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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).

Video Transcode with Android MediaCodec

Struggling with Android MediaCodec, I'm looking for a straight forward process to change the resolution of a video file in Android.
For now I'm trying a single thread transcoding method that makes all the work step by step so I can understand it well, and at high level it looks as follows:
public void TranscodeVideo()
{
// Extract
MediaTrack[] tracks = ExtractTracks(InputPath);
// Decode
MediaTrack videoTrack = tracks.Where(o => o.IsVideo).FirstOrDefault();
MediaTrack rawVideoTrack = DecodeTrack(videoTrack);
// Edit?
// ResizeVideoTrack(rawVideoTrack);
// Encode
MediaFormat newFormat = MediaHelper.CreateVideoOutputFormat(videoTrack.Format);
MediaTrack encodeVideodTrack = EncodeTrack(rawVideoTrack , newFormat);
// Muxe
encodeVideodTrack.Index = videoTrack.Index;
tracks[Array.IndexOf(tracks, videoTrack)] = encodeVideodTrack;
MuxeTracks(OutputPath, tracks);
}
Extraction works fine, returning a track with audio only and a track with video only. Muxing works fine combining again two previous tracks. Decoding works but I don't know how to check it, the raw frames on the track weight much more than the originals so I assume that it's right.
Problem
The encoder input buffer size is smaller than the raw frames size, and also related to the encoding configured format, so I assume that I need to resize the frames in some way but I don't find anything useful. I'm correct on this? I'm missing something? What is the way to go resizing Raw video frames? Any help? :S
PD
Maybe you will notice that I'm using C# (Xamarin.Android) for more fun. But the underlaying API is of course Java.
I'm using ByteBuffers, not Surfaces because it seems easier. I will be the next step using surfaces, any advice is welcome.
I know that the single thread process is highly inefficient, but makes it simple. It will be another next step to connect the decoder output buffer to the encoder input buffer.
I digged through PhilLab, Grafika and Bigflake examples but nothing seems to be very useful for me.
Avoiding to use ffmpeg on Android.
Thank you everyone for your time.

Going off of the comment above to implement libVLC
Add this to your app root's build.gradle
allprojects {
repositories {
...
maven {
url 'https://jitpack.io'
}
}
}
Add this to your dependent app's build.gradle
dependancies {
...
implementation 'com.github.masterwok:libvlc-android-sdk:3.0.13'
}
Here is an example of loading an RTSP stream as an activity
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.camera_stream_layout);
// Get URL
this.rtspUrl = getIntent().getExtras().getString(RTSP_URL);
Log.d(TAG, "Playing back " + rtspUrl);
this.mSurface = findViewById(R.id.camera_surface);
this.holder = this.mSurface.getHolder();
ArrayList<String> options = new ArrayList<>();
options.add("-vvv"); // verbosity
//Add vlc transcoder options here
this.libvlc = new LibVLC(getApplicationContext(), options);
this.holder.setKeepScreenOn(true);
//this.holder.setFixedSize();
// Create media player
this.mMediaPlayer = new MediaPlayer(this.libvlc);
this.mMediaPlayer.setEventListener(this.mPlayerListener);
// Set up video output
final IVLCVout vout = this.mMediaPlayer.getVLCVout();
vout.setVideoView(this.mSurface);
//Set size of video to fit app screen
DisplayMetrics displayMetrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);
ViewGroup.LayoutParams videoParams = this.mSurface.getLayoutParams();
videoParams.width = displayMetrics.widthPixels;
videoParams.height = displayMetrics.heightPixels;
vout.setWindowSize(videoParams.width, videoParams.height);
vout.addCallback(this);
vout.attachViews();
final Media m = new Media(this.libvlc, Uri.parse(this.rtspUrl));
//Use this to add transcoder options m.addOption("vlc transcode options here");
this.mMediaPlayer.setMedia(m);
this.mMediaPlayer.play();
}
Here is the documentation of vlc transcoder options
https://wiki.videolan.org/Documentation:Streaming_HowTo_New/

You are right, the input buffer size of the encoder is smaller because it expects input to be of the specified dimensions. The encoder only, like the name suggests, encodes.
I read your question as more of a "why" than a "how" question so i'll only point you to where you'll find the "why's"
The decoded frame is a YUV image (is suggest to quickly skim through the wikipedia article), usually NV21 if i'm not mistaken but might be different from device to device. To do this i suggest you use a library as every every plane of the image needs to be scaled down differently and it usually takes care of filtering.Check out libYUV. If you are interested in the actual resizing algorithms check out this and for implementations this.
If you are not required to handle the decoding and encoding with bytebuffers, i suggest to use a surface as you already mentioned. It has multiple benefits over decoding to bytebuffers.
More memory efficient as there is no copy between the native buffer and app allocated buffer, the native buffers are simply geting swapped from and to the surface.
If you plan to render the frame, be it for resizing or displaying, it can be done by the devices graphic processor. On how to do that check out BigFlakes DecodeEditEncode test.
In hope this answers some of your questions.

OpenCVFrameGrabber javacv in MATLAB doesnt work

I am using this code in MATLAB R2015a:
javaaddpath('javacv.jar')
import org.bytedeco.javacv.*
grabber = OpenCVFrameGrabber(0)
grabber.start()
img = grabber.grab()
The first time I use this code, it works, opens the camera and grub some image.
After I use grabber.stop(), the code doesn't work any more.
Even if restart MATLAB, and make sure I can open the camera in other programs and made sure the camera is available.
When I run this line: grabber.start(), a new window 'Video Source' is opened.
It does not open when I use the code for the first time.
Then I press ok, and there is exception:
Java exception occurred:
org.bytedeco.javacv.FrameGrabber$Exception:
cvCreateCameraCapture() Error: Could not create
camera capture.
at
org.bytedeco.javacv.OpenCVFrameGrabber.start(OpenCVFrameGrabber.java:179)
How I can solve it?

as #Samuel Audet as Mention,
I switch to VideoInputFrameGrabber( for windows )
for linux we need to use FrameGrabber.createDefault(0) , 0 is device index as webcam is at 0 by default
Now the code is look like that, and it work. (Maybe It what i was using in the first time??)
javaaddpath('javacv.jar')
import org.bytedeco.javacv.*
grabber = VideoInputFrameGrabber(0)
grabber.start()
img = grabber.grab()
EDIT:
as #Samuel Audet as Mention,
For cross platform code, I switch to FrameGrabber.createDefault()
javaaddpath('javacv.jar');
import org.bytedeco.javacv.*
grabber = FrameGrabber.createDefault(0);
grabber.start();
img = grabber.grab();

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