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• OpenCV 4.5.2 VideoWriter produces “can't find starting number” error

  28 avril 2021, par Peter Kronenberg

  There are several issues with similar names, but none of them seem to have a definitive answer. Using the last version of OpenCV 4.5.2 with Java on Windows 10. Below is a short reproducible test case which results in

  


  [ERROR:0] global C:\build\master_winpack-bindings-win64-vc14-static\opencv\modules\videoio\src\cap.cpp (589) cv::VideoWriter::open VIDEOIO(CV_IMAGES): raised OpenCV exception:

OpenCV(4.5.2) 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): C:/testfiles/output.avi in function 'cv::icvExtractPattern'


  


  Here is the code :

  


  public class OpenCVError {

    public static void main(String[] args) {
        System.loadLibrary(Core.NATIVE_LIBRARY_NAME);

        final int fourcc = VideoWriter.fourcc('m', 'j', 'p', 'g');
        final double fps = 30.00;
        Size frameSize = new Size(1080, 1920);
        VideoWriter videoWriter = new VideoWriter("C:/testfiles/output.avi", fourcc, fps, frameSize, true);
    }
}


  


  Update

  


  Found out from https://forum.opencv.org/t/error-in-java-cant-find-starting-number-in-the-name-of-file/3014 that I seem to be missing opencv_videoio_ffmpeg452_64.dll
I am using the Maven distribution at

  


    <dependency>&#xA;            <groupid>org.openpnp</groupid>&#xA;            <artifactid>opencv</artifactid>&#xA;            <version>4.5.1-2</version>&#xA;  </dependency>&#xA;

  


  which doesn't appear to have this file. I tried adding the file to my classpath (using IntelliJ), but it still doesn't seem to work.

  


  Anyone have any ideas ? Why isn't this file part of the openpnp distribution ?

  


• Can we provide a raw stream of microphone data Unit8List as a Input to ffmpeg and save the output file as .wav or .mp3

  21 juillet 2023, par Uday

  The goal is to listen to a live microphone stream (don't want to store it locally)and try to pass it to the RTSP server or to a .mp3 or .wav file locally.

  


  FFmpeg lib :ffmpeg_kit_flutter

  


  Mic Stream lib : https://pub.dev/packages/mic_stream

  


   stream = await MicStream.microphone(
        audioSource: AudioSource.DEFAULT,
        sampleRate: 44100,
        channelConfig: ChannelConfig.CHANNEL_IN_STEREO,
        audioFormat: AudioFormat.ENCODING_PCM_16BIT);

listener = stream!.listen((recordedData) async {
  await processData(recordedData);
});


  


  And in Process data, I want to convert this raw Unit8List data to .mp3 or transmit it to rtsp server live.

  


  any of the commands i want to execute

  


  Future<void> processData(Uint8List data) async {&#xA;//var command = &#x27;-i "$data" -f rtsp -rtsp_transport tcp -y "$RtspUrl"&#x27;;&#xA;&#xA;&#xA;//var command = &#x27;-i "$data" "/storage/emulated/0/Download/androidvideo.mp3"&#x27;;&#xA;&#xA;FFmpegKit.execute(command).then((session) async {&#xA;  final returnCode = await session.getReturnCode();&#xA;  final logs = await session.getLogs();&#xA;  for (var element in logs) {&#xA;    print(&#x27;logs:${element.getMessage()}&#x27;);&#xA;  }&#xA;  if (ReturnCode.isSuccess(returnCode)) {&#xA;    print(&#x27;Command execution completed successfully.&#x27;);&#xA;  } else if (ReturnCode.isCancel(returnCode)) {&#xA;    print(&#x27;Command execution completed CANCEL.&#x27;);&#xA;    listener.cancel();&#xA;  } else {&#xA;    print(&#x27;Command execution completed ERROR.&#x27;);&#xA;    listener.cancel();&#xA;  }&#xA;});&#xA;}&#xA;</void>

  


• How to scroll and zoom an image at the same in ffmpeg ?

  8 décembre 2024, par neeebzz

  I have an image of the height 1200px. I want to create a video from this single image.

  


  My final video will be height 450px.

  


  At 0seconds I want to show a 2xZoomed version of the image. Then it in 2 seconds it should zoom out to it's original width. And then it start scrolling to the bottom and then at the end it starts scrolling back. This should be on loop until the end of the video.

  


  Also I am want the this whole image to be faded to 50% since I will overlay another video on top of it.

  


  I am trying to use the zoompan filter but it seems to be not working. Especially I tried using t variable in it to change zoom based on duration but it doesn't accept.