Legacy example · C++ · Version 1.0.0

Qt Video Replayer

Authors	Holoscan Team (NVIDIA)
Supported platforms	x86_64, aarch64
Language	C++
Version	1.0.0
Compatibility	HSDK 0.6
Contribution level	Level 1 · Very high-quality code
Source	HoloHub

Legacy HoloHub application

This application comes from HoloHub and was last tested with Holoscan SDK (HSDK) 0.6. It runs with the HoloHub CLI, ./holohub.

Qt Video Replayer

This application demonstrates how to integrate Holoscan with a Qt application. It support displaying the video frames output by a Holoscan operator and changing operator properties using Qt UI elements.

flowchart LR
    subgraph Holoscan application
        A[(VideoFile)] --> VideostreamReplayerOp
        VideostreamReplayerOp --> FormatConverterOp
        FormatConverterOp --> NppFilterOp
        NppFilterOp --> QtVideoOp
    end
    subgraph Qt Window
        QtVideoOp <-.-> QtHoloscanVideo
    end

The application uses the VideostreamReplayerOp to read from a file on disk, the FormatConverterOp to convert the frames from RGB to RGBA, the NppFilterOp to apply a filter to the frame and the QtVideoOp operator to display the video stream in a Qt window.

The QtHoloscanApp class, which extends the holoscan::Application class, is used to expose parameters of Holoscan operators as Qt properties.

For example the application uses a QML Checkbox is used the set the realtime property of the VideostreamReplayerOp operator.

    CheckBox {
        id: realtime
        text: "Use Video Framerate"
        checked: holoscanApp.realtime
        onCheckedChanged: {
            holoscanApp.realtime = checked;
        }
    }

The QtHoloscanVideo is a QQuickItem which can be use in the QML file. Multiple QtHoloscanVideo items can be placed in a Qt window.

import QtHoloscanVideo
Item {
    QtHoloscanVideo {
        objectName: "video"
    }
}

Run Instructions

Note: This application container is pinned to Holoscan SDK 3.2 since it requires CUDA Driver 550+ for running with Holoscan SDK 3.3+.

This application requires Qt.

For simplicity a DockerFile is available. To run this application:

./holohub run qt_video_replayer

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