picam | video recorder for Raspberry Pi

I want to take a frame from an Open CV webcam stream, produce a JPEG thumbnail and then encode it as Base64 (It will then be sent as an MQTT message, but this is not the problem).

My Python "sendimage" function is:

I am currently trying to incorporate a temporary stream in my card panel layed out like this.

Layout

Where it says scan your QRCode im trying to get a stream from the picam. Here is the issue.

I dont know how i can buffer that into the Java application

I got the command i want --> "raspistill -w 200 -h 200 -q 100 -t 5", but i just dont know how this would work. This is the first time im dealing with any video stream.

As for the second part. I need that "preview" to take a picture whenever it is able to grab the QRCode. I checked both apis for the raspberry pi camera but im still lost as in for direction. I also need this buffered so i can instantly parse it into my decodeQRCode method. What component do i need to accomplish this?

I am trying to compile some code using visual studios cross platform feature, but I am having some issues, I copied over the include files like they say you should and intellisense works fine. during compiling at the linking stage I get the can not find lib...

I see a ton of info about piping a raspivid stream directly to FFMPEG for encoding, muxing, and restreaming but these use cases are mostly from bash; similar to:

raspivid -n -w 480 -h 320 -b 300000 -fps 15 -t 0 -o - | ffmpeg -i - -f mpegts udp://192.168.1.2:8090ffmpeg

I'm hoping to utilize the functionality of the Picamera library so I can do concurrent processing with OpenCV and similar while still streaming with FFMPEG. But I can't figure out how to properly open FFMPEG as subprocess and pipe video data to it. I have seen plenty of attempts, unanswered posts, and people claiming to have done it, but none of it seems to work on my Pi.

Should I create a video buffer with Picamera and pipe that raw video to FFMPEG? Can I use camera.capture_continuous() and pass FFMPEG the bgr24 images I'm using for my OpenCV calculation?

I've tried all sorts of variations and I'm not sure if I'm just misunderstanding how to use the subprocess module, FFMPEG, or I'm simply missing a few settings. I understand the raw stream won't have any metadata, but I'm not completely sure what settings I need to give FFMPEG for it to understand what I'm giving it.

I have a Wowza server I'll eventually be streaming to, but I'm currently testing by streaming to a VLC server on my laptop. I've currently tried this:

I am working on a project for which I have to stream live video from raspberry pi camera module in a network. For the purpose I am using nginx server and picam software but I am having hard time with it. I added the path to the directory in nginx.conf file uder the http section like this:

I like to capture images using RPi at least 60Hz. My code is in C++ and we have a library here for C++ interface. But that library has maximum 30Hz. My target is minimum 60 Hz. So far what I found is raspistill can make upto 90Hz, so I am trying to interface my C++ program to raspistill code. I found one library here PiCam that has direct interface to raspistll. Not very sure, it can go to 60Hz, I am still trying to test it and have a few issues. My queries are

(1)How is it possible to have 60Hz fps at RPi using C++?

(2)To interface to PiCam, I have already compiled, build and installed the library with no issues. But I get black image when I capture. What could be the issue? A part of my code is shown below.