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• How to link and call function of prebuild static native library from android studio

  23 janvier 2017, par Janaki

  I need to change pitch and time stretching of an audio. For this I am using prebuild static library. Currently I am having libZtxAndroid.a static library and corresponding header file which contains function declaration. But I don’t know how to load this library in my android studio app and call native function from java code. I explored many links and tried to load this library. But all attempts are failed. This is the one link which I have tried last time https://tariqzubairy.wordpress.com/2012/03/12/use-of-prebuild-static-library-compiled-with-android-toolchain/

  Also I am using FFMPEG shared library and MP4Parser (https://github.com/sannies/mp4parser) library in this app for adding water mark to video and merging audio respectively. Can any one help from basics.

  1. How to load static library ?
  2. Where I need to place that static library ?
  3. Where I need to create jni folder (folder structure) ?
  4. How to call function available in that static library with the help of header file from java code ?

• "method DESCRIBE failed : 401 Unauthorized" in Ffmpeg, yet VLC accepts the exact same RTSP URL

  30 septembre 2021, par IpsRich

  I've an RTSP URL that includes the username and password (i.e. of the form rtsp://username:password@server:554/path) and this works in VLC, but using this as an input to Ffmpeg, I get back the above DESCRIBE error and it aborts.

  


  I wondered if it might be the version of Ffmpeg I've got, but I used a fresh one via Docker (alfg/ffmpeg:latest) and the result was the same.

  


  Is there something I have to do, perhaps some extra information/hint I have to provide to Ffmpeg, to get it to accept the credentials and get past the DESCRIBE ? Or if it's the DESCRIBE bit that's the problem, can I get it to skip that (perhaps by providing all the source stream details manually) so that it doesn't fail ?

  


  I'd hoped that this might be the same problem, but it's not - my URL is quoted and doesn't contain anything like ? or *.

  


  (In case it has any bearing, I'm trying to take an RTSP stream that requires credentials, resize it on the fly using Ffmpeg, and "pipe" the new RTSP to RTSP Simple Server. Most of this I can do : it's just the credentials that are tripping me up.)

  


  UPDATE : One thing I didn't mention previously (because it didn't seem relevant) is that the RTSP stream comes from Milestone's Open Network Bridge server. It seems that ONB does not now allow URLs containing credentials, although this does not explain why the same URL works in VLC. Perhaps VLC extracts the credentials and provides them another way ? I've a support case open on this to try to get to the bottom of it. I'll update here if I discover anything helpful...

  


• How to stream frames from OpenCV C++ code to Video4Linux or ffmpeg ?

  6 juillet 2022, par usamazf

  I am experimenting with OpenCV to process frames from a video stream. The goal is to fetch a frame from a stream, process it and then put the processed frame to a new / fresh stream.

  


  I have been able to successfully read streams using OpenCV video capture functionality. But do not know how I can create an output stream with the processed frames.

  


  In order to do some basic tests, I created a stream from a local video file using ffmpeg like so :

  


  ffmpeg -i sample.mp4 -v 0 -vcodec mpeg4 -f mpegts \
        "udp://@127.0.0.1:23000?overrun_nonfatal=1&fifo_size=50000000"


  


  And in my C++ code using the VideoCapture functionality of the OpenCV library, I am able to capture the above created stream. A basic layout of what I am trying to achieve is attached below :

  


  cv::VideoCapture capture("udp://@127.0.0.1:23000?overrun_nonfatal=1&fifo_size=50000000", cv::CAP_FFMPEG);

cv::Mat frame;

while (true) 
{
    // use the above stream to capture a frame
    capture >> frame;
    
    // process the frame (not relevant here)
    ...

    // finally, after all the processing is done I 
    // want to put this frame on a new stream say at
    // udp://@127.0.0.1:25000, I don't know how to do
    // this, ideally would like to use Video4Linux but
    // solutions with ffmpeg are appreciated as well
}


  


  As you can see from comment in above code, I don't have any idea how I should even begin handling this, I tried searching for similar questions but all I could find was how to do VideoCapture using streams, nothing related to outputting to a stream.

  


  I am relatively new to this and this might seem like a very basic question to many of you, please do excuse me.