src/main/java/org/jcodec/containers/mp4/QTTimeUtil.java
public static String qtPlayerTime(MovieBox movie, int mediaFrameNo) {
        TrakBox videoTrack = movie.getVideoTrack();
        long editedTv = mediaToEdited(videoTrack, frameToTimevalue(videoTrack, mediaFrameNo), movie.getTimescale());

        int sec = (int) (editedTv / videoTrack.getTimescale());
        return String.format("%02d", sec / 3600) + "_" + String.format("%02d", (sec % 3600) / 60) + "_"
                + String.format("%02d", sec % 60);
    }
public static String qtPlayerTime(MovieBox movie, int mediaFrameNo) {
        TrakBox videoTrack = movie.getVideoTrack();
        long editedTv = mediaToEdited(videoTrack, frameToTimevalue(videoTrack, mediaFrameNo), movie.getTimescale());

        int sec = (int) (editedTv / videoTrack.getTimescale());
        return String.format("%02d", sec / 3600) + "_" + String.format("%02d", (sec % 3600) / 60) + "_"
                + String.format("%02d", sec % 60);
    }
Calculates and formats standard time as in Quicktime player

@param movie
@param mediaFrameNo
@return