Invalid keyframe timestamps

Hi @saudet ,

I'm coming again with new issue. It looks like the timestamps of keyframes might be incorrect

import java.awt.image.BufferedImage;
import java.io.File;
import java.util.concurrent.TimeUnit;

import javax.imageio.ImageIO;

import org.bytedeco.javacv.FFmpegFrameGrabber;
import org.bytedeco.javacv.Frame;
import org.bytedeco.javacv.Java2DFrameConverter;

public class VideoAnalyzer {

    public static final String PICTURE_FORMAT = "jpg";

    public static void main(String[] args) throws Exception {
        extractKeyFramePictures(true);
        extractKeyFramePictures(false);
    }

    public static void extractKeyFramePictures(boolean alternatives) throws Exception {
        try (FFmpegFrameGrabber video = new FFmpegFrameGrabber(
                "https://www.dropbox.com/s/ba3plzmv84y2qxd/keyframes_test.mp4?dl=1")) {
            video.start();
            long endTimeMicros = video.getLengthInTime();
            Frame frame;
            //an alternative way to grab keyframes based on Frame.keyFrame flag
            if (alternatives) {
                while (video.getTimestamp() <= endTimeMicros && (frame = video.grabImage()) != null) {
                    if (frame.keyFrame) {
                        savePicture(frame, video.getTimestamp(), "_alternative");
                    }
                }
            // default keyframes grabbing
            } else {
                while (video.getTimestamp() <= endTimeMicros && (frame = video.grabKeyFrame()) != null) {
                    savePicture(frame, video.getTimestamp(), "");
                }
            }
        }
    }
    
    private static void savePicture(Frame frame, long timestamp, String suffix) throws Exception {
        long timestampInMills = TimeUnit.MICROSECONDS.toMillis(timestamp);
        File frameFile = new File(timestampInMills + suffix + "." + PICTURE_FORMAT);
        BufferedImage image = new Java2DFrameConverter().convert(frame);
        ImageIO.write(image, PICTURE_FORMAT, frameFile);
    }
    
}

See two pictures 10677_alternative.jpg

13580.jpg

Correct keyframe appears at 10677 mills but FFmpegFrameGrabber.grabKeyFrame has the time 13580 mills with this keyframe.

It happens with some videos, not permanent.