[WIP] Two video streams

[d0vgan]

[WIP] Two video streams

Description

You can treat this as a lite alternative to the #8017 .
To be honest, I don't really know QML, and this is just a small attempt to add the support of 2 video streams to QGC.
Here is what it does:

• it assumes there are 2 cameras, and each of these cameras has an HQ and a LQ videostream;
• an "Enable auxiliary video streams" checkbox has been added to QGC's Video Settings;
• once the "Enable auxiliary video streams" checkbox, you can specify the Cam 1 HQ, Cam 2 LQ, Cam 2 HQ and Cam 1 LQ streams there.

This is work-in-progress and demonstrates the current state. Any hints and contributions are welcome.

Test Steps

1. Start mediamtx: ./mediamtx
2. Start video stream 1: ffmpeg -re -stream_loop -1 -i anim1.mp4 -c copy -f rtsp rtsp://127.0.0.1:8554/stream1
3. Start video stream 2: ffmpeg -re -stream_loop -1 -i anim2.mp4 -c copy -f rtsp rtsp://127.0.0.1:8554/stream2
4. Start QGC and specify the given streams in the Video Settings
5. In QGC's window, right-click the small video and select "Switch to auxiliary video stream"

And here is the problem: currently, the switching between the video streams is very "heavy". This is how the video receivers seem to work. Maybe this can be improved by updating the GStreamer-related code, but I don't have such expertise.

Related Issue

#8017

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[DronecodeBot]

This pull request has been mentioned on Discussion Forum for PX4, Pixhawk, QGroundControl, MAVSDK, MAVLink. There might be relevant details there:

https://discuss.px4.io/t/qgc-to-support-multiple-cameras-videostreams/47878/6

[DonLakeFlyer]

Is this to provide display of two video streams simultaneously or is it for switching between two streams. If it's for switching between streams QGC support for mavlink v2 camera protocol already support that. Not super interested in creating some other way to do this.

[d0vgan]

Could you provide more details on "QGC support for mavlink v2 camera protocol" ?
Our reasoning to do the changes in the code were the following:

1. A drone has 2 cameras
2. Each of the 2 cameras provides 2 streams: HQ stream and LQ stream
3. We need to see a HQ stream from 1st camera and a LQ stream from 2nd camera simultaneously and to be able to switch between them (i.e. when clicking a small view with the 2nd camera LQ stream, we are replacing it with a bigger view with the 2nd camera HQ stream, while the previously shown 1st camera HQ stream is replaced with the small view with the 1st camera LQ stream).

Let me iilustrate this by an image:

[DonLakeFlyer]

Mavlink Camera protocol: https://mavlink.io/en/services/camera.html

That said, even with that qgc does not have support to show two video streams at once. Adding support for that on top of the existing Mavlink camera protocol is interesting. But adding support for the whole thing as a one-off from the new camera protocol is not interesting for regular QGC codebase.

[DonLakeFlyer]

Closing this since it isn't something we are going to support unless it uses mavlink camera protocol