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Get the latest image from IP Camera in Java

I'm working on Java APP that will process the stream from the IP Camera (Milesight MS-C2682-P) located on Local network. It will detect objects and trigger actions depending on what's in the image (let´s say it will start an alarm, when a person is detected) - for that I need it to be with minimal delay.
I have an RTSP link "rtsp://username:password#ip_addr:rtsp_port/main", to access stream from my IP Camera, but in my JAVA app there is a 12 seconds delay (and it's increasing). This happens, when images are not handled fast enough, so they are buffered. There are "hacks" and "workarounds" (OpenCV VideoCapture lag due to the capture buffer), but I believe there has to be a prettier solution.
The other link I was able to get is an HTTP one, that uses also H.264 codec (can be used with MJPEG and MPEG4, if there is a possible way to use them effectively). "http://username:password#ip_addr:http_port/ipcam/mjpeg.cgi" - works like a charm.. in Python and browser. However, it doesn´t work in Java, an error is thrown:
OpenCV(4.2.0) C:\build\master_winpack-bindings-win64-vc14-static\opencv\modules\videoio\src\cap_images.cpp:253: error: (-5:Bad argument) CAP_IMAGES: can't find starting number (in the name of file): HTTP_URL in function 'cv::icvExtractPattern'
Both links work smoothly in VLC.
So, the network is not a problem ('cause VLC handles stream with minimal delay) and Python using OpenCV is also doing a good job. It all comes down to Java implementation of OpenCV.. I guess.
Here is a Java code:
VideoPlayer videoPlayer = new VideoPlayer(); // My Class, just creates and updates JFrame, works like a charm with laptop's webcam, so certainly no issues here
Mat image = new Mat();
VideoCapture ipCamera = new VideoCapture(RTSP_URL);
// or the HTTP link
// VideoCapture ipCamera = new VideoCapture(HTTP_URL);
// verify if u got access to camera
if (!ipCamera.isOpened()) {
System.out.println("ERROR: Camera isn't working !!! ");
return;
}
System.out.println("OK: Connected to camera.");
while (true) {
ipCamera.read(image);
videoPlayer.updateVideo_MatImage(image);
}
And this is the Python code I'm using:
import cv2
cap = cv2.VideoCapture(RTSP_URL)
# or the HTTP link
# cap = cv2.VideoCapture(HTTP_URL)
while True:
ret, image = cap.read()
cv2.imshow("Test", image)
if cv2.waitKey(1) & 0xFF == ord('q'):
break
cv2.destroyAllWindows()
I just need to get the latest image, when a request is made. So I need to avoid any kind of buffering. It has to be implemented in Java since it's a requirement for this project.
So is there a way to get only latest image from camera?
What could cause the error mentioned above?
Thank you guys for any advice.

VLCJ - Visualizer has no output

I am trying to get VLCJ to do a visualizer for the mp3 files its playing from a HTTP stream. Video shows up when I stream one. But when audio plays, nothing happens.
This is my code on the cliente side
EmbeddedMediaPlayerComponent empc = new EmbeddedMediaPlayerComponent();
String[] op = {"audio-visual=visual", "effect-list=spectrum", "effect-width=800", "effect-height=80"};
empc.mediaPlayer().media().play("http://127.0.0.1:" + port, op);
There's a lot more code, but nothing directly related to VLCJ.
I can post the server code if you think it's necessary, but I think it's not needed since the media reaches the client perfectly.
So, audio and video work fine, but the visualizer simply doesn't show up.
Any help would be appreciated.

First, check if you have the visualisation plugins installed on your OS distribution.
I am using Linux Mint and those plugins are NOT installed by default when you install VLC.
Do this:
sudo apt install vlc-plugin-visualization
Second, it seems you have to set the visualisation options on the MediaPlayerFactory rather than passing them when you invoke play() on the media player.
For example:
String[] options = new String[] {"--audio-visual=visual", "--effect-list=scope,vuMeter,spectrometer,spectrum"};
factory = new MediaPlayerFactory(options);
mediaPlayer = factory.mediaPlayers().newEmbeddedMediaPlayer();
This example configures the factory before creating a media player from it, you can use any of the media player factory creation methods.
The visualisations scale with the size of the window, I could not get the width and height parameters to do anything.
This is fine for audio.
If you play video, then the video will go the video surface embedded in your application and VLC will open up a new separate window to show the visualisations (probably you don't want that).

How to change a photo?

I am trying to change photos in android studio by clicking on my button.
When I put code for changing the photo in my MainActivity.java I keep getting this type of error messages and it says :
Cannot resolve symbol "image"
image.setImageResource(R.drawable.xxx);
I am watching Udemy course for android development and I have done everything same like the professor on that video.
I have tried to restart android studio.
I have tried to make new project.
I have tried to clear invalidate caches and restart.
public void changeImage(View view)
{
ImageView bitcoin = findViewById(R.id.bitcoin);
image.setImageResource(R.drawable.xxx);
}
I hope there is actual error with android studio,because code is clone of the video that I am watching.

You are binding your layout's ImageView in Java file with bitcoin variable and you are trying to set an image on an unknown variable 'image'(maybe it's not defined in the class). So you have to set as below.
ImageView bitcoin = findViewById(R.id.bitcoin);
bitcoin.setImageResource(R.drawable.xxx);

Set Your Code Like this
ImageView image = findViewById(R.id.bitcoin);
image.setImageResource(R.drawable.xxx);

change your this line
image.setImageResource(R.drawable.xxx)
to this one:
bitcoin.setImageResource(R.drawable.xxx)

Citymaps questions on Android studio

I have some new questions in today's citymaps development.
In the Android studio,if I develop the code for citymap, there are always no logs showing but for others that does not happen. Why?
According to the citymaps official website, to create a map instance with CitymapsMapFragment, but in the sample project which citymaps provides, it uses SupportCitymapsMpaFragment ,What is the difference between them?
When the map is loading complete, is it automatically positioning to the current position or some other default position? Where is it?
If I open the GPS location，I can locate to the current position and show a blue arrow quickly, but too much power consumption,are there any other location way like network or base station location?
Code follows:
CitymapsMapFragment fragment = (CitymapsMapFragment)fragmentManager.findFragmentById(R.id.map);
if (fragment != null) {
fragment.setMapViewListener(this);
}
I did not find the fragment have the method setMapViewListener but setMapViewReadyListener,does it right?
Other code:
CitymapsMapView mapView = new CitymapsMapView(this, options, this);
When I add animate in additional methods like this：
mapView.setMapPosition(position, 300, new MapViewAnimationListener() {
#Override
public void onAnimationEnd(boolean completed) {
Log.d("SomeApp", "Move Complete!");
}
});
the project fails and exits,I tried to surround the code with try-catch block to catch exception for purpose, but nothing shows in logcat view. Why?

I am developer on the Citymaps project. I will do my best to answer all your questions
1) If you are not receiving log statements, this is likely an issue with your own application, IDE, or device configuration. In our own application, which uses the Citymaps SDK, we have no issues with logging.
2) Prior to using the Citymaps SDK, it is highly advisable that you familiarize yourself with fragments, but the short version is that SupportCitymapsMapFragment extends from the Fragment class in the v4 support library.
3) It is up to you to set the default position the map.
4) If you create a class which implements from the LocationSource interface, and then call mapView.setLocationSource, you can modify the behaviors of the map's location services. For an example, have a look at CitymapsLocationSource.java, which is the default implementation for this interface used by the SDK.
As for the exception you are having, you have not provided nearly enough information. Please show a stack trace, and I may be able to help.
Thank you for using our SDK, feel free to post again with any more questions.

Take Screenshot of Android screen and save to SD card

There are a few questions here on SO about capturing screenshots of an android application. However, I haven't found a solid solution on how to take a screenshot programatically using the android SDK or any other method.
So I thought I would ask this question again in the hopes that I can find a good solution, hopefully one that will allow capturing full length images that I can save to the SD card or somewhere similar.
I appreicate any help

This is not possible directly on the device/emulator, unless it is rooted.
to honest all I need it for is the emulator as this is for a testing application on a PC
This sounds like a job for monkeyrunner.

monkeyrunner tool can do the job for you with bit of adb command, [python script]
from com.android.monkeyrunner import MonkeyRunner, MonkeyDevice
//waits for connection
device = MonkeyRunner.waitForConnection()
//take the current snapshot
device.takeSnapshot()
//stores the current snapshot in current dir in pc
device.writeToFile('current.png')\
//copy it to the sd card of device
os.subprocess.call('adb push current.png /sdcard/android/com.test.myapp/current.png')
Note: call this jython script file
monkeyrunner.bat <file name>

You will most likely not be happy with this answer, but the only ones that I have seen involve using native code, or executing native commands.
Edit:
I hadn't seen this one before. Have you tried it?:
http://code.google.com/p/android-screenshot-library/
Edit2: Checked that library, and it also is a bad solution. Requires that you start the service from a pc. So my initial answer still holds :)
Edit3: You should be able to save a view as an image by doing something similar to this. You might need to tweek it a bit so that you get the width/height of the view. (I'm inflating layouts, and specify the width/height when I layout the code)
View content = getView();
Bitmap bitmap = Bitmap.createBitmap(width, height, Config.ARGB_8888);
Canvas canvas = new Canvas(bitmap);
File file = new File(pathAndFilename);
file.createNewFile();
FileOutputStream ostream = new FileOutputStream(file);
bitmap.compress(CompressFormat.PNG, 100, ostream);
ostream.close();

You can look at http://codaset.com/jens-riboe/droidatscreen/wiki (with a write up at http://blog.ribomation.com/2010/01/droidscreen/): this is a Java library that uses adb to capture a screen shots. I've been able to (with a lot of elbow grease) modify the source to let me automatically capture a timed series of screen shots (which I use for demo videos).
You can see the class structure at http://pastebin.com/hX5rQsSR
EDIT: You'd invoke it (after bundling all the requirements) like this:
java -cp DroidScreen.jar --adb "" --device "" --prefix "" --interval