However, this still left film shot at cinema frame rates as a problem. The obvious solution is to simply speed up the film to match the television frame rates, but this, at least in the case of NTSC, is rather obvious to the eye and ear. This problem is not difficult to fix, however; the solution being to periodically play a selected frame twice. For NTSC, the difference in frame rates can be corrected by showing every fourth frame of film twice, although this does require the sound to be handled separately to avoid "skipping" effects. A more advanced technique is to use "2:3 pulldown", discussed below, which turns every second frame of the film into three "fields" of video, which results in a slightly smoother display. PAL uses a similar system, "2:2 pulldown". However, during the analogue broadcasting period, the 24 frame per second film was shown at a slightly faster 25 frames per second rate, to match the PAL video signal. This resulted in a fractionally higher audio soundtrack, and resulted in feature films having a slightly shorter duration, by being shown 1 frame per second faster.