Fastest way to navigate to needed frame

Hi.
 
Given pipeline «filesrc ! decodebin ! appsink»  I need fastest way to navigate to given frame number in file.
Say, I need frame number 9, what is the fastest way to obtain this frame — iterate in cycle and skip frames via
PullSample, like :
                
                var step = 0;
                while (step < frameNumber)
                {
                    appSink.PullSample();
                    step++;
                }
                var neededSample = appSink.PullSample();
 
or there is better and faster option like  Seek  with some parameters like buffer and so on?
 
Thanks in advance.
 
KR