code: @Override
      public void position(long pos) {
          log.debug("Position: {}", pos);
          log.debug("Current frame: {}", currentFrame);
          int len = frames.size();
          MP4Frame frame = null;
          for (int f = 0; f < len; f++) {
              frame = frames.get(f);
              long offset = frame.getOffset();
              //look for pos to match frame offset or grab the first keyframe 
              //beyond the offset
              if (pos == offset || (offset > pos && frame.isKeyFrame())) {
                  //ensure that it is a keyframe
                  if (!frame.isKeyFrame()) {
                      log.debug("Frame #{} was not a key frame, so trying again..", f);
                      continue;
                  }
                  log.info("Frame #{} found for seek: {}", f, frame);
                  createPreStreamingTags((int) (frame.getTime() * 1000), true);
                  currentFrame = f;
                  break;
              }
              prevVideoTS = (int) (frame.getTime() * 1000);
          }
          //
          log.debug("Setting current frame: {}", currentFrame);
      }
docs: Put the current position to pos. The caller must ensure the pos is a valid one.
  
  @param pos
  position to move to in file / channel