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• Opencv cv2.VideoCapture('file.avi') shows first frame then throws exception

  3 novembre 2014, par holografix

  I’m trying to read a .avi included in the OpenCV original package, it’s called 768x576.avi and shows a few people walking around a street.

  The code below shows what seems to be the 1st frame and runs for a few seconds before returning an Exception.

  import cv2
  
  cap = cv2.VideoCapture('768x576.avi')
  
  cap.isOpened() # returns True
  
  cap.get(3); cap.get(4) # returns 768 and 576
  
  
  
  while (True):
  
      ret, frame = cap.read()
  
      cv2.imshow('frame', frame)

  Hands me this error after a few secs on the cv2.imshow line, I think it means the returned frame had no data associated it in.

  error: /tmp/opencv-7y6HHt/opencv-2.4.9/modules/highgui/src/window.cpp:261: error: (-215) size.width>0 && size.height>0 in function imshow

  I have no idea why this is happening, I’m running Yosemite, brew installed Python, OpenCv and Ffmpeg.

  opencv: stable 2.4.9, HEAD
  
  http://opencv.org/
  
  /usr/local/Cellar/opencv/2.4.9 (219 files, 38M) *
  
  
  
  ffmpeg: stable 2.4.2 (bottled), HEAD
  
  https://ffmpeg.org/
  
  /usr/local/Cellar/ffmpeg/2.4.2 (199 files, 40M) *
  
    Poured from bottle
  
  From: https://github.com/Homebrew/homebrew/blob/master/Library/Formula/ffmpeg.rb
  
  ==> Dependencies
  
  Build: pkg-config ✔, texi2html ✘, yasm ✘
  
  Recommended: x264 ✔, faac ✔, lame ✔, xvid ✔

• failed to set frame number in opencv in cpp

  28 février 2018, par Madhu Nadendla

  I am trying to set frame position of opened videofile using OpenCV in C++ but it returns 0.

  solution 1

  bool success = capture.set(CV_CAP_PROP_POS_FRAMES, noFrame);
  
  
  
  double frameRate = capture.get(CV_CAP_PROP_FPS);

• Ffmpeg output stream closed

  29 novembre 2023, par excalibur

  There is one problem in my code that uses ffmpeg to convert webm videos to mp4 and set duration to 10 seconds, it works well but, sometimes returns "output Stream closed" error. What can be a reason of this problem, and how can i solve it ?

  


  My code :

  


  async convertWebmVideoToMp4(buffer: any) {
    try {
        return new Promise((resolve, reject) => {
            const videoMp4Buffer = Buffer.from(buffer);

            const readable = Readable.from(videoMp4Buffer);

            const outputBuffer = [];

            const outputStream = new Writable({
                write(chunk, encoding, callback) {
                    outputBuffer.push(chunk);
                    callback();
                },
            });

            const ffmpegProcess = ffmpeg()
                .input(readable)
                .outputFormat('mp4')
                .videoCodec('libx264')
                .audioCodec('aac')
                .duration(10)
                .outputOptions([
                    '-movflags frag_keyframe+empty_moov',
                    '-preset ultrafast',
                    '-c:a aac',
                    '-r 30',
                    '-tune fastdecode',
                ])
                .on('end', () => {
                    outputStream.end();
                    const finalOutputBuffer = Buffer.concat(outputBuffer);
                    resolve(finalOutputBuffer);
                })
                .on('error', (err, stdout, stderr) => {
                    console.error(err);
                    reject(err);
                });

            outputStream.on('error', err => {
                this.logger.error(err);
            });

            ffmpegProcess.pipe(outputStream, { end: true });
        });
    } catch (error) {
        throw error;
    }
}


  


  My code should return the buffer of video that type is mp4 and length is 10 seconds, but it returns "output stream closed" error.