built as a standalone shared library.
- Great fit for media analytics tools like [qctools](https://github.com/bavc/qctools) or [dvrescue](https://github.com/mipops/dvrescue).

In short, QtAVPlayer replaces a typical `FFmpeg` + `FFplay` pipeline — but integrated natively into Qt (QML or Widgets):

```bash
$ ./examples/qml_video :/valbok "if:you:like[cats];remove[this-sentence]"
```

---

## Quick Start

The simplest possible playback example:

```cpp
QAVPlayer player;
player.setSource(rtsp);

QObject::connect(&player, &QAVPlayer::videoFrame, &player,
    [&](const QAVVideoFrame &frame) {
        QVideoFrame videoFrame = frame; // compatible with QVideoFrame
        videoSink->setVideoFrame(videoFrame);
    }, Qt::DirectConnection);

player->play();
```

Check out the [examples folder](https://github.com/valbok/QtAVPlayer/blob/master/examples) for full QML and Widgets sample apps.

---

## Usage Examples

### Opening a source

QAVPlayer can open a URL, a local file, a `QIODevice`, or a device/camera:

```cpp
player->setSource("~/Videos/Generative-Pre-trained-Transformers-and-WW3.mkv");

// Adaptive streaming (DASH/HLS)
player->setSource("https://bitdash-a.akamaihd.net/content/MI201109210084_1/m3u8s/f08e80da-bf1d-4e3d-8899-f0f6155f6efa.m3u8");

// Playing from a Qt resource (qrc)
QSharedPointer<QIODevice> file(new QFile(":/alarm.wav"));
file->open(QIODevice::ReadOnly);
QSharedPointer<QAVIODevice> dev(new QAVIODevice(file));
player->setSource("alarm", dev);

// Camera input
player->setSource("/dev/video0");                 // Linux
player->setInputFormat("dshow");                  // Windows
player->setSource("video=Integrated Camera");
player->setInputFormat("avfoundation");            // macOS
player->setSource("default");
player->setInputFormat("android_camera");          // Android
player->setSource("0:0");

// These options will go to AVFormatContext
player->setInputOptions({{"user_agent", "QAVPlayer"}});
// Options for AVCodecContext
player->setVideoCodecOptions({{"fflags", "nobuffer"}, {"flags", "low_delay"}});

// Using FFmpeg protocols
player->setSource("subfile,,start,0,end,0,,:/root/Downloads/why-qtmm-must-die.mkv");
```

### Getting video, audio & subtitle frames

```cpp
QObject::connect(player, &QAVPlayer::videoFrame, player,
    [&](const QAVVideoFrame &frame) {
        QVideoFrame videoFrame = frame; // compatible with QVideoFrame
    
        // Convert to a different pixel format if needed
        auto convertedFrame = frame.convert(AV_PIX_FMT_YUV420P);
    
        // Map the frame to access raw data (downloads from GPU if needed)
        auto mapped = videoFrame.map();
        qDebug() << mapped.format << mapped.size;
    
        // Frames may carry OpenGL or Metal textures for copy-free rendering
        qDebug() << frame.handleType() << frame.handle();
    }, Qt::DirectConnection);

// Audio
QObject::connect(player, &QAVPlayer::audioFrame, player,
    [&](const QAVAudioFrame &frame) {
        qDebug() << frame.format() << frame.data().size();
    }, Qt::DirectConnection);

// Subtitles
QObject::connect(player, &QAVPlayer::subtitleFrame, player,
    [&](const QAVSubtitleFrame &frame) {
        for (unsigned i = 0; i < frame.subtitle()->num_rects; ++i) {
            if (frame.subtitle()->rects[i]->type == SUBTITLE_TEXT)
                qDebug() << "text:" << frame.subtitle()->rects[i]->text;
            else
                qDebug() << "ass:" << frame.subtitle()->rects[i]->ass;
        }
    }, Qt::DirectConnection);
```

### Hardware accelerated decoding

Hardware decoding is automatically negotiated based on the platform:

| Platform | Backend | Frame type |
|----------|---------|------------|
| Linux | VA-API / VDPAU | OpenGL |
| macOS / iOS | Video Toolbox | Metal |
| Windows | D3D11 | D3D11Texture2D |
| Android | MediaCodec | OpenGL |

Most platforms expose only a single device context, but enabling `CUDA` support adds more options to choose from. In that case, the platform's native device context is prioritized by default. If you want `CUDA` to be used instead, you can force a CUDA-based codec, which selects the CUDA device context:

```cpp
player->setInputVideoCodec("h264_cuvid");
player->setSource(file);
```

Notes:
- Set the `QT_AVPLAYER_NO_HWDEVICE` environment variable to force software decoding.
- You can also call `player.setInputVideoCodec("software")` to force software decoding for a specific player.
- Set the `QT_AVPLAYER_MAX_QUEUED_BYTES` or `QT_AVPLAYER_MAX_QUEUED_SEC` environment variables to limit the amount of data buffered in the audio and video queues while demuxing. Once the configured limit is reached, demuxing pauses until packets are consumed by the decoder.
- Not every FFmpeg decoder/filter supports hardware acceleration — QtAVPlayer falls back to software decoding automatically when needed.


### Rendering

#### Video

- The `QAVWidget_OpenGL` widget renders to OpenGL, also supports `D3D11Texture2D` textures in Windows — see [examples/widget_video_opengl](https://github.com/valbok/QtAVPlayer/blob/master/examples/widget_video_opengl).

```cpp
auto w = new QAVWidget_OpenGL(mainWidget);
QObject::connect(player, &QAVPlayer::videoFrame, w,
    [w](const QAVVideoFrame &frame) {
        w->setVideoFrame(frame);
    }, Qt::DirectConnection);
```

- Since `QAVVideoFrame` is compatible with `QVideoFrame`, `QtMultimedia` can render frames directly to QML or Widgets — see the [examples](https://github.com/valbok/QtAVPlayer/blob/master/examples/qml_video).

```cpp
QObject::connect(player, &QAVPlayer::videoFrame, this,
    [this](const QAVVideoFrame &frame) {
        if (videoSink) {
            // If the non-copy-free render is requested
            // map the frame before converting to QVideoFrame.
            // This will force rendering mapped data instead of texture handles.
            if (!m_copyFreeRender)
                frame.map();
            QVideoFrame qframe = frame;  // Converts to QVideoFrame
            videoSink->setVideoFrame(qframe);
        }
    }, Qt::DirectConnection);
```

#### Audio

The audio frames could be played using `QAVAudioOutput`:

```cpp
auto audioOutput = new QAVAudioOutput(&mainWidget);
auto audioDevices = QMediaDevices::audioOutputs();
if (!audioDevices.isEmpty())
    audioOutput->setAudioDevice(audioDevices.first());
QObject::connect(player, &QAVPlayer::audioFrame, audioOutput,
    [&](const QAVAudioFrame &frame) {
        audioOutput->play(frame);
    }, Qt::DirectConnection);
```

#### Subtitles

- Subtitles could be rendered directly to the video frames using `subtitles` filter, but requires to have software decoders:

```cpp
// Render bundled subtitles (requires not using hw_device_ctx — this is a software filter)
player->setFilter("subtitles=file.mkv");

// Render subtitles from an external .srt file
player->setFilter("subtitles=file.srt");
```

- Subtitles could be parsed and extracted from `QAVSubtitleFrame`:

```cpp
QAVSubtitleTextParser subtitleParser;
subtitleParser.load(player.currentSubtitleStreams().first());
QObject::connect(player, &QAVPlayer::subtitleFrame, player,
    [this](const QAVSubtitleFrame &frame) {
        QString text;
        if (subtitleParser.parseText(frame, text) >= 0)
            emit subtitleTextChanged(text, frame.duration() * 1000);
    }, Qt::DirectConnection);
```

- Subtitles could be rendered to `QImage`:

```cpp
QAVASSRenderer subtitleRenderer;
subtitleRenderer.load(player.currentSubtitleStreams().first());
QObject::connect(player, &QAVPlayer::subtitleFrame, player,
    [this](const QAVSubtitleFrame &frame) {
        auto img = subtitleRenderer.toImage(frame, size.width(), size.height());
        if (!img.isNull())
            emit subtitleImageChanged(img, frame.duration() * 1000);
    }, Qt::DirectConnection);
```

See the [qml_player](https://github.com/valbok/QtAVPlayer/blob/master/examples/qml_player).


### FFmpeg filters

```cpp
player1->setFilter("crop=iw/2:ih:0:0,split[left][tmp];[tmp]hflip[right];[left][right] hstack");
player2->setFilter("scale=iw/2:-1");
```

- Apply multiple filters at once, `QAVVideoFrame::filterName()` returns the filter name if any:

```cpp 
player->setFilters({
    "drawtext=text=%{pts\\:hms}:x=(w-text_w)/2:y=(h-text_h)*(4/5):box=1:boxcolor=gray@0.5:fontsize=36[drawtext]",
    "negate[negate]",
    "[0:v]split=3[in1][in2][in3];[in1]boxblur[out1];[in2]negate[out2];[in3]drawtext=text=%{pts\\:hms}:x=(w-text_w)/2:y=(h-text_h)*(4/5):box=1:boxcolor=gray@0.5:fontsize=36[out3]"
});
QObject::connect(player, &QAVPlayer::videoFrame, player,
    [&](const QAVVideoFrame &frame) {
        qDebug() << frame.pts() << frame.filterName();
    });
```

- Some filters could be hardware accelerated, like `scale_cuda` or `scale_vaapi`:

```cpp
// Requires to force cuda based codec
player->setInputVideoCodec("h264_cuvid");
player->setFilter("scale_cuda=1920:1080");
```

### Multiple streams

- `QAVPlayer::availableStreams()` returns all available streams in the source.
- `QAVPlayer::setAudioStream()`, `QAVPlayer::setSubtitleStream()`, `QAVPlayer::setVideoStream()` can change current decoding streams on fly.

```cpp
qDebug() << "Audio streams:" << player->availableAudioStreams().size();
qDebug() << "Current stream:" << player->currentAudioStreams().first().index()
         << player->currentAudioStreams().first().metadata();

player->setAudioStreams(player->availableAudioStreams()); // Decode all available audio streams

// Per-stream progress: pts, fps, frame rate, frame count, etc.
for (const auto &stream : player->availableVideoStreams())
    qDebug() << stream << player->progress(stream);
```

### Muxing streams

- Mux all streams to a file without re-encoding. It will use the same codecs without decoding the frames.

```cpp
player->setOutput("output.mkv");
```

- Combine streams from multiple players into a single file. This will decode frames first and then encode using the same codecs:

```cpp
QAVPlayer p1, p2;
QAVMuxerFrames muxer;

// The players must be loaded before loading the muxer
QTRY_VERIFY(p1.mediaStatus() == QAVPlayer::LoadedMedia);
QTRY_VERIFY(p2.mediaStatus() == QAVPlayer::LoadedMedia);

auto streams = p1.availableStreams() + p2.availableStreams();
muxer.load(streams, "output.mkv");

QObject::connect(&p1, &QAVPlayer::videoFrame, &p1,
    [&](const QAVVideoFrame &f) { muxer.enqueue(f); }, Qt::DirectConnection);
QObject::connect(&p1, &QAVPlayer::audioFrame, &p1,
    [&](const QAVAudioFrame &f) { muxer.enqueue(f); }, Qt::DirectConnection);
QObject::connect(&p2, &QAVPlayer::videoFrame, &p2,
    [&](const QAVVideoFrame &f) { muxer.enqueue(f); }, Qt::DirectConnection);
QObject::connect(&p2, &QAVPlayer::audioFrame, &p2,
    [&](const QAVAudioFrame &f) { muxer.enqueue(f); }, Qt::DirectConnection);

p1.play();
p2.play();
```

### Accurate seeking

If a frame exists at the requested timestamp, it's returned first.

```cpp
QObject::connect(&player, &QAVPlayer::seeked, &player,
    [&](qint64 pos) { seekPosition = pos; });
QObject::connect(&player, &QAVPlayer::videoFrame,
    [&](const QAVVideoFrame &frame) { seekFrame = frame; });

player.seek(5000);
QTRY_COMPARE(seekPosition, 5000);
QTRY_COMPARE(seekFrame.pts(), 5.0);
```

### Stepping frame by frame

Stepping emits exactly one frame.

```cpp
QObject::connect(&player, &QAVPlayer::videoFrame, [&](const QAVVideoFrame &frame) { receivedFrame = frame; });

if (player.state() != QAVPlayer::PausedState) {
    player.pause(); // Pausing always emits exactly one frame
    QTRY_VERIFY(receivedFrame);
}

player.stepForward();  // Advances and emits exactly one frame
player.stepBackward(); // Same, but backward
```

### Listening to player signals

Every action is confirmed with a signal, delivered in the correct order.
If `play()`, `pause()`, and `seek()` is called, then `played()`, `paused()` and `seeked()` is emitted accordinally.

```cpp
QObject::connect(p, &QAVPlayer::played,
    [&](qint64 pos) { qDebug() << "Playing started at" << pos; });
QObject::connect(p, &QAVPlayer::paused,
    [&](qint64 pos) { qDebug() << "Paused at" << pos; });
QObject::connect(p, &QAVPlayer::stopped,
    [&](qint64 pos) { qDebug() << "Stopped at" << pos; });
QObject::connect(p, &QAVPlayer::seeked,
    [&](qint64 pos) { qDebug() << "Seeked to" << pos; });
QObject::connect(p, &QAVPlayer::stepped,
    [&](qint64 pos) { qDebug() << "Stepped to" << pos; });
QObject::connect(p, &QAVPlayer::mediaStatusChanged,
    [&](QAVPlayer::MediaStatus status) {
        switch (status) {
        case QAVPlayer::EndOfMedia:
            qDebug() << "Playback finished, no frames left in queue";
            break;
        case QAVPlayer::NoMedia:
            qDebug() << "Demuxer threads finished";
            break;
        default:
            break;
        }
    });
```

---

## Installation & Build Options

QtAVPlayer is meant to be bundled directly into your application. A few compile-time defines let you opt into extra features.

### Build Flags

| Define | Enables |
|--------|---------|
| `QT_AVPLAYER_MULTIMEDIA` | `QtMultimedia` support (requires `QtGUI`, `QtQuick`, etc.) |
| `QT_AVPLAYER_CUDA` | CUDA support |
| `QT_AVPLAYER_VA_X11` | `libva-x11` hardware acceleration (Linux only) |
| `QT_AVPLAYER_VA_DRM` | `libva-drm` hardware acceleration (Linux only) |
| `QT_AVPLAYER_VDPAU` | `libvdpau` hardware acceleration (Linux only) |
| `QT_AVPLAYER_WIDGET_OPENGL` | The OpenGL-based widget |
| `QT_AVPLAYER_LIBASS` | `libass` support and `QAVASSRenderer` |

### QMake

Add [QtAVPlayer.pri](https://github.com/valbok/QtAVPlayer/blob/master/src/QtAVPlayer/QtAVPlayer.pri) to your `.pro` file:

```qmake
DEFINES += "QT_AVPLAYER_MULTIMEDIA"
INCLUDEPATH += ../../src/
include(../../src/QtAVPlayer/QtAVPlayer.pri)
```

If FFmpeg is in a custom location:

```bash
qmake INCLUDEPATH+="/usr/local/Cellar/ffmpeg/6.0/include" LIBS="-L/usr/local/Cellar/ffmpeg/6.0/lib"
```

### CMake

Include [QtAVPlayer.cmake](https://github.com/valbok/QtAVPlayer/blob/master/src/QtAVPlayer/QtAVPlayer.cmake) in your project:

```cmake
include_directories(QtAVPlayer/src)
set(QT_AVPLAYER_DIR QtAVPlayer/src/QtAVPlayer)
include(QtAVPlayer/src/QtAVPlayer/QtAVPlayer.cmake)
add_executable(${PROJECT_NAME} ${QtAVPlayer_SOURCES})
target_link_libraries(${PROJECT_NAME} ${QtAVPlayer_LIBS})
```

If FFmpeg is in a custom location:

```bash
cmake ../ -DQT_AVPLAYER_MULTIMEDIA=ON -DCMAKE_PREFIX_PATH=/opt/Qt/6.7.1/macos/lib/cmake -DCMAKE_LIBRARY_PATH=/opt/homebrew/Cellar/ffmpeg/7.0_1/lib
```

### Building as a Shared Library (`libQtAVPlayer`)

If bundling directly isn't convenient, build QtAVPlayer as a standalone shared library instead:

**1. Build and install:**

```bash
cmake ../src/QtAVPlayer \
  -DCMAKE_PREFIX_PATH=/opt/Qt/6.8.2/gcc_64/lib/cmake/Qt6 \
  -DCMAKE_INSTALL_PREFIX=/opt/QtAVPlayer/install \
  -DCMAKE_LIBRARY_PATH="/opt/ffmpeg/install/lib;/opt/Qt/6.8.2/gcc_64/lib" \
  -DCMAKE_CXX_STANDARD_INCLUDE_DIRECTORIES=/opt/ffmpeg/install/include \
  -DQT_AVPLAYER_MULTIMEDIA=On \
  -DQT_AVPLAYER_VDPAU=ON
make -j32
make install
```

**2. Link against it in your `CMakeLists.txt`:**

```cmake
find_package(QtAVPlayer REQUIRED)
target_link_libraries(${PROJECT_NAME} QtAVPlayer)
```

**3. Point CMake to the install location if needed:**

```bash
cmake ../ -DCMAKE_PREFIX_PATH="/opt/QtAVPlayer/install/lib/cmake;/opt/Qt/6.8.2/gcc_64/lib/cmake/Qt6" -DCMAKE_LIBRARY_PATH="/opt/Qt/6.8.2/gcc_64/lib"
```

### Android Setup

Point these environment variables to your prebuilt FFmpeg libraries for each target architecture:

```bash
export AVPLAYER_ANDROID_LIB_ARMEABI_V7A=/opt/mobile-ffmpeg/prebuilt/android-arm/ffmpeg/lib
export AVPLAYER_ANDROID_LIB_ARMEABI_V8A=/opt/mobile-ffmpeg/prebuilt/android-arm64/ffmpeg/lib
export AVPLAYER_ANDROID_LIB_X86=/opt/mobile-ffmpeg/prebuilt/android-x86/ffmpeg/lib
export AVPLAYER_ANDROID_LIB_X86_64=/opt/mobile-ffmpeg/prebuilt/android-x86_64/ffmpeg/lib
export CPLUS_INCLUDE_PATH=/opt/mobile-ffmpeg/prebuilt/android-arm64/ffmpeg/include:$CPLUS_INCLUDE_PATH

qmake DEFINES+="QT_AVPLAYER_MULTIMEDIA"
```

Then add the extra libraries to your app's `.pro` file:

```qmake
ANDROID_EXTRA_LIBS += \
    /opt/mobile-ffmpeg/prebuilt/android-arm/ffmpeg/lib/libavdevice.so \
    /opt/mobile-ffmpeg/prebuilt/android-arm/ffmpeg/lib/libavformat.so \
    /opt/mobile-ffmpeg/prebuilt/android-arm/ffmpeg/lib/libavutil.so \
    /opt/mobile-ffmpeg/prebuilt/android-arm/ffmpeg/lib/libavcodec.so \
    /opt/mobile-ffmpeg/prebuilt/android-arm/ffmpeg/lib/libavfilter.so \
    /opt/mobile-ffmpeg/prebuilt/android-arm/ffmpeg/lib/libswscale.so \
    /opt/mobile-ffmpeg/prebuilt/android-arm/ffmpeg/lib/libswresample.so
```

---

## License

See the [QtAVPlayer repository](https://github.com/valbok/QtAVPlayer) for license details.
