How video is played in the QML? - c++

I am new to qml. I would like to know how the video is played in the qml. How the video is handled in the back-end(The classes and modules responsible for video playback). How can i add a custom player to play back video in QML? Is there any documents on this? Is there any tutorial for writing the qt-plugin for video playback.
I don't know where to start looking? Please Help. Thanks in advance.

It seems that you are a newcomer to the topic, so I will start with the basics.
The responsible part of the Qt architecture is QtMultimedia for this. That is the module I would start taking a look at. This essential modul is responsible for the audio and video bits in Qt. It deals with the boiler plate as well as the convenient higher-level interface like QML.
It really depends on what video playback you would like to write. You can find the existing backends in here.
As for writing a new backend and/or plugin, this post gives some insight how this has been achieved for one. The official documentation about is also a recommended material for reading.

Related

How can I control and receive video stream from SITL drone using px4,gazebo and C++ without using ROS?

I want to program a drone to fly with a C++ project using image processing analysis in real-time (using OpenCV). I want to do it with PX4, Gazebo simulator. The final goal is to run the project on a real
drone using Jetson-Nano and Pixhawk drone.
I have 2 main problems.
I can't manage to get the video stream of the px4 drone models without using ROS. I have followed this official guide to install the relevant software (Gazebo, Px4, GCS).
For python we have Drone-kit library to control the drone, but I want to use C++ for my project. what are the alternatives tools instead of the Drone-kit to control drones with C++ and how I can receive the video stream from the gazebo px4 drone?
After that I tried to search for information online for hours and go through the documentations, I could not find a suitable guide or solution.
thanks.
Posting this as an answer after details in the comments made things more clear.
For an application like this ROS should most definitely be used. It comes with a wide range of pre-built packages and tools to enable easy localization and navigation. When looking at UAVs the MoveIt! package is a good place to look. It handles 3D navigation and has a few UAV implementations already. The Hector Quadcopter package is another good option for something like SLAM.

Audio plugins. Mapping MIDI to audio files

I am a reasonably experienced programmer who is pretty inexperienced with C++ and brand new to creating plugins.
Thus far I have looked into http://martinfinke.de/blog/tags/making_audio_plugins.html but it seems incredibly dated, I'm hitting a whole load of compilation issues and don't know where to get the legacy SDKs which would mean I had the exact same set up that the author is using.
I have also looked into JUCE but there isn't a vast amount of resources out there that I can find.
What I am trying to do is create a plugin, VST only for now (will look at compatibility with other vendors later) which simply maps a MIDI input to an audio file which my partner, who is a sound engineer, has already created. We have enough samples for randomising and also various velocities
I highly recommend just working your way through the JUCE Tutorials or watching through the JUCE videos by The Audio Programmer on Youtube to get you started on JUCE. Whilst the first tutorials do not produce audio plugins, the components used within them are crucial 'building blocks' to creating a full plugin.
When you're happy with creating basic GUI elements and how audio can be played/ synthesised within both the Audio App and Audio Plug-In projects, I recommend you try building the smallest part of your plugin you can and, getting that working and slowly building upon it. I suggest starting with how to load an audio file into the buffer (take a look at the looping audio tutorial) as once that is complete it is just a case of using the tutorials again to create and handle the MIDI data.

DirectShow filter to detect specific frequencies

loving and gracious Internet community. I am working on building an application that uses DirectShow to play HLS streams and run some processes on them.
I used Graphedt.exe to render the URL that we use and it works great, but we need to be able to detect specific sub-audible frequencies. I assume that a filter would serve that purpose well. Just not totally sure how to analyze the incoming frames for an audio frequency.
I am new to C++ programming but am willing to learn and work on it.
Any help is greatly appreciated. Thanks.
If you are using the default DirectSound audio renderer, then you should try writing a TransInPlace filter to Account the buffers flowed.
Furthermore, you can add a property page to be useful when debugging.

how to write a music player in linux using ffmpeg

i have a course project in making a music player in linux with ffmpeg, can anyone give me some instruction about it. Does anyone know of any good resources for learning how to use ffmpeg? Considering I just want to write a simple music player with support for a broad range of formats and codecs, is ffmpeg too heavyweight for a project of this scope? thank you!
This is not a specific question, there are a lot of tutorials on the Internet like http://dranger.com/ffmpeg/tutorial01.html and other tutorials.

my first Qt application, c++ (little opencv)

I am to make a little demo app to learn some Qt and c++ and if anyone know some guides that might be good for this project i am happy to hear about it.
What i wanna do:
I want to make an app where i can open a folder location of training data(images). Then i want to show the images one by one and mark ROI (rects, cirles, polygons) or bounding boxes of objects. The reason is to mark objects in pictures and then same this regions to a file for later use for image processing in matlab or similar apps.
Thanks.
Qt has lots of very good official tutorials
Try playing with example projects. You can start by changing an example projects to suite your needs.