How to create a .mp4 Video from a collection of QOpenGLFramebufferObjects /QImages / Glunit textures

[Roby Brundle]

I am developing a Qt app for iOS, Android & OSX.

Situation:
I have an std::vector of QOpenGLFramebufferObjects. Each QOpenGLFramebufferObject can of course provide its own QImage or a GLunit texture by doing a takeTexture. So you can also say that I have a collection of QImages or GLunit textures.

Problem:
I want to create a .mp4 video file out of these QImages/QOpenGLFramebufferObjects which works on iOS, Android & OSX.

How should I do this? Any examples doing this with Qt? Which classes in Qt should I be looking into?

I am thinking to use ffmpeg or GStreamer whatever works best in Qt. But I want to know how to pass these QImages or Glunit textures to create the video. Is there Qt support to do this without having to use a 3d party library?

Should I use QVideoEncoderSettings to create the video?
Are there any examples in Qt doing this?
Which classes/components in Qt I should be looking into?

Is there something in Qt Multimedia that I can use?
If not then what is the best option wrt to making this work on Android & iOS?

PS :
I am using Qt 5.9.1 commercial version on Android & iOS

[SGaist]

Hi,

Something is not clear from your description, do you want your application to record a video file on all three platforms ? Or do you want to generate video files that can be played on all these platforms ?

If the former, what is the source of images ? Are you using widgets or QtQuick ?

[Roby Brundle]

@SGaist I want to generate video files that can be played on all 3 platforms.

The source QImages are are some are QOpenGLFramebufferObjects which are populated after some processing using OpenGL.

I am using Qt Quick commercial version for Android & iOS. And working on Qt 5.9.1.

Simplistically saying, I just want to create a video file from QImages or Glunit textures whichever option works with Qt.

[SGaist]

Well, I'm sorry to say that it's still not that clear, so let me rephrase that: will your application create these video files on iOS and Android ? Or are you creating a desktop only application that should create these video files ?

In any case, QOpenGLFramebufferObject has a toImage method that returns a QImage.

[Roby Brundle]

@SGaist Yes. My application will create these video files on iOS and Android. It is not a desktop only application. It is primarily for iOS & Android. But the application runs on MacOS as well which is my development environment.

Yes. QOpenGLFramebufferObject has toImage method to return a QImage. I already know that. But my question starts after this.

Rephrasing my question here again:
Consider you have 15 QOpenGLFramebufferObjects in memory. Each one of course can return a QImage. I wan to create a video (.mp4) out of these 15 QImages. How do I do this with Qt.

And of course, as I said I am running commercial paid version of Qt based Qt latest 5.9.1 released recently. It is a Qt quick based application.

[SGaist]

QMediaRecorder would be the starting point.

Note that there's no system encoder for h264, it's a non free-format.

[Roby Brundle]

@SGaist How can I pass QImages into QMediaRecorder & create a video out of it?
Is there a example or some code snippet you could point to?

Note that I don't need audio. I just want to programmatically create a video out of multiple QImages. And, this is has nothing to do with the camera . I am not trying to get images from camera.

Trying to see the examples of QMediaRecorder, all of them hooking on to the camera which I don't need to do with my program . Simply, I have some QImages in memory. Want to create a video from say 10 QImages.

[SGaist]

You need to create a QMediaObject that will provide the images to QMediaRecorder.

[Roby Brundle]

@SGaist said in How to create a .mp4 Video from a collection of QOpenGLFramebufferObjects /QImages / Glunit textures:

QMediaObject

Is there an example doing something similar? would be really helpful if you could point to an example doing something close

[SGaist]

AFAIK, no. You will have to take some inspiration from the Qt Multimedia sources.