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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 assert a screen with Sikuli java API(Not Sikuli script)

In Sikuli script, we have different ways of asserting like Screen.exists(a.png) etc for image assertion. But can someone please tell me how to assert an application screen with a screenshot file.
My requirement is that, I'm logging into a windows application, and after logging in I want to verify the screen that appears with a screenshot file(.png) captured earlier.
Sikuli api 1.0.2
Windows 7 64 bit

This should help you-
int timeout = <Specify timeout in millis>;
String imagePath = <give the path of your screenshot image here>;
ImageTarget target = new ImageTarget(new File(imagePath));
ScreenRegion result = desktop.wait(target,timeout);
Here if result is null after the timeout, it would mean the image found in the application does not match the one at the path of the screenshot you would have mentioned.

Webcam - detect QR code, take snapshot and decode

I am currently trying to write a java program to utilize either a built in laptop webcam or an external USB webcam. This would hopefully be compatible with both PC and Mac.
I was wondering if anyone knew of a library that can deal with it all? I don't really want to reinvent the wheel and I wouldn't have any idea where to start in 1) detecting a webcam, 2) taking a snapshot when a QR code is detected.
I am familiar with ZXing for decoding barcode images however.
I have searched high and low, I strongly suspect the library I look for doesn't exist, however its worth an ask!
My first question on here, so I hope it is clear!
edit: alternatively, if one doesn't exist, could you point me in the right direction of how to take a snapshot from webcam when a QR code is detected? :)
Thanks

This example present how to read QR code data with Webcam Capture library together with ZXing. Webcam Capture is compatible with both 32- and 64-bit Windows, Linux and Mac OX. For Linux it also supports ARM architecture.
The code is pretty simple:
Webcam webcam = Webcam.getDefault(); // non-default (e.g. USB) webcam can be used too
webcam.open();
Result result = null;
BufferedImage image = null;
if (webcam.isOpen()) {
if ((image = webcam.getImage()) == null) {
continue;
}
LuminanceSource source = new BufferedImageLuminanceSource(image);
BinaryBitmap bitmap = new BinaryBitmap(new HybridBinarizer(source));
try {
result = new MultiFormatReader().decode(bitmap);
} catch (NotFoundException e) {
// fall thru, it means there is no QR code in image
}
}
if (result != null) {
System.out.println("QR code data is: " + result.getText());
}

zxing has a port to Actionscript, which would make it usable via Flash, which can access a webcam. The port is a little old and not 100% complete, but ought to work.

You could use gstreamer in order to interact with your camera. For windows it could be gstreamer again or DirectShow. In both cases you will need to capture your data by using some special filters, in DirectShow it would be SampleGrabber. I think that gstreamer should provide some similar plugins.

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